89 SN 351w Coolant Conundrum
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=50058
Printed Date: April-28-2024 at 1:44pm
Topic: 89 SN 351w Coolant Conundrum
Posted By: 89skiowner
Subject: 89 SN 351w Coolant Conundrum
Date Posted: July-25-2021 at 2:53pm
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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 |
Replies:
Posted By: SNobsessed
Date Posted: July-25-2021 at 4:05pm
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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.” Ben Franklin |
Posted By: 89skiowner
Date Posted: July-25-2021 at 11:26pm
| This is my first time for everything, any more direction to plugging/charging the water system? |
Posted By: wayoutthere
Date Posted: July-26-2021 at 12:07am
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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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Posted By: WakeskateNW
Date Posted: July-26-2021 at 12:53pm
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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. |
Posted By: 89skiowner
Date Posted: July-26-2021 at 2:26pm
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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. |
Posted By: 89skiowner
Date Posted: August-04-2021 at 11:17pm
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I have a cracked block. Two of the freeze plugs appear to reset/tampered with. Looking for a block or a motor. |
Posted By: KENO
Date Posted: August-05-2021 at 5:09am
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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. |
Posted By: Nautiquehunter
Date 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. |
Posted By: gun-driver
Date Posted: August-05-2021 at 10:04am
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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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Posted By: 89skiowner
Date 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. |
Posted By: Gary S
Date Posted: August-05-2021 at 10:47am
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Are you saying the plugs are wet or they look steam cleaned? Could be exhaust problem ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: TRBenj
Date Posted: August-05-2021 at 11:00am
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. |
Gary S wrote:Posted By: Dreaming
Date Posted: August-05-2021 at 11:17am
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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. |
Posted By: 89skiowner
Date Posted: August-05-2021 at 12:55pm
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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. |
Posted By: KENO
Date Posted: August-05-2021 at 1:22pm
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  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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Posted By: KENO
Date Posted: August-05-2021 at 1:31pm
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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) http://www.correctcraftfan.com/forum/forum_posts.asp?TID=35808&title=cracked-block-sudden-milky-oil-351w" rel="nofollow - link He was hoping for the best like you are
I'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. |
Posted By: 89skiowner
Date Posted: August-05-2021 at 1:59pm
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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? |