1989 Ski Nautique 351w Hot

I had my 89 ski nautique out for the first time this year and I noticed about 3 minutes in to running it at just idle, the temperature got to 220 and didn’t come back down. I kept going with about 1/4 throttle for 20 seconds and then I shut the engine off. I let it sit for a few minutes and then try to start it again. The engine tried to turn over but it wouldn’t. So I paddled back to the dock and loaded up. When I got home I took out all the spark plugs and cranked the engine over by hand. Water came out of most of the cylinders. I did not put a new RW impeller in this year. I used the best looking one that I had. I take it out over the winter. I did a compression check today on all cylinders and the highest consistent reading I got on a few of the cylinders was 180. The other cylinders were at 150. I did take the thermostat out last night and it did open up. What should I do next? TIA. Josh

It happened last Saturday evening. Any ideas on how the water got into the cylinders? I’ll start doing what you said and report back.

Just took off port side riser and everything looks ok. Now on to the starboard riser.

Yes. You won’t learn anything removing the risers.

I suspect cracked exhaust manifolds. Look for signs of water in the runners. Pressure test them either way. I’m not buying Tom’s theory, never seen that happen before.

I took both exhaust manifolds off, the bolts sure came out easy, I noticed they have anti seize on them. Anyhow, no noticeable cracks that I could see inside the manifolds. Definitely rusty and crusty inside of them though. I’m guessing the next step before I do anything else is to have the manifolds pressure tested? Thanks.

Chris - I’ll pressure test the cooling circuit this weekend. I did drain the exhaust manifolds and block last fall and put antifreeze in. I did not run the Timmy-T before we went out even though I wanted to. I am pretty sure the valve was shut. If for some reason the valve was open, could that have caused the overheat by not sucking in enough water? I did reuse the best raw water impeller you had. I wonder if I should have used a new one instead.

SNobsessed wrote: Josh - You might want to pressure test the engine cooling circuit instead. You will have to plug all the holes except for 1 which you feed 15 PSI into. I still think intake manifold. You drained the exh manifolds last fall, correct? Unless they both froze-cracked, it is really unlikely they both failed simultaneously. Did you perhaps run the engine from the Timmy-T before the overheat happened? Maybe you left the valve open.

I haven't seen any mention of whether there's water in the oil That's where the water ends up on an intake manifold leak.

And besides it's good to know if there's water in the oil after something like this happens

As far as the cause of the overheat, I didn't see any mention or question about pump orientation after changing the impeller,   

Skinautiqueobsessed wrote: How do I pressure test the exhaust manifolds? Any pointers? I don’t think I have any water in the oil. I’ll check again tonight just to be sure. I changed the oil last fall before storage. I’m 100% positive I had the impeller going the right way. Probably should have used a new one though.

The real question though, is was the pump reinstalled in the right orientation so it would suck from the lake and push water through the cooling system?

Yours should be like the left picture that says LH with the cam screw facing in towards the engine since this is a normal (LH)rotation in an 89 SN

Skinautiqueobsessed wrote: How do I pressure test the exhaust manifolds? Any pointers?

Josh,
You'll need to make a block off plate where the manifolds bolt up to the risers/elbows. Then it plugging up any extra threaded ports, adding water to another port and then a fitting to that port for regulated compressed air. Add the air and take a look inside the exhaust cavities for signs of water

For an easy overnight test, just prop them upright, hook hoses a couple feet long to the inlet holes, raise hoses above top of manifold, & fill them.

Leave them over night & look for water on floor in the AM.

RWP had 'UP' marked on top, just FYI.

Have you pulled impeller back out? No vanes missing?

BTW, it doesn't matter which way the vanes are when you install impeller, they will self flip.

Oil and oil level look great.

The RWP is installed the correct way. I can read the word “UP”.

The vanes on the impeller look great, none missing or burnt looking.

Should I put acetone or just water in the exhaust manifolds?

It would take a lot of acetone.

There is always the possibility you sucked up a plastic bag or such against the intake at the ramp.

Regardless, after you get the exh manifolds sorted out & back on, run the 5 gal bucket RWP test to verify that it is working.

Faceplant- I saw a guy on YouTube use it as a way to find the leaks in the exhaust manifold because it is supposed to by 4 times thinner than water.

I am now officially edumacated . Thank You.

Skinautiqueobsessed wrote: I’m going to pressurize the exhaust manifolds and if those check out I’m going to run the engine off of a 5 gallon bucket.

I'm confused. I thought you already did a check on the manifolds.

Skinautiqueobsessed wrote: The exhaust manifolds survived the night, no leaks..

Was the first test without any pressure?