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Tensioner failure >opinions?<

Ok, so long story short, after 150 miles I had a PRESSURE FED tensioner fail on my newly rebuilt SC motor. The motor came with the tensioner upgrade when I got it.

The question I have is this. Should I just replace the bad tensioner

OR

replace the entire pressure fed setup with the turbo tensioners?

Opinions?

Edit: Forgot to mention that I am running a Daugherty cam with race springs.

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Last edited by Trackrash; 03-02-2017 at 08:53 AM..
Old 03-02-2017, 08:19 AM
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Everything is expensive, put another used one in. Buying new hydraulic is as or more expensive than the Carrera pressure fed.
Usually the few I've seen had the bleeder broken off or vibrated out.
Bruce
Old 03-02-2017, 11:13 AM
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Get a new set.........

Quote:
Originally Posted by Trackrash View Post
Ok, so long story short, after 150 miles I had a PRESSURE FED tensioner fail on my newly rebuilt SC motor. The motor came with the tensioner upgrade when I got it.

The question I have is this. Should I just replace the bad tensioner

OR

replace the entire pressure fed setup with the turbo tensioners?

Opinions?

Edit: Forgot to mention that I am running a Daugherty cam with race springs.


Gordon,

Buying a used set is cheaper but it does not have any warranty. Buy a set from our host and you will have less aggravation. I have three (3) sets from PP before finally able to do the right bleeding procedure. Actually the two (2) previous sets were not properly bled (my mistake) until I used John Walker's method of priming the tensioners using an oil manual pump/feeder.

Are these tensioners the one you have been tinkering before? Time to bite the bullet.

Tony
Old 03-02-2017, 01:58 PM
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Yes, I have ordered a new OEM unit to replace the one that failed. Yes, it was the one that I "fixed" in the other thread. I will update the other thread when I have some more info to share.

The tensioner went soft after three weeks and about 150 miles. The weird thing is, after I removed the failed tensioner I used a clamp to fully compress it. The piston extended after I removed the clamp and it then felt solid. So I am guessing smething to do with the check valve at the top, I guess, not working properly with the vibrations of the chain are pounding on it. I will have to do some more testing and post when I get a chance.
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Old 03-02-2017, 02:25 PM
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Right choice to replace with new, not used. Have not had an issue with these using DR cams and springs in the past.
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Old 03-02-2017, 03:48 PM
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Do you have the wider idler arms? My understanding is that the narrow ones cause many of the failures.

-Andy
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Old 03-03-2017, 07:55 AM
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Yes, wide bushed idler arms. Just checked and they are freely moving on the shaft. Not binding.

I also checked to confirm the supply line was sending oil to the tensioner.
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Last edited by Trackrash; 03-03-2017 at 12:10 PM..
Old 03-03-2017, 09:52 AM
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Quote:
Originally Posted by Eagledriver View Post
Do you have the wider idler arms? My understanding is that the narrow ones cause many of the failures.

-Andy
100% true.

We offer our Supertec update tensioner Arms and will soon offer rebuilt factory wide tensioner arms as well.
Ken @ 911 Vintage Parts, 760-731-4911 0r info@911vintageparts.com has good used factory wide tensioner arms in stock.




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Old 03-03-2017, 02:16 PM
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^ True.

The 3,0 and 3,2 motors with race springs will put stresses on the chain mechanisms that were not there before.
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Old 03-03-2017, 05:13 PM
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QQ if I may - if both the mechanic and I have heard chain lash at one time or another, is that particular Carrera tensioner serviceable? Or should it be replaced without question? Tensioners have been fitted for at least 20k miles now.
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Old 03-04-2017, 07:11 AM
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According to Porsche, if the tensioner's piston is not firm, it is defective.

Remove the chain cover and see if the tensioner is firm or not. In my case, when I looked at my tensioner, it was collapsed. So new tensioner it is.
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Old 03-04-2017, 09:29 AM
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The tensioner is not really serviceable. You can (with some difficulty and risk of damage) disassemble them, so you could clean it. But I am dubious that oil contamination or debris would be found in a tensioner and not throughout the motor. There are no replacement parts available as far as I know.

If it were worth it, some shop somewhere could replate the cylinder, and the piston too, and rebore/hone things back to within whatever spec there is. And fix anything else which could go wrong, but there isn't much:

Obviously any physical obstruction in the port leading into the supply chamber would be an issue, but it is fairly large so that is unlikely. If the small drilling to the supply chamber relief valve were blocked, or perhaps enlarged, that might be an issue. The relief valve, being external, is vulnerable to being knocked off, and of course it is important. Then there is a passage from the supply chamber to the working cylinder. And there is a one way valve (looks just like the relief valve) which allows oil to pass up into the cylinder below the piston whenever the piston is pushed by its spring upward a hair as the chain bounces around. If this fails, the piston can just push the oil back into the supply chamber, defeating the purpose of the oil and piston acting as a shock absorber. The spring does all the tensioning, and the oil stuff just dampens the significant vibrations caused by the chain and gears, just as a shock does for your tires.

Of course, if the piston, the cylinder, or both are worn or have a big groove along one side of the piston, the oil can escape and not do its job.

Then there is the system whereby the pressurized oil, when the piston is compressed, can ooze up and out at the tip of the piston. I suppose this is to allow some minor further adjustment of the dampening, but perhaps really to allow the oil to circulate some, so you don't have the same old oil sitting in there for 100,000 miles. In any event, this is part of what allows you to compress the pistion for reinsertion in a vice or the like. So if that is clogged there might be problems.

I don't know of anyone who has disassembled a lot of failed tensioners to try to figure out just what fails. The only failure I have had was having the external relief valve pop off - and that was my fault, because I had somehow dislodged it, and then shoved it back in, hopping it would hold. And it did - for some months, but not forever.

But I suppose you really mean by serviceable should you replace it.

I am dubious of my ability to tell much about the internal state of things by ear, especially if it is something which comes and goes. If you want to frighten yourself, just take your engine stethoscope and probe around all over things - what a cacophony. The best one can do is careful comparison from this spot to some equivalent spot to persuade yourself that rod 3 is or is not louder than the others, or exhaust valve 2, and so on. With the chains it is only side to side. Lick doctors who have listened to hundreds of hearts or chests, at some point you can tell quite a lot.

Me, I'd not assume that some transient noise in this area, especially if it went away at some point, meant impending doom. Fact is, if the tensioner quits you can still drive the car home, or to a shop. You just keep the revs down, and maybe find an RPM where the noise is least because the chain vibrations are least.

The bugaboo with the earlier cars about skipped timing _ which indeed ould wreck the engine instantly - seems to have had to do with the rubber based chain rails. The rubber would harden, and some would break off, and in the fullness of time a chunk would bet into the chain gear and physically force the chain off the sprocket enough for a tooth or two to slip, etc.

So I'd not be going into a street car motor with 20K tensioners based on some noises which came and went.
Old 03-04-2017, 09:54 AM
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Thanks chaps - my engine is apart right now anyway and this was one area we wanted to investigate. My engine builder will dig a bit deeper. I was surprised to hear chain lash after 20k miles, more surprised to hear it quieten down again somewhat, with no other changes made. The engine builder doesn't think its oil viscosity related either (running 5/40 for past 30k miles).

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Old 03-04-2017, 11:48 AM
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