I have a 1980 5 spd with 43000 mile that continually fouls the number 8 plug. I have done compression tests and talked with local mechanics about the results. The consensus is a leaky valve guide. None of the locals want to tackle the job. I live in north central Arizona, about 100 miles from Phoenix. Are there any shops or dealers that any of you would recommend to do this work? Or is this something that I might do myself, I have slightly better than average mechanical abilities and a good assortment of tools, but most of my experience has been in repairing construction equipment, backhoes, compactors, small engines, etc.
Any suggestions would be appreciated.
Thanks, Marvin

 

I've got limited experience with this, so this is more of a question than any kind of answer-
Are you seeing blue smoke when you accelerate from idle, after sitting for a few moments?
That's one indication of a worn valve guide on the intake side.

 

MJ,

If you are 100% certain of the comp tests (did you do leakdown as well? hot?) then it might be the fault mode.

Before I undertook the task, I would be 100% that I do not have a leaky/over flowing injector or an intermittent short in the #8 plug wire (either of these can cause fouling).

Can you do it in the garage with a decent set of hand tools? All but the machine work. You'll need a flywheel lock tool (~$50) and a couple of other things, but it IS quite doable. If you have a cherry picker, I HIGHLY recommend pulling the motor - it is MUCH easier to perform all the tasks with the motor out. I have pulled the heads with the powerplant in situ once, just to see how much fun it was. It wasn't. But, if you're on a leisurely pace and don't mind some funny stretching, it can be done with the motor in the car.

If you can work on an engine, you can work on a Porsche engine. No Black Forest Magic, just a few things that are different than a multi-cylinder whatever. If you don't have the manuals, get them, or find the info on disks package. You MUST have that data to do the work. If you're not comfortable doing it, no biggie, just find somebody in PHX, I'm sure some of the Phonecians will chime in soon.

The most critical part of any of this stuff is to get the machine work done by somebody who does water-cooled Porsche stuff (928/944/951/968). The machine work must be done right, not by ol' Cooter who does a cheap job on 350 Chebbys. It's not that high-tech, but you GOTTA know the set-up and measurement procedures to do it right. Spend an extra $100 and ship them wherever you have to. You will have to replace the head gaskets while you're in there, and a good machine shop will mill a couple of 10thousandths to get the heads flat and strongly recommend a valve job - it's really very little extra to get those things done as well as getting new guides.

BTW- Hope all is well in Sedona. Nice place, used to go up on weekends all the time when I lived in PHX.

Greg

 

Either valve guide or could be the seal If compression numbers are good), I messed up and forget to seat one fo the seals when I re-assembled my engine. Would foul the Platinum + 4's, single plat ran much better.

I would imagine that the seals on a 1980 car with low mileage would be v brittle.

As Greg mentioned well within the capability of a competant DIY mechanic, you'll find the gasket set is probably the most expensive part. Now while you are in there you could make quite a list of other things to do too !!

Chris

Chris

 

Gregg K,
Yes, I do get blue smoke after a short idle.

gbyron,
I have changed the injector and swapped the plug wire with the same result. I live a mile from paved roads, if I replace the plug at home and drive slowly to the pavement, I can tell that the plug is starting to foul. Sometimes, if I punch it, it will clear itself.
I have had bad experiences in the past with dealers in general and am reluctant to just take my chances with whoever the service manager might give the job. If I had a name, I would feel much better.
Any idea what this might cost?
Thank you both for your replies,
Marvin

 

Marvin,

You can pull the intake spider inlet off of that cylinder and see the intake valve. If it has an abnormal amount of carbon on the backside and stem, your valve guide is bad.

Dennis

 

mj... sounds like you're in/near Sedona.

How 'bout:
Franke's European Auto Werks

or, Burk's Auto Haus,

both in Flagstaff, on N. West, No. of I40.

Can they help? or point you right way?

G'luck. (How 'bout Prescott?)

 

Marvin,

Sounds like you did the simple stuff - sorry it wasn't one of those items. Dennis is right on with pulling appropriate intake tube - that will give you a much better idea.

I do still recommend a leak-down test on that cylinder if you haven't already done so.

I'm afraid I'm not plugged into the PHX area anymore and as such have no specific recommendations for a shop. There's more than a few 928ers in the area, I hope they jump in here soon.

As to the cost, in VERY ballpark terms you're looking at ~$500 in machine work (valve job, mill heads to true) and maybe $400 in parts. The parts are things like the head gaskets, guides, and a bunch of sundry items that are absolutely suicidal not to replace when you've gone to the trouble of pulling the heads. (As you might have noticed, I strongly suggest doing both. You can do just one, but it's really little more time/$ for both. And you need new head gaskets. Or, you will find out soon that you do.)

If I find anything about a localish shop for you, I'll let you know.

Greg

 

Thanks everyone for your comment/suggestions.
macreel, I tried the 2 shops in Flagstaff that you suggested, no listing for Burk's in the book, Franke's is closed for vacation until the 21st. I will try them again then.
Dennis, thanks I will try pulling the intake and taking a look.
Greg, thanks again, I will try the leak-down, I know I did it several years ago, but don't remember the results. The car has been sitting for some time. I just used a jumper on the fuel pump relay yesterday and got it started for the first time in over a year. I ordered a new relay, oil sending unit, hood and hatch struts today.
I need the weatherstripping where the hood meets the body, any recommendations on where to buy this?
Thanks again for your help,
Marvin

 

marvin... for supplies & good words, try any of TheBig 3:
(they're sponsors here at Rennlist)

928 International
928 Specialists
Devek