Jason_86_951

My latest fun little noise is a erratic knocking that sounds like (and feels) its coming from behind the timing belt cover. It only happens during the first minute or so from a cold start-up. During this time it decreases bit by bit untill it warms up, then there is no noise at all. Anybody hear this before?
Thanks in advance
-Jason

Ahmet

Could be a bearing going bad, (possibly a pulley, or an idler too)or even a lifter. Is it higher up in the front of the engine? What weight oil are you using, and how long has it been making this noise, has it changed?
Ahmet

Jason_86_951

Ahmet-
It is right up front in the upper part of the timing belt cover, I'm using Mobil 1 10w30, Its been happening since I got the car about 3 months ago. I first thought it was the heatshield or something with the exhaust untill I stuck my head in there and listened.
Thanks
Jason

Ahmet

I'm gonna go with either a lifter, or a pulley...

Let's see what others think, sorry I couldn't help further.
Ahmet

Jason_86_951

It sounds like something is actually hitting the inside of the timing belt cover. It has the same sound as if you took a screwdriver and hit your timing belt cover with it.
Hope this help.

Ahmet

Hmm, hope it's not your belt coming apart, look through the hole in the dist. housing cover, see how the belt looks...

I'd pull one of the plastic covers too, if that belt breaks, you're going to be in for some major work...
Ahmet

Tabor

You need to either:

1. Open her up.

2. Take her to a mechanic.

Quick!

Dave in Chicago

Had the same problem with mine after a belt change a year ago. The balance shaft belt was adjusted too lose and was slapping the belt cover at start up for about 3 - 10 minutes. The belt tension is wrong. Why the belt tension is wrong is a different question. Have someone who knows how to tension these timing/balance belts or it will be wrong.

Even after the supposed fix, I had a very good P-car wrench look at it a year later. He found that 2 rollers needed changing, the wrong size balance shaft belt was on the car, and the tension was still wrong.

It's the one thing that will go wrong and not just ruin your day, it'll ruin you whole year when it takes the valves/pistons with it. My advice, it pays to get this part done really well.

Just my opinion, hope this helps.

Greg Hammond

Ditto on what Dave said. There isn't much "behind" the cam belt cover -- except for the belts and pulleys themselves. If you're sure it's something hitting the cover, I'd strongly recomend either taking the top cover off and inspecting it yourself - or take it to a reputable 944 mechanic and have it corrected, ASAP.

If your balance belt snaps, it will wrap itself around the timing belt. When it does, the timing belt snaps, and bingo - you got a $2000+ repair job.... more more if you sustain more serious piston damage.

Greg

Dave in Chicago

Jason,

How did it turn out? Is the car safely back together and worry-free?

Jason_86_951

Well, got the cover off and discovered my balance shaft belt was way too loose because the tensioner is toast. I've got parts ordered to have my mech change the belt and tensioner. We took a look at the other belts and all looks good. Hopefully I'll be back driving my sweet speed machine again soon.

Thanks for everyone's feedback!!! This forum is the best on the net!

s85b50

Exact symptoms here. Exactly what parts did you replace?

tempest411

It would be foolish to leave ANY of the two belts and rollers alone. Replace them all! There's tons of vendors out there selling the Conti branded kits at decent prices. Also get the Arnworks tool for tensioning.