The boat is a 1992 Malibu with the Mercruiser Magnum Skier (Chevy 350 block)
and the hour meter says 996, if that makes a difference. The raw water pump
went out and I drove it maybe 1/2 mile before noticing the temp was maxed out
at 212. Stopped and let it cool some and idled back to the ramp in 3 segments
(ran till temp went back to 200, stopped and floated 20 minutes or so and did
it 2 more times).

Checked compression and ran 175 -180 across all 8 cylinders. I pulled the
intake manifold hoping to find evidence of it leaking, but could not tell as
the gasket tore up as I pulled it off. The intake was still full of water, so
the motor didn't run dry (the engine water pump still circulates this water
through the engine even if the fresh/cool water has stopped coming in).

Questions, when an engine overheats and water gets into the oil, what is the
most likely cause and is there a way to test? Since the compression tested OK,
I was hoping to find a bad intake gasket, but cannot tell. Does the good
compression point more towards a head gasket than a crack in the head (assuming
the combustion chamber is the hottest and would be the first to crack). Also,
does overheating tend to crack blocks? Is there some path that lets water
(steam) into the crankcase without there really being a serious problem?

Any advice or shared experience appreciated.

You can reply here or at
bbusselman at hotmail dot com

I would not waste too much time wondering. Now that you have the intake off,
just pull the heads and either check them yourself for cracks or warpage, or
bring them to an automotive machine shop. To properly check them for cracks,
they should be disassembled so the valve seats and valve guides can be
checked. You might as well have them freshened up. Generally speaking, heat
will damage the heads before the block or pistons. If you want to try and
spot the damage yourself, look carefully at the areas around the exhaust
valves, particularly the middle two which are adjacent to one another.

--
Ron White
My boatbuilding website is:
www.concentric.net/~knotreel

Ron White wrote:

I would not waste too much time wondering. Now that you have the intake off,
just pull the heads and either check them yourself for cracks or warpage, or
bring them to an automotive machine shop. To properly check them for cracks,
they should be disassembled so the valve seats and valve guides can be
checked. You might as well have them freshened up. Generally speaking, heat
will damage the heads before the block or pistons. If you want to try and
spot the damage yourself, look carefully at the areas around the exhaust
valves, particularly the middle two which are adjacent to one another.

--
Ron White
My boatbuilding website is:
www.concentric.net/~knotreel


I pulled the heads last night and they are on the way to the shop. I didn't
look at them too closely, but did look at the head gasket real hard trying to
find where it was leaking. All pistons had equal carbon (expected this as
copmression tested good) and after tearing the head gasket up while removing
the heads, I could not see anything that looked like it had been leaking.
Should I have seen something? Since the block was still full of water, I don't
think I got it too hot (didn't fry it or burn any paint off of the heads). The
motor didn't die when I throttled back and restarted (turned slowly though and
did kickback, probably from preigniting). The temperature gauge only went as
high as 210 but the sender is a bit removed from the heads so it was sensing
steam temperature. Cannot say how hot the rest of the motor was. Still
wondering if there is any other way water could enter the oil as I'm not sure I
found a problem yet (unless the shop tells me they found a crack)?

Thanks again to all who responded and will respond.

bobby wrote:

The boat is a 1992 Malibu with the Mercruiser Magnum Skier (Chevy 350 block)
and the hour meter says 996, if that makes a difference. The raw water pump
went out and I drove it maybe 1/2 mile before noticing the temp was maxed out
at 212. Stopped and let it cool some and idled back to the ramp in 3 segments
(ran till temp went back to 200, stopped and floated 20 minutes or so and did
it 2 more times).

Checked compression and ran 175 -180 across all 8 cylinders. I pulled the
intake manifold hoping to find evidence of it leaking, but could not tell as
the gasket tore up as I pulled it off. The intake was still full of water, so
the motor didn't run dry (the engine water pump still circulates this water
through the engine even if the fresh/cool water has stopped coming in).

Questions, when an engine overheats and water gets into the oil, what is the
most likely cause and is there a way to test? Since the compression tested OK,
I was hoping to find a bad intake gasket, but cannot tell. Does the good
compression point more towards a head gasket than a crack in the head (assuming
the combustion chamber is the hottest and would be the first to crack). Also,
does overheating tend to crack blocks? Is there some path that lets water
(steam) into the crankcase without there really being a serious problem?

Any advice or shared experience appreciated.

You can reply here or at
bbusselman at hotmail dot com

I'm an advocate of posting "the rest of the story" as I often read a thread but
never know what acutally fixed the problem or what was the final outcome.
Anyway, got the heads back today and the shop said they were warped enough to
have been a problem. I will repost if this didn't fix the problem, but pretty
confident. Won't have gaskets until tomorrow.......

On Wed, 13 Aug 2003 17:19:14 -0500, bobby
wrote:



bobby wrote:

The boat is a 1992 Malibu with the Mercruiser Magnum Skier (Chevy 350 block)
and the hour meter says 996, if that makes a difference. The raw water pump
went out and I drove it maybe 1/2 mile before noticing the temp was maxed out
at 212. Stopped and let it cool some and idled back to the ramp in 3 segments
(ran till temp went back to 200, stopped and floated 20 minutes or so and did
it 2 more times).

Checked compression and ran 175 -180 across all 8 cylinders. I pulled the
intake manifold hoping to find evidence of it leaking, but could not tell as
the gasket tore up as I pulled it off. The intake was still full of water, so
the motor didn't run dry (the engine water pump still circulates this water
through the engine even if the fresh/cool water has stopped coming in).

Questions, when an engine overheats and water gets into the oil, what is the
most likely cause and is there a way to test? Since the compression tested OK,
I was hoping to find a bad intake gasket, but cannot tell. Does the good
compression point more towards a head gasket than a crack in the head (assuming
the combustion chamber is the hottest and would be the first to crack). Also,
does overheating tend to crack blocks? Is there some path that lets water
(steam) into the crankcase without there really being a serious problem?

Any advice or shared experience appreciated.

You can reply here or at
bbusselman at hotmail dot com

I'm an advocate of posting "the rest of the story" as I often read a thread but
never know what acutally fixed the problem or what was the final outcome.
Anyway, got the heads back today and the shop said they were warped enough to
have been a problem. I will repost if this didn't fix the problem, but pretty
confident. Won't have gaskets until tomorrow.......


Thanks for the update. Hope your problem is solved.
noah

Check your exhaust hoses, if they ran without cooling water they may be
damaged.

Paul
..
"bobby" wrote in message
...


bobby wrote:

The boat is a 1992 Malibu with the Mercruiser Magnum Skier (Chevy 350
block)
and the hour meter says 996, if that makes a difference. The raw water
pump
went out and I drove it maybe 1/2 mile before noticing the temp was
maxed out
at 212. Stopped and let it cool some and idled back to the ramp in 3
segments
(ran till temp went back to 200, stopped and floated 20 minutes or so
and did
it 2 more times).

snip
I'm an advocate of posting "the rest of the story" as I often read a
thread but
never know what acutally fixed the problem or what was the final outcome.
Anyway, got the heads back today and the shop said they were warped
enough to
have been a problem. I will repost if this didn't fix the problem, but
pretty
confident. Won't have gaskets until tomorrow.......