140 Mercruiser Q's

[Shorty]

Ok, it's been a while since I've worked on this stuff, so looking for pointers in case I am overlooking anything

I've got two engines here:

one that was known to have taken on water, runs, compression is 150 on all 4 (Give or take a couple lbs)
Other was said to be good to go, but compression is 25-100-100-125

Tomorrow I'm going to pick up a pair of head gaskets and a valve spring compressor

Plan is to open em up. clean em up. Inspect the valves and seats, maybe do a little port work quick, then get the new head gaskets in and test again

Aside from this and visual inspection I really don't know what else to do to test them out.... so for a little time, and $22/head gasket, why not give it a go?

Any other pointers? I'll be inspecting cylinder walls, pistons, checking to ensure rings aren't stuck, etc..... any other tricks for checking for cracks though? aside from just visual, and then running em and checking for water in em?

[Jason]

Most seem to crack on port side under intake. This was a strange one that cracked to the inside but was very small. Good info in here: http://forum.cgoamn.com/index.php?topic=4963.0

If they were mine, I'd get them running first, see what happens, (maybe you did that). Hook a hose and and see if it's visually leaking water anywhere from hose pressure. If still no leaks, then tear the head off and figure out what's with the low compresion.

[Shorty]

I did run the one. Video is posted in another thread

That outdrive was not pumping from the impeller, so I fed it no water because of this..... But, there was old water in it - I filled it with oil, but didn't think to drain it first Boo. I was later told that this engine was known to take on water. But compression is good. So, I figure I'll throw in a new gasket.... then hook hose to the engine directly rather than through the outdrive, for test purposes.

.... the other one was low compression, so I didn't even bother to attempt to fire it.

Tomorrow I'll put gaskets in em and see what they do.... obviously thorough inspections with the heads off....

crossing my fingers for at least one good engine.

[Plugcheck]

IMHO compression tests only go so far, I would recomend a leak down test, especially of the low reading cylinder.  Issues with valves, rings, head gaskets and such are able to be located easier by this method.  As suggested, maybe getting them to run first may help determine whether thay are any good or not, it also would help free up any stuck rings which could cause low compression readings.

[buckz6319]

IMHO compression tests only go so far, I would recomend a leak down test, especially of the low reading cylinder.  Issues with valves, rings, head gaskets and such are able to be located easier by this method.  As suggested, maybe getting them to run first may help determine whether thay are any good or not, it also would help free up any stuck rings which could cause low compression readings.

I 2nd that