The head gasket isn´t the problem.The problem are the owners.The coolant should be changed every 2 years and a lot of cars haven´t had a change for a decade.
So the coolant went acid and corrosion eats the gasket and parts of the heads away.

 

Yep, I can vouch for the coolant.. I neglected mine... left the car sitting for 9 months.. the result was 2 very rotten head gaskets

 

Just in the middle of doing this job on a '83 S Auto, the PO pulled one of the heads as the engine had been diagnosed with a head gasket failure - how they decided which head to pull I have no idea - BUT it was not a head gasket but the failure of the transmission cooler in the radiator.

Check that your engine oil cooler has not failed in the radiator - it may not be your head gaskets.

 

I'm not convinced it is just a coolant problem, I believe that after 30 years of being immersed in even perfect coolant the material of the head gasket will have turned to mush.

What I found with mine was that where the fire ring is crimped around the material, the material had broken down and wasn't supporting the fire ring any longer, under the extra pressure of 7 psi boost the fire ring collapsed and a coolant leak ensued. Fortunately it didn't hydroloc.

It is a little disturbing to think that the early 928 models are already over 30 years old and the newest are over 15 years old !

Cheers Roy

 

Because it's very difficult to hold the engine still enough to undo the Crank bolt (Think about 450ftlbs torque to undo) once the engine is not in the 928.

Put it at 45 ATDC 1 then lock the flywheel then remove or loosen the crank bolt then remove the engine.
If you need to undo the crank bolt after the engine is out it will probably cost you about 3 slabs of beer to persuade enough friends to visit and sit on the engine to prevent it moving while you use a 6 foot long lever on the breaker bar.

 

USA 16 valve timing is not an issue. You just line up the crank and cams as you put the belt back on...no worries about any valve interference. You can freely rotate the camshafts no matter where the pistons happen to be. Putting the crank at 45 degrees was added to the workshop manual for the 32 valve engines and not a bad practice, just not needed.

 

How do you check for this type of failure?

I had coolant in the oil and my actual coolant was clean when I drained it out. I had coolant going out the exhaust (white smoke) and coolant disappearing. As far as I can tell this is would be a head gasket issue.

Chris

 

I changed the head gaskets in my 1984 US S back in 1996.

I left the engine in the car, but it took a lot of gymnastics and short tools to get to everything. If you want to do the job with any speed, I'd pull the engine (I'm saying that not ever actually pulling an engine myself). The short tool I needed was an allen socket for the cam box bolts. It's just real tight, but if you're pulling the engine, it'll be easy!

Get some fender covers if you don't already have them.

Be careful with the block water plugs. There is some suspicion that the WSM torque values are too high. The block has been known to break away at that part of the casting when tightening to specification. Some people recommend not fooling with them. In my case, I didn't break the block, rather, I stripped one of the holes on the reinstall. This required the use of a slightly longer bolt, but was enough to make me bitter!

The rest of the stuff was straightforward. I ended up learning a lot about my car during the process. In my case, the PO had modifications done (cams, headers, shaved heads, emissions/exhaust mods). I was at the wear limit on the head surface, so I worried a little about how that went. I ended up going with a slightly thicker gasket -and- considering I never wanted to repeat the job if at all possible, I followed the machine shop recommendation to O-ring the heads.

This little procedure is apparently something you run into on a turbocharged car: the machine shop trued the heads as per normal, but then cut a groove around each of the combustion chambers and installed a ring, similar to a wire. This has the effect of pinching the head gasket when the heads are reinstalled. Supertight. I ran the car for ~13k miles after this without a problem. (I then later sold the car but know the car is running fine as someone's daily driver)

Beyond that, definitely take the heads to a quality machine shop and have them resurface them. I also had the valves replaced. I didn't have a problem with the valves per se, but was told by the machine shop that the valve seals should be replaced to avoid any oil leaking into the chambers. So, I replaced the valves and seals. This involved also having the valve seats were re-ground, after which I was confident that the heads were like new.

Lastly, the final "hard" thing is setting up the cam timing again. This is just a matter of following the WSM instructions and getting/using a tensioning tool. There is any number of tutorials/writeups on that topic.

WYAIT - inspect all the hoses (fuel, power steering, brake) and wiring. Replace anything out of whack. Inspect all the wiring, too. Clean things up.

Once you're done, you can definitely enjoy the result with some pride. While a head gasket is a routine thing for a mechanic, I think there's few jobs that really get you as deep into the engine or are more difficult: perhaps a full rebuild, or transmission overhaul? For me, it was a truly rewarding experience. I did the project solo and without much prior experience. It took almost a year of evenings and I learned an amazing amount of auto engineering and 928s in the process. To this day, I count it as a big achievement (ok, that's the cue for the experienced wrenchers to raz me!)....

Have fun!

 

ok thanks for the comments and suggestions appreciate it.
Chris

 

Well I am bringing this thread back, A little late I know but last year was a complete bust for the shark. I didn't get a chance to do the required work last year, The wife got hurt and we were down to one income. Anyway here we go again. Removal has begun. I have the oil cooler lines disc from the rad, the plug in front of the rad undone and the two 6mm bolts out with the mounts at the top, coolant hoses removed and the rad will not lift out is there anything that could be holding it in at the bottom any mounts there?
Oh and its great to be back.
Thanks Chris

 

I managed to get the rad out..just a bit of persuasion was needed.
Chris

 

Well, somehow I manged to put 370k miles on an 83s while driving the **** out of it and never changed the head gaskets....