khalloudy

Hi All,

Following up on my previous post on a sound coming from the timing belt area as the belt moved forward, I proceeded in having the front torn up again to replace the water pump with a new one from Porsche (old one was about 20 years old with about 10k miles on it). The biggest surprise came at the tensioner where the boot seems t have turned to Jelly at the top causing it to flutter, the pin was disconnected and the whole thing loose. I am wondering if this was part of the issue and more importantly what would turn the boot into Jelly! I am using Porsche transmission/axle fluid (75W-90) 000-043-305-03.

Also the lower plastic shroud for the belt cover has a broken piece where it connects to the metal upper shrowd.

Any feedback is greatly appreciated.



Jelly Boot

Jelly boot Part II

Totally softened out and the clip seperated from the pin piston

Inspected inner gasket and it is tight and rubber did not feel impacted by whatever softened the outer rubber

All cleaned up and ready for reinstall - Dwayne writeup

Center belt cover has plastic piece broken where it meets the upper right aluminum belt cover. I wonder if this has anything to do with anything.

FredR

No idea why you would use diff oil in the tensioner- it is designed as a damper as well as a tensioner. Maybe there was an additive in the lube you used that softened the rubber up the way it did but who knows? As long as you have the tips on how to assemble it you should be ok- it is easy. The problem child is the bolt if you reuse it. The threads have some kind of sealant in them to prevent the oil from escaping as the threads are not of the sealing type- some kind of thread sealant is the order of the day if you do not have a new bolt.

khalloudy

Fred,

Thank you for the feedback. I used the Porsche fluid as it said 75w-90 and I thought that is what is required for the tensioner! as for the bolt unfortunately it was a new one I just installed last year. I will look for some thread sealant. I did notice it had Loctite blue on it and has some kind of coating.

What do you recommend for tensioner oil? Also you think the cover with that broken lip is ok to be used until the next time I tear thing apart?

Sincerely,
Khaled

FredR

Khaled,

Apologies- brain fade my end! I have only services my tensioner once about 8 years aog when I did my first TB job. List recommendation was to use STP which I did but it was a sod of a job to get the stuff into the body- used a syringe in the end of heating the stuff up in hot water. For some weird reason I had it my head that the stock fill was engine oil but in fact in the WSM it suggests a striaght 90 wt oil.

Given that is the factory fill then forget my comment about the oil being the case- more like something that hit it from the outside perhaps- was the engine bay cleaned with any solvents by any chance?

Rgds

Mrmerlin

I use STP oil treatment oil to fill the tensioner,
something in the oil you used is eating the rubber of the tensioner

Adamant1971

I use STP also. I usually warm it up a bit to make it easier to pump into the tensioner. You will need to take it off and clean out all of the gear oil and get a new adjustment bolt.

khalloudy

Fred,

Don’t recall cleaning the engine with anything but there was some residue from the coolant there when it was drained/refilled and pooled up and around. Not sure if the coolant had anything to do with it. Also the guys like to use Kerosene to clean the front of the engine from oils when done with work… I will look for STP regardless to use.. even though to note that the massive degradation of the boot was from the top meaning contact with something that ate it away. It was like putty glue literally. The sealing ring inside was new!

Thank you Stan, will look in the market for STP. I see it is available. Hope it is the same type.

Thank you buddy. I will work out the STP as we put thing thing back together tomorrow.

ROG100

It is usually rock hard with age, like plastic.

Mrmerlin

NOTE dont use a hand pump to fill the tensioner you can over pressure the boot and blow the inner C ring off
I use a Visene bottle with the tip drilled out a bit this way you can not over pressure the tensioner

Petza914

Just one more reason the Porken tensioner is the way to go for normal 928s - no adjustments, no oil, no tensioning tool required, etc

just saying

mj1pate

no issues with factory tensioner either…if installed correctly. Both are good choices.
the fuel crossover hose (under the oil fill neck) could have been leaking. But I don’t know if any hydrocarbon could melt that rubber.

khalloudy

Hi Guys,

Just an update. We redid the whole front end thingie with a new belt and rebuilt tensioner and refilled with oil. I tried the STP for half the day and the sucker would not get in at all. It has the viscosity of glue! Went back to 75W90. Anyhow, I did notice that I did make a boo-boo that I filled the tensioner with oil after installing it and before checking and adjusting the tension. Not sure if this makes a difference and is a cause of the mess. Any feedback is appreciated!

khalloudy

Good call Michael. I will check though I do not have any fuel smells from the engine bay. On the other hand, as I mentioned earlier, they tend to clean the engines here from oils and residues with Fuels and Kerosene… maybe one of them was super abrasive.

FredR

The belt tension is purely mechanical. I see nothing wrong with what you did

Speedtoys

Stop leak additives will do this.

Should be a warning to people that rely on those for atf/oil leaks.