Dougs951S

Hey all, I've got an 83 motor I'm about to reseal and drop into my 86 NA. Since I don't have the bellhousing on (seeing as its on a stand) is there any decent way I can do a compression check? I've got an air compressor so I plan on doing a leakdown test as well. Also, is there any way to check the integrity of a head gasket with the motor on the stand? I bought a new HG set just in case, but is there a way to know if I even need it?

Thanks!

Techno Duck

Cap off the water ports on the engine; cylinder heat outlet, water pump inlet, heater core inlet / outlet. Figure out how to pressurize the cooling system and bring it up to about 10-12psi. Assuming you capped everything off tight enough it should hold pressure.

Dougs951S

that's a good idea to test the water jacket seal but what about testing the seal of combustion gases from getting into the jacket? it might be fine at 15 psi but fail under the huge pressure or combustion and I guess there is no way to test that? looks like the head is coming off then, I dont want to have to touch this motor once i drop it in.


As for the compression check, any ideas to turn the engine over at ~200 rpm or so safely using the crank bolt? I know an impact is not going to work and I cant bolt the starter on with the motor on a stand.

Noahs944

delete

Pizpot

You could do a cylinder leakage test in lieu of a compression test. If you have audible air hissing from a coolant port rather than from crankcase, intake, or exhaust it would point to head gasket (or cracked head/block).

Van

Not really. A standard leak down test and listening to the coolant passage, like pizpot sez, will be about the best you can do.

But the block won't be up to operating temp... and the pressure won't actually match combustion pressure...

Dave W.

If it's original, you can assume the HG is decaying and needs to be replaced. Especially if you plan to make decent power with this engine.

Dougs951S

Its ok guys, thanks for all the suggestions. I went ahead and yanked the head and boy, am I glad I did. The PO assembled the damn thing with NO GASKETS! As in; the water pump, head gasket, and cam tower were simply slathered in grey RTV and bolted down. The head was literally glued to the block and it nearly took an act of god to remove it. What a hack. I've got lots of cleaning of the surfaces to do, but I was rewarded for my hours of work with an extremely clean motor with excellent bores and very clean piston tops.


Here are some pics, this is how it looked when I opened it. I didn't clean anything. All the bores were perfect except for one tiny vertical scratch on #1 that just barely caught my fingernail and doesnt worry me.


The bore in this pic is representative of the other 3, I think this is #2?

konakat

Poor man's high-compression motor

StoogeMoe

Ha. That's why you never trust a PO! What a hack.

WTF is with the scratches on the piston?

Dougs951S

PO had to have wire wheeled them. It was recent too judging by how clean the motor is. I'm guessing he did a HG/WP job on it and decided to save 80 bucks by not using any gaskets. It leaked shortly after, resulting in the motor being sold to the guy I bought it from.

CyCloNe!

I use copper rtv for my water pump but rtv for a head gasket?! Craziness