Red84Cab

Team 928,
I have been working on my 85 928 and could really use some help. I have discovered a few things that I need help with.
1-When started cold the engine is quiet and awesome. As it gets warm, there appears a rattle noise on the passenger side valvetrain area. I am assuming this is timing chain tensioner/guides? I have read on the forum that this is not really an issue, but has me concerned. Any ideas on whether I should replace?
2- I am having the timing belt tensioner light come on at times. The belt was replaced a couple of years ago. I readjusted the tensioner, but the light continues to come on intermittently. Any thoughts?


I could really use some help/guidance on this before I get beep down the rabbit hole.

Thanks!

Kevin in Atlanta

Mileage?
I am a worrier by nature- I would not run the engine until:
1 - Replace the chains and chain tensioners now. Consider using 87+ version. I had an 86 where the pads disintegrated and the engine would not turn.
2 - Timing belt warning system is very reliable. Loss of fluid in the tensioner will result in intermittent warnings - ask me how I know.

Kevin

Mrmerlin

What oil grade and make are you using

Red84Cab

I am running 20W50 High Zinc.
I want to say the noise is the tensioners/pads. The sound comes from the drivers side of the engine.

GregBBRD

Obviously there's no way for me to know what your engine serial number is,
but the first 1000 (up to March 1985) '85 928's had a chain tensioner which had a design flaw..
You can find this information in Technical Bulletin #8608 (Book C, page 23.)

Very simple to modify. You need 2-928 105 614 01 spring guides.

The other option is to update to the '87 to '95 tensioners.
This used to be simple, when Porsche had the different oil lines required for the '85/'86 head.
While I believe people heat and modify the S4 oil lines...I'm just not comfortable doing that.
However, I can occasionally find the correct S3 head to S4 tensioner oil lines at 928 International.

Landseer

If intermittent light after proper tensioning, I'd be thinking about whether the correct spacer washer was installed onto the tensioner or if the circuit was damaged. Is it new behavior, or a car that is new to you?

Might be smart to strip it down and redo the TB job, unless you are confident that all wear parts were addressed, and fix the electrical circuit in the process. If car is out of service anyway for chain tensioners, assuming you are doing the work yourself or can pay for somebody else to do it. Seems like scope creep, but it can add to peace of mind.

Red84Cab

Thank you all for the feedback and guidance. You guys/gals ROCK!

I will be redoing the TBelt and update the tensioner. Also will look for the S4 tensioner and lines. If anyone has them.... please PM me!

THANK YOU!