Cam Chain Tensioner Replacement Interval
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From: Mile High
Cam Chain Tensioner Replacement Interval
I have an '89 944S2 with the 16 valve head. There is no "official" recommendation for changing the tensioner on the cam chain.
Is there a recommended interval for the 928?
If so;
How often should the assembly ($315 from dealer) be replaced?
How often should the nylon ramp from dealer, $25 from Zims) be replaced?
There is a long thread titled "Cam Chain Tensioner - Plastic Ramp" in the 924/944/951/968 board from August that has a picture of the part in question.
Thanks in advance.
Is there a recommended interval for the 928?
If so;
How often should the assembly ($315 from dealer) be replaced?
How often should the nylon ramp from dealer, $25 from Zims) be replaced?
There is a long thread titled "Cam Chain Tensioner - Plastic Ramp" in the 924/944/951/968 board from August that has a picture of the part in question.
Thanks in advance.
Burning Brakes
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When I had the heads rebuilt at 111kmiles, I replaced the check valves and chains. I also replaced all exhaust valves, the 2 bent intake valves, the associated 18 valve guides, gasket set including: cam cover gasket, head gasket, intake gasket, o-rings for bolts, oil seals for spark plugs and cam shaft ends. Of course, always replace crush washers at check valves. I found the fuel injector o-rings at parts plus. Wear on the tensioners was visible, but minimal. Therefore, I do not advise replacement of chain tensioner, and did not replace such. Does the 32 valve repair apply to the 16 valve? My tensioner was between the cams on each head. However, if you are in that far, and want to spend the money, why not? Your heads may be different.
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From: Mile High
There is a chain between the second and third cylinder that operates the exhaust valves.
The cahin has a nylon ramp/guide that is held in position with a hydraulic tensioner.
The part number for the ramp is a 928 part so I am assuming it the same in the 32valve 928 motors.
The motor is working fine right now, I'm thinking of doing this as a preventative measure.
Thanks again in advance
The cahin has a nylon ramp/guide that is held in position with a hydraulic tensioner.
The part number for the ramp is a 928 part so I am assuming it the same in the 32valve 928 motors.
The motor is working fine right now, I'm thinking of doing this as a preventative measure.
Thanks again in advance
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From: Ball Ground, GA
This chain tensioner is one of the little mysteries of the 928. The tensioner is virtually identical on the 944 and the four-valve 928 - yet tensioner failure is apparently common on the 944, and virtually unknown on the 928.
As a result, 928 owners don't usually replace the tensioners.
As a result, 928 owners don't usually replace the tensioners.
Burning Brakes
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Hi Tom and Wally:
I am glad to see Wally's explanation. I looked at the picture on the link. The plastic in the 944 is orange. It seems it was a different color on the 928. The 944 ramp seems longer too. Perhaps the 944 plastic is more brittle, and receives more levered force.
I was told that the chain, and check valves should be replaced. I doubt you can replace the chain without removing the cams. I have a procedure for removing cams without use of special tools on Greg Nichol's site. You need to be very careful, and loosen bolts slowly, in a diagonal crossing pattern. You need Loctite 574 for cam towers. I would replace the rubber mentioned in my earlier post too. If I can be of help, send me an email, or respond to this board.
I am glad to see Wally's explanation. I looked at the picture on the link. The plastic in the 944 is orange. It seems it was a different color on the 928. The 944 ramp seems longer too. Perhaps the 944 plastic is more brittle, and receives more levered force.
I was told that the chain, and check valves should be replaced. I doubt you can replace the chain without removing the cams. I have a procedure for removing cams without use of special tools on Greg Nichol's site. You need to be very careful, and loosen bolts slowly, in a diagonal crossing pattern. You need Loctite 574 for cam towers. I would replace the rubber mentioned in my earlier post too. If I can be of help, send me an email, or respond to this board.
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From: Mile High
Thom,
From what I understand, the nylon ramp starts out white then become orange.
I called a local repair shop that specializes in Porsches, and was recommended by the parts guy at the Porsche dealer.
I was told the cam tensioner is replaced when it goes bad. He offered to listen to my cam with a stethoscope to see if the valve cover should be opened/removed.
I think I'm just gonna change the nylon ramps on the tensioner next oil change when the car has 69K just to be safe.
I will then listen/monitor for the chain to start slapping, and when it starts slapping a bit, I will replace the hydraulic tensioner. That is unless someone finds something to tell me to do it sooner.
Thanks
From what I understand, the nylon ramp starts out white then become orange.
I called a local repair shop that specializes in Porsches, and was recommended by the parts guy at the Porsche dealer.
I was told the cam tensioner is replaced when it goes bad. He offered to listen to my cam with a stethoscope to see if the valve cover should be opened/removed.
I think I'm just gonna change the nylon ramps on the tensioner next oil change when the car has 69K just to be safe.
I will then listen/monitor for the chain to start slapping, and when it starts slapping a bit, I will replace the hydraulic tensioner. That is unless someone finds something to tell me to do it sooner.
Thanks
Burning Brakes
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Hi Tom,
That sounds good. I quess chain slop would be audible. At that indication, I would replace the chain, and probably not the tensioner. The chain is about $15. Loctite is about $30. Rubber pieces should come in a head gasket set... don't know that cost. Mine also has a check valve. It can be called a hollow bolt. Oil passes through it, and is prevented from back flow. Therefore, it is a check valve. Mine were $15 each. They can go bad... cheap preventive maintenance. I was also concerned that your rubber would leak oil after it was disturbed.
Note that I keep revising my earlier post periodically when I think of more things that I replaced.
Good Luck,
That sounds good. I quess chain slop would be audible. At that indication, I would replace the chain, and probably not the tensioner. The chain is about $15. Loctite is about $30. Rubber pieces should come in a head gasket set... don't know that cost. Mine also has a check valve. It can be called a hollow bolt. Oil passes through it, and is prevented from back flow. Therefore, it is a check valve. Mine were $15 each. They can go bad... cheap preventive maintenance. I was also concerned that your rubber would leak oil after it was disturbed.
Note that I keep revising my earlier post periodically when I think of more things that I replaced.
Good Luck,
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