gazz678

Hi Guys.
Can anyone tell me if you break a belt on an 84, 928s, 4.7l. If it will do any damage to valves. I read somewhere that on the 16 valve motors that it doesn't bend valves as there is clearance between piston and valve. Plus car was only doing about 20kmph at the time. Reason being as a mate had this happen to him and has lost interest in the car and i am thinking about buying it. And can i test to see if there is damage and how.
Any ideas appreciated.
Thanks.
Gary

Doug Hillary

Hi,

As you can see I live at Airlie Beach, a fair way from you
Ring T&D Austomotive in Brissie 3852-1730
See us on Landsharkoz.com - you will be welcomed by the 928 group

There are a lot of great people here at the Rennlist site - good to see you are a paying Member!!

Regards

gazz678

Hi Doug.
Great to hear from you. Actually i get all my parts through T&D. Thanks anyway. I applied to join Landshark in Jan. of this year and for some reason i was rejected. So it sort of left a sour taste with that group.
Regards.
Gary

Doug Hillary

Hi Gary,

I think I paid you a visit about a year ago to inspect some wheels that you had for sale - is that correct?

Regards

gazz678

Hi Doug.
Ummmm, you got me there. Not real sure.
Seeya.
Gary

Jfrahm

The motor may or may not have bent valves, you can always get lucky. Trouble is, in order to inspect it for damage, you need to put a belt on it first so you can rotate the engine without bending valves. Then you can check the compression. Instead of putting a belt on the motor, you can also pull the cams, which closes all the valves, and then see if some are not closed all the way, or check the compression in the normal manner. The 3rd option is rotating the top end by hand at the same time as the bottom end, at the appropriate rate. You have a little wiggle room but not a lot. Making timing tapes for all three sprockets with colorful markings would help, then just rotate the engine in ten degree increments, keeping the top ends within ten degrees of the bottom (I believe 10 degrees + or - is safe,) and watch for valves that do not close (or better still, check the leakdown on each cylinder when the valves are closed.) You will need to remove the plugs from all the cylinders of course.


If you were spinning the engine at a decent RPM when the belt let go, you are unlikely to have avoided valve damage IMO.

Good luck,
-Joel.

ViribusUnits

Is it the US motor? If so, you almost certanly could have gotten lucky. Me, and a few other owners f the US car have broken the belt, w/o problems.

If it's a Euro, your on unknown territory...

karl ruiter

The easiest check would be to put a belt on, spin it, and check compression or try to start it. All it will cost is a belt and a perhaps a battery. Can you get your mate to agree on a price, let you do this, and then let you back out of it's no go? My '82 US and my '79 Euro both had broken or slipped belts when I bought them and they both were fine. The belt change is very easy as such things go. If you don't have a tension gauge be carefull not to overtighten the belt though as you can break the driver side cam pretty easily and cams are getting harder to find.

Don.

Yep, you're going to need a compression check to be sure. I have heard varying reports, but I believe all US and maybe some other 16V 928 are non-interference. The problem is that if your pistons have any carbon deposits on them it may tweak the valves anyway. That's why there have been some reports of 16V US 928s getting bent valves from a broken timing belt.

-Don

1978_porsche

Hmm i have a motor if you need it ,its a m28.19 out of a 1983 only asking $1000.00 for it . i bought it for my car but its not a 4.5 its a 4.7. so i didnt use it. good luck. email me if you need it make offer..