'91Q Noise at Startup

[timatt]

I haven't posted in awhile because I haven't had any problems with my Q. '91Q, 117k miles, running well. Chain guides replaced 18 months ago, plenum job with new injectors year (30k miles) ago. Recently I've noticed a rattley noise on startup after the car has been sitting for at least a few minutes. It seems like it is oil pressure related however the oil pressure light will go out around a second after startup and the the rattley noise will last longer maybe 2 to 3 seconds. There is no noise at idle or during any mode of operation other than startup after sitting for a bit. This will occur whether the engine is hot or cold, but the engine has to have been off for at least a few minutes (probably 10 - 15 or maybe more) for it to happen.

I haven't been able to pinpoint the origin of the sound because it is pretty fleeting, but it sounds like I would expect loose timing chains to sound (or at least how they sounded on my 911). Could this be the chain tensioners? Are tensioners known to fail? How concerned should I be? What are my options?

Thanks

Tim

[DAEDALUS]

I've noticed new tensioners are quieter than old ones. Assume you didn't replace the tensioners when you did the guides? Are you certain the noise isn't accessory related? Try running a heavier oil on your next change and see if it makes a difference. You can also try frequent flushes for a few months with BG MOA. An oil pressure check would set my mind at ease--make sure it's not a symptom of an underlying problem.

[elwesso]

Very interesting Tim... What oil are you running...? have you run any additives like BG quick clean or something? last time I remembered you were running 10w30 M1 synthetic...

possibly a clogged HLA or something, i remember seeing your Q having a litlte bit of varnish...

personally id try running some BG quick clean, and a fresh oil change...

[timatt]

Very interesting Tim... What oil are you running...? have you run any additives like BG quick clean or something? last time I remembered you were running 10w30 M1 synthetic...

possibly a clogged HLA or something, i remember seeing your Q having a litlte bit of varnish...

personally id try running some BG quick clean, and a fresh oil change...

Wes:

I'm running Mobil 1 5w30 (I believe). Actually last year when we re-sealed the valve covers when we did the plenum job, Dan, the mechanic was remarking how clean things looked under the covers, so I don't know about varnish.

That being said, it probably wouldn't hurt to run some BG quick clean. Where can I get this stuff?

Tim

[timatt]

I've noticed new tensioners are quieter than old ones. Assume you didn't replace the tensioners when you did the guides? Are you certain the noise isn't accessory related? Try running a heavier oil on your next change and see if it makes a difference. You can also try frequent flushes for a few months with BG MOA. An oil pressure check would set my mind at ease--make sure it's not a symptom of an underlying problem.

We did not replace the tensioners when we did the guides. I am not positive that its not accessory related however I did turn the climate control to OFF and it still did it.

What is BG MOA and where can I purchase it?

Thanks

Tim

[elwesso]

Tim..... im coming to the lake tomorrow (this weekend)..... Call me when you get a chance, i can see whats going on and you can see my Q (its finally done! )...

You can get the quick clean from Joe or on ebay (thats where I got mine)

[DAEDALUS]

We did not replace the tensioners when we did the guides. I am not positive that its not accessory related however I did turn the climate control to OFF and it still did it.

What is BG MOA and where can I purchase it?

Thanks

Tim

Wes is right--it's quick clean, not MOA (good stuff for keeping in the oil). Remove all the accessory belts and start the car (cold only). Do NOT let the car run for more than 20 seconds, or however long it takes to determine the difference in the sound of things. Don't risk an overheat without the water pump for this one.