Stuck valves

[DjEep]

Posted: Today 5:30 pm Post subject: Stuck valves
I just picked up a '65 Ghia, 1200cc. It had been sitting in a covered garage for 10 years, due to a minor wreck, but supposedly has ~2000mi on the engine. I work at a VW shop, so I'm no stranger to getting old dubs running after long sleeps.

I pulled the tank, drained the ancient gas, flushed w/ solvent for a while, replaced the sock, flushed the metal lines and replaced all soft lines. After an oil change and carb clean, she fired right up. I drove her for about 8 miles, then put her to bed. Next day I went to adjust the valves, and afterward, it was loping on 2 cylinders. Re checked them, and #2-I was extremely tight, but no evidence of a valve/seat issue. Re adjusted and she was purring again. Drove about 15 miles home, running great. Next morning, crank it over and pop-clack, she bends 3 of 4 intake pushrods, with the #4 intake stuck open.

Pulled the heads, and found all the intake valves basically glued into the guides with some sort of tarry-varnishy goop. Tapped them all out with a brass punch, cleaned them up,gave a light wirewheeling to the stems, blasted the guides out with 3M melt-your-face-off brake cleaner, pre lubed with Lucas assembly lube, and they were sliding like butter again, with just a smidgey of smidges of lateral play.

Reassembled, reinstalled, replaced stupid tuck away muffler with OG peashooters, and she was singing like a sewing machine. Tuned, testdrove about a mile and parked. Half hour later, went to start and pop-pop-clack, three bent intake pushrods.

WTF? First theory was that old gas puddled in the ports had turned to goop over ten years, but I cleaned it all out! I'm pretty damn handy with a dub, but not quite a old pro, but even the shop owner, who's been working on 'em for 20 years is stumped, says he's pulled dozens of buses and bugs out of swamps, garages and fields and has never seen this.

[SlowLane]

As it's only the intakes, it could be residual crap in the oil being drawn into the guides by manifold vacuum. How thoroughly did you clean out the crankcase?

I've heard great things about Marvel Mystery Oil and Seafoam for engine cleaning. Never tried either one, myself.

[DjEep]

That was my next theory. Thinking I'll try again and run some ATF or MM Oil in it for about a half hour then switch back to 20w50. Good thing we have more 40-horse pushrods, so Hopefully It'll just be more time and a couple new pushrod tubes.

[SlowLane]

'nother thing: when you had the valves out for cleaning, did you check their side-play to make sure they were in tolerance? Not too tight?
Rocker arm geometry correct?

[Amskeptic]

Drove about 15 miles home, running great. Next morning, crank it over and pop-clack, she bends 3 of 4 intake pushrods, with the #4 intake stuck open.

Pulled the heads, pre lubed with Lucas assembly lube, and they were sliding like butter again,

testdrove about a mile and parked.
Half hour later, went to start and pop-pop-clack, three bent intake pushrods.

WTF?

Fresh 1200 rebuild at time of storage.

Same symptoms *after cleaning the varnish* out.

Same symptoms *after a warm-up brief cooldown*

Suggests insufficient clearance between stems and guides.

The wiggle test may be good 'nuff for finding the wear limit for worn engines but it does not tell you anything about good .001" /bad .0008 too tight. I think the aluminum/brass may be contracting faster after shut-down than the steel valves. At full cold, you're fine. At full warm you're fine. At one to three hours cool down, you're pinching. Ream the guides a smidge.
Colin
(International Harvester gas V8s had a very similar problem with wrist pins)

[DjEep]

Ummmm, and a little something I'm ashamed to admit, I noticed the heads say GEX. Debating whether to try again with the clean-ream-then-flush-with-ATF, or just send 'em off to our local machinist to have some quality valves and guides fitted. Do I spend 6 hours, but little money, trying again to possibly have the same result, or just spend a couple bills on parts on parts and labor and be done with it...? 'tis the question

[ruckman101]

I sense a koan.

My first impulse was to blame clogged oil passages in the case.

Yet Colin's post suggests different issues my mind grapples to grok.

But beyond that, GEX 1200cc heads? Inconceivable.



neal

[Bleyseng]

I'd agree with Colin that its too tight of guide to valve stem clearance.

[SlowLane]

Ummmm, and a little something I'm ashamed to admit, I noticed the heads say GEX.

Which way you go depends on your long-term plans for the engine and vehicle, and how much you are willing to invest in a reliable ride.

GEX has a bad enough reputation that I'd consider ash-canning these heads altogether and replacing them with ones of known provenance.

Or take this as a warning sign that you need to thoroughly inspect every parameter on these heads. Short list includes (but is not limited to):

• correct size valves (one of Colin's TBRRD lessons)
  correct valve margin
  cracks between valve seats/spark plug hole
  equal cc volume across all cylinders
  equal valve stem height
  equal spring compression
  co-planar sealing surfaces on each head
  badly-repaired exhaust stud mounting
  solid (ie. no heli-coil) rocker arm studs
  co-planar rocker arm mounting pads
  etc...

In short, scope out these heads with no assumption that anything was done right on them. If your machinist works on a lot of aircooled VWs, then he ought to know what to look for and be better able to advise you, assuming you've established a relationship of trust with him.

[DjEep]

Heads seem fine, aside from the valve sticking deal. No cracks, no evidence of shoddy welding, run smooth as silk when they do, no feeling of compression unevenness. It's more of a toy car than anything else, picked up on a whim. My machinist has done countless ACVW jobs for us, from re-valving AMC heads to line bores, to polishing cranks. So I'll trust his judgement.

Thanks for the replies, guys!

[Sylvester]

Can we see a picture of this find?

[RSorak 71Westy]

The black tar like stuff that stuck the valves came from someone running old gas thru it. I've seen this before.

[Amskeptic]

The black tar like stuff that stuck the valves came from someone running old gas thru it. I've seen this before.

Varnish is a real problem. It is not *the* problem after washing it all off and reassembling the engine with assembly lube too, and having it screw up again within a day.
"a smidgey of smidges of lateral play" is a scientific way of saying, "not enough".
I personally shoot for clickitish, but definitely not kagatongitigongatagong. That is, as everyone knows, too loose.
Colin

[DjEep]

haha, nice colin. Dingo one said he used to set valves that way. And you're probably right. Usually are.

@ Rsorak: The tank was pretty bad, sat open for ten years with about 2 gallons left in it when I found it. I flushed it with solvent for a while, but there could be a decent layer of goo on the bottom. The gas in the carb smelled and looked old even though it's fresh. Perhaps varnish left in the tank is turning the new gas into synthetic old gas, combining with tight valve guides and making my life frustrating

I've seen worse tanks and had no problems beyond plugged carbs, but those were all on engines with some miles on 'em already, so tight tolerances were long gone.

[DjEep]

Looks like we were all right. Just pulled the heads and the ports and guides were once again filled with varnish. I'll post pics in a minute, when I get the valves out of the other head. Gonna try once more to just put it back together before I call the machinist. Only thing holding me up is that I missed the order deadline today to get some more pushrod tubes delivered this afternoon. Gotta love being held up by $15 in parts. Oh well.

A bus came in the other day after "accidentally" filling up with E-85, so I had to drain the tank. Can't run a bus on it, but it makes a great solvent, so I poured a few gallons in the Ghia's tank to chew on the varnish while I do the rest. Come firing time, I'll drain it out and replace with a tankful of fresh gas and a can of BG 44K, then run some ATF in the case for a half hour. We'll see how it goes.