Intermittent Engine Knock And Removing The Serpentine Belt - Corolland: the Toyota Corolla Forums

My 2000 Corolla with 184,000 miles has developed a noticeable knock until it is completely and thoroughly warmed up. It sounds to me pretty much like what I would call a connecting rod knock. Not a good sound.

When thoroughly warmed up (5 to 10 miles of driving), there is still a minor ticking sound, but the expensive sounding knock is gone. That it goes away puzzles me.

I was thinking of removing the serpentine belt for the accessory drives (alternator, AC, Water pump, and PS) to eliminate these as potential causes of the knock. I am concerned about running without the alternator especially.

Is it OK to do this? It would be just for a minute or so when cold, not nearly long enough to overheat.

Also any ideas on what the knock might be? I don't really have the means to post audio/video or I would. I know that not being able to hear this is a major impediment to diagnosis, but thought I would solicit ideas anyway.

thanks

jim

For a very short time - you could run without the alternator and other accessories. Weather being cooler as all should be just fine - oil pump is driven off the crank directly, so you still would get plenty of oil pressure and circulation. Would be sucking juice directly from the battery, I would not attempt it if the battery is too old - as it might not recover. but can be done without any issues. I used to do it all the time, back when I was hitting the drag strips in my college days on built up import (one of the very few back then).

An automotive stethoscope may help pinpoint the noise - as the 1ZZ-FE is a relatively noise engine. Hard to pinpoint potential sources. I doubt that it is rod knock - as these tend to be present at certain RPM ranges when you hear that distinctive knocking noise. My money would be on a bad belt tensioner assembly or a bad pulley somewhere. Could also be heavy deposits in the combustion chambers that are causing initial hots spots (detonation/preignition issues) until it reaches operating temps.

K_Watson

This sounds similar to what mine is doing.

Fish:

Thanks for the reply and a good list of possibilities. The heavy deposits in combustion chamber sounds like a possibility. I've got lots of mileage, excessive oil consumption, which would imply possible large CC deposits. I didn't mention that when thoroughly warm, I also get pinging when it is close to a shift point. The pinging goes away after the shift, then starts again as it nears the next shift point.

Also, this summer, when things were hot as blazes, no knocking. When the weather cooled off, it knocks. It did this early this spring, and I took it to a mechanic, but when I got there it had stopped knocking. Then it got hot, so I quit worrying.

I'll try removing the belt when cold this weekend, and if the knock goes away, it would point towards the tensioner or one of the pulleys. If it keeps knocking, then more likely deposits.

I'll also try to get the mechanic to listen when cold, but that requires a drop off night before and all the problems that entails.

thanks

jim

Bikeman982

The alternator not running for a short time would not be a serious problem.

You can always put a quick charge on the battery afterwards.

I use a Battery Tender to top off a batteries charge and it works great.

The battery in my corolla is only about a year old, so I'm not worried about that part. I need to replace my serpentine belt anyway, so its a simple matter of running for a minute or so without the belt, then putting the belt on.

I know that there are no magic cures in a bottle, but are there any products people could suggest for reducing combustion chamber deposits?

There was a recent thread on Seafoam. Anyone think that would be worth a try for reducing CC deposits?

Maybe fill up with premium once to see if that impacts knocking and pinging? Although not a long term solution, if knocking and pinging were reduced significantly, would that tend to point to CC deposits as the culprit?

I'm not real knowledgable about this aspect of car problems.

thanks

jim

Maybe fill up with premium once to see if that impacts knocking and pinging? Although not a long term solution, if knocking and pinging were reduced significantly, would that tend to point to CC deposits as the culprit?

This would be a great test for checking for CC deposits - borescope would be the best way to visually inspect the chamber but not something that even a dedicated DIY might have in their tool box.

Some swear by seafoam to clean the CC up - in the past, I'd use just plain distilled water, alcohol, or solvent dribbled into a carb to clean it up. Principle is very similar - introduce a liquid with a vaporization temp lower than the combustion champer temperature - as soon as it hit the hot combustion chamber, it will instantly turn into a gas and literally blow the deposits off. Sometimes that all it takes - but generally, it is only temporary. As soon as you resume nromal driving, the deposits will return. Short of pulling the head and going at it with a polishing buff and some heavy solvent - like Berryman Chem-Dip or similar - not much else you can due.

Might also try a stronger fule injector cleaner and see if that helps - I like to use Redline fuel injector cleaner - if that is not around, I use the Chevron stuff or Valvoline SynPower fuel injector/fuel system cleaner. Both are cheaper and easier to find than the Redline stuff for most people (I used to live about 20 -30 minutes away from Summit Racing physical store - so it wasn't a big deal for me).

Fish:

I put some Valvoline FI cleaner in the last fillup. I can ask around for a boroscope. On using water, i had a datsun wagon years ago that had a cracked cylinder head. It was a beater, we lived in Phoenix and it used a lot of anitfreeze due to the cracked head. Otherwise it ran fine. So I just put water in it.

Drove the car from Phoenix to Wisconsin and back with the cracked head one summer. Just kept a gallon bottle of water in the car.

Much later when i got around to removing and replacing the head it was easy to see which cylinder the water was leaking into. Clean as a whistle. Put the rebuilt head on, and drove the thing for two or three more years.

jim

I had what I believed was excessive engine noise and I too, tried taking the serpentine belt off and YES, it does make quite a bit of difference. More than half of the objectionable noise disappeared! I found out that it was mostly the belts, pulleys and belt tensioner that was making the extraneous noises.

Fish is right too, when he said the 1ZZ-fe engine is somewhat noiser than most other Toyota engines. I just got used to it.

In short, as long as you don't run the car TOO long, no, there should be absolutely not problems with running the engine with the serpentine belt removed.

timkedz

Bikeman982

I had what I believed was excessive engine noise and I too, tried taking the serpentine belt off and YES, it does make quite a bit of difference. More than half of the objectionable noise disappeared! I found out that it was mostly the belts, pulleys and belt tensioner that was making the extraneous noises.
Fish is right too, when he said the 1ZZ-fe engine is somewhat noiser than most other Toyota engines. I just got used to it.
In short, as long as you don't run the car TOO long, no, there should be absolutely not problems with running the engine with the serpentine belt removed.
timkedz

Probably not a lot you can do about normal engine noise.

Keep the correct tension on the chain with the tensioner.

Make sure all the belts are good and keep the engine properly lubricated.

You might try just switching to a higher octane fuel.

at ~$0.10 - $0.15 extra per gallon you'd have to drive pretty far to lose money over some of the other alternatives

otter:

I put half a tank of premium in on friday. The pinging near shifts points seems to have improved, but not the cold knock. Haven't had a chance to try running without the belt yet. Might get the chance over the thanskgiving weekend though.

jim

At 180K miles, you have to expect some kind of engine noise.

My 2000 Corolla has only 39K miles on it and it makes a lot of noise on startup. The first minute or so it sounds like a diesel!!

On the other hand, it uses NO oil and has excellent acceleration!

Like Fish mentioned previously, the 1zz-fe engines are simply much noiser than previous generation engines.

If my Corolla makes it to 180-200K miles and then quits, I will feel that I have gotten my money's worth and then some!!

Hope this helps........

timkedz.

Will put a few cents on this

I have been living with this noice (to me sounds like valve train knocking) for past 6 years out of 10 years of ownership.

it is not gas, not the belt tensioner, although it does contribute to the noise,

You may go and get a valve clearence checkup , but I'm pretty sure it would be in the range.

The other sorce of noice is the chain and chain guides.

I decided not to bother with it - car still runs great, gas millage is above 30 mpg

This engine is noisy.

Bikeman982

Noisy cars - seems to be typical for that year models/engine.

Not a whole lot to be done, except keep the oil level up.

The car may last forever, even though it sounds like the rod is about to break.

friendly_jacek

For people considering removing the serpentine belt, isn't water pump driven by the belt?