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Early connecting rod noise

I have a 95 Accord Wagon with the 2.2 Vtec motor. After adjusting the valve lash at 180K miles, I am now able to hear a lower pitched knock between 1800 and 2800 rpm, especially on throttle release. It seems to be about the frequency of the con rods. Honda’s mechanic says ‘just drive it’. Is this the beginning of bearing slop, and how many miles could be gotten before complete failure? Would going to Maxlife/higher viscosity/full Syn help?

Do you mean “a Honda mechanic” or THE Honda mechanic? Why does not anyone want to do any more diagnostics? does the noise go away if you remove the spark plug wire from the noisy cylinder?

Why do you not want to pull the pan and check the bearings? Will your only loss be being stuck some where with a inop car?

Would it not be nice if there was a product you just poured in and it repaired your rod bearings,the holder of the patent would make millions.

Usually when a knowledgeable mechanic says “just drive it” he has evaluated the situation as hopeless due to economics or overall condition of the car.

You already have 180K miles. This motor will run for many more years and miles, just with a bit more noise. If you want to rebuilt the motor go ahead.

To prolong the life using full synthetic oil will help. Max life is more about stopping leaks and swelling seals, which I’m skeptical about - sounds like marketing to get a few extra bucks out of the consumer. A higher viscosity will cover up the noise but won’t lubricate as well at lower temps. In summer or if you live in a warmer climate year round you can go to higher viscosity. In winter cold I’d stick to mfg recommended viscosity.

I just ran the info on the Valoline site. It looks like full synthetic 5-40 is about the same viscosity at 40 C as 5-30 conventional, but has 1.5 x higher viscosity at 100 C. Good choice for maximum “gap filling” in the bearing slop?

The Honda mechanic–as in the dealer. This is very early stages, if rod noise. I only get hear in now because I quieted down the valve noise. I get it only at an RPM band. I will try pulling a plug wire, but this sounds fast enough to be all 4 conrod bearings, not a single bad one.

This motor will run for many more years and miles, just with a bit more noise

IF it is a rod knock, it will be only a matter of time. Thicker oil will not help. This engine will throw that rod soon. Your only hope is to baby it, keep the revs down. But, it’ll break soon. The only cure is a rebuild or another (salvage) engine.

How can you say what you say? Knucles is dead on with his apprasial. What are you thinking? “Run for many more miles” “full synthetic will help”. We are talking about a suspected rod bearing failure here.

OK Oldschool—I hear what you are saying. The repair manual is indicating that the only good bearing measurement is with platigage. Have you ever tried dropping the pan and getting enough oil off the journals to use this “in-situ”? I am assuming you can get to the bearing caps from the pan.

I’d either get another tech to listen to it or re-check the valve adjustment, which is when the noise started. Rocketetman

If your bearing is worn enough to be making noise you wont need the plastigague,it will be evident by the condition of the bearing. Now I am not saying it will be down to the backing material but the bearing will show the cause of the noise.

If you do pull the rod caps and things don’t really look so bad (which is possible) plan on at least replacing the bearings with a new set of the same size. And then dumping the car.

Or plan on doing a rebuild,then the plastigague is use to check if you have the right bearing set and the crank was turned to the right dimension. It won’t tell you if the rod journal is tapered (at least I am not that good with plastigague)

Are you trying to keep from getting stuck with a broken down car or have you accepted you need some level of internal engine repair and want to try and save the crank at least for turning. Is doing a complete overhaul even a possibility (maybe a salvage yard engine is better) Or are you still trying to conclude for sure if your noise is from a rod bearing? Failing all at once is odd, I would be more comfortable with only one failing,the part of your post that says it sounds like they are all failing at once doesn’t quite fit.

Someone on this forum suggested that using Max-Life will swell seals, but will also cause seals and gaskets to turn into jelly.  I don't know myself, but I think that I would investigate just WHY did the noise start in the first place?  You said you began to hear it only after the valve adjustment.  Was that because the valves were too loud to hear it before, or did the valve adjustment cause the noise?  Rocketman

I stand corrected. I assumed that quieting the valves could make it possible to hear this noise then it must be a very slight noise. A connecting rod failure is major, not to be messed with.

use a mechanics stethoscope to determine locale of noise, sounds like a lower bearing. Pull btm. pan and you will be able to see condition of bearings/crank and see if this is one cyl or all. Rebearing them and use the car until failure, with 180K in it, this is worth it. No great loss if failed but will possibly double your usefull life of car. You need to think about what may have damaged the bearing in terms of oil pumping and galleys and sludge etc…may be a need for screen, filter, and pump replacement…that is a lot of miles on an oil pump on a small engine car and may be short on output. Depends on what you normally do for maitenance and condition of the oil and your habits.

A few parts of this are unclear to me.
Did this new noise only surface immediately after the valve lash adjustment?

How many miles on the car?

If it’s a rod bearing knock then why is it more prevalent on throttle release? It should be most noticeable during acceleration and with a load on it.

Absolutely sure the valve lash is adjusted correctly and this is not by chance one of the adjusters left too loose? Normally valves that are too loose can tick a bit but it’s possible if one were excessively loose this could come across as a knock.

I had two cars with rod knock noises that I tried to nurse home. The first one was a VW back when I was very young, and never experienced it before. It threw the rod while I was coasting down hill in gear. The second was a car I found with a rod noise I picked up very cheap. I knew the engine was shot, but had one that would fit in it from a previous wreck. This one also let go when my foot was off the gas.

My best guess is that the rod cap gets pounded the worst when the intake vacuum is highest. The crankshaft is putting pressure on the rod cap as it tries to pull down the cylinder on the intake stroke. As the cylinder compresses the charge on the compression stroke, then as the charge burns on the power stroke, then expelling the charge on the exhaust stroke, all the pressure is on the rod side of the bearing, not the cap side.

Thanks BK–I just now got out from under the car. Its too bloody cold to drop the pan right now, but I did an oil change (want to see whats floating around). I do changes every 3K-4K miles, been running DuraBlend for the last 90k. This car takes a beating–short trips with cold starts all its life (my daughters car). The oil has no metal in it and filter is clean—so is it possible a bearing cap is just loose? This will surely cause an eventual bearing failure, so I will get the pan off.

Once you hear the knock, it’s a done deal. The bearing is certainly shot, and the rod bearing surface is most likely out of round, and the crank surface is scored to hell. You’d need to get the crank out to have it turned smooth again, and remove the piston to fix or replace the rod. At this point, your already looking a rebuild. There is no easy fix for this.

are you sure this is a bearing noise and not a slapping piston,?

Maybe–but this doesn’t have a ‘ring’ to it. I was thinking that piston slap sounds a little like a bell.

I’m still curious as to whether or not this problem existed before the valve lash adjustment.