Big_Tee

I recently bought a 98 Civic EX non-vetec (d16y7) Manual, Stock as far as I can tell.


It has a raspy sort of clap/knock under load.


At about 2300 rpm this raspy sort of rasp/clap/knock presents and carries through to about 3700rpm. I have not revved past 4000. When I let off the gas the noise stops. If in neutral and revving usually I cannot hear this and the engine sounds healthy. After a fair bit of driving though, and the right throttle manipulation I can hear the rasp even when in neutral but I have to work to hear it, pumping the gas in certain ways.


Listening with my head under the hood it is hard to locate the sound while working the throttle but it sounds like it's coming from the general engine area.


When the car is dead cold it does not present at all, 2 min in and you can start to hear it. After a long drive the sound seems to present more easily and at even lower rpms (approx.: 2000rpm)


So far I have tried the following to no effect:

• Changed the Rod bearings and thrust washers (they were in decent shape with just a slight bit of brass showing on the upper half of the #4 piston rod bearing (one farthest from pulley system)

• Changed lower halfs of the main bearings: They seemed in quite good shape already with little to no wear so I didn't hazard to change the upper mains bearings.

• Changed spark plugs.

• Tried thicker oil: 20w50

• Changed the exhaust Manifold : The original was cracked.




Here is a link to a webpage with the live audio recordings taken inside the cabin, under the hood and by the tailpipe.


http://tinyurl.com/n8ek4m9


What do your mighty Civic ears hear?



T

Jjbaehr

Sounds like a rod knock to me bro. You suck up any water?

rovafa2002

Rod knock my friend! I had the same exact sound at arround those RPMs Last weekend I had replaced mine and it now sounds great.

If you do this quick you might get it done without changing the crankshaft. Just the rod bearings.

Is your car having cooling issues? I heard the fan come on, check that you are not overheating. This might have happend due to too much timming advance.

Big_Tee

Thats the thing, I did change the rod bearings. And there was no change in the sound at all? If the crank was bent then I thought there might be short grace period of no sound for a a few Miles but there was no change at all?

I have posted photos of the rod bearings and mains under the sounds in the original link above. (you can click to expand http://tinyurl.com/n8ek4m9). You can see the slight brass showing on only one of the halves (Either rod 1 or 4 , I think it's 4 now closest to transmission)

Could it be a rod is bent?

No cooling issues that I know of the temp rises to middle and maintains.

The timing advance theory is interesting I'll have to check that. I have been running 87 octane since I got it.


I have not sucked up water but the previous owner could have. Where should I check for that.. under the distributor cap?

When I changed the oil it seemed fine / uncontaminated so hopefully there was none in the actual engine.




T

Jjbaehr

Well if it did suck water at any given time it only takes a little bit in the combustion chamber to bend a rod. I'm pretty certain that's what's going on here

Big_Tee

I agree that would happen, but if the rod was bent would it's main prob be knocking and wearing against the rod bearings /mains or would it cause other issues like somehow slapping or clapping the piston?

rovafa2002

Could be also crankshaft main bearing or even piston slapping. Have you checked for compression?

I suggest you do that, if you dont have the 4 cylinders near the same number it might tell you something.

Big_Tee

I will check valves and do a compression check. I'm starting to think it's got to be piston slap. The main crank just doesn't make sense to me considering the condition of the mains bearings and no change after switch.

Also: I just tried taking off each spark plug lead and revving the throttle, no difference.

slowcivic2k

Piston slap is most notable when stone cold, and it improves as the engine warms up. I have seen the number 4 rod develop a knock a lot due to lack of oil. Leakage from every other part going to number 4 makes this one the first to lose pressure, and the first to fail.

The progression of wear on the main bearing halves supports lack of lubrication (caused by a looser fit and oil leakage on the other bearings) or out of round. Your rods also need to be reconditioned or replaced as the big ends are out of round, causing the shining on the top of the bearing. What do the top halves of the mains look like? The same, or mirror opposite?

Big_Tee

That is is good information to know thanks.

I did not take attempt to change the top halves of the main bearings because a little scared of messing it up, and also due to the fact that the bottoms seemed to be in pretty decent condition.(there is really not much wear showing on the bottom halves, I know the photo turned out to show copper but in reality there is not even the matt finish removed. ) So I just changed the rod bearings, lower mains and thrust washers, to no effect at all.

It was my understanding that the bottom half of the mains and top half of the rods get the most amount of wear. I suppose I could go under and remove/change the top halves.

I guess either way the rods are going to have to come out.


Yes #4 rod bearing had the most wear which would support the lack of oil theory.

slowcivic2k

The top halves of the rods will typically see the most wear, if any wear at all. The crank bearings will show some type of wear pattern depending on where the out-of-round is in the crank, usually it is towards the clutch disc.

Big_Tee

SOLVED!!!!!!! And it was Not rod knock !!!!


While checking the valve lifter clearances I took off the top plastic timing belt cover. The timing belt felt loose to the touch. I put the top head cover back on and plugs in but left the timing belt cover off and ran the engine. The Timing belt looked very loose and wobbling on both sides.


I changed the timing belt, tensioner and water pump. The sound is gone

I believe it was the timing belt slapping against the plastic cover, hence the strange sound: not quite metal not quite wood, not quite exhaust, sort of raspy. It could have also been the timing belt moving the tensioner around too much although the tensioner seemed in good condition and fixed in tight.


In hind sight from the first post you can really tell that it would not be rod knock or bent rods (main reason being changing bearings to no temporary effect). So I have to say I'm kind of glad I followed my instincts to looking and not start a full engine tear down, or else I would have changed the rods for no reason.

Rod knock was the first guess, yet, after the rod bearing change and bearing condition, it negated that theory.


I hope someone in the future reads and benefits from this post because it was a tricky caper for me.


PS Is there a way to put "Solved " in the main title?

BeatDX

iTrader: (1)

A stock EX has a D16Y8 VTEC.

It's either not a EX or it isn't stock.

EX VIN should have EJ8 as the 4th, 5th and 6th characters.

Big_Tee

OK.... My Vin Has EJ6... so I was duped!!! The engine is certainly a d16y7, I checked the engine stamp.

It does have power windows and some nice chrome trim features around the windows and a fancy "EX" chrome label on the back.... well I'll be!!!

to be honest I didn't really know the difference anyway and just wanted a reliable civic in this age range for winter driving so I'm not mad hahah.

BeatDX

iTrader: (1)

Sounds like a LX or DX value package (VP). The badge or the whole deck lid were swapped, EXs have color matched mirrors and moon roofs as standard. Besides the Y8 they have bigger front brake rotors too.

http://en.wikipedia.org/wiki/Honda_C...xth_generation)

Big_Tee

Failed to mention I'm in Canada, and after further research this is normal for Canadian Versions:

"Only the EX sedan, Si coupe and SiR coupe had power locks and power windows, the Si and SiR coupes were the only Canadian Civic models with a power moonroof."

So it is an EX but a Canadian EX so basically a normal US LX with power locks, windows, and chrome trim. In Canada it's the Si's that are the fast ones!

BeatDX

iTrader: (1)

There you go, EH?