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-   -   chain tensioner issue 86' 911 (http://forums.pelicanparts.com/porsche-911-technical-forum/1109374-chain-tensioner-issue-86-911-a.html)

moush993 12-26-2021 09:01 AM

chain tensioner issue 86' 911
 
I wonder if anyone has any insights on chain tensioners in early 911s.
I had been having an oil leak since I purchased the car and decided to finally track it down assuming it might be rocker shaft seepage or cam cover gaskets. I discovered that the source was from the oil feed line out of side of cam cover that leads to the tensioner and sending unit. The crush washer was somewhat disintegrated from not being the right size from what I can tell.
I also was getting a faint rattling sound from the back right side under deceleration around 1500-2200 rpm when cold. When at running temp it would go away.
My question is is there a chance the oil line sucked in some air from the gap in crush washer and messed with the tensioner pressure? Would it make sense and if so is there a way to bleed out the air?

Thanks for any inputs

yelcab1 12-26-2021 01:52 PM

There is no way that will happen. You need a new tensioner.

Walt Fricke 12-26-2021 10:05 PM

So you fixed the leak. Can you elicit this noise still? First off, I can't imagine that air could be sucked in against the oil being pushed out at way more than atmospheric pressure. And if air got in, it would fairly quickly be expelled out the valve at the top of the first chamber in the tensioner. One must remember that the oil in the tensioner only serves to dampen the normal oscillations of the chain - it is the internal spring which does the actual tensioning.

When the old, non-pressurized tensioners failed, you got a pretty constant rattle unless you babied the engine (which was convenient - you could usually drive home or to a shop). Temperature didn't seem to have much to do with it.

Before concluding you need a new tensioner, I suggest you pull the chain box cover (bit of a PITA with the engine in the car, but many have done it when converting older cars to the pressure system), and see how hard it is to compress the tensioner. If you can do it with your hands, for sure it is shot. When reinstalling a tensioner removed from a running engine, I have to squeeze it slowly in a vice in order to insert the keeper pin (which you pull out after installation).

proporsche 12-26-2021 11:34 PM

when you do as Walt said be very careful your camshaft stay put and it does not move...
Can you make a video of the sounds?

Ivan

mikedsilva 12-27-2021 12:53 PM

Quote:

Originally Posted by moush993 (Post 11557247)
I wonder if anyone has any insights on chain tensioners in early 911s.
I had been having an oil leak since I purchased the car and decided to finally track it down assuming it might be rocker shaft seepage or cam cover gaskets. I discovered that the source was from the oil feed line out of side of cam cover that leads to the tensioner and sending unit. The crush washer was somewhat disintegrated from not being the right size from what I can tell.
I also was getting a faint rattling sound from the back right side under deceleration around 1500-2200 rpm when cold. When at running temp it would go away.
My question is is there a chance the oil line sucked in some air from the gap in crush washer and messed with the tensioner pressure? Would it make sense and if so is there a way to bleed out the air?

Thanks for any inputs

When was the last time a valve clearance check was performed?
On a car I used to own, at cold start, the engine was silent. Then as the oil started to warm the valves would sometimes get a little noisy. But as the engine got to full temp, it was perfectly silent again.

As others have said, pull the tensioner to check. Getting the cover off is not that hard really. Here is a vid I took ages ago when I went through the processs of "what's causing that noise"....
<iframe width="560" height="315" src="https://www.youtube.com/embed/yUA8n75kt9c" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

moush993 12-27-2021 02:33 PM

Thanks for the replies and suggestions guys. I fixed the leak by replacing the crush washers. The rattle sound seems have to gotten less obvious.
The sound is similar to a rattling sound and im picturing a slack in chain under deceleration at a sweet spot roughly 1500-2000 RPM its a slight sound coming from inside the car from about the passenger side rear seat cushion.
I can sometimes hear it when standing still and applying accelerator right at that sweet spot if I get it just right. its hard to diagnose from the rear of car standing at the back of engine using my hand on the throttle. I don't seem to hear it at the chain box. its a bit elusive. I did take it to an old-timer Porsche guy and he could not find the sound and said it didn't seem to be a problem.
I guess I could either wait till it gets louder or take it apart and check the tensioner. I'm hoping it will start to show more obvious signs of failing slowly and not just explode out on the road.

proporsche 12-27-2021 02:46 PM

if you can hear it ,make a video with sound, so we can hear it...that would the best .

Ivan


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