livelarg

Ok. This is an emergency.

First, I have a 88' 4Runner with the 3.0.

I started hearing a knocking under the hood. It did not sound engine related. The knocking was independant of the RPM, and the engine ran great. A mechanic was pretty sure it had nothing to do with the engine.
THe sound seemed to come from behind the timing belt cover. The mechanic said it sounded like the timing belt tensioner was going bad, and that was the sound. That sounded reasonable.
It took me a little while to get to a point where I could get to it, and I had to drive it a little while. The sound got much worse.

Tonight, I took the engine apart and was getting ready to change out the timing belt tensioner. Btu when I got to them. They seemed perfectly fine. The top pulley rolled smooth and without much friction. The tightner pulley was also smooth spinning.
Now I don't know what the problem is!
Could it be the water pump under there?
WHAT COULD IT BE???? :cry: :cry:

livelarg

Surely someone else has had this problem.

Is there a way to check the water pump?

Another question.
My truck front is apart now. The radiator is off. so no coolant, the timing belt is exposed. Can I run the engine for just a minute or two to see where the sound is coming from? or will that ruin something?

please help

Gadget

Yes, you can fire it up for a very short time to locate the source.

The part that you said about it not being RPM dependant has me a bit confused. If it is something in the timing belt drive or accessory drive it should change with RPM changes.

I checked out a 2nd Gen 3.0 not to long ago that had a bad rattle when it was running. It clearly sounded like it was coming from under the timing belt. I laid my hand on the upper radiator hose connection and I could feel it. There was no question in my mind it was the upper timing belt idler pulley that surrounds the upper radiator hose connector. Odd design.

You can use an mechanics stethescope to figure out what is making the noise. Also be sure to check the large crank shaft pulley. They can come loose from the crank and wobble around while they eat up the nose of the crankshaft. Also they are ususally two parts joined by an elastromeric material that can sometimes give out and allow the two parts to bang together.

If you do take the timing belt loose to replace any of the parts there besure to install a new water pump while you are in there to save all that labor for when it does fail.

Let us know what you figure out.

Gadget

www.GadgetOnline.com

its2slo

Victor

I had read that the idler pulley that surrounds the upper radiator outlet should be replaced with every timing belt change as it is prone to failure. I second the vote for a new waterpump since you'll have a new idler, tensioner, and timing belt.

livelarg

Well, after taking apart the entire front end to fix the rattle in my timing belt tensioner pulley. I found the rattle is from the pulley/clutch of the A/C condensor!:pat:

After all that work, I still have the problem! They have clutch/pulley kits for it for $210:cry:
I am going to try and get a used compressor and get the pulley off of that and put it on mine. That way I don't have to mess with re-charging my system. My A/C works awesome now. I really don't want to mess it up.

Anyone ever have to change the compressor pulley? As this will be my first time, any help would be appreciated.