Ding, ding, ding...

An update to this thread...That horrible knock....

Turns out the oil galleries were plugged. There was inadequate lubrication to the top end. Blowing compressed air through gallery plug (at the rear of engine) seemed to solve the problem. Oil sprays everywhere, now.

You guys were right. She runs very well, now. Thanks.

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1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

That begs the question.............why??

And, how did you correct it............did you need to remove the head for that job??

Why? Good question. There appeared to be some sludgy goop dribbling out from the bores. It was like tar, really. I'm just happy my car runs well. The car originally had a K+N filter and a Slick50 sticker on top of the air-filter element cover. If that's a clue.

I simply used an air gun and blew through the oil cavity at the rear of the engine accessed via a 7mm (I think) allen bolt . Tight squeeze, but I got in there. The head, cam, and lifters stayed in place for this. I only had to remove the valve cover. I directed air through until I observed the bores dribble oil over the lifters. The engine is super, now! But I'm watching it. I drained the oil and now I'm running Marvel Mystery Oil 1.5 qts, and synthetic. We'll see.

__________________
1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

The mix you now have in the crankcase will hopefully clean all the gunk out everywhere . Perhaps a past owner was just an oil additive believer.

I have heard that viscosity increasers can be found as a mass lump in the bottom of the oil pan on teardown occasionally for example. Does sound like there was something in that engine oil to build up enough to partially plug passages. A good warning to others perhaps.

Of course it could have been just sludge from something else like using non detergent oils long term. I suppose they might be still on the market. I well remember nu gold oils sold through a national chain in Canada for .25 cents a quart. That was awhile ago though. Your american equivelent might have been about 15 cents a quart.

We used tons of the stuff in our oil burning gas cars. . In fact it was thought that changing an old car from non detergent to detergent type oils might increase oil consumption signifigantly. Times have changed. Even worse is the possible senario that slick 50 actually does something in an engine. You could drop them a testimonial.