camelman

I got the deets on my cylinder head today.

1) The corrosion definitely got underneath the fire ring and allowed coolant into the combustion chamber on the #1 and #4 cylinders.
2) All cylinders had some degree of corrosion around them, but not all had compromised fire rings.
3) The head gasket wasn't showing any issues, but I believe that's because it is a wide fire head gasket, so the fire ring still had sufficient clamping load on it where the head wasn't compromised with corrosion.
4) The #2 exhaust valve seats weren't sealing well, which is likely why I lost compression in the #2 cylinder.
5) Keeping my fingers crossed that there's no corrosion on the block!!!

My machinist is going to get the head welded up to fill in the corrosion pits. Then, install all new guides, recut the seats, deck the head 1-1.5mils, and install new valve seals. I'm doing a full gasket and seal replacement including the various rubber bits in the valve cover. I'm also getting new front and rear timing covers in black, and will powder coat the valve cover black. I will probably pull off all the metal tubes around the engine and get them powder coated black, or have them re-plated. Might as well make the engine look new again!

I'm now debating a 3-piece cross member conversion for this car. I'm not sold on it since I'll probably only get into the bottom of the engine once to do the oil pan gasket and rod bearings, but there's always a chance I'll need to get back in...

Camelman


Corrosion is marked with red ink.

Otto Mechanic

Does this involve mosquito repellent or furniture polish? . Sorry, couldn't resist on the "deets" idea...


I happen to have a spare single piece cross member for sale if you need one for a core. I live in earthquake country and couldn't send mine in before I got the 3 piece back.

camelman

Otto M, where do you live? I’m in SF, and the car is currently in Martinez.

Otto Mechanic

I wish I could say. I'm "between residences", but home base is Paso Robles. I'll be in and out of Los Gatos and Big Basin for family reasons the next few weeks, but the parts are still in Paso.

Why do you ask? I've installed the Lindsey 3 piece in my car already but still have the single piece core if you're interested.

camelman

PM sent

Stevieporsche

Camelman.

Nice job on this so far looks like a lot of effort to keep another one of these rare beasts going strong for years to come!

How long have you had the car and what type of oil do you use type and viscosity? Just wondering if thicker oil causes issues with top end not getting enough lube and causing sticky valves and tappets. Any suggestions on a car with 130K and how I can prevent a full top-end rebuild at 167k? (Aside from the obvious change your belts and cam pads regularly).

Wondering if any skimping or holding off of maintenance which I may have done from time to time would create this same scenario for me in near future.

Was it burning oil or losing coolant at any time before in its past? Ticking or clicking at all before this happened? Curiosity here.

Thanks for sharing on this so far.

camelman

Stevie P,

Thanks, I hope this is useful for someone else down the road. BTW, my cylinder head welding and milling should be about $300 total. Nice benchmark to know...

This car had sat for at least five years before I got it. I've had it about 18 months, but the first 8 months it wasn't driven much until I could get around to replacing the timing belt (I tore my ACL in the interim). Then, I drove it off and on for about 8 months before it started acting badly and parked it at my friend's house to pull the head.

I use the standard oil weight for the San Francisco climate, but don't remember the type. As for the sticky tappets, I think the issue was non-use and irregular oil changes. If you're worried about your car, then I recommend just driving it. Stay on top of the maintenance too, and only use deionized water with the coolant! Something caused the cylinder head to corrode in my engine, and I have a feeling it had to do with old coolant and possibly tap water.

No oil burn, maybe some steam in the exhaust... maybe, no frothy oil or coolant of note, but definitely a ticking and power fluctuation with the bad lifters. It was like a cylinder would turn on and off with the ticking sound of the lifters.

Regards,
Camelman

KEVIN ANDERSON

Totally agree. I rebuilt a head for a guy with a 1987 944 Turbo. It had 110,000 miles. It still had the original factory head gasket. When I took the head off, most of the head gasket was rusted apart. There were holes bigger than a Quarter in a bunch of places. There were little strands connected to the fire rings. Numerous pits in the head. I wish I could find the pictures of the head gasket. I couldn't believe it ran. It actually ran really good. Some tiny bits of the HG had to have gotten in to 2 of the cylinders because they had some very minor scratches that my finger nail could not catch. With a 30 year old HG I think it would have rusted through even if distilled water was used the whole time. I brought the head to my machine guy. He cleaned it really good, got the pits filled in and shaved it to a beautiful finish. I was pretty aggressive with the port work because a huge turbo was being installed along with the 274 grind Web Cam. I put in the ISKY valve springs from the Nissan 280Z that Shawn Deal turned me on to. Once everything got put back together, it definitely idled rougher with that cam, but it was the fastest 951 I have ever driven. It had every upgrade that you can think of. .