| 2type2 |
Sun Feb 15, 2004 1:48 pm |
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Greetings all! Today is a good day but I sure do need some advise! Good because I pulled my engine yesterday and today I removed the right head (#1&2). I had battled with what I believed to be bled down lifters
(O Yeah..this is a stock 2 ltr with 009,pertronix, and Weber progressive,less than 4000 miles on the longblock.1978 )I was pleased to find out that there are no valve or seat problems which I expected.
A compression test revealed only 80 lbs in no.1 and 9o lbs at #2 So when I pulled the head I found the copper (presumably) gaskets at the head to cylinder mating surface to be burnt for about 3/4 inch at the topside of the engine---and the carbon showing the leakage at the lower side of the head. My questin is WHY? Low torqued and heads got loosened?
Are the gaskets absolutely necessary to a good seal? What's the cause and what's the solution?! I am kinda frustrated because this Bus gets all the attention it deserves and I baby it! This problem seemed to develop on my last trip camping, only about 220 mile trip.. or it likely was happpening all along as miles added up
Any advise is welcomed so I can put the engine back in asap! |
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| Amskeptic |
Sun Feb 15, 2004 6:40 pm |
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Believe it or not, the compression lower limit is 71 psi for the 2000cc engine. Normal is 85-135 psi. The factory has suggested deleting the cylinder head gasket and using a shim at the lower end of the barrel against the case if you have deck height issues. Since you are this far down, you might want to re-ring if you have oil on your pistons, otherwise, clean and lap your cylinder barrels to their positions in the head. If you have over .060 deck height, I would delete the cylinder head gaskets and not worry about the shims at the bottom of the barrels, just use the spacers in the overhaul gasket set. Check to make sure that the heads haven't been flycut too much or anything stupid like mine were, the cylinder barrels should contact the sealing surface on the head with the fins sufficiently away from the lower head surface to not interfere. Do both sides of the engine. With your heads off, check the cylinder head studs for tightness, clean the heck out of the threads so you get a real torque reading when you put the thing back together. Check the BostonBob web site for hydraulic lifter hygiene as you reassemble.
Colin |
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| ratwell |
Sun Feb 15, 2004 10:17 pm |
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2type2 wrote: So when I pulled the head I found the copper (presumably) gaskets at the head to cylinder mating surface to be burnt for about 3/4 inch at the topside of the engine---and the carbon showing the leakage at the lower side of the head. My questin is WHY? Low torqued and heads got loosened?
Are the gaskets absolutely necessary to a good seal? What's the cause and what's the solution?!
It's a design flaw. There are twice as many sealing surfaces between the head and cylinders with the gasket there and it burns as you saw.
This is how to do it right: http://www.dolphinsci.com/techbull.html |
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