Christopher Zach

So I looked at another 928S in SC on the way back from a vacation in Fl. Guy met me near 95, I hopped in and took it for a spin. 120k miles, pretty ok shape person got the car from the first owner a few years ago and wants to sell it before going to Mexico.

Not too bad, car is a 85 928S, 32V motor, after about 3 minutes of driving the warning light and BELT TENSION lit up on the left instrument cluster. Guy pressed the clear button saying it pops up from time to time. Great.... However the rest of the drive was pretty good, engine had a slight tick in the cam gears on the passenger side which made me think Hm.

These things do not rev up much. Most of the power is down at the bottom end, so unlike the 944S I really couldn't wind it up past 5000 in normal driving. Which might have been good as I got home and see that means the timing belt tension is not good. WHOAH!

So before I buy this (and the thought of driving it back from SC to MD has been shelved for now :-) how bad a problem is that and how difficult is it to swap the belt? Or could it be the tensioner needs rebuilding (I have the automatic-ish tensioner in the 944S, and belt replacement is a pain but not the end of the earth). I know exactly what happens when the belt fails....

Or should I keep looking for the blue one?

PorKen

The [BELT TEN. o<0] light is not something to take lightly with an original tensioner! The belt tension was probably quite loose due to belt age and/or worn parts. (A 3-minute delay after startup is built into the warning system to mask the shortcomings of the stock tensioner system when the engine is cold.)

'85-'86 are pretty peppy in good tune. There are many defects which could keep it from winding up. Although it could be something simple like a disconnected air-temp sensor, more likely it's at least an original MAF sensor in need of a rebuild.

Most everything mechanical on a 928 is fairly easy to repair. I look for a good interior, first, anymore. (Working A/C is something I like now too. )

worf928

-^ What PorKen wrote.

I'll add: Don't even think about doing your first 928 timing belt job under schedule- or location pressure and then driving it across a couple of states.

Furthermore, just swapping the belt won't do. 99% of the time the belt is fine. It's other bits that the belt touches that are causing the low tension warning.

Christopher Zach

Hm. I wonder what causes a loose timing belt like that. On the 944S the belt has a spring tensioner (tensioning it is a piece of cake, loosen bolt to let spring take up proper slack, tighten bolt, do when cold, don't even really need the tension adjusting tool)) but it usually breaks due to wear (well, the .00 belts did, the .02 belts are much better) or the balance shaft belt breaks which tangles the timing belt with the usual results.

It looks like the 928S has something more like the old 911 tensioners, but I don't see if it's true hydraulic or just the normal oil filled model. Perhaps it collapsed due to bad o rings (quite possible) or evil spirits.

I wouldn't drive it back knowing this, would get it on a tow truck. However I'm wondering if this is a good basic 928 (well, it's not water damaged like the last one) but then again it's complete, but then again there is a blue one out in Pittsburgh PA, but that's an Ebay queen now and I remember it on there awhile back so maybe it was a callback or something.

Oi.

Christopher Zach

Oddly enough I just got done re-converting my 944S to R134a. I did it years ago with POE oil, which is not a good idea and the condenser got a hole in it from road crud so I finally bit the bullet, got new condenser, new dryer, and dropped the compressor, purged all the lines several times to get the old oil out, purged the compressor, put in 6 ounces of new PAG oil, new condenser, new dryer, and now I have excellent AC with 30/250 psi readings which is enough for government work. Only problem is the engine gets quite warm at idle in 95 degree temps, but the answer there is to drive fast. :-)

I guess the question is would this little guy be worth it or should I take a pass.

I think it wanted to wind up but I wasn't quite up to punching it on someone else's car when it's an unknown. Still it could be the MAF (I assume there are two as this is two 944S engines. Does it have two knock computers, I had one of those fail and the result was oddly similar)?

James Bailey

There are no o-rings no hydrolics .....the oil which you must put into thr detensioner is primarily there to transfer heat. So much misunderstanding...... it never ever increases tension the cup shaped stack of bimetallic Bellville washers reduce tension as the block heats up and expands....

skpyle

Let me address one of your early comments with my limited perspective: my 86.5 S3 happily revs up to 6000 rpm when I put my foot in the water pump.

Makes for entertaining shifts.

Landseer

85 should pull off the line; if an auto it will grab 1st, wind fast, and redline shift. Good news is that the adjustments to liven one up are simple. Bad news is the one you tested is poorly setup, poorly maintained and owned by somebody without much of a clue. Still could be a good deal, that would depend on all the ancillary condition info. It is possible for a newer Conti belt to stretch and require multiple tensionings... happened to me on 85 and 86. But when that TB light popped up ( several times, several cars), I knew everything under the covers was brand new, the exact right parts were utilized ( no substitutes ) and correctly installed, so I was reasonably confident I could add some more tension. I also knew that situation had to be addressed right them. No "comes and gos" logic without addressing it.

Doing a TB/WP job on a 944 variant is like a rock song; doing it on 928 is a more of a symphony. It is a very focused endeavor, and quite costly these days just for the parts.

The tick is likely timing chain guide wear, something its prone to. I ignored it with an 85 and suffered a derailment. (total neglect on my part / hard lesson). On the 85/6 some of those parts are NLA so you'd need to do custom fitting.


There is really zero comparison to the 911, 944, 951 or 944 S2. We get that you know them, many of us do too, this is really that different.

Christopher Zach

Fair enough. Timing chain guide wear can lead to the ramps cracking which can result in a snagged chain on the metal part of the ramp which can result in broken teeth on the cam gears in addition to the usual 12 bent valves. If the ramps are NLA that's also a problem, I doubt they are making them like they used to....

Is there a good write up for the steps to do the TB replacement? Or a site like Clark's Garage for the 928 things that just blow up from time to time.

Landseer

Yes, a couple.
Maybe the best first read is Dwayne's Garage, where Dwayne does timing belt on 87 S4.

Engine and accessories are very similar to 85.
The process is similar.
87 has different belly pans and fan shroud... some parts you have to skip through.
85 also has a bit different way the idler roller and tensioner are supported by the water pump. Overall, though, a pretty good rendition with superb pictures.


Third from bottom.
http://dwaynesgarage.norcal928.org/


Couple pics I've saved either from other peoples posts to give you a feel...

syoo8

Chris, I have an 86.5 928S and I used Mike Frye's detailed instructions to do my timing belt. It is only available in hard copy but it is totally worth it because it goes step-by-step for a 1985-86 (S3.)

Good luck-- hope you end up getting the car!

928NOOBIE

D@mn skippy they will...and with Poken's chips and new injectors and good vacuum they'll go well past 6k on accident if you aren't careful...you're kissing 80mph in 2nd if you push her past 6k with a 5 speed

Christopher Zach

Yeah, did that and got the car stuck in first, that was fun. Right now the car is down and I'm taking off the passenger's side cam covers to check and adjust the belt tension. No more fun driving without proper belt tension (and the belt ten light came on too).

Question: Is there a rubber thing on the bottom of the pedal arm that engages the upshift switch? Also how many bolts are holding on that tower cap; I have two off, can't yet find the other two...

C