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Discussion Starter #1
My car makes this noise like an intermittent knocking sound on the left side of the engine. It happens at idle with a warm engine. A kid told me at a saab event that my oil was too thin and the bearings were knocking because of low oil pressure, so I threw in a quart 25w-50 into my 5w-30(temporarily) He convinced me to buy Voll-synthese so that will be here tomorrow. But it still makes that sound even with a whole quart of thick oil in there. AHH not my bearings I hate to drive on that but I work 50 miles away! Anyone thinking anything please respond.
 

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Anything out of me would be speculation so I won't even try.
 

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Short answer, I don't know.

There are more than a few things on the left side of the engine. The transmission, the clutch assembly, the differential are there in addition to the crank position ring inside the block. Even if you are sure it is from inside the engine, there is simply no way to ascertain without opening it up. If I have been feeding my 9k synthetic oil regularly, I'd be skeptical of a random out of the hip comment on a peculiar noise.

But again, what do I know?
 

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First off, is the oil pressure light flickering or on at tickover when hot? If not then I would guess the knocking noise you are hearing is the timing chain, which usually gets worse when the engine is hot. When was the last time it was changed?
 

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I wouldn't expect anyone to change the timing chain on a 9k, barring a disaster, at 110k miles. There is no service period on a timing chain.
 

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yaofeng said:
I wouldn't expect anyone to change the timing chain on a 9k, barring a disaster, at 110k miles. There is no service period on a timing chain.
Be that as it may, they can fail prematurely, not necessarily the chain itself but the guide assembly; just because there is no specified service schedule does not imply that it does not require 'listening too' to ensure it is in good working order.
 

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TD:

Here you go, some speculation, based on the "knocking" noise, and likely similarity between the 9000 engine and my 1996 900SE turbo, now at 108k:

What you are hearing is a loose timing chain, and/or balance chain.

The person who mentioned bearings was half right, the knocking may not be "from" the bearings, but they are not far behind. I just replaced my rod and main bearings, and one of the first signs of trouble was a knocking noise from the timing cover end of the engine. Bearing damage will show up as elevated wear metals if you send a sample of old oil for a UOA (used oil analysis, about $20 at Blackstone Labs or anyone else who does it).

The person who said there is no service interval for the timing chain was also half right, there isn't, but it is very important to check and measure the timing chain tensioner if you hear chain noise, or suspect engine problems. Took me about 45 minutes, and I assume a mechanic can do it in half the time. I checked my EPC CD, and the timing chain tensioner on the 9000 is similar.

The shop that replaced my bearings was expecting a 9-5 with a hole in the block the same day I picked up my car.

My last post on the ng900 board, showing pics of bearing damage:
http://www.saabcentral.com/forums/showthread.php?t=53285
Link to a page showing what I found when I checked my timing chain tensioner:
http://www.geocities.com/ng900set/TC_tensioner/tc_tensioner.html

Good luck.
 

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I had to do the balance chain (so I did the whole lot) at 90,000 miles on my '97 CSE, because of a metallic knocking noise, especially on overrun, at first just when cold but eventually all the time.

By the way, left side of the engine looking which way? Mine knocking was very clearly from the chain end of the engine, which is of course the left, as you stand in front of the car and look toward the back.
 

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johncc said:
IBy the way, left side of the engine looking which way?
Ditto, I did not even notice that...<LOL>. Btw, by "whole lot", do you mean both chains and both sets of guides, with or w/o sprockets, oil pump, bearings?
 

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Maybe TD could give us a little more history of the 9k he suspects having the engine knock. That would save some unnecessary speculations.

Of the four 9k's I have had, I opened up the engine on all four. The worst is the 94cde I converted to 5 speed last October. It is to be expected. It was bought on Ebay for $250, sight unseen. I flat bed it home because it won't start. This is what the sump pan looks like. The oil pik-up screen was also full of sludge. I cleaned as best as I could off the sludge found in the pan, timing cover, and valve train. Replaced all seals and timing chain guides and then sealed it up. The timing chain was tout so I left it untouched. The timing sprockets and balance chain sprockets were also very good.

At 142k miles, the engine sounds much hoarse than the other 9k's I own after I put the drivetrain back together. It is currently undergoing Auto-Rx treatment with dino oil at 1,000 miles with 500 mile to go before next treatment. I plan to do two treatments and then open up the valve cover to see and compare.


 

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yaofeng said:
...It is currently undergoing Auto-Rx treatment with dino oil at 1,000 miles with 500 mile to go before next treatment. I plan to do two treatments and then open up the valve cover to see and compare.
Sounds familiar. I ran one cycle with Auto-Rx, but could not do the second immediately because I could not take a chance to run another 3000 miles with bad bearings. Still planning on it when the new bearings have broken in. Did you inspect the bearings on yours?
 

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No I did not remove the bearings to inspect. When I bid on Ebay, I was prepared to replace the engine in a worst scenario. I am reasonably confident it will last two treatments, at 1,500 miles each, to see the daylight.
 

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I think you need to do the rinse cycle between the two treatments, also, unless I misread the instructions. In any case, best of luck with it!
 

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5W 30 is not thick enough for these engines IMHO.Use 5W 50 synthetic or 10W 40 conventional (or 20W 50 Castrol).

"left" side of these engines is not helpful, especially since they are sideways to start with!

There is a motor mount under the "front" of the engine where the drive belts are which can produce a heavy intermittent knocking noise if it fails, which they do.

Bearing knock cannot be intermittent. Either the bearing clearance is too high and it knocks or it isn't and it doesn't. Thin oil will not cause bearing knock all by itself but it can eventualy lead to bearign failure if the oil film isn't strong enough.

Worn timing chains don't knock as a rule, they clank. Most timing chains are life of the car components unless the tensioner craps out which they sometimes do or it is a 90-93 engine with balance shafts which are known to suffer from failing gear teeth on the balance shaft gears.
 

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Discussion Starter #16
So yes I have switched to VollSynthese 5w-40(acts as 40 when hot). Directly after putting the new oil in the sound was still there, but when i go back tonight (after having a few drinks) i let it idle with the hood open and i dont think i heard it, have to try again tomorrow though. Does that make sense to anyone? Thin oil causing something to make a noise like that, and then thicker oil fixing it?

More history about the engine: I have only had it for 3,000 miles so I cant give a long history. The car has 112k miles but the engine has 70k miles it is from a 95 saab 9000 from a salvage so its a gamble engine, though it may have been rebuilt by a company BMI industries in Florida. I have not checked the chain tensioner or balancing chains(though i do get a slight vibration in the pedal when i get on it could that be an indication?), but i have opened the valve cover and the top guide looks like new, the chain looks good and all is very clean inside valve cover. Engine leaks nothing! Oil stays clear. It misses at idle. Gets 32 mpg highway.


More on the noise. Tap tap tap not a steady tap but erratic tapping. Not loud but audible. Over Chain/belt area. Happens more at idle, a warm idle i believe, If I open the throttle then let it drop back to idle reall fast it does it seems to do it even more so.

Alot of questions i know, but please give me any info you got. Thanks!
 

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TD said:
So yes I have switched to VollSynthese 5w-40(acts as 40 when hot). Directly after putting the new oil in the sound was still there, but when i go back tonight (after having a few drinks) i let it idle with the hood open and i dont think i heard it, have to try again tomorrow though. Does that make sense to anyone? Thin oil causing something to make a noise like that, and then thicker oil fixing it?

More history about the engine: I have only had it for 3,000 miles so I cant give a long history. The car has 112k miles but the engine has 70k miles it is from a 95 saab 9000 from a salvage so its a gamble engine, though it may have been rebuilt by a company BMI industries in Florida. I have not checked the chain tensioner or balancing chains(though i do get a slight vibration in the pedal when i get on it could that be an indication?), but i have opened the valve cover and the top guide looks like new, the chain looks good and all is very clean inside valve cover. Engine leaks nothing! Oil stays clear. It misses at idle. Gets 32 mpg highway.


More on the noise. Tap tap tap not a steady tap but erratic tapping. Not loud but audible. Over Chain/belt area. Happens more at idle, a warm idle i believe, If I open the throttle then let it drop back to idle reall fast it does it seems to do it even more so.

Alot of questions i know, but please give me any info you got. Thanks!
mine is doing the same exact thing, I'm not sure if it a knocking or a clanking, just sounds metal to metal to me, [email protected] I can give you my phone number and start it up for someone... mine sounds as if it comming from the passenger side of the engine directly below the valve cover...
 

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can you clarify some thing for us, when you say the left hand side of the engine, do you mean looking in to the engine bay from the front of the car or from sitting in the drivers seat? which is the recognised way of IDing the left or right side of the car, cus if you mean the clutch end of the engine your problem is most likely to be a blocked oil pick up pipe and as a result the piston at the clutch end is starved of oil and wares out the big end shells, if its the other end of the engine then its probably as already stated your chains, iether way you need to get things looked at before the engine is totaled
 

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Discussion Starter #19 (Edited)
sorry i meant left as in right side sitting in car looking forward.


whats a guess on cost of getting the engine opened up to look at chain parts and bearings and then replacement?

Should I be driving to work:eek: keep in mind my knock is very quiet and only at idle.
 

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Perhaps you should try to eliminate the serpentine belt, tensioner, idler pulleys, and all the driven components, since one of these could be the culprit.

Firstly, if you watch the belt while the engine is running, is it fairly steady, or is it jumping around?

You should also be able to start and run for 30 seconds or so with the belt removed without any problem, to see if the noise goes away.
 
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