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Well, problem solved. Turns out I own what may be the dirtiest 944 cylinder head in north america. It was so incredibly crusty that carbon was holding an exhaust valve open, which was hitting the piston ~5-10* before TDC. These pictures are AFTER we cleaned it up some.
There were sacrifices made for the greater good...
I just need a HG set now and the head cleaned up at a shop and I'll be back on the road with my spare cam tower.
I don't know about that being the worst...that 951 that just died on the turbo forum may have you beat. They never changed the oil for two years and killed the engine, probably everything else too. I see the cam tower plug didn't want to play with you. Well great thing you found out the problem. I beat your relieved and bummed all at once. More $, but found the problem.
That had to have been the fastest head pull ever....1 hour in an apartment parking lot with hand tools. Crank spun freely with the head off, so the problem had to have been there.
If it wasn't the valve being held open, the next best guess is that there was so much s**t between the piston and the head itself, that the #4 piston couldn't fully come to TDC. There was ~1mm of pure grime on some parts of the combustion chamber, and at least that much on the piston itself. That theory is supported by a recent discovery we made when setting the car's time this morning... right when it was 5-10* before TDC, it would bind. Then, after rotation back the other way it would bind 5-10* before reaching TDC on that side. So something was keeping down #1 or #4, as those are at the top of their stroke when the TDC indicator is in the right place.
Does anyone know the clearance between the top of the piston, and the flat face on the head next to the valves? Pic of the area on the head that I'm talking about:
And here is a chunk of the grime we scraped off from that area:
Upon further inspection, the valve reliefs on the #4 piston were simply filled with the grime, in this picture you can see how the closed valves were actually compacting the carbon buildup in the valve reliefs:
The head gasket was also toast...check out the bubbling. It was pressurized for sure.
This very interesting thread became great with the photographs. How many miles are on this car, Doug? What's the reason for so much buildup? Good luck.
This very interesting thread became great with the photographs. How many miles are on this car, Doug? What's the reason for so much buildup? Good luck.
2xxk miles on it, ultra deferred maintenance. Michael and I determined that the motor had never been opened. More than likely the original head gasket, original cam tower seal, 27 year old water pump, original BS and crank seals, even original intake and exhaust manifold seals. It's pretty impressive that the car made it that long honestly, it was leaking from every seal and the water pump literally spun the impeller off the shaft but damn if it didn't still start up (almost) every time.
As a tribute to it being a true workhorse in every sense; it's being reassembled with every single gasket replaced, except the RMS, the oil pan, and the rear BS seals. The bores looked impressively pristine despite the insane amounts of sludge, seems it was the soft kind of carbon deposits that are not prone to scratch the walls of the cylinder bores.
The intake manifold was full of the same **** the head was coated in, more pictures to come of that later. The cam tower also full of foul smelling sludge. That had to have been from previous owners, as I've always used M1 synthetic 15w50 and changed it often. I take good care of my vehicles.
I have a spare cam tower that will be going back into the car, and a HG set on the way.
Now, as far as how all that stuff got there in the first place? I dont know. The sludge had the same appearance as from what I've seen in engines that have run for long periods of time with a malfunctioning PCV. Now, of course our engines do not have a traditional PCV valve.
We rely on the AOS to perform the function and return blowby/excessive oil back into the pan. Now, my thoughts are two fold on this. Number one, it is clear to me my AOS is somehow malfunctioning. Secondly, I believe this is ultimately the cause for both the sludge in the motor, as well as the sludge in the intake.
I deduce from all of this that the AOS seals are beyond shot. Only thing weird about all of this is that the car never smoked, ever. Also weird to me that the fouling was so much worse on #4 than any other cylinder. #2 was bad too. Not sure what to make of that, but I am pretty positive of my diagnosis. I would love others to chime in.
Quick question... does anyone know if the factory 1986 NA head gaskets were the same part as the 1986 951 head gasket? Asking because this one had "TURBO" printed on the gasket, I'm curious if that was factory, or if the 951 gasket superseded the original part.
BTW, Tiger03447, Doug and I collectively owe you a case of beer....that Irwin bolt extractor kit you mentioned is a real tool to have. There were at least 6 seized allen bolts today, it was on the money with all of them.
Well, problem solved. Turns out I own what may be the dirtiest 944 cylinder head in north america. It was so incredibly crusty that carbon was holding an exhaust valve open, which was hitting the piston ~5-10* before TDC. These pictures are AFTER we cleaned it up some.
Well done, looks like you've caught it in time and can now benefit from a clean up etc..
Quick question... does anyone know if the factory 1986 NA head gaskets were the same part as the 1986 951 head gasket? Asking because this one had "TURBO" printed on the gasket, I'm curious if that was factory, or if the 951 gasket superseded the original part.
BTW, Tiger03447, Doug and I collectively owe you a case of beer....that Irwin bolt extractor kit you mentioned is a real tool to have. There were at least 6 seized allen bolts today, it was on the money with all of them.
Yes, all of the Porsche/Victor Reinz head gaskets will say "Turbo" on them.
More pictures after cleaning. These photos were taken about 4 hours ago, I've since cleaned most of the aluminum chips and dust out from under the hood and scraped the deck clean with a razor blade to prepare it for the new Head Gasket. While I was in there (famous last words) I also pulled off the coolant hoses running to the heater core since they were original and about to burst. I removed the two bellhousing grounds and polished them til they gleamed.
I removed all the vacuum lines (even though I replaced everything I could get my hands on with the intake still bolted down about a year ago) and intend to do like my 951 and simplify the vacuum system.
For starters, that means deleting the lines running to the thermovacuum valve on the cylinder head
The two ports can be left uncapped with no ill effect.
Secondly I deleted the charcoal canister, the lines going to and from it, and the little electrical tester port and vacuum valve attached to all that nonsense. I put a small cone filter on the line coming from the fuel tank to keep crap out of it.
I deleted the fuel jumper line and the fuel pressure damper off the rail, and replaced my fuel lines with Gates Barricade hose.
I removed the AOS today and the damn thing practically fell apart in my hands....well gee there's yeeer problem!
I have a spare and new seals on the way, it was clear to me that that was the source of all the sludge since it was absolutely full of it.
Upon reassembly I will need to look and figure out what vacuum lines I can combine/delete to make it as simple as possible. I am less familiar with the NA vacuum routing than I am with that of the 951, and until now I've never attempted to strip the NA vacuum system of non essentials like I have the turbo cars, so at the moment I am unable to comment further on what exactly those modifications will entail. Essentially though, I will only be running for vacuum accessories: Brake booster, heater control valve, FPR, IACV, and the AOS.
And now for your enjoyment....The first picture is #4, the same cylinder which was so dirty before it was keeping the piston from reaching TDC!
12-18-2015, 08:29 PM
