Open Road

Anyone else follow this one? I love the car, but when I looked at the photos of the heads, and the coolant cancer, I wondered whether they fixed it. Apparently not. Do you guys who see lots of these consider this corrosion bad? A few spots looked rather deep to me.

Linky: https://bringatrailer.com/listing/1991- ... nding_Soon

I think those guys didn't have a 928 shop manual.

Here's a copy of a response that I sent via email to someone asking me about it:

I wrote: I looked through the pictures the other day when it popped up.

I have no idea who viscomotorsports (whatever) are. They have no rep in the 928 world I inhabit.

I have zero idea how good is their work. But, I can tell you that I don't half-disassembled a 928 engine *before* pulling it to put on a stand. (See pictures.)

And when I pull an engine, the 928 get's fender covers (minimum) and I don't just drape bits and pieces on the painted parts of the car like those guys did.

They could have done good work. Or maybe not.

I didn't look super-closely at the pictures. I scanned the invoices. Meh.

It sure isn't clear that they did a thorough job.

As for head cancer. In general, IMO, 90+ heads are quite a bit more porous than pre-'90. If there are any pinholes in the deck you can be sure that there are "wormholes" of corrosion under the deck.

And you can't really confirm suspicions until you remove metal - which then requires welding.

Their explanation of why they pulled the engine is suspect to me: A burned valve is a symptom, not a cause. And I have trouble thinking of a realistic 928 failure mode with fueling that could cause "a" burned valve. (I suppose a zombie injector could cause this, but it would misfire and run badly and then you'd have to drive the piss out of it in that condition... Now that I think about it... I was asked to diagnose a piss-driven-outwards misfiring GT at Frenzy a couple of years ago... but it was white IIRC. LoL.)

Especially with low-mileage GTs/GTSs, I have found engines with poor compression and/or bad leak down and - it's almost always been carbon buildup on the valves and seats. That written, at higher mileages, a bunch of 32v engines are running around with one or two slightly bent valves based upon my experience.

If the shop had written "bent" not "burned" I would be somewhat less skeptical of the "value" of their work.

They did do one thing "right" in my book: Permatex copper gasket sealant on the head gaskets (see pictures.)

So...maybe it's not all bad.

The problem is: you never know how go is someone's work until you take it apart.

Thanks for posting that link and making me look at that car again.

I look at BAT every so often to see what kind of 928s are for sale. Not so much interested in the prices, but just to see what is generally available these days and take a read from the peanut gallery (general trends in people's thinking.)

So, I looked briefly at the car but did not see the heads after shaving. When I went back and looked at the pictures, well.... For me, that is a head gasket re-do project for sure. Even if they did everything else right to refresh the motor, that kind of corrosion will immediately continue to degrade when coolant hits it. The only solution here was to drill it out and weld it up by somebody whe knows what they are doing.

Both my GTs needed welding of the heads. The 91 only needed minor welding, and I had GB do it. The 90 needed substantial welding despite the record of regular coolant changes. The 90 heads were so bad that only professional counsel and actions from Worf could save them.

The black GT that was just RNM on Bat is another example of "not getting what you pay for."

I don't think the repair pics did them any favors. Showing that they didn't weld up the heads shows they did a good enough skim on the heads and probably didn't even check or replace any valve guides.