Annoying timing cover rattle

[brian10x]

[/bI tried searching through every forum I could find for help, but my google is exhausted, and I'm hoping someone here has a solution.

I have a 1981 Rabbit diesel, 5 speed. I recently put a used (40k) engine in it.

The engine runs great. The car drives great. However, there is slight vibration (I'm guessing at around 2000 rpm) as I upshift through the gears. You can't feel it inside the car, but it makes an annoying rattle that I'm trying to eliminate. As the rpms increase, it goes away.

I've felt this slight imbalance on other engines, but this one really irritates me.

I've positively tracked it down to the timing cover. If you  increase the rpms until the rattle is present, pressure on the center of the cover makes it go away.

What have I done to reduce the rattle?
I removed the cover and put a narrow bead of silicone on any area where it seems to contact something else.
I checked the rubber bushings on all the mounting points.
I looked for any area that may be bent.
Finally, as an experiment, I glued foam strips to several areas in an attempt to deaden the rattle.

So, far, it just laughs at every attempt I make. Absolutely no change.


Now, I may have left a rubber spacer off the forward motor mount when I installed the engine. Could this be causing my problem?

Thanks!

Brian Souza]

[burn_your_money]

I would be extremely hesitant to put anything (including silicon) on the inside or the edges of the timing belt cover. If it gets loose, although unlikely it could cause the belt to jump.

Could you get a picture showing what bolts you have holding the cover on?

[brian10x]

I would be extremely hesitant to put anything (including silicon) on the inside or the edges of the timing belt cover. If it gets loose, although unlikely it could cause the belt to jump.

Could you get a picture showing what bolts you have holding the cover on?

I have no problem taking pictures, but trust me, its all factory original. I have compared it to my old engine several times.

[burn_your_money]

It's been a few years since I worked on a mk1 so it will help trigger my memory :wink:

[Op-Ivy]

I know the heat shielding on the firewall of the engine compartment on my mk2 used to rattle as well. Rattles are hard It fell off afterwards though.

Also, after rereading your post, a little while ago a flange on the exhaust was rattling at around 2000rpm as well.

Just some ideas in case it isn't with the belt cover.


Matt

[brian10x]

I know the heat shielding on the firewall of the engine compartment on my mk2 used to rattle as well. Rattles are hard It fell off afterwards though.

Also, after rereading your post, a little while ago a flange on the exhaust was rattling at around 2000rpm as well.

Just some ideas in case it isn't with the belt cover.


Matt

Thanks for the suggestions, but like I said in my post, applying pressure to the cover stops the rattle-every time. I have no heat shield on the firewall, and have removed all shielding from the exhaust as part of the testing. Also re-secured the air filter housing.

I'll see about getting some pictures up tonight.

[brian10x]

It's been a few years since I worked on a mk1 so it will help trigger my memory :wink:

Ok, this is my first shot uploading photos to this site.
This first shot is the front mounting bolt, just behind the alternator:

[brian10x]

Second shot is the mounting bolt on the front of the timing cover:

[brian10x]

Third shot, back of cylinder head:

[brian10x]

Fourth, and last mounting bolt, front of cylinder head, just below valve cover:

[brian10x]

Last picture, of timing cover:
I hope that helps. Mounting is rock solid.

[burn_your_money]

Second shot is the mounting bolt on the front of the timing cover:

Have you tried increasing the size of the rubber washer under this bolt? This is around the area that you press on to stop the rattle right?

[brian10x]

Second shot is the mounting bolt on the front of the timing cover:

Have you tried increasing the size of the rubber washer under this bolt? This is around the area that you press on to stop the rattle right?

Good suggestion. I'll try that.

[rabbitman]

My rabbit started the same thing from idle up to about 2000rpm only since I put a new injector pump on. It's kinda a low pitch rattle and if I push or pull on the intake snorkel it stops, so like you I put a piece of foam tape on the belt cover were the snorkel rests. It didn't fix a thing.
Maybe try removing your snorkel and see if anything changes, if you take the cover off does it still do it? Good luck!!

[brian10x]

My rabbit started the same thing from idle up to about 2000rpm only since I put a new injector pump on. It's kinda a low pitch rattle and if I push or pull on the intake snorkel it stops, so like you I put a piece of foam tape on the belt cover were the snorkel rests. It didn't fix a thing.
Maybe try removing your snorkel and see if anything changes, if you take the cover off does it still do it? Good luck!!

Nothing changes when removing the snorkel. Thr only thing that makes it stop is applying pressure to the cover with my finger.

I'm going to drive it around with the cover off Wednesday and make sure it goes away.