Hifive

Hi all,
First post so sorry it's one where I'm looking for technical advise.

I'm in the middle of a T belt change on my 1989, 928 S4 (RHD) and I've found significant wear on the oil pump sprocket.
I started this job because the car developed a clattery tapping noise from the front of the engine last week.
I assumed the tensioner was on the way out, and while the tensioner boot is cracked the rollers seem OK.
Could the oil pump cause this kind of noise and what could be the cause of the wear on its sprocket.
The wear is so bad that there is a pronounced lip at the very rear of the sprocket where the belt was not running.
I am awaiting the loan of a tensioning tool but it the belt doesn't seem too tight and the cam sprockets seem OK.

heres a pic of the sprocket/gear with the wear arrowed in blue.

Regards, Mark.

Edit: car has 137000 Miles

Landseer

That is common. I've had to replace 3 or 4.
Expect a similar pattern on the crankshaft gear and be sure to replace it despite the elevated cost.

gbgastowers

That engine is a little on the dirty side. You might possibly have less problems if it was clean(or maybe cause more by messing something up in the cleaning process). Gunar

123quattro

Mine was worn like that on my 84 from having the belt too tight. I replaced it with a good used piece for about $20.

Mrmerlin

I would venture a guess they your waterpump is bad.
Since you have the engine taken down i would suggest to replace all of these parts use new pieces,
so to prolong usefulness,
plus since you have an interference engine,
a belt failure will be big money compared to replacing these parts
1 kempf belt tension tool
New crank drive gear,
New water pump
New pivot arm bushings
new belt tension roller
new idler roller
new Oilpump gear in steel remove the 1mm spacer behind gear when fitting steel unit
new cam gear pullies
New tensioner boot,
new tesnioner gasket
new O ring in tensioner
3 oil pump bolt O rings
New oil pump O ring
new oil pump radial seal
new crank radial seal
new timing belt
a few cans of brake cleaner to remove all of the crud
STP oil treatment to fill the oil pump and fill the tensioner

Then you can go from this to this..

NOTE these are 16V pictures your engine will be slightly different but you will get the idea

jpitman2

I thought the oil pump gears went to steel early on, or was that the crank gear?
jp 83 Euro S AT 52k

123quattro

My 84 was aluminum.

the flyin' scotsman

What Stan said except junk the OEM tensioner and pullies and get yourself a Porkensioner with a good Bates timing belt. If you have the money then theres the updated water pump that essentially with the other upgraded components gives many many years of worry free driving.

BTW............first thing is clean that thing.

Jadz928

I think the oil pump sprocket went from aluminum to steel mid-year '87.
Crank sprocket has always been steel.

Hifive

Thanks so much for all the good advise guys.

This car is new to me so It's good to know the wear on the oil pump sprocket is not uncommon.

I'll now go and tot up the price of all the parts suggested by Mrmerlin, divide the total by 2 and see can I run that plan past she who must be obeyed

Who sells the porktensioner?

Thanks again,
Mark.

Picture of the patient and her Stable mates.

Mrmerlin

since your a member click on user CP at the top of the page then click on edit signature then add your year of car trans type and model and any other options or colors , good luck with your patient

SeanR

Have yet to see any with a steel oil pump gear in the later years. All have been alum. If anyone has one with round teeth they want to get rid of, I want one for my car.

ROG100

Malcolm,
Is that a Master Bates Timing Belt you recomend??????????
Roger

SeanR

Those are the only ones I use, frequently too. But mine are the deluxe issue ones, 1/2 the time to get the job done.

ROG100

Hifive,
Welcome to the Shark tank - that is a nice collection you have.
I like the way the front door matches the car colours.

I sell the PKensioner and all 928 parts if I may be of service.
Best,
Roger