These are some of the more common problems you will see in Honda engines.
The chances of blowing up a motor can be drastically reduced, as preceding failure symptoms occur such as; engine noises, low oil pressure, engine overheating, won’t start, lack of throttle response, erratic behavior. So I will go over some failures and how and why. This is related to street cars, not race cars.
Engine noises. This could be attributed to a number of factors; the most obvious would be too much clearance somewhere in a mechanical system.
-If the motor had a terrible valve adjustment and there was .030 tappet to valve, that would make noise. Not only would it make noise it will also wear down the cams.
-Excessive piston to wall clearance. If your pistons call for .003 installs and they are over .004 they are going to rattle and make noise sort of like a diesel engine does. This causes more wear on the cylinders and piston skirts, but is not an immediate threat at blowing up your motor. It becomes a threat when your cylinder walls are so worn that you’re not getting your initial compression out of them and you start leaking good amounts of oil past the rings. At this time, it requires rebuild with oversize pistons.
-melted piston. On the outer edge of most Honda pistons you can see that the valve relief is quite thin because the valve is such that it comes close to the outside of the bore. This area can and will crack/melt under high heat conditions if it’s too thin. This is called a hotspot in your piston. Too thin might be like less than .050. You will see the piston companies create a little valley, or recession in these areas of the valve relief on the edge of the piston. They simply grind it down a little until it’s over .050. If your detonation or heat is severe enough, it will melt your piston all the way down to the ring grooves. When this happens, your motor is going to make a tapping sound, and it sounds like a bad valve adjustment, or even rod knock at low RPM. This is prevalent on turbo motors using cast pistons especially or people using 4032 higher silicon pistons with turbo motors.
-Black death is noisy as well. Black death is where the piston skirt hit the cylinder wall and causes scoring and the skirt of the piston turns black from the heat. This problem kills your compression in that cylinder because the ring cannot seal on a non-smooth surface, and oil will leak in droves past the oil ring and burn in the combustion chamber leading to a lot of smoke out the back of your car. The reasons this happens could be these:
A: Overheating the piston. Too much heat on the piston causes expansion of the aluminum. A typical Wiseco piston is installed to .003, and it has a coating on it that’s a couple tenths thick, so it might go metal on metal at say .0033. So if the piston is heated to where it expands that much, there is nowhere to go except to metal on metal and that’s where your going to get black deaths and failure immediately. Overheating is caused from the following reasons:
1: Too lean of a fuel condition for too long. This can vary depending on how lean it is over X period of time. It would be able to handle say 13.5:1 longer than 15.5:1. This is why say, stock GSR motors are so tolerant. You can drive them around with way out air/fuel and they can last years. Because they are only 10:1.
2: pre-ignition/detonation: Not only is this a monumental amount of heat, it’s a monumental amount of shock to your piston. If your piston doesn’t die to overheating, it might crack, melt, or fall apart. You might see the work of detonation from a chunk of the corner of the valve relief being gone, or a chuck of the ring land gone, or even a flat out hole in the top of the piston. Detonation can also cause valve seats to fall out or come loose as well. Detonation can cause dmg to bearings, due to the extreme force of pressure downward on the piston/rod. It can cause wrist pin galling for the same reason. In other words, detonation is to be avoided at all costs, and just detonating once can cause catastrophic engine failure. Here are some more engine noises.
-A bearing that has become worn allowing for excessive play between the rod and the crank will make noise. This will cause the rod to be “thrown” more distance, thus increasing its force. In perhaps an instant, or over a day this force will lead to a spun rod bearing, or a snapped rod. No rod can take it, its too much force and heat.
-A loose wrist pin improperly clearances, or worn will cause noise.
-A slightly melted piston (side) will cause a tapping noise.
-A wearing timing belt can cause excessive noise.
-A wearing or malfunctioning pump can cause noise.
All of these noises can be identified by a good mechanic, and diagnosed. Often the problem is people will start hearing noises of the above like and think it’s an anomaly and keep driving on it and ignore it. Folks, once a noise like the above comes into play, it could be a matter of seconds or minutes, or miles before that engine lets go. Some problems are greater than others, obviously, but you need to diagnose the problem to see the severity. Problems severe like a rod bearing going out and causing noise is one of those things you probably won’t make it another few miles on, as that failure spirals worse every moment. Problems such as slightly melted piston, I have seen motors drive thousands of miles after that problem was diagnosed. That case was a minor melting of the piston relief that caused a tapping type noise. It did not scar up the cylinder wall, which was why it could run so long.
Low Oil Pressure is another problem that will lead to massive engine wear in a short period of time. Obviously, parts of your motor, like the cams, rod bearings, etc, need a certain amount of oil pressure to buffer the forces from coming together. If that pressure becomes too little, the forces will collide, causing wear. With the wear comes massive heat from friction. If your oil pressure is not enough, your rod bearing could come in contact with your crankshaft and start wearing, heating up severely and rapidly. This will lead to excessive clearance, due to the wear, and cause excessive force to be brought onto the rod bolts. No rod bolt is going to save it, its going to fail. Each rotation of the crank with excessive clearance compounds the force on the rod bolt, and it will simply stretch until the bearing spins, or it will break and the rod will come apart. You can see evidence of this on blown up motors from looking at the big end of the rod, and the crank area, as it is usually “blackened” or scorched from the heat of the bearing wearing.
Lack of good oiling can also affect the rods through the wrist pin. If the wrist pin does not have sufficient clearance with an oil buffer, and it “locks up” per se for a brief moment that is going to put an instant, very heavy shock on the main beam of the rod. So say your rod angle was at its maximum and the wrist pin locked up and the piston no longer rotated with the stroke of the crank, and the rod and piston position is locked. Something has to give. Either the piston pin bosses crack or break or the rod could just bend or even snap in half cleanly. When your motor is spinning at 8,500 RPM, it doesn’t take much for catastrophic consequences to happen. The small end of the rod may slightly bend only and you get away with that. When you see the small end of the rod slightly bent, or the rod snapped clean in half, one explanation could be that it was caused by seizure of the wrist pin for a brief moment, or longer. Or it could be caused by hydro locking, or a valve slamming a piston and staying down.
Engine Overheating is fairly common as it will happen if your cooling system has any leaks or has a lot of air bubbles in it and not full. It also happens when your thermostat is not working properly or your cooling fan is broken. Aluminum blocks and heads don’t tolerate overheating that well, and will severely warp in a very fast period of time. The problems this causes can be several fold. Here are the problems generally.
1) The head gasket will blow due to the head or deck of the block severely warping, and water will leak into the cylinders. Your piston rings require lubrication, and water is the anti lubricator. So if water washes down the cylinder walls, you’re going to get heat caused by the rings. Water “washes” out the rings, and causes a condition where your rings are going to wear heavily on the cylinder walls. In bad circumstances, so much water can leak into the cylinder that it can affect the entire oil system by causing the oil to become like milk. This milk (oil and water mixed) will wear everything where good lubrication is required, and wear it quickly depending on how bad the water leak is. The heavier load on the motor, the worse the wear.
Also, when you lose compression from a blown head gasket, and your still getting the same level of fuel, your running fat, or rich. Running too rich is really bad because water and Fuel both serve to kill piston ring lubrication. The good news is that when your head gasket blows its fairly obvious even to non engine knowing peoples. Loss of power, rough idle, noises, radiator overflow probably steaming, etc. It’s pretty obvious.
Spark Plugs can cause problems as well. When you’re running a domed piston, with say a .300+ dome rise, you need to properly clearance the spark plug because it could tap the piston during driving and shut, effectively flooding that cylinder with fuel and not combusting. Again, back to bad for the rings I talked about before. You might drive around for a little while, especially at light throttle and not even notice your running on 3 cylinders because you have the stereo turned up, and/or the road is rough and you can’t “feel” or hear the motor at all. What you need to do is get what we call a “shorty” spark plug, or commonly known as an NGK 8 series spark plug, which has a much shorter tip on it to give you much more clearance. Or you could just put 2 washers on each spark plug to give you more clearance that way as well. Either one is fine.
Cylinder Head problems. Typically, the problem to watch out for is too loose of valve guides, which will cause too much play in the valve, which will cause excessive wear. When the guide is too loose, the valve will roam around in the valve pocket of the piston. When the valve wears out the guide enough, the valve will then effectively hit the side of the valve relief and either break, or bend and possibly blow up your motor right there. This is not really a rampant problem in Honda motors as the guides are still good in motors with 200k miles in a lot of cases. But, each guide should be checked when the cylinder head is off the car each time, as this is just the right thing to do and can save you a large expense down the road.
Another problem with cylinder heads can be with Titanium retainers. When you put 2 metals up against each other, the harder one is going to wear the softer one. Titanium is the softer one. It wears. So when you put titanium retainers in your motor, you want to make sure they are a tight, interference fit with the springs, so they don’t have play and move around. If they have a little bit of play, its still going to work, but probably not as long of a time. It’s a good idea to inspect your retainers after 15k miles or so, by just popping off a random retainers and looking at the bottom of it. If it’s got a 1 MM rut in the bottom from the spring, its time to replace them. Titanium retainers can last 50k+ miles in your motor, they just have to have the right fit and not move around. If your titanium retainers have movement slightly and start to wear, eventually what will happen, and does happen in people’s motors is that the middle of the retainer will just separate from the outer rim, and then outer spring will loose all its tension and you’ll be running off the inner spring only. In other words, your valve is going to bounce all over the place and your motor is going to blow up or shut down probably instantly after failure.
Cylinder Head Oil Problems. In Honda motors, the oil pump is on the other end of the motor from the cams. So when you start your motor up, it takes time for the oil to pressurize in the cams because it comes from the other end. Do not run too thick of oil without a pre-luber or a stronger pump driving your system. The thicker the oil you run, the longer it takes to get throughout the system when you start it. You could get galling or even seizure from running too thick of oil in a cold climate especially, which is why the common oil in a colder climate is 5W30 on an overhead cam engine with the oil pump in the block is common.
Lastly, when it comes to cylinder heads, you need to make sure the parts your installing in your head rotate correctly, without binding. On motors, its possible to overheat your motor so severely that it actually warps the entire thing so that the cam caps are now out of alignment. You need to make sure when you install something, they turn freely, when properly oiled and torqued down.
Over revving. Perhaps the most common problem with Honda’s. There is a common misconception about over revving in the import community and that is electronic rev limiter versus mechanical rev limiter. You see, there is no mechanical rev limiter, only electronic rev limiter. So you have a Hondata and you rev limit it at 9,000 RPM. That’s all great and everything, and if you either free rev or accelerate to 9,000 you’ll get a cut off and it will just sit there and bounce off the rev limiter. But what the Hondata can’t do is limit the mechanical parts from going past 9,000 if you miss-shift your transmission. You all have done it, your cruising or whatever in 3rd gear, and you go to drop it straight down in 4th and you get excited or whatever and you drop it in 2nd. The motor is going to mechanically rev to whatever RPM 2nd gear at that speed would give you, which is probably well over 10,000 RPM. Now you can realize what you did almost instantly and save it with the clutch and it barely revs up at all, but if you don’t that thing is going to go to the moon. Your fuel might cut off at 9k, or ignition, or both, but it doesn’t matter because your parts are going to the moon rpm wise. Your motor might take 10,000 RPM with the right parts if you revved it to that normally, but it’s a different story when you miss-shift. That’s a huge shock to the system, and what your motor can take normally, it cannot take with the huge shock added. This is how rod’s end up through the block, and motors grenade. Watch your shifting. Goes without saying, but your investment depends on it.
There are a few ways customers can limit their miss-shifting blow-ups for street cars. One way is to granny shift your car, by not leaving the accelerator pegged to the floor each time you shift. That gives you more time to save it with the clutch. The other way is to lower your rev limiter to give you more time as well. So take these 2 circumstances.
#1 your rev limit is at 9200 RPM and you miss-shift and it goes to 10,000 RPM. It might live, it might not. The rotating mass gets pretty heavy in most cases at that RPM, and the valves will probably float badly as well, but it could live with the right parts.
#2 your rev limit is at 8200 RPM, you miss-shift and you go to 9,000 RPM with the same parts as #1. It’s still a big shock on the parts, but you have a much, much greater chance of living than in case #1. You simply sacrifice a little speed from not being able to use the optimal power band. What you gain is reliability.
There are more problems in motors, but these are the more common ones you’ll find, and that you can avoid. It goes without saying that building the motor correctly is assumed when dealing with a reliable motor.
Jeff
The chances of blowing up a motor can be drastically reduced, as preceding failure symptoms occur such as; engine noises, low oil pressure, engine overheating, won’t start, lack of throttle response, erratic behavior. So I will go over some failures and how and why. This is related to street cars, not race cars.
Engine noises. This could be attributed to a number of factors; the most obvious would be too much clearance somewhere in a mechanical system.
-If the motor had a terrible valve adjustment and there was .030 tappet to valve, that would make noise. Not only would it make noise it will also wear down the cams.
-Excessive piston to wall clearance. If your pistons call for .003 installs and they are over .004 they are going to rattle and make noise sort of like a diesel engine does. This causes more wear on the cylinders and piston skirts, but is not an immediate threat at blowing up your motor. It becomes a threat when your cylinder walls are so worn that you’re not getting your initial compression out of them and you start leaking good amounts of oil past the rings. At this time, it requires rebuild with oversize pistons.
-melted piston. On the outer edge of most Honda pistons you can see that the valve relief is quite thin because the valve is such that it comes close to the outside of the bore. This area can and will crack/melt under high heat conditions if it’s too thin. This is called a hotspot in your piston. Too thin might be like less than .050. You will see the piston companies create a little valley, or recession in these areas of the valve relief on the edge of the piston. They simply grind it down a little until it’s over .050. If your detonation or heat is severe enough, it will melt your piston all the way down to the ring grooves. When this happens, your motor is going to make a tapping sound, and it sounds like a bad valve adjustment, or even rod knock at low RPM. This is prevalent on turbo motors using cast pistons especially or people using 4032 higher silicon pistons with turbo motors.
-Black death is noisy as well. Black death is where the piston skirt hit the cylinder wall and causes scoring and the skirt of the piston turns black from the heat. This problem kills your compression in that cylinder because the ring cannot seal on a non-smooth surface, and oil will leak in droves past the oil ring and burn in the combustion chamber leading to a lot of smoke out the back of your car. The reasons this happens could be these:
A: Overheating the piston. Too much heat on the piston causes expansion of the aluminum. A typical Wiseco piston is installed to .003, and it has a coating on it that’s a couple tenths thick, so it might go metal on metal at say .0033. So if the piston is heated to where it expands that much, there is nowhere to go except to metal on metal and that’s where your going to get black deaths and failure immediately. Overheating is caused from the following reasons:
1: Too lean of a fuel condition for too long. This can vary depending on how lean it is over X period of time. It would be able to handle say 13.5:1 longer than 15.5:1. This is why say, stock GSR motors are so tolerant. You can drive them around with way out air/fuel and they can last years. Because they are only 10:1.
2: pre-ignition/detonation: Not only is this a monumental amount of heat, it’s a monumental amount of shock to your piston. If your piston doesn’t die to overheating, it might crack, melt, or fall apart. You might see the work of detonation from a chunk of the corner of the valve relief being gone, or a chuck of the ring land gone, or even a flat out hole in the top of the piston. Detonation can also cause valve seats to fall out or come loose as well. Detonation can cause dmg to bearings, due to the extreme force of pressure downward on the piston/rod. It can cause wrist pin galling for the same reason. In other words, detonation is to be avoided at all costs, and just detonating once can cause catastrophic engine failure. Here are some more engine noises.
-A bearing that has become worn allowing for excessive play between the rod and the crank will make noise. This will cause the rod to be “thrown” more distance, thus increasing its force. In perhaps an instant, or over a day this force will lead to a spun rod bearing, or a snapped rod. No rod can take it, its too much force and heat.
-A loose wrist pin improperly clearances, or worn will cause noise.
-A slightly melted piston (side) will cause a tapping noise.
-A wearing timing belt can cause excessive noise.
-A wearing or malfunctioning pump can cause noise.
All of these noises can be identified by a good mechanic, and diagnosed. Often the problem is people will start hearing noises of the above like and think it’s an anomaly and keep driving on it and ignore it. Folks, once a noise like the above comes into play, it could be a matter of seconds or minutes, or miles before that engine lets go. Some problems are greater than others, obviously, but you need to diagnose the problem to see the severity. Problems severe like a rod bearing going out and causing noise is one of those things you probably won’t make it another few miles on, as that failure spirals worse every moment. Problems such as slightly melted piston, I have seen motors drive thousands of miles after that problem was diagnosed. That case was a minor melting of the piston relief that caused a tapping type noise. It did not scar up the cylinder wall, which was why it could run so long.
Low Oil Pressure is another problem that will lead to massive engine wear in a short period of time. Obviously, parts of your motor, like the cams, rod bearings, etc, need a certain amount of oil pressure to buffer the forces from coming together. If that pressure becomes too little, the forces will collide, causing wear. With the wear comes massive heat from friction. If your oil pressure is not enough, your rod bearing could come in contact with your crankshaft and start wearing, heating up severely and rapidly. This will lead to excessive clearance, due to the wear, and cause excessive force to be brought onto the rod bolts. No rod bolt is going to save it, its going to fail. Each rotation of the crank with excessive clearance compounds the force on the rod bolt, and it will simply stretch until the bearing spins, or it will break and the rod will come apart. You can see evidence of this on blown up motors from looking at the big end of the rod, and the crank area, as it is usually “blackened” or scorched from the heat of the bearing wearing.
Lack of good oiling can also affect the rods through the wrist pin. If the wrist pin does not have sufficient clearance with an oil buffer, and it “locks up” per se for a brief moment that is going to put an instant, very heavy shock on the main beam of the rod. So say your rod angle was at its maximum and the wrist pin locked up and the piston no longer rotated with the stroke of the crank, and the rod and piston position is locked. Something has to give. Either the piston pin bosses crack or break or the rod could just bend or even snap in half cleanly. When your motor is spinning at 8,500 RPM, it doesn’t take much for catastrophic consequences to happen. The small end of the rod may slightly bend only and you get away with that. When you see the small end of the rod slightly bent, or the rod snapped clean in half, one explanation could be that it was caused by seizure of the wrist pin for a brief moment, or longer. Or it could be caused by hydro locking, or a valve slamming a piston and staying down.
Engine Overheating is fairly common as it will happen if your cooling system has any leaks or has a lot of air bubbles in it and not full. It also happens when your thermostat is not working properly or your cooling fan is broken. Aluminum blocks and heads don’t tolerate overheating that well, and will severely warp in a very fast period of time. The problems this causes can be several fold. Here are the problems generally.
1) The head gasket will blow due to the head or deck of the block severely warping, and water will leak into the cylinders. Your piston rings require lubrication, and water is the anti lubricator. So if water washes down the cylinder walls, you’re going to get heat caused by the rings. Water “washes” out the rings, and causes a condition where your rings are going to wear heavily on the cylinder walls. In bad circumstances, so much water can leak into the cylinder that it can affect the entire oil system by causing the oil to become like milk. This milk (oil and water mixed) will wear everything where good lubrication is required, and wear it quickly depending on how bad the water leak is. The heavier load on the motor, the worse the wear.
Also, when you lose compression from a blown head gasket, and your still getting the same level of fuel, your running fat, or rich. Running too rich is really bad because water and Fuel both serve to kill piston ring lubrication. The good news is that when your head gasket blows its fairly obvious even to non engine knowing peoples. Loss of power, rough idle, noises, radiator overflow probably steaming, etc. It’s pretty obvious.
Spark Plugs can cause problems as well. When you’re running a domed piston, with say a .300+ dome rise, you need to properly clearance the spark plug because it could tap the piston during driving and shut, effectively flooding that cylinder with fuel and not combusting. Again, back to bad for the rings I talked about before. You might drive around for a little while, especially at light throttle and not even notice your running on 3 cylinders because you have the stereo turned up, and/or the road is rough and you can’t “feel” or hear the motor at all. What you need to do is get what we call a “shorty” spark plug, or commonly known as an NGK 8 series spark plug, which has a much shorter tip on it to give you much more clearance. Or you could just put 2 washers on each spark plug to give you more clearance that way as well. Either one is fine.
Cylinder Head problems. Typically, the problem to watch out for is too loose of valve guides, which will cause too much play in the valve, which will cause excessive wear. When the guide is too loose, the valve will roam around in the valve pocket of the piston. When the valve wears out the guide enough, the valve will then effectively hit the side of the valve relief and either break, or bend and possibly blow up your motor right there. This is not really a rampant problem in Honda motors as the guides are still good in motors with 200k miles in a lot of cases. But, each guide should be checked when the cylinder head is off the car each time, as this is just the right thing to do and can save you a large expense down the road.
Another problem with cylinder heads can be with Titanium retainers. When you put 2 metals up against each other, the harder one is going to wear the softer one. Titanium is the softer one. It wears. So when you put titanium retainers in your motor, you want to make sure they are a tight, interference fit with the springs, so they don’t have play and move around. If they have a little bit of play, its still going to work, but probably not as long of a time. It’s a good idea to inspect your retainers after 15k miles or so, by just popping off a random retainers and looking at the bottom of it. If it’s got a 1 MM rut in the bottom from the spring, its time to replace them. Titanium retainers can last 50k+ miles in your motor, they just have to have the right fit and not move around. If your titanium retainers have movement slightly and start to wear, eventually what will happen, and does happen in people’s motors is that the middle of the retainer will just separate from the outer rim, and then outer spring will loose all its tension and you’ll be running off the inner spring only. In other words, your valve is going to bounce all over the place and your motor is going to blow up or shut down probably instantly after failure.
Cylinder Head Oil Problems. In Honda motors, the oil pump is on the other end of the motor from the cams. So when you start your motor up, it takes time for the oil to pressurize in the cams because it comes from the other end. Do not run too thick of oil without a pre-luber or a stronger pump driving your system. The thicker the oil you run, the longer it takes to get throughout the system when you start it. You could get galling or even seizure from running too thick of oil in a cold climate especially, which is why the common oil in a colder climate is 5W30 on an overhead cam engine with the oil pump in the block is common.
Lastly, when it comes to cylinder heads, you need to make sure the parts your installing in your head rotate correctly, without binding. On motors, its possible to overheat your motor so severely that it actually warps the entire thing so that the cam caps are now out of alignment. You need to make sure when you install something, they turn freely, when properly oiled and torqued down.
Over revving. Perhaps the most common problem with Honda’s. There is a common misconception about over revving in the import community and that is electronic rev limiter versus mechanical rev limiter. You see, there is no mechanical rev limiter, only electronic rev limiter. So you have a Hondata and you rev limit it at 9,000 RPM. That’s all great and everything, and if you either free rev or accelerate to 9,000 you’ll get a cut off and it will just sit there and bounce off the rev limiter. But what the Hondata can’t do is limit the mechanical parts from going past 9,000 if you miss-shift your transmission. You all have done it, your cruising or whatever in 3rd gear, and you go to drop it straight down in 4th and you get excited or whatever and you drop it in 2nd. The motor is going to mechanically rev to whatever RPM 2nd gear at that speed would give you, which is probably well over 10,000 RPM. Now you can realize what you did almost instantly and save it with the clutch and it barely revs up at all, but if you don’t that thing is going to go to the moon. Your fuel might cut off at 9k, or ignition, or both, but it doesn’t matter because your parts are going to the moon rpm wise. Your motor might take 10,000 RPM with the right parts if you revved it to that normally, but it’s a different story when you miss-shift. That’s a huge shock to the system, and what your motor can take normally, it cannot take with the huge shock added. This is how rod’s end up through the block, and motors grenade. Watch your shifting. Goes without saying, but your investment depends on it.
There are a few ways customers can limit their miss-shifting blow-ups for street cars. One way is to granny shift your car, by not leaving the accelerator pegged to the floor each time you shift. That gives you more time to save it with the clutch. The other way is to lower your rev limiter to give you more time as well. So take these 2 circumstances.
#1 your rev limit is at 9200 RPM and you miss-shift and it goes to 10,000 RPM. It might live, it might not. The rotating mass gets pretty heavy in most cases at that RPM, and the valves will probably float badly as well, but it could live with the right parts.
#2 your rev limit is at 8200 RPM, you miss-shift and you go to 9,000 RPM with the same parts as #1. It’s still a big shock on the parts, but you have a much, much greater chance of living than in case #1. You simply sacrifice a little speed from not being able to use the optimal power band. What you gain is reliability.
There are more problems in motors, but these are the more common ones you’ll find, and that you can avoid. It goes without saying that building the motor correctly is assumed when dealing with a reliable motor.
Jeff
