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89 SN 351w Coolant Conundrum

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89skiowner View Drop Down
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    Posted: July-25-2021 at 2:53pm
89 SN new to me, found water in the oil after first run, immediate overheat. Nautique dealer performed compression test - all cylinders had strong compression.

130psi--O-O--135 PSI
135psi--O-O--125 PSI
135psi--O-O--125 PSI
130psi--O-O--145 PSI

New thermostat installed at my request, dealer changed the oil twice to remove all water - ran it for 2.5 hours with not issues.

My First water test was short, noticed a small hesitation around 1000 rpm. No water noted in the oil after run. Needed some carb tuning, I assumed.
It ran successfully off a bucket for 45 minutes to tune carb/adjust front float. Still no water in oil.

Next water test, ran well at 2k rpms for 20+ minutes, 3200 was about as high as I pushed for a small period. Small hesitations after coming off plane for a minute 1100rpm, but no overheating held solid never above 170. Back to dock to test a restart. Would not restart. Boat immediately overheated alarm light on, with oil in bilge, water in oil. Towed her in.

Besides a head gasket, what else could be causing my issues here?
Bad Manifold or gaskets?
Backwash through exhaust (doubtful)?

Thanks
B

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Post Options Post Options   Thanks (0) Thanks(0)   Quote SNobsessed Quote  Post ReplyReply Direct Link To This Post Posted: July-25-2021 at 4:05pm
You might want to plug the cooling system up so that you can push 15 PSI air pressure in & see if it holds when hot. 

Disengage RWP & run it in driveway for a couple minutes, that should tell the story.
“Beer is proof that God loves us and wants us to be happy.”

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 89skiowner Quote  Post ReplyReply Direct Link To This Post Posted: July-25-2021 at 11:26pm
This is my first time for everything, any more direction to plugging/charging the water system?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wayoutthere Quote  Post ReplyReply Direct Link To This Post Posted: July-26-2021 at 12:07am
Ya know, i posted an idea but after thinking it thru, the whole thing was a pnuematic projectile launcher with a mind of it's own.

Just be careful plugging and pressurizing anything.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WakeskateNW Quote  Post ReplyReply Direct Link To This Post Posted: July-26-2021 at 12:53pm
congrats on your  new '89. a couple thoughts from a fellow '89 owner. just keep in mind I'm no expert.
 the "back to the dock to test a restart" overheat issue could just be related to heat soak after turning the engine off. how long did you wait until trying to restart? 
the more concerning issue seems to be the water in oil and oil in bilge. 
Is the gasket connection between your exhaust manifold and riser rusty or corroded?
do a full visual inspection of the engine and try to pinpoint where the oil in the bilge area is coming from. maybe the previous owner neglected to properly winterize. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 89skiowner Quote  Post ReplyReply Direct Link To This Post Posted: July-26-2021 at 2:26pm
That’s interesting on the heat soak point, I will keep that in mind for the future.

I’m chasing the oil issue first, I suspect a seal that is blowing out at higher RPMs or between cylinders. The fact it ran for 3 or so hours before getting oil out or water in is what baffles me.

The previous owner was supposedly a good mechanic working for a shop in Wisconsin. Not trying to cause anyone issues by sharing more than that, but I’ve clearly learned trusting someone on a used boat is a bad idea. Hoping the block isn’t cracked but honestly I wouldn’t be surprised.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 89skiowner Quote  Post ReplyReply Direct Link To This Post Posted: August-04-2021 at 11:17pm
I have a cracked block. Two of the freeze plugs appear to reset/tampered with.

Looking for a block or a motor.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 5:09am
Probably the only one tampering with your block/freeze plugs was named "mother nature" due to a bad winterization by somebody before you bought the boat.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Nautiquehunter Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 7:46am
I have a 351 block and other parts . It has been to the machine shop cleaned checked and new cam bearings installed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gun-driver Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 10:04am
Can you post pictures of the cracked block and freeze plugs.
 May help others when looking to buy an older boat.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 89skiowner Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 10:37am
The crack hasn’t been identified exclusively, but the plugs seem to tell the story. When I pickup the boat from the shop I’ll hopefully snap some pics.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 10:47am
Are you saying the plugs are wet or they look steam cleaned? Could be exhaust problem
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TRBenj Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 11:00am
Originally posted by Gary S Gary S wrote:

Are you saying the plugs are wet or they look steam cleaned? Could be exhaust problem

Agreed. Not that it’s impossible for a block to crack and allow water into the oil and still pass a compression test cleanly… but it wouldn’t be suspect #1. I’d be looking hard at exhaust and intake manifolds, in that order.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 11:17am
agree with TRBenj above.   I bought mine knowing it had been frozen.      As I tore the engine apart, I discovered the intake and Exhaust manifolds were cracked.  The casting/freeze plugs were laying in the bottom of the bilge, so I was pretty aware of the hard freeze, but the block was not cracked.  The block is pretty strong, and while you may be absolutely correct about it being broken/cracked,   The Exhaust manifolds and intake are the more fragile parts of this set up.   Both of them will be needed for your new engine build if you have to go that route, so no harm in pulling those off and testing or replacing now. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 89skiowner Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 12:55pm
I like the thinking here. What am I looking for?

Logically - I’m baffled by two things, one the good compression numbers, and two it runs for two marinas and myself for a period of time before dumping oil - I’m pretty sure they said from the manifold.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 1:22pm
Originally posted by 89skiowner 89skiowner wrote:

I like the thinking here. What am I looking for?

Logically - I’m baffled by two things, one the good compress ion numbers, and two it runs for two marinas and myself for a period of time before dumping oil - I’m pretty sure they said from the manifold.

Any leak from the intake manifold water passages or the block or timing cover internally goes straight to the oil sump with the help of gravity and you have no affect at all on the compression numbers unless you went all out and cracked the cylinder wall too.

An internal crack may not be the first place some people think to look but it may be the last  Wink

I'm baffled by you saying "dumping oil", is it all frothed up, emulsified, foamy and coming out from somewhere like the valve covers or where is it coming from?.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 1:31pm
Here's a link to an old thread about an internally (and externally) cracked block with a freeze plug issue also. (minus the pictures that were originally there)


He was hoping for the best like you are WinkI'd be pulling the intake manifold off and that'll give you a good view of the water jacket internal to the engine around the cylinders and also the cooling passages and bottom of the thermostat housing in the intake.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 89skiowner Quote  Post ReplyReply Direct Link To This Post Posted: August-05-2021 at 1:59pm
Appreciate all the replies, those symptoms sound familiar. I get oil in the bilge and water in the oil at the same time. I visually haven’t pinpointed where the oil is coming from, but the marina said the manifold.

If I go with a rebuild, what is reasonable from a cost prospective?
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