2001 Mercruiser 4.3 Overheat on plane Water in pan

[THenning]

HI all,

2001 Sea Ray 182 With Mercruiser 4.3 Alpha 1 Gen II

302 Hours on engine

Winterized last season, Changed Water pump in off season. Been boating about 2 months now with 2 weeks off for lakes closed due to flooding. Put ~25 hours on the engine so far this year.

Yesterday I was up on plane for about 15 minutes, 3000 - 4000 RPM. Look down at temp gauge and it's at 220. Slow down a little bit and it goes back to 170, then up to 220 again. Engine dies and I have steam coming up through the carb.

Check engine dipstick, oil looks fine.

Get towed in, pull the plugs and #4 has beads of water inside, #6 dumps about 1/4 cup of lake water. I spray WD40 into the plug holes as I didn't have fogging oil on hand.

Put the boat on trailer and brought back to my driveway.

This morning I sprayed air down dipstick hole, turns the oil to milk.

Best case/Worst case scenario? Probable points of failure?

What I have planned for today:
Compression test engine
Buy leak down tester
Leak down test cylinders
Pressure test cooling system.
Inspect 2 piece manifolds and risers

I'm thinking I may need to check head gaskets tomorrow.

Should I be checking the vortec intake gasket?

Any other things I should be doing/checking?

 

[Rick Stephens]

All good steps. You are on the right track. A head gasket is likely, but not very common with that motor, which is strong as an ox. Not sure if I would start with leak down. I think the pressure test cooling as the test will indicate the more important consideration here. You aren't really concerned with compression leak, and a leakdown probably won't tell you much if it's a head gasket. Compression test, then pressurize cooling system. If neither show a problem, pull the head. Manifolds are last on my list as they won't effect high speed cooling like a head gasket. Leak down is not on my list at al unless the compression test shows something major.

 

[Rick Stephens]

In hindsight - you might run your compression test at the same time you have the cooling system pressurized. Cranking over the motor with compression on one cylinder, if that one blew a head gasket, would show up on the cooling system pressure gauge.

 

[THenning]

Not Good Compression
#1 - 155
#2 - 70
#3 - 140
#4 - > 0 but less than 10
#5 - 70
#6 110

Port, 155, 140, 110
Starbord 70, ~5, 70

Head gasket, or new Motor?

Worth tearing apart to fix?

 

[Rick Stephens]

That is spectacular. And you bet. Tear it down. May be head gasket. Look careful when you disassemble.

Still may need to do a rebuild, but a looksee is next.

 

[THenning]

Thanks a ton! Time to tear into it.

 

[Bondo]

or new Motor?

Ayuh,..... Quicker, 'n easier to get back on the water to crate motor it,......

If ya do,.... Figure out what killed this motor, so ya don't smoke the new one,.......')

 

[THenning]

Looks like the port side cooling was blocked by blue green algae and chopped seaweed past the temp sending unit. Temp sender didn't inform about the temp rise until the block was cooking.

 

[harringtondav]

Head gasket, or new Motor?
Worth tearing apart to fix?

I tread lightly when disagreeing with Bondo Your 302 hr engine still had lube, even if milkshake.
Head gaskets are relatively inexpensive. You know the value of your time. You didn't have a serious overheat so I'd throw the new gaskets in w/o head resurfacing. You have nothing to loose except the cost of the gaskets and your time.

If this works, happy-happy. If not, back to Bondo and a crate engine.

 

[THenning]

Update: Took a couple hours to have a beer and regroup, then pulled starboard exhaust manifold and riser. 3 of 4 water channels bone dry, flappers NOT melted, #4 was puking Oil & water into exhaust passage.

Valve covers tomorrow, heads after.