Engine Pull, Investigation, Let's see where this leads

[sped372]

I'll try to keep this updated... basically now that camping season is over I'm pulling the bus engine after less than 10k miles on a rebuilt longblock from aircooled.net. Continually tightening valves (viewtopic.php?t=6972&highlight=) have me nervous and I need to investigate an oil leak that I'm pretty sure is coming from the front main seal.

It'll also be a good time to check out the "non-concentricity" issue Colin mentioned when he was here and felt my clutch pedal. I'm not entirely sure what I'll be looking for on that one but hopefully something will jump out at me.

So, observation number one... yesterday I got as far as I could without a helper to maintain balance. Should be only another ten minutes or so to get it out and on the ground. But, I did pull the plugs and noticed a significant difference between the two sides of the engine. These are lined up from left to right 1, 2, 3, and 4.

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What could cause this? Leaky manifold gasket on one side? I'm intrigued.

[vwlover77]

Looks to me like you've got a vacuum (air) leak somewhere along the path from the carburetor to the 1-2 side of the engine. The extra air being sucked in is leaning out the mixture. What is your carb setup on the engine? Stock?

[sped372]

Stock, single port manifold.

[sped372]

Well, it's out! Let the dissection begin!

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[RSorak 71Westy]

1&2 are way lean and 3&4 are way rich....I'd say very rich carb and a vacuum leak to 1 2.....

[sped372]

That's what I was thinking. How to know if you've crushed the gaskets enough other than the torque spec on the manifold bolts?

[vdubyah73]

That's what I was thinking. How to know if you've crushed the gaskets enough other than the torque spec on the manifold bolts?

I make my own intake gaskets out of heavy Garlock brand gasket material. pretty thick stuff kind of a wax impregnated cardboard. coat both sides of the gasket with wheel bearing grease instead of RTV, keeps them supple and they come apart in one piece if you have to remove them for some reason. Can and do use for exhaust also, although they aren't reusable on exhaust.

[Amskeptic]

That's what I was thinking. How to know if you've crushed the gaskets enough other than the torque spec on the manifold bolts?

I make my own intake gaskets out of heavy Garlock brand gasket material. pretty thick stuff kind of a wax impregnated cardboard. coat both sides of the gasket with wheel bearing grease instead of RTV, keeps them supple and they come apart in one piece if you have to remove them for some reason. Can and do use for exhaust also, although they aren't reusable on exhaust.

I think the single ports use copper rings at the manifolds.
Sped, be very engineering alert, think like a forensic pathologist, look for subtle soot, dirt, washed areas, cracks in the manifold. Cracks in the head can also screw with engine vacuum/fuel delivery. That would be on the lean side of the engine.

You will see evidence of the clutch non-concentricity right away once the engine is out, look at the release bearing ring on the pressure plate for evidence of swiping versus true rotational wear marks. See if it is slightly cocked instead of dead-accurate parallel with the pressure plate friction surface. Look for any broken or lost-tension springs. Look at the clutch cross shaft for looseness or cracks.
Colin

[vwlover77]

What are the symptoms of this possible non-concentricity? (he asks thinking of his own horribly chattery clutch)

[sped372]

Release bearing surface and corresponding pressure plate area both look pocked / scored. Clips were in place and seem to be ok. I'll try to snap some pictures when daylight comes back around.

I wasn't able to identify any cracks in the pivot shaft or it's little arms. They do seem well-worn though (so do the pivots on the throwout bearing itself). Nice shiny metal where there's relative motion and sharp edges. Also, I was able to wiggle it (the cross shaft) some, not sure if this is acceptable or not. Might have to remove the return spring to get a better feel?

Keep the suggestions coming. I want to do this all right this time. Thanks guys.

[sped372]

Here are some photos.... surfaces look beat up to me but I don't have anything to compare to. If they are, here is evidence of the symptoms but what's the solution?

[Amskeptic]

Here are some photos....

Note that the pressure plate ring is held on with those wire spring loops. Can you see the space between the spring and the slot on the one closest to the camera? Is it sloppier than the other two. Those things look beat. Look for any "wobble" in the shine/dull borders of the wear surfaces on the release bearing as you spin it.
Colin

[sped372]

The wire spring loops seem "loose" to me. I can easily move them around by hand and slop the whole center section around. I can push it in, out, up down, you name it. I'm sure it's supposed to have some give but I'd guess it's currently excessive?

Think if I add a new pressure plate and throwout bearing to my purchase list I'll cure up the vibrating clutch pedal?

[Bookwus]

Hiya sped,

You might want to try this...........

Lay your pressure plate on a known level surface, clutch face down. Then place a torpedo level on the throwout bearing face. It too should be dead level. I found this to a problem in a rebuild I did recently. That led me to buying a new pressure plate and now everything is smooooth.

[bus71]

maybe it's the photo, but the crosshaft looks slightly off center to the left.