I almost bet that is where your oil was going--straight into the cylinder from the valve that was fouling the guide and sealing surface.

Now, MF, here's a good time to find out what CUTS THROUGH that crap.

The only thing I've found is carb cleaner. Paint thinner won't do a damn thing for it.

But right after that, I realized that brake fluid is an EXCELLENT gum & varnish remover. Coincidentally, you can use it in the engine oil, if you're trying to get rid of slime, sludge, and varnish. or fix a slightly leaky seal. I do it myself here and there, and I immediately put 1/2 pint of it in the 740T that I was having problems with the constantly gumming valves. Also, after pulling the gas tank in the 740, I found out that the fuel was SO contaminated it was almost sick to smell and see. That might have been because of either bad gas or long period of storage. The reformulated fuel has one HELL of a short shelf life.

Try a little brake fluid on the gum in the head and see if it loosens it.

If so, you've done everyone a great service, at the very least. You've identified what can UNDO the process from the inside. A little help.

So there was probably a coincidental problem with several things, but I'd suspect that the fuel was the real problem.

That's pretty scary. There's no indication whatsoever that anything is wrong except for a sudden failure. The only other thing that might indicate it is sudden knocking when the debris ignites, IF it ignites. LOng periods of idle with marginal fuel are a certain way to test the limits, as the engine's temp doesn't sufficiently heat the valves. You might start to use oil through fouled seals, or worn seals. The valves aren't running at a high enough speed to scrape the crap off. And then you are in deep sh*t.

At the same time that problem happened to the 740T, it happened to a 6-cyl Isuzu Rodeo. Two different cars, one problem. The Rodeo was towed out as a parts car to fix a wreck, but it will be back (didn't happen). I'll have more information at that time.

Have you run any highway trips lately? That should really sizzle the debris off of the valves.

My theory not having seen a DAMN thing, is that the oil was weeping down the valve stem and fouling with the fuel on the stem. Naturally this is of no assistance to you at this point, BUT for future reference, you've proved one hell of a good point for everyone else. I'm going to guess that you haven't run a big highway trip in quite some time. The day to day 10 or 20 miler, and that's about it. That's my guess. Not enough time for everything to get hot and start working on itself. There is a gradual loss of compression because of the debris building on the valves. The #3 is not QUITE as efficient as the others at clearing itself, since it was the one injured last time and is perhaps SLIGHTLY out of spec, slightly damaged, slightly imperfect.

The cylinder's compression and valve travel gradually decreases, such that you don't notice in day to day driving. Then the junk builds enough so that the worse it gets, the worse it gets. And then it catches the top of the piston, and that's the end. Zero compression.

That reformulated CRAP gas is the worst. If you could actually have a constant (same cars, same miles, same conditions, but different gas) you'd probably find something different. There is SOMETHING in the fuel that disagrees with the intake process, and totally rots the valve stems, locking them tight.

Also, there's probably something in the oil that doesn't help. I bet your oil was flushing straight through the #3 cylinder. The cat was probably running hot because of the slightly rich condition in the #3, due to insufficient (slightly) compression, and burning the oil up before it hit the pipe. You'd never see it if that was the case.

Whatever the case, I'm glad to hear that you have top end problems instead of lower end problems. At least you don't have to yank the whole engine out of the car. I'm still sorry that you have to go through that crap twice, and that there is bona fide damage to the valves. But you CAN get that bucket back together and running right, and I'll bet it will run very well again.



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Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240