Imo000

The simplest way is to, after flushing everything out with water, clamp the in and out hose so fluid can't circulate in the heater core. OR you can disconnect the in and out lines and install a loop. Clampting it the easiest but make sure not over do it damaging the heater hose.

OBehave

Before we make this poor guy rip his car apart,maybe take a look and see if there may be an external coolant leak that might be migrating towards that hole, just sayin'. Is it overheating or running poorly? Good luck and let's hope for the best! Ed

Lizard928

Ed,

I thought about that already too, and there is nothing in that area that could leak into the #7 plug hole.

Richter12x2

Better to confirm -

Velocipus, when you say #7, you mean the 2nd spark plug from the passenger cabin on the driver's side, right? Not the passenger side? Agreed, if it's driver's side, there's no coolant that's supposed to be over there on the '85. If it's on the passenger side, it could be a pinhole leak in the hose going to the overflow bottle. You're not seeing any spots where coolant's evaporating off the top of the valve cover, I guess?

OBehave

Have you actually blown out the spark plug hole dry with compressed air and seen it fill back up? And your saying that you put 1 shot glass worth of coolant in your car every 150-200 miles? I've had coolant bottles leak more than that and not cause any ill engine problems.I would pressure test the cooling system and confirm by sight the plug hole filling up with coolant before tearing into the engine.And even after that you may get away with using a lower pressure radiator cap and still be able to use the car safely. Check it out and keep us updated! Ed

velocipus

#7 Plug as marked on the head. Driver's side, second from the rear or second from the passenger's cabin. There are no coolant hoses in the area. I've looked at PET diagrams and can only see the coolant path running through the block. i can't tell if it reaches into the head. Car runs great until enough coolant fills the well (about a shot glass full, little less) then the car starts to miss. I assume caused by the spark plug shorting. I can suck out the fluid, blow the well dry and it runs great for another 200 miles.

PO claims that he was able to see the pin-hole inside the well using a flash light and inspection mirror. I haven't been able to see/ feel it. I have not inspected with the system under pressure.

The car is somewhat apart now. I'm in the midst of an intake refresh that has become a hose refresh (coolant/ vacuum/ power steering) and now morphing into a TB/ WP replace and prepping for Porken's S300 chip. It's becoming an expensive/ time intensive project, but I'm not ready to pull the motor if I don't have to. I'm waiting on 928 Specialist to ship an order (some items apparently have to be brought in from Porsche) before I can begin to put it back together. Guess I can fix the sunroof while I'm waiting.

I want to publicly thank everyone contributing to this thread as well as everyone who have written write-ups. Without the wealth of information here on Rennlist and elsewhere, I would not have been willing or able to address the issues I have so far. I've dug in pretty deep, but don't feel like I've gotten in over my head yet.

I hope all that was clear

fredfox

If you do pull the engine, take the injector harness off the motor and lay it across your covered windshield, it is much easier that way than pulling the harness out of the firewall as the manual tells you to do.

Imo000

Block seals are made exactly for leaks like this. Try it, follow the instructions, don't skip ANY steps and you'll be a happy guy.

velocipus

Thank you. I have a bottle of Barr's and I can't wait to use it.
Saw a 944 turbo, 968, and a GTS all in one day. I really miss the sound of my 928. Can't wait to get it back up and running.