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The mkiv Supra Owners Club

Sealant, its use and misuse


Chris Wilson

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I posted in a thread a bit ago, but can't find it now, commenting how a member had used far too much sealant building his own engine, and how it would not only have oozed outside the joints, but would now also be similarly ejected *INSIDE* his engine. The maelstrom of hot hoil that is churning in the sump erodes this and it ends up in the oil pick up strainer. The engine oil pump is then fighting the blockage, cavitates the oil, and bearing failure or pump erosion results. BIG BILLS, LOTS MORE WORK!!

 

I enclose a link to photos of a supposedly professionally rebuilt Skyline RB26DETT engine I have in, from a car that ran two big ends during mapping. You can see the excess sealant, but worse, on cleaning the sump / front diff casting, I found a little finger end sized piece of broken off cast iron. I thought immediately that it was probably hydrauliced off from somewhere, and sure enough it was. Whoever had gone crazy with the sealant had not heeded the warning of a sump bolt feeling tight as it was turned, and carried on going. It had compressed excess sealant down a blind bolt hole in the base of the block, and the thousands of PSI thus generated literally exploded off a bit of the block. It will dress up to stop it forming a stress raiser, and a bit of Hylomar on that bolt thread will stop an oil leak from within to without the block, but it could have been far worse, effectively scrapping the block if it had occurred elsewhere. Oil and water down head bolt holes are favourites, that usually does scrap a block....

 

Use a fine bead, and don't go mad around bolt holes!! Use an air line to blow all blind holes out. Poke down them with a long fine screwdriver, make sure you feel solid metal at the bottom, not old sealant, or that the screwdriver comes out looking like a dipstick.

 

http://www.gatesgarth.com/Skyline/skyline.html

 

More is not better!!!

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