Jim Chambers

After sitting for 3 months waiting for the thaw, the GT was exercised today. Damn, what a car. My only other 5 speed was a '78 and I think it had 100HP less than the '90. What a ride! Could not believe the power and the handling. I am in love with the car.
To my surprise and delight all instruments, computer, seat adjustments, seat heaters, seat memory, mirrors, sunroof, heater/ventilation,etc work as intended (didn't try the AC at 40 degrees). Made 90 mph with no shake or shimmy.
First event of concern was the vibration of the shift lever at high rpm. The engine winds fast and smooth but at about 5000 the shift lever vibrates excessivly and loudly. I could not hold it still with my hand. I have to believe it should not do that. Where do I look for the cause?

Second event, which really got my attention, is that the "toothed belt service" light appeared. I quickly stopped, shut it down and checked the manual. It said belt needs to be tensioned. When I restarted the warning was gone. I drove another 10 miles or so and it did not reappear. I then stopped for gas and it did not appear again on restart. I drove at normal rpms/speed but did not play "hot shoe" like I had done earlier.

The belt was repalaced 80 miles ago at Guy's Indpendent Porsche in San Luis Obispo, Ca. He has a good rep as an experienced Porsche shop. I was expecting to re-tension the belt at 2500 miles. Should I wait to see if the light reappears? All advice/experiences appreciated.

Leon Speed

The warning is there for a reason. Have it checked asap! Most folks prefer not to drive it (not even start it) until it has been checked (and solved).

Hilton

My experience with timing belt was light came on 500 miles after replacement, when pushing it to 6k+ rpms. I promptly drove home and re-tensioned it. Checked it again after another 1k miles, and it was still correct.

50 miles sounds like it hasn't been fully tensioned after fitting - in threads comparing the Kempff tool to the Porsche tension meter, the correct 32V tension is the high side of the window on the kempff tool. Depending on Guy's 928 experience and tool setup, he may have set it to the standard for 16V cars?

Also note that after turning the engine off, the belt warning will not come on for 3 minutes, regardless of belt tension. There's a delay in the system, presumably due to how much the tension varies as the block expands when warm.

The vibration could be transmission mounts, or broken bushings in the shifter linkage.

Jim Chambers

Thanks Hilton. I drove the car for about 15 minutes after two different shut downs without the light coming on. I did take it to about 5500 a couple of times, the second time to re-experience the shifter vibration. Other than the dealer, I don't think there is a Porsche shop in my town. The closest I trust is 165 miles away in Portland. I'm not sure about the dealer on a 20 year-old car. I don't have a tool but I think I see one in my future.

Mrmerlin

First i would check the belt tension at TDC, you can do this yourself by removing the right cam belt cover, if you dont have a socket to crank the engine over put the car in 5th gear and push it forward till the cam and crank are at TDC, dont let the car roll backwards.
( Note the rotor tip will be pointing to the left fender when its getting close to TDC)
then check the tension, a bent 17MM wrench with a box on one side and open end on the other is a good tool to make .
Then get some STP and a visene bottle drill out the tip so oil can flow then remove both of the bleeder nipples on the tensioner, fill the STP with the bottle from the port thats closest to the right fender ( the visene bottle tip fits perfectly into the fill port, and its very hard to overpressure the tensioner)put a rag under the other hole to catch the old oil, keep filling till you see the STP come out, it seems to be able to push out the old oil as its thicker..

Jim Chambers

A member here has kindly volunteered a loan of the Kempf tool. I just read the instructions for its use on my most excellent CD set. Will the tensioner and its fill/bleed ports be accessible with only the top passenger side cam belt cover off? Or will more disassembly be required? Thanks for the advice.

Hilton, Is the "high side" for 32V the tight side or loose side?

pcar928fan

Jim,

I don't think you can save it...might ought to just send it to me down here in Texas bro'! You don't really want to have to mess with T-belt issues and stuff. I'll take it off your hands for $10...and I'll pay to ship it down here even...

Just trying to help out!

Jim Chambers

What a guy! Now maybe if you throw in the lady in your avatar..........Don't forget I have something for you in a week or so.

Now, tell me where to look to solve the very strong vibration in the shift lever at 5000 rpm. Quiet until then.

pcar928fan

Jim,

Can't help you with the shifter...I use the superior RogerBoxes in my cars! As for the beautiful woman in my avatar...well, I can't speak for MRS. USA, but I can tell you she is as nice as she is lovely!

Hilton

"High side" is on the tighter end of the marker gap on the kempff tool. 16V cars should aim for the mid-point - I aim for just inside the tight end of the window. There's a thread here somewhere where someone compared all the different tension tools that forms the basis of this.

My preferred way to do timing belt tension is put the front wheels up on ramps and drain the radiator into a bucket - you can weddge a good-sized funnel into the gap between the hole in the spoiler and the base of the radiator, so that coolant only goes into the pucket and not all over you or the floor.

Then remove the top radiator hose for access (10mm socket)

Next, unplug and un-screw the distributor cap on the right-side (passenger side for LHD cars) (8mm socket, or flat-head screwdriver).

Then turn the engine to TDC using a deep 27mm socket on the crank bolt - the distributor rotor should be pointing to an embossed arrow on the timing belt cover once there. If it points the other way, you're at TDC on cyl. 6, and need to keep turning another crank revolution.

Lastly, undo the two M6 bolts (10mm socket) holding the right-side belt cover on, and all is revealed to measure tension.

Once you've got the tension right, turn the engine over a couple of revolutions by hand and re-measure. Then I like to pull the fuel pump fuse, and crank the engine using the starter for a final check, before buttoning it all up.

edit: "High side" threads:

https://rennlist.com/forums/928-foru...tting-32v.html
https://rennlist.com/forums/928-foru...omparison.html

Mrmerlin

nothing to remove to get to the tensioner bleeder nipples

Lizard928

For the shifter vibration you will need to replace the motor and tranny mounts.

WYIT list gets bigger with OPG and a few other things.

However I would also check the TT bearings and ensure that they are in their proper locations.

Chuck Schreiber

Jim,

You're in the PacNW and this is one of the most active 928 club areas in the nation.

Someone close (I know it's all relative) like Tom, Louie, Adam, Keith, et al are somewhere there to help you out. Call em up and help you if there is ANY question. I guarentee someone will help you out!!

GregBBRD

Check and see if he forgot to fill the tensioner with oil. That is very common and will allow the belt light to come on. Hard to imagine having a tension problem after 80 miles...unless they were clueless.

Whatever the cause, you need to look into it...before you crank the starter motor again.

Your vibration might be mounts...or a bearing migration issue inside the torque tube...as Colin said.

S4ordie

The PacNW is bigger than Texas. It is relative, just a big relative

Louie in Mosier City (150 mi from Bend 97N - 197N to The Dalles, turn left on 84W) is your closest and best resource.

You live in some of the best car roads in the nation, after winter leaves.