1.8T timing chain problems/questions
09-12-2002, 01:58 AM
#1
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1.8T timing chain problems/questions
My 2001 A4 makes a god awful rattle on startup. Been slowly getting louder till now it's real ughly. At first, we believed it was an exhaust component - heat shield, something. Nope, nothing could be found. Once running, no bad sounds.
Finally drove by the dealership, service chief - I didn't make that up
- comes out to listen. He says that he believes the timing chain tensioner is shot; this engine is a 2001.5 variable cam timing (I realize that one cam is driven by a belt and then that cam drives the other with a smaller chain). He believes it happened because of a failure in the oil drainback check valve right above the oil cooler mount, thus allowing too much (all?) of the oil to drain out of the head and the tensioner goes dry.
Car goes in next Wed for replacement of the check valve, new tensioner etc. Unless they find something else of course.
Car has 24k miles. Is there anything else that might have caused that damage? Does the diagnosis even sound reasonable? IE is this something that can fail in this way? And with such a young engine?
Oil is Mobil 1, never let drop low. Some hard driving but no major abuse or anything. Just wanting to be prepped for a non-covered situation since the car has been modified ie exhaust, shocks, that sort of basic thing. Mostly they know all about those mods - ie they put the shocks/springs on the car for me.
thanks
Finally drove by the dealership, service chief - I didn't make that up
- comes out to listen. He says that he believes the timing chain tensioner is shot; this engine is a 2001.5 variable cam timing (I realize that one cam is driven by a belt and then that cam drives the other with a smaller chain). He believes it happened because of a failure in the oil drainback check valve right above the oil cooler mount, thus allowing too much (all?) of the oil to drain out of the head and the tensioner goes dry.Car goes in next Wed for replacement of the check valve, new tensioner etc. Unless they find something else of course.
Car has 24k miles. Is there anything else that might have caused that damage? Does the diagnosis even sound reasonable? IE is this something that can fail in this way? And with such a young engine?
Oil is Mobil 1, never let drop low. Some hard driving but no major abuse or anything. Just wanting to be prepped for a non-covered situation since the car has been modified ie exhaust, shocks, that sort of basic thing. Mostly they know all about those mods - ie they put the shocks/springs on the car for me.
thanks
09-12-2002, 06:27 AM
#2
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Well... if the tensioner was broken, you would not be driving the car right now.
The tensioner is what keeps that belt snug up to the crank and cam gears. If the tensioner is damaged or breaks, it will allow the belt to come loose, which would cause the camshafts to stop turning, thus destryoing everything from the head gasket up. That would be very bad.
I don't know much about what can cause them to go bad at 24k miles. But, lack of oil sure does sound like a reasonable cause. Timing belts and tensioners are items that can fail and that must be replaced at a certain interval. I think on most 1.8T engines, that interval is 60k miles... but a lot of people do it soon after 50k. There are a lot of stories of people who have 52k miles on the car and the tensioner breaks....
One good thing is, none of your mods would be the reason for any damage. Another good thing, you will (should) have a brand new timing belt and tensioner, so you really don't have to worry about it for another 50-60k miles!
Hope that helps.
PeteH
I don't know much about what can cause them to go bad at 24k miles. But, lack of oil sure does sound like a reasonable cause. Timing belts and tensioners are items that can fail and that must be replaced at a certain interval. I think on most 1.8T engines, that interval is 60k miles... but a lot of people do it soon after 50k. There are a lot of stories of people who have 52k miles on the car and the tensioner breaks....
One good thing is, none of your mods would be the reason for any damage. Another good thing, you will (should) have a brand new timing belt and tensioner, so you really don't have to worry about it for another 50-60k miles!
Hope that helps.
PeteH
09-12-2002, 07:25 AM
#3
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the way he talks
this isn't the normal cam timing belt that is at the front of the engine, it's a smaller like device which guides the chains which connect the 2 camshafts. And it dry rattles pretty darn nicely 
09-12-2002, 07:27 AM
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Heh...
All 1.8s have the chain and belt arrangement. I've never seen the chain tensioner, I don't even know if it has one. The pictures that I have seen don't show one, but my EKTA predates the variable cam. The belt tensioners fail, but they don't make noise.
If there was a chain tensioner, all it does is take up slack. They are typically spring-loaded nylon/teflon blocks, so there is little that needs lubrication. As the other poster said, you have nothing to lose and everything to gain by having them go in and change everything.
If there was a chain tensioner, all it does is take up slack. They are typically spring-loaded nylon/teflon blocks, so there is little that needs lubrication. As the other poster said, you have nothing to lose and everything to gain by having them go in and change everything.
09-12-2002, 09:38 AM
#6
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Mine is sure loud, sounds really bad. As long as the tech is good, I agree.
New(er) parts are better than older ones as long as they are installed with care I just hope (1) the chain tensioner is the only thing damaged (why wouldn't the cam have extra wear?) and (2) the failure of the check valve is a fluke.
I just hope (1) the chain tensioner is the only thing damaged (why wouldn't the cam have extra wear?) and (2) the failure of the check valve is a fluke.
09-12-2002, 06:21 PM
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Chain tensioner adjusts the advancement of the intake cam....
Makes noise on cold startup only, (usually) due to the oil draining out of it. there's a check valve in it, too, I've replaced them but never a check valve down at the cooler(?). Wonder what exactly makes the noise. Slack in the chain? I guess.....
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09-13-2002, 06:26 AM
#9
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Re: 1.8T timing chain problems/questions
Had the same thing happen with my 2001 1.8T A4 at about 28K miles. It was indeed the timing chain tensioner. Replacement part was different than the original, indicating to me that the original is a faulty design. If you do a search of all forums on "timing chain tensioner" you'll find that this is a recurrent problem on the 1.8T since as early as '96. In my view, Audi should issue a recall. Mine (and yours) is covered by warranty, but it would have been quite costly post warranty, especially if chain failure had resulted in warped valves, etc. I mean, we're talking about thousands of american dollars.
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