Car guru's... Timing chain question

SchecterC4 · #1 09-09-2009, 11:14 PM

I know this isn't a car forum, but the car specific forum I frequent doesn't have the numbers of this forum and a lot of the times the responses are sub-par or non-existent, which sucks.

So maybe one of you can help me.. The car in question is a 1988 Saab 900 16 valve turbo. I was wondering about the state of my upper timing chain guide and what it means for the rest of the timing chain system. I'm getting an intermittent rattle at start up which points me to the timing chain, but the rattle happens even when the car is warm and has been sitting for 30-45 minutes. Via searching I've found that most of the time the rattle happens at cold start up and this isn't always the case with my car. Though just tonight after driving home from practice the noise was sharper than normal and lasted quite a bit longer

So here is the upper guide in the cam cover:

and here's the timing chain closer:

It's been a few months since I've taken those and things have obviously either not changed or gotten worse. If that guide is worn past it's life, what does it mean for the tensioner, chain and other guides? I have not yet checked the tensioner, but when I had the cover off the chain felt taut and solid, and looked just about the same as the chain in my 2001 Saab 9-3 (had ~123k miles on it at the time).

I bought this car for 500 bucks and the odometer happens to be the only thing on the instrument cluster that doesn't want to work, so the mileage is unkown, but in the 10 months I've had it I've probably only driven it 5k-7k miles.

Thoughts/speculation?

carl h. · #2 09-09-2009, 11:23 PM

Rattle on startup = low oil pressure. Hydraulic tappets building up pressure probably are what the noise is. Buy the best oil filter you can find with a good anti-drainback valve and fill with good oil.

NO FRAM!!!

El Jefe · #3 09-09-2009, 11:37 PM

ya sounds like lifters, run some seafoam in the crank case for a bit then change the oil.

SchecterC4 · #4 09-09-2009, 11:53 PM

Quote:

Originally Posted by carl h.

Rattle on startup = low oil pressure. Hydraulic tappets building up pressure probably are what the noise is. Buy the best oil filter you can find with a good anti-drainback valve and fill with good oil.

NO FRAM!!!

S**tty.. the one time I put on a Fram filter.. lol. I'll swap that out asap for a K&N or something similar. If that isn't the problem what then? After more searching and contacting one of my Saab guys, I've found that it could be the A/C Idler pulley. Also, I've changed the oil regularly on our other cars with Fram filters and have had no problems. What gives?

What would it run me to roll in a new timing chain anyways?

SchecterC4 · #5 09-10-2009, 12:01 AM

Quote:

Originally Posted by El Jefe

ya sounds like lifters, run some seafoam in the crank case for a bit then change the oil.

I've always been leery of seafoam. Heard a lot of horror stories about it and people burning oil/coolant after using it. Any other more commonplace alternatives?

cardboardJoe · #6 09-10-2009, 04:48 AM

HMMMM lifters in an ohc motor....

Mike N · #7 09-10-2009, 05:04 AM

Not real experienced with Saabs, but I'd be looking at the tensioner and/or chain itself and not just the guides. With the valve cover off, can you roll the crankshaft back and forth and see how much slop the chain itself has in it?

With the mileage being unknown it's kind of a crapshoot as to what's making the noise.

MoD_Scotty · #8 09-10-2009, 07:19 AM

The cause of the rattle could very well be the tensioner going bad. That could cause slack in the chain, and allow it hit the guides. If it's an '88 and still has the original chain, you might want to think about replacing both the tensioner and the chain itself. Timing chains can stretch slightly over time (21 years is definitely enough time), and wreak all kinds of havoc. Especially in turbo cars, which tend to run significantly hotter (both in regards to cylinder temperature and under-hood temperature) than normally-aspirated cars.

Looking at those pics though...it seems like it'd be a HUGE pain to change the chain. Good luck!

carl h. · #9 09-10-2009, 08:24 AM

Go for a Wix or Mann filter, K&N is over priced for what it is.

OHV, doh!

I still think it is oil pressure related, and FRAM FTL.

Bob Lee (QSC) · #10 09-10-2009, 10:50 AM

What Mike N said--put the car in neutral, put a wrench on the crankshaft pulley, and rock it back and forth. Watch the timing chain while you do this and see if there's any significant slack.

The guide in the valve cover looks like it might be primarily for protecting the cover from wear.

If you can check and monitor the oil pressure, do so. Turbos vitally need oil pressure, especially those with sleeve bearings (which most have). If the pressure is low with the engine hot, switching to a slightly heavier oil viscosity may help and allow you to get a bit more life from the engine.

Do you have a repair manual for that car? Even a Haynes/Chiltons book is better than nothing.

RAM · #11 09-10-2009, 11:12 AM

I don't know that much about cars, but the advice given here seems very sound. From my knowledge, timing chains (themselves) are either broken or they're not - no in-between.

hbarcat · #12 09-10-2009, 11:43 AM

Timing chains rarely break but they can wear and stretch and eventually jump time. But they usually don't rattle even when they're worn. And you say it's only on cold startup or after the car has been sitting for awhile so I would say this may be helped by using a higher viscosity oil. Or not.

Mike N · #13 09-10-2009, 12:59 PM

Quote:

Originally Posted by hbarcat

Timing chains rarely break but they can wear and stretch and eventually jump time. But they usually don't rattle even when they're worn. And you say it's only on cold startup or after the car has been sitting for awhile so I would say this may be helped by using a higher viscosity oil. Or not.

Problem with a higher viscosity oil is it flows slower, especially in colder weather. If he's having a problem with oil drainback when it sits he needs a filter with a anti drainback valve and a thinner oil to get there quicker and quiet things down.

Of course I don't know where Santa Clara CA is, so the colder weather bit may not apply here.

Mike N · #14 09-10-2009, 01:04 PM

Quote:

Originally Posted by RAM

I don't know that much about cars, but the advice given here seems very sound. From my knowledge, timing chains (themselves) are either broken or they're not - no in-between.

You should have seen the chain and gears in my old 73 Blazer. The truck developed an oil leak that got progressively worse, and when I went to see what was leaking I could see the timing chain had rubbed through the side of the chain cover. The chain and gears were so worn the chain actually had enough slack to hit the cover. Naturally with a hole in the cover it sprayed oil all over the place.

I still can't believe the chain never jumped time on the gears.

Bob Lee (QSC) · #15 09-10-2009, 01:24 PM

Quote:

Originally Posted by Mike N

Problem with a higher viscosity oil is it flows slower, especially in colder weather. If he's having a problem with oil drainback when it sits he needs a filter with a anti drainback valve and a thinner oil to get there quicker and quiet things down.

Of course I don't know where Santa Clara CA is, so the colder weather bit may not apply here.

It doesn't get very cold in Santa Clara. Not like upstate NY!

I think I'd be hesitant to use a thinner oil in a clacking engine with high mileage (unless I were using a too-high viscosity in the first place), as the bearing clearances presumably would be a little bit larger from wear.

Meyatch · #16 09-10-2009, 01:32 PM

I don't know nearly enough about cars to help you, but try saablink.net Those guys have always been super helpful to me. Saabcentral.com is also pretty good, and more populated than saablink.

SchecterC4 · #17 09-10-2009, 01:35 PM

Sounds like I'm going to need to check the oil pressure and swap out the filter either way.

Quote:

Originally Posted by MoD_Scotty

The cause of the rattle could very well be the tensioner going bad. That could cause slack in the chain, and allow it hit the guides. If it's an '88 and still has the original chain, you might want to think about replacing both the tensioner and the chain itself.

I have a Bentley manual for this car and it says that if the tensioner is extended more than 11 mm then the chain and tensioner are no good, but it doesn't do a very good job of explaining how to actually do the checking.

I know for sure that the car has had a headgasket job done, and anyone that doesn't check the timing chain parts when the head is off is an idiot, so I'm going to bank on the side of this stuff having being replaced at least once. The chains on these cars last from 150-250k normally and the car probably sat for a few years with minimal use before it went to auction.

Quote:

Originally Posted by Mike N

Not real experienced with Saabs, but I'd be looking at the tensioner and/or chain itself and not just the guides. With the valve cover off, can you roll the crankshaft back and forth and see how much slop the chain itself has in it?

With the mileage being unknown it's kind of a crapshoot as to what's making the noise.

I'll try this and I agree. I took a huge gamble in buying this car and so far I've been extremely lucky that it hasn't quit on me. It could be anything, but I think we've narrowed it down quite a bit here.

Quote:

Originally Posted by Mike N

Of course I don't know where Santa Clara CA is, so the colder weather bit may not apply here.

Bay area/San Francisco weatherish. Doesn't normally get below 50 at night. I don't think viscosity is a huge issue with regards to the weather. I run 0w40 on my 01 and 02 Saab 9-3's.

Quote:

Originally Posted by carl h.

Go for a Wix or Mann filter, K&N is over priced for what it is.

Mann filters are Saab factory spec, actually.

Thanks for your help guys.

carl h. · #18 09-10-2009, 01:43 PM

I'm lucky, the Mann filters I bought for my turbo Volvo also fit my MG.

Timing belts are the troubled links, timing chains, not so much.

Quote:

I'm getting an intermittent rattle at start up

Try some Castrol high mile and a new Mann filter.

Are you letting it idle before shutting down? That turbo spins for a long time after shut down.

SchecterC4 · #19 09-10-2009, 01:45 PM

Quote:

Originally Posted by Meyatch

I don't know nearly enough about cars to help you, but try saablink.net Those guys have always been super helpful to me. Saabcentral.com is also pretty good, and more populated than saablink.

This is the reason I posted here and not there. I've gotten 15 replies here and none there. Some solid replies at that. Saabcentral has been good to me in the past, but recently it's really gone downhill, aside from the fact that I got scammed in the classifieds section.

I also posted here because it's more general and not specific to Saabs, which is lucky for me.

Mike N · #20 09-10-2009, 04:01 PM

Quote:

Originally Posted by Bob Lee (QSC)

I think I'd be hesitant to use a thinner oil in a clacking engine with high mileage (unless I were using a too-high viscosity in the first place), as the bearing clearances presumably would be a little bit larger from wear.

If the engine was clacking all the time I'd agree with you. Being it's an intermittent noise I'm thinking that it may be taking the oil longer to get somewhere it needs to be, thus I suggested a thinner oil since it will move through the engine quicker than thick oil would.

I certainly wouldn't put 0w20 in it, but at the same time 20w50 isn't the hot setup either. I don't know what weight oil is spec for that car, but 5 or 10w30 is were I'd want to be with it based on age and suspected mileage. If it's still making alot of noise with either of those in it, either run it 'till she blows or pull and rebuild it.