I have a 2002 honda accord I4 coupe (ULEV edition) with a peculiar problem. The problem is that the pistons are pushing down too hard on the connecting rod/crank shaft bearings (creating a banging noise when I drive or accelerate in neutral). It could be a timing issue (spark igniting too early?) but the check engine light is not on.
I have had a mechanic look at the engine and they have determined that
Oil pressure is normal
Bearing clearance is good (meets specification)
Cam timing is good.
Balance shaft clearance is good
Thrust clearance is good
The mechanics are not sure what is causing the problem. Does anyone here have any ideas on what else to check? Seafoam was added to the gas tank weeks before the problem surfaced. Could the car’s computer be damaged?
A few questions first of course.
Does this knocking noise occur while the engine is idling?
Are you saying they went to the trouble of removing the oil pan and physically checked the bearings and oil clearances on all of the crankshaft bearings; both rods and mains?
I too am wondering, in general, about what has been done to check out the car - this all sounds weird.
See what you can do to describe the noise a bit better. Banging isn’t the most common word people use for mechanical noises from the engine. “Knock” would be common. “Ping” is another thing. Something people would describe as a knock could sound like a “thump.” So see what you can do beyond saying banging noise.
Did the mechanic hear this noise? I’m also wondering about idle. Is it steady and rhythmic, and will happen anytime you rev the engine? Or is it once in a while and unpredictable?
How many miles are on the car? What do you know about how its been treated over its lifetime - driving styles and maintenance. (Be as specific as you can about maintenance).
Maybe an excessively loose valve lifter with too much lash? If that’s the case it should be tapping away at idle although at this point tapping, rattling, knocking, or banging hasn’t been clarified very well.
how exactly did they determine that the clearences were good? The only way to determine that the main bearings’ clearences are good is to open the engine’s “bottom end” and actually measure the clearences with plastigage. Checking the thrust and balnace shaft clearences is also an “open the bottom end” process. Did they do this? And if they did go in this deep, did they comment on the CONDITION of the bearings, vis-a-vis possible damage?
how exactly was it determined that the knocking is coming from lateral movement of the rod and/or crank surfaces in the sleeve bearings? This diagnosis contradicts the statement that the “clearances are good” UNLESS there’s damage.
Since they apparently checked the oil pressure and it’s good, and they’ve claimed that the bearing clearebces are good, than I can’t see how you could have bearing knock unless either there was bearing surface damage or the lubrication path (at least one of them) was plugged up. If there’s sufficient oil pressure, the clearances are good, the surfaces are not damaged, AND the paths through which the oil is traveling aren’t plugged, than the surfaces would HAVE to be riding on a pressurized barrier of oil and nit knocking.
By the way, how many miles are on this puppy?
What else did they check? Engine mounts? Exhaust clearances? Anything else?
I don’t think you have an internal problem. I would like to know how anyone could come up with the diagnosis of “the pistons are pushing down too hard on the connecting rod/crank shaft bearings”.
I agree with mountainbike about motor mounts and exhaust clearance. When you put a load on the motor, it tips in one direction. A broken motor mount could allow it to tip too far and cause the exhaust pipe to hit something.
I have actually seen this condition on a Honda once, much older Honda where the owner backed into a curb and hit the muffler, knocking it and the rest of the exhaust out of position. It made the knocking sound exactly as you describe until it was fixed.
Sorry I wasn’t able to reply sooner (was busy with work) but here are some answers I can give (I’m not that good with cars so please bear with me):
Before the engine noise started happening I had the oil changed and the folks at Jiffy lube said the oil was almost gone for some reason. (I usually change oil at 3K miles but this time let it go to 5K).
I guess the sound is more like a rattling/knocking sound (when I took it to various shops different mechanics immediately said I had a rod knock problem).
The car has around 190,000 miles on it (bought it used at around 90K miles) and this is the first time I’ve heard the sound. I don’t know about the previous owner but I drive really conservatively (nice and easy, not too fast, etc…). the car has been maintained well with regular oil changes.
The knocking/rattling does not occur when the engine is idling. It only happens when I accelerate (either in drive or in neutral) It usually kicks in around 2,000 RPM give or take.
The engines bottom end has been removed and parts (bearings were machined to factory spec due to damage from the knocking. (the car was good for a few days after the engine rebuild but the knocking came back so I took it back to them and they said that the car seems to be doing the same thing again and if I continue driving it the same damage will occur within 500 miles to the new connecting rod/crank shaft bearings).
Since there is bearing damage I don’t think this is related to an exhaust problem.
The car has been in the shop for months now as they just can’t seem to figure out what’s wrong.
You need a new mechanic. You REALLY need a new mechanic.
This is as simple as mechanics gets. A round piece of metal rotating in a round bearing and fed by lubricating oil. It’s no different from any other crankshaft bearing in any other car. The tolerances have to be held in check during the rebuild and the oil has to be kept clean and in constant supply. Correctly assembled the bearings will last for hundreds of thousands of miles in any engine, Honda or otherwise, as long as it’s properly maintained.
Your mechanic is missing a step or two, not making sure the crankshaft surfaces are round and/or in spec, not verifying the oil pressure is adequate or simply not making sure the clearances are correct. Nobody can tell you exactly what this mechanic is doing wrong over the internet, but it’s a sure bet he’s missing something basic.
Two things stand out. 190,000 mi and “oil was almost gone” IMO One or more of the bearings failed spreading metal bits throughout the engine. The mechanic just fixed the bearing problem. What you really needed was a complete engine rebuild or replacement. The new bearings are failing again because of the metal still in the engine. It is taking so long because the mechanic doesn’t want to tell you all of the money you spent so far has been for nothing. Hope I’m wrong.
This what I think happen. The mechanic did not have the rods resized. He just droped the crank and had it ground. This is why the bearings failed. The rods are out of round. Also I would guess he did not replace the oil pump. Anytime the rod bearings get bad enough to knock. The rods will be out of round. Also with the high milage I would have replaced the oil pump as cheap insurance.
the oil was almost gone for some reason. (I usually change oil at 3K miles but this time let it go to 5K).
Hondamn: no matter what car you drive, please check your oil regularly and have a couple quarts in your vehicle ready to add as needed. Oil is consumed by an engine, sometimes just a little, sometimes a lot depending on many factors. Checking oil is a simple, one minute chore. You might find it easiest to do it at home so you can wash your hands afterwards, and doing it with a cold engine may be less unpleasant than at a gas station after your engine heats up. But do have a few quarts of oil on hand, instead of needing to go buy some, in order to make the whole process much simpler.
I hope your current problem can be resolved easily, but I fear that lack of oil may have played a role in the problem you are having. That’s a situation which you can avoid in the future.
It could be that this rattle or knock as it’s described could be due to an EGR system fault considering the RPM at which it apparently starts.
The EGR helps prevent engine pinging which often comes across as a rattle.
The original post described it as a banging and the latter post referred to it as a rattle or knock and all of those words can be subject to interpretation.
Banging would not be an EGR fault but rattle or knock could possibly point in the EGR direction. Just something for consideration anyway.
“Before the engine noise started happening I had the oil changed and the folks at Jiffy lube said the oil was almost gone for some reason. (I usually change oil at 3K miles but this time let it go to 5K).”
Do you ever CHECK your oil level??? Oil almost gone, engine knocking, in-car bearing replacement, (unsuccessful) equals it’s time for a new engine…
One point to consider. If the lower end had lubrication problems, the upper end had worse lubrication problems. Since the cam journals ride on machined surfaces in the head, any wear there will allow pressurized oil to escape instead of lubricating the lower end. I don’t know if the head can be machined to take inserts or an over size journal cam. But now we are talking head work and you might just include a valve job as well. Ergo, a rebuilt or used engine sounds better
BTW what was the gauge measured oil pressure at idle cold, idle hot, and 3000 RPM hot.
During the thinking I forgot about the not rattling/knocking while revving in neutral so scratch the EGR comment.
Putting a crank kit in a 190k miles engine that has been run nearly out of oil was not a wise thing to do in my opinion.
At this point I could think of a number of things but they’re all just wild guesses at best.