how do i find if my engine is cracked?

[jeffbriggs18]

ok, been working on this problem for 2 months now, first boat ive had, i do have a few years of auto mechanics training so i know how to turn wrenches. 72 Volvo penta AQ130C with 270 out drive We have replaced the exhaust manifold, head gasket, adjusted the valves, rebuilt the water pump, changed the plugs, points, condensor, cap, rotor, changed oil couple times, change the lower unit gear oil. when we got it the oil pan was off and the guy said he changed the head gasket. put the pan on filled her up and she started right up. first time out she wouldn't go very fast, so we cleaned both solex carbs, alot of crap came out. So now we got the boat doing about 35MPH with 3 people on it at about 5000 RPM. ALOT of smoke comes out the breather. we were getting water into the oil and driping out of the water pump holes, so i took it apart to find the 3 gasket were either torn or not their. got the new gaskets, rebuilt water pump, drained oil, filled it up with 2 qts, turned it over with filter off till good oil came out of filter plate, drianed, added 3 qts, got to running temp added a napa sludge cleaner, ran 5 min, drianed, flushed 2 qts thru, then filled and ran for about 15 min. Now we got oil coming out the exhaust( we put the lower unit in a half 55 gallon drum instead of muffs, and the water in their had patches of gray oil crap floating in it after 5 mins of running it)and the oil still turned milky and level was higher than were we started off. I also noticed a bunch of milky sludge dripping from the left side of where the engine bolts to the lower unit, rear main seal bad? getting back to the head gasket, about the 3rd or 4th time on the water, it wasnt getting good power and eventually we heard a pop and a hissing noise from the first cylinder, head gasket blew, we ordered a new one, replaced it and in doing that we noticed the holes in the block for the water were kinda tri shaped, but the holes in the gasket were round, so this resulted in the gasket covering some of the block holes, does that seem right? got it running with about 120 PSI in all 4 cylinders. Sorry this was such a long post, I just want to know 1. how to find a crack in the block if their is one, 2. Is the engine worth it to keep putting money into it( just parts i can do all the labor), 3. Where i can find a replacment block or engine fairly priced. the engine sounds like she runs good and we can get up to speed a slong as theirs no more than 3 people in the boat, we only have about 500 sunk into the entire boat and engine as of now. Thanks for any help

 

[dingdongs]

Re: how do i find if my engine is cracked?

as the previous owner said he changed the head gasket alarm bells should start ringing.obviously it was not winterised and either the head or block or both has cracked internally.you could test by plugging all holes and pressure testing to 30psi with water filled journals and should hold for 30 mins.you may find your answer after a lot of caps and thick rubber to hold water back whilst testing or try and find another lump cheap as i think when you find the problem it will cost another lump anyway.

 

[jeffbriggs18]

Re: how do i find if my engine is cracked?

How do i perform the pressure test? plug the water inlet and outlet at the thermostat housing? do i need a specific guage? adapters? Should i visually take the head off and look for cracks?