Corolla knock.

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BaileySims
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Corolla knock.

Post by BaileySims »

Posting here in case anyone might know what the hell this knock could be. It only does it under load. It sounds like it's coming from the front of the head. I thought it was the rod bearings and just replaced them before filming this.

My mechanic buddy told me is was ping due to bad gas. I drained the tank and added fresh gas and the sound still remains. cylinder compression is 120 120 80 80. Any help in the right direction would be greatly appreciated.

https://youtu.be/T4G0RyU9MYE


Edit: all valve clearances are within spec. There was no metal in the oil pan. Timing chain is not loose.

The engine is quite through the whole rpm range too which is weird. Once under load, the sound comes out and it runs poorly.

Edit 2: isolated the knock to cylinder 3 by pulling injectors. Giving up for today though, still have to finish my truck .
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NWMO
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Re: Corolla knock.

Post by NWMO »

Hey Bailey,

Compression numbers point to a failed head gasket between 3/4 and that sounds more like a “knock” than a ping. The best check for “ping” or detonation would be to retard your timing some and see if it changes. I’ve never done a leak down test, but most say it is a better diagnostic evaluation.

Chris
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BaileySims
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Re: Corolla knock.

Post by BaileySims »

NWMO wrote: Wed May 13, 2020 8:50 pm Hey Bailey,

Compression numbers point to a failed head gasket between 3/4 and that sounds more like a “knock” than a ping. The best check for “ping” or detonation would be to retard your timing some and see if it changes. I’ve never done a leak down test, but most say it is a better diagnostic evaluation.

Chris
It's definitely a knock of sorts but I cannot pinpoint to what the cause may be. The car doesn't have a dizzy but I can watch the timing do it's thing on the obd2 scanner and it checks out. I did add oil to the cylinder after a dry compression test and it matched the first two cylinders at 120psi. Also when I removed the oil pan to do the bearings, there was a bunch of smoke in there for some reason? All I want to do is have this car safe enough to drive around for my step kid but I seem to be wasting more money than the car might be worth. Haha.
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NWMO
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Re: Corolla knock.

Post by NWMO »

Bailey,

Improvement with a “wet” compression check would point to worn rings/cylinder walls, but it would be unlikely the that two low cylinders would both be low and so similar in compression. Smoke may be the oil burning off after it passes the rings. Unfortunately, I can’t imagine it will last long with that knock.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
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BaileySims
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Re: Corolla knock.

Post by BaileySims »

You're more than likely right. I added a can of restore in hopes to increase compression but I think the engine is too far gone to save. Oh boy. Thanks Chris.
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Re: Corolla knock.

Post by NWMO »

Bailey,

I watched the video a few more times, that my be head/valve noises which could also explain what you've described. I had a valve spring break not that long ago and it was similar, of course it was obvious when I removed the valve cover. However, I don't think you would see the "change" with the wet compression test if it was a head problem.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
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Re: Corolla knock.

Post by teranfirbt »

There's not much to be done with an engine with compression numbers that low. 1zz's are a dime a dozen, I recommend finding a decent engine from a yard and doing a swap.
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Re: Corolla knock.

Post by Petros »

could be a number of items, did you try pulling the spark plug wire from that cylinder and see if you still get the knock?

as stated, compression that low in 2 cylinders means at the very least the head has to come off. do not discount that it could also be coming from a problem with the piston (broken skirt from too much cylinder wear).

But try to find the cause, just to make sure to know what caused it before you start replacing parts, including the whole engine.
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Re: Corolla knock.

Post by xirdneh »

Number 3 is the cylinder that has the most problems. Worn cylinder, cracked piston, skirt falls off piston., Head gasket leak between 3 and 4.
Love those Tercell 4x4 wagons but they sure suffer from road noise.
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Re: Corolla knock.

Post by xirdneh »

xirdneh wrote: Mon May 18, 2020 5:09 pm Number 3 is the cylinder that has the most problems. Worn cylinder, cracked piston, skirt falls off piston., Head gasket leak between 3 and 4. At least on the 3as it is
Love those Tercell 4x4 wagons but they sure suffer from road noise.
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