Identify this thing on my cam tensioner please...

[nimskov]

Hey
I bought this damaged 1975 US 2.7S engine to use as a temporary engine, while I rebuild my car's original engine.

The new engine has had a valve failure and needs a new cylinder, piston and perhaps also head.

Anyway, I was wondering what caused the broken valve - the seller told me, that he had been told by the po of the car, that the engine had been rebuilt about 30k km earlier.

So the chain tensioner came to my attention. It looks like the original mechanical type.

Part # on the housing is 930.105.P.O.KF

Its not possible to move the rod in/out at all. It can be rotated though. So I'm guessing the tensioner is dead.

Whats the obviously not original thing clamped on the rod? anti collapse thingie?

[Henry Schmidt]

Chain saver. It is designed to limit the travel on a collapsing tensioner.
It also produces a tapping noise to warn you of the problem.

[4sd911]

If you can move the tensioner rod by hand it needs to be rebuilt, it takes a vice to compress the tensioner.

[nimskov]

Thanks guys.

The seller did talk about "a strange sound" that occured periodically before the failure - naturally it was never there when he went to his mechanic...

I did try to compress it in a vice up to the point where I felt it was too much force, it did not move more than 1mm perhaps.

Does it look collapsed to you?

I'll go for the carrera tensioners when fixing this engine anyway, just curious as to the reason for the failure.

Thanks again for your replies.

[TibetanT]

Well, first and foremost, I am no expert but if you tried to compress the tensioner in a vice and it did not move much (1mm), that sounds to me like it is still a good tensioner.

Those tensioners are suppose to be better than the stock hydraulic tensioners, if these are in fact the 930 Turbo tensioners. I have a pair of these and they are installed with the safety collars to ensure there is no catastrophic failure to the engine should the chains fail, or rather the tension is lost to keep the chains tight.

Hopefully, you can still use these. Unless of course I am wrong about my reasoning and approach with regard to how a tensioner is suppose to function.

However, Wayne's book does cover the "upgrade" to the better Carrera Pressure Fed Tensioners which became stock with the introduction of the 3.2L engine in 1984.

Good luck with the engine rebuild.

[Jon B]

Nimskov,

Genuine Porsche chain tensioners had Porsche trademarks cast into the support arm, begining in the late 1960's. Your tensioner is an early "049" aftermarket 930 version with wide idler boss, meaning your engine has narrow pre-80 idler arms without bushings. Check your idler shafts for galling, and replace the idler arms with the wide, bronze-bushed versions. If you believe these tensioners have 30k km but aren't sure, be safe and replace them with new "053" Turbo or Carrera tensioners.