Preston2207

Just bought a 928. I've been looking on these forums for months now and yall convinced me to make the purchase!! Got a few questions for you experienced folk. I have a 85' 928s 32V and when I run high (full) throttle at around 40-60mph the belt tens. Light comes on. If I run her normal (easy) nothing ever pops up. If yall could aim me in the right direction id sure appreciate it! Also, I have a problem with the sun roof. The driver side has a small little hinge bracket that's broke. It takes Phillip screws. And it mounts the Pop up bracket thing to the roof. Anyone know what this is called so I can order a new one!

Mrmerlin

I would suggest to not run the engine till you have figured out why the belt light is coming on.
It may need an adjustment and or the water pump may be failing or worse the cam could be damaged.
A kempf tool is a good tool for checking the belt tension.
This is done with the engine at TDC and the engine cold.
for your engine the pointer should be at the top edge of the window .
That said I would suggest you get the WSM as most info is in the manual.

If you have not read the FAQ at the top of the page that is another great resource

WallyP

I'm sure that in your reading you have discovered that the more you learn about the timing belt, the more paranoid you become. The price of a belt failure on the 32-valve cars is very high. You need to make yourself knowledgeable enough to be able to pull the covers and make a reasonable guess of the belt tension, age and condition, as well as condition of the tensioner, idler, sprockets, etc.

Most folks on here will tell you that the best approach is to do the timing belt job ASAP, so you know where you are. Not always, perhaps not even usually, necessary - but it can give some peace of mind.

WyattsRide

Purchase Jim Morehouse's CD with the Work Shop Manual and PET. It is invaluable. The PET (Electron Parts Catalog) will help with determining part numbers.

Also, contact Roger at 928sRus or 928 International. They can also help with determining the parts you need.

Instead of trying to describe what you need, pictures are worth a thousand words. Many here will figure out what it is, very easily.

zekgb

As others have said if you don't know the last time the Timing Belt and Water Pump were changed you should consider them in need of changing and shouldn't drive the car until you do. That said, your car has a particularly finicky belt tension warning circuit - there is a copper strap with one end connected to the tensioner that grounds to the block when the proper tension is present - the other end connects to a male spade connector mounted on the tensioner idler arm. To that spade connector is attached a short wire which threads through a grommet in the center cover. On my 85 I had multiple belt warnings that were caused by the orientation of the male spade connector on the tensioner idler arm which caused it to come in contact with the center cover, the vibrations from which eventually caused the spade connectors to intermittently lose contact - very frustrating to diagnose as at rest the circuit tested fine. Also that copper strap can break as well causing permanent belt tension warnings (mine eventually did) when you do your belt you can replace this part with the wire based one from an S4 that is much more reliable (and costs $8 vs. $38 to boot.)

Anyway, long story short - get very familiar with everything having to do with the Timing Belt tensioning system, this is not an area you can ignore or even skimp on taking care of correctly.

davek9

All good advice given, OP do you know any history on the car, any service records, whats the mileage?

Just speculating that she was sold knowing a T belt job was in the immediate future and the average cost "if you do the work" can easily reach $2k.

My only addition to all of the above advice given, is to do it, do it now and do it right, don't skimp on parts or known quality parts.

Many a 928 have been scrapped due to bent valves and the cost of that (engine out/removal) repair

Dave K

davek9

Not trying to scare you off and I'd like to add that as noted the warning light could be as simple as a bad wire connection for the light and all else is good to go.

However the only way you can be sure is to look at the belt and the gears/pulleys.

Recently I seen one that was doing the exactly what you described, when I removed the belt covers a lot of Belt dust/rubber.
Turned out to be an over tensioned belt that was chewing its way through the Oil pump gear, and soon would have resulted in a complete failure.

James Bailey

This is a disaster waiting to happen.......

depami

Could also be that the belt is new and just needs a re-tension.

Preston2207

Talked to the PO. He had the TB and tensioner changed 4yr 5k miles ago. Can it be the accessory belts slipping? Or loose? Going to check proper tension to avoid a catastrophic failure. Hopefully a sensor malfunction??? Thanks guys. Yall make jumping into the exciting/scary world of the 928 more enjoyable!

hwyengr

Since there's a separate belt for each of the accessories, slipping belts there would not cause the TB light to turn on.

You should ask the PO whether they re-tensioned the belt 2,000 miles after changing it. If not, that could explain why the light is on. But since you should check it anyway, calling them back isn't super important.

You'll need to buy or borrow the timing belt tension check tool. Don't just crank the tension adjuster blindly, too much tension and you'll ruin the cam gears.

bureau13

It's unrelated to the accessory belts...the light only affects the timing belt. Now, if the PO changed the belt and never went back in to adjust tension, it could simply have loosened up a bit, as depami indicated above. I wouldn't assume it though. Take off the covers and inspect, order a Kempf tool to check tension, etc. Do you know if the water pump was replaced when the belt was changed? How are your engine temps when driving? I'm not sure how to diagnose an impending water pump disaster, which seems to be the culprit behind timing belt failures a good portion of the time, but if you see temps climbing when the tension light comes on, that would be a bad thing. In any case, I wouldn't drive it until I've checked tension with the Kempf tool and inspected the workings under the timing belt covers. Take pics of anything you need feedback on and post 'em here. I'm just learning this stuff too.

mark kibort

pretty easy to check the belt tension .. i have some tricks to do it with no effort, for crude checking. (i make a hole in the cover with a 1/4" drill bit and use a small dowel to push on the belt for feel.)

anyway, the accessory belts have nothing to do with the timing belt. you could tension it by (1/4- 1/2 )turn if you are really worried , since it is running and not slipping now. that would give you insurance until you check it the proper way.

Preston2207

The water temps stay steady in the normal zone. I plan on checking tension with a kempf tool and while I'm in there should I change the belt? Like a while you are there thing? Light doesn't come on unless I give her extreme throttle at around 60mph when she drops a gear. If I drive it like its a regular car I never see the light.

Preston2207

And btw to ease everyone's mind it's parked until I resolve this issue! I don't want to trash my new favorite ride!!!