whizkidsdad

I am new to the forum, although I have read some of the posts here regarding the idler pulley and timing belt.

I have just recently had to have the upper idler pulley bolts re-tightened for the second time since I owned this vehicle. It is the v6 engine on a 94 4Runner. This is the part that the upper radiator hose hooks up to. The mechanics are at a loss as to why this is happening. This time they put Lock-tight on the bolts. It occurs after 15 month or 12-15K miles. I need a dependable vehicle for my son to drive. Has anyone heard of this happening? Both times the only symptom was the immediate loss of fluid. You could grab the gooseneck to the radiator and wiggle it.

Thanks for any help

celica

I have never had it come loose but here is a bump for you

Matt

4Crawler

iTrader: (3)

I might be tempeted to tear it apart for a look if it were my vehicle. Not sure what the bolts attach to, maybe the threads are worn or something like that.

I had a similar problem on my VW where the A/C belt was always coming loose. My attempts to tighten it only held for a few weeks, I determined it was a missing bolt at the base of the compressor, but very hard to get to. Took it to a dealer shop, told them what was wrong, they spent a day or two "repairing" it only to have the thing loosen up some time later. FInally, when I had to replace a watrer pump on the engine, I had to tear the A/C compressor out and only to find out that bolt bolts at the base of the compresor were missing. Seems to have been a bad factory design, they had like 8mm bolts but a 10mm bolt hole and that let the compressor slip back and forth and that ultimately sheared off the bolts. My fix was to drill out the small threaded hole and use a full size bolt and nylon lock nut to hold the compressor to the bracket. Once back together it worked perfectly, never had to touch the A/C belt tension again.

DH6twinotter

I've never heard of this happening either. The pulley is bolted down to the intake manifold and is held in by 4 bolts from the top.

How deeply has the issue been looked at? Have they pulled off the timing belt cover? Have they checked the bearings in the pulley? Only thing I can think up, off the top of my head, is that maybe the bearings are bad causing the pulley to spin off center which is causing the pulley to vibrate which is causing the bolt holes to slowly get eaten away.

Beats me. Just my $.02.
Have fun all.
Daniel

DH6twinotter

BTW, welcome to the forum!

whizkidsdad

I have had 2 independent shops and one dealer look at this. No one can figure out why the bolts are backing out. The Idler pulley/bracket has been replaced twice. This time they just re-used it and put the lock-tight on the bolts. I have replaced all the parts that engage the timing belt twice in the last 30-months/25K miles. (Water pump, both Idler pulleys, tensioner, belt, cam seals, etc.). They checked to make sure the surfaces were not crowned, and that the bolt holes were OK where it bolts up to the engine.

This had not happened until I had the timing belt replaced after I bought it three years ago. That was the first time I had all the parts replaced. What bothers me is if there is something else wrong, will this only work for a while again. I am contemplating selling it, but my experience with Toyotas has been great other than this. (I own three).

DH6twinotter

Well, I don't know what to say. Worse case scenario would probably be to replace your intake manifold. You might be able to find one at a junkyard maybe. Other than that, I don't know what else to say. Sorry.

coryc85

Could it be as simple as the bolts are too short to fully engage enough threads to really hold it in there? Someone could have easily put the wrong ones back in the first time you had the timing belt changed.

whizkidsdad

Using the wrong bolts is a possibility I had not considered. I guess you could still torque them properly, but without enough thread surfaces, they may not hold. I will run that by the shop that did the last repair.

Thanks for the idea.

WKD