[PMI]

While trying to sort out my own engine issues I was looking at some examples of broken 4-cyl Saab engines at an independent Saab repair shop. Came away with a few samples of old chain guides. So, for anyone with prematurely worn timing and balance chains...

First attachment is a balance chain guide from a broken 9-3 engine. Same guide as on my '96 900 SET I believe, not sure. The guide is worn to a depth of 3 mm into the plastic. That may not seem like much, but that engine was scrapped at only 47k miles (I did not have time to look for the timing chain guide from that one).

Second attachment, guides from a 9K with 170k miles. I compared the same part and THAT one was worn only to a depth of little more than 1 mm in the same place. In other words, after 47K miles, the guides in the 9-3 were worn down much more than a 9K at 3x the mileage when the chains broke on that one (pic shows the broken timing chain guide).

At least I've had a warning thanks to a few friendly independent mechanics and previous posts here and elsewhere on the web... bit depressing looking at all the scrapped engines... don't think the average driver is looking for that to happen, or doing google searches for timing and balance chains.

 

[TigerSilhouette]

Hey PMI

Any reason the 9k timing chain snapped at 170k? Dont they tend to last longer with proper lubrication and what not? Kinda scary considering im at 169,200 miles. Also, why did the 9-3 engine go so early? Was it due to sludge and blocked oil passages? Thanks for posting these pictures. Is the infamous chain slap the sound you hear when the chain rubs on the guide?

Lawrence

 

[PMI]

Any reason the 9k timing chain snapped at 170k? Dont they tend to last longer with proper lubrication and what not?

I do not know if 170k is early on a 9k. The owner of that car probably thinks it was.

Also, why did the 9-3 engine go so early? Was it due to sludge and blocked oil passages?

Since it was a 9-3, that would be a good guess, but no way to tell now.

Is the infamous chain slap the sound you hear when the chain rubs on the guide?

A lot of good questions... I much prefer posting answers, and if I had them I would be happy to post them.

Chain slap on older engines was when the chain got loose enough that you could hear the slack slapping on the guides. Rubbing you don't hear. What happens on this engine is that the tensioner takes up the slack until it extends all the way and runs out of adjustment. I am not sure you will hear chain slap before things start breaking, because the guides wear along with the chain, and there would be very little warning when a guide breaks. The 9k broke a guide, who can say if it happened before or after the chain broke.

At 105k there is no chain "slap" on my car, just a rattling noise you can hear below the other engine noises with the hood up. Once I got the valve train to run right, it was obvious what it was, but not before that, at least not to me. The mechanic with the engine collection said he heard worse.

There are lots of theories. An article in the "nines" blames a new oil pump design. An experienced professional Saab mechanic who posts on SN claims it happens mostly on the 2.3L non-turbo engine. Some people feel it is sludge and think their car is immune if it is not one of the models covered by the extended Saab warranty. Take your pick.

 

[brewtide]

Hey PMI

Any reason the 9k timing chain snapped at 170k? Dont they tend to last longer with proper lubrication and what not? Kinda scary considering im at 169,200 miles.
Lawrence

Don't feel bad, I owned my 92' 9k for 3 months, 115k on her, and she snapped... Going 85mph. No noise prior, purred like a kitten.

I'm assuming prior owner was a klutz.

-bny

 

[earthworm]

The short term solution is to measure the chain adjuster-plunger at 100K miles and report..

It galls me when a manufacturers states : Ha ! No timing belt, but a much superior chain - but no one asks : "does it last forever ?"
Of course not, but I suspect that many car-makers think forever means 100K miles.. IMO, a well conceived Kevlar-fabric timing belt is better, but still must be changed every 75 to 100K miles..

The long term solution is the 42 volt system and solenoid activated valves - this is in the works - it is a matter of engineering excellence and balls...

 

[philosophicaldreamer]

It galls me when a manufacturers states : Ha ! No timing belt, but a much superior chain - but no one asks : "does it last forever ?"
Of course not, but I suspect that many car-makers think forever means 100K miles.. IMO, a well conceived Kevlar-fabric timing belt is better, but still must be changed every 75 to 100K miles..

If we have to change our timing chains every 100K, then why not switch to timing belts and get rid off all the confusion about the greater longivity of timing belt technology. Nowadays timing belts go 100K miles. I know that on my Volvo the recommendation is to change the timing belt at 105K miles. So what is the adavantage of timing chain vis-a-vis timing belt?

Thanks.
Ta-ta, janusz

 

[V6man54deg]

Back in 93 when the V6 engine was launched, the designers said it was a life long timing belt - within the first year and a re-design it went down to 40000 miles - think they did a lot of testing on durability rigs - not a lot of rpm change, its hard acceleration that wrecks all engines - not just timing issue's but oil condition due to excessive blow by.

at the end of the day its how you drive the car that effects how long it will last - if you buy a used one - at least have the oil system flushed and have regular oil and filter changes, and pray that the last owner didn't have lead boots!!!

If we have to change our timing chains every 100K, then why not switch to timing belts and get rid off all the confusion about the greater longivity of timing belt technology. Nowadays timing belts go 100K miles. I know that on my Volvo the recommendation is to change the timing belt at 105K miles. So what is the adavantage of timing chain vis-a-vis timing belt?

Thanks.
Ta-ta, janusz

 

[philosophicaldreamer]

Back in 93 when the V6 engine was launched, the designers said it was a life long timing belt - within the first year and a re-design it went down to 40000 miles - think they did a lot of testing on durability rigs - not a lot of rpm change, its hard acceleration that wrecks all engines - not just timing issue's but oil condition due to excessive blow by.

at the end of the day its how you drive the car that effects how long it will last - if you buy a used one - at least have the oil system flushed and have regular oil and filter changes, and pray that the last owner didn't have lead boots!!!

Thanks for the explanation.

Ta-ta, janusz