What a total mare !!
Discussion
hi, nearly all of the bolts that I have tried to take off the 390 engine have sheared off, totally pee'd off now. I have to take heads off and strip block so I can drill and tap without swarf getting inside. NOT HAPPY. So question is does anyone have a list of bolt sizes for the V8. I know they aint metric so must be imperial. Are they UNC or BSW............cheers
p.s Do you think its OK for all new bolts going to be covered with copper grease ?
p.s Do you think its OK for all new bolts going to be covered with copper grease ?
Unfortunately galvanic corrosion is a fact of life with older aluminium engines. Corrosion is an electrochemical process and when you have two dissimilar metals (read metals with different galvanic potential) and some moisture in there too, you've effectively got an electrolysis cell, the aluminium tends to corrode, and the corrosion salt produced is of course less dense (bulkier) than the parent metal, which produces very high hoop stresses in the aluminium threaded boss, and the friction easily exceeds the torsional rupture strength of the bolt. I'm actually not sure why copperslip stops this reaction, but ESPECIALLY anywhere near a cooling system, I would put a rather generous coat on the bolts. I've heard it said that you must not put copperslip on wheel bolts because they'll work loose - tosh.
Modern tintops tend to have an anti-seize type lubricant spaffed onto the bolts at manufacture. Honda's is a coat of dry green goo.
If you have a large number of knackered threads of the same size I would advise paying up for a Timesert kit - Helicoils are really good, but they can back out, they're not so good for through holes, and I believe they do not give a fluid-tight seal, whereas timeserts do.
Porsche 928 - a VERY well engineered car indeed. Just about all of the threads in the alloy engine have thread inserts in them. I would bargain they did it to prevent this sort of problem.
Anyway, I need tea.
Modern tintops tend to have an anti-seize type lubricant spaffed onto the bolts at manufacture. Honda's is a coat of dry green goo.
If you have a large number of knackered threads of the same size I would advise paying up for a Timesert kit - Helicoils are really good, but they can back out, they're not so good for through holes, and I believe they do not give a fluid-tight seal, whereas timeserts do.
Porsche 928 - a VERY well engineered car indeed. Just about all of the threads in the alloy engine have thread inserts in them. I would bargain they did it to prevent this sort of problem.
Anyway, I need tea.
Usually this is a problem around the water pump but not anywhere else, although sometimes you get the odd head bolt siezing.
Around the water pump area the swarf would only enter the water galleries, if you are careful you can keep it out and not need to disturb the heads.
But I agree, PITA.
Around the water pump area the swarf would only enter the water galleries, if you are careful you can keep it out and not need to disturb the heads.
But I agree, PITA.
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