1996 Ski Nautique - Loud clunking noise won't turn over now [VIDEO ATTACHED]

[WLskinautique]

When first starting the engine, it made a loud clunk sound, struggled to turn over and then some smoke started coming out of the engine compartment.

Any preliminary thoughts? oil pump failure / oil flow issue or main bearing going bad?

1996 Ski Nautique - 351 Ford engine

[Scooter G]

Why does that look & sound hot, and I don't mean in a sexy way. Did you glance at the temp gauge?
You said clunk sound when you "1st started" the engine. Was this a cold start, 1st start for the day, or had you been running for a while and restarted?

[WLskinautique]

Scooter G not good indeed.

I was not up there for this unfortunately. But they had been idling around the lake, stopped to watch the sunset, then tried to start it up going back in and this happened. Prior to this happening, the engine temp was normal.

[Scooter G]

I've rarely seen "a loud clunk" result in anything good. 101 things...
My 1st guess would of been a bad impeller and over heat, but just a random pick something guess. Check the color, condition of the oil on the stick. I would pull the spark plugs and see what she says when you spin the starter, that will eliminate 50 of the 101, you're not going to make it any worse.

[WLskinautique]

• Yeah the loud clunk is scary, but also the slight smoke that came up at the end of the video is concerning (video was taken the next morning).
• There was a new impeller put on after winterizing last fall.
• Color and condition of oil is good, full and clear.

I've got a diagnostic appt scheduled for Thursday, will let you know what they say. I'm prepping the family for the worst though...it's a '96 with 906 hours and a cracked block already so yeah....thoughts and prayers please!

[NautiqueJeff]

That smoke is your starter burning up. I would not continue trying to crank that engine until you determine what is causing it to struggle to turn over. That starter will die quickly doing that.

Pull all of the plugs and see if it spins easier. If it does, see if water came out of the cylinders through the plug holes. If it did, you're seeing hydrolock, and have likely bent a rod trying to start it like that.

Possible sources of water in the cylinders: overheat condition that caused the head gasket to fail, or even possibly those bad exhaust riser gaskets I see on your exhaust elbows. If they are leaking enough to cause those rust stains, they are leaking enough to allow water back into the engine from the exhaust side. I'd change those gaskets immediately, once you figure out your bigger issue.

You mentioned that you had a cracked block before. How was that repaired? This could also be a result of an incomplete block repair, where the water jacket is allowing water into the cylinders. If that's the case, that block is trash. Don't bother trying to rebuild it. New engine time if that is the cause of your issues.

[WLskinautique]

Thanks for chiming in NautiqueJeff - I appreciate your time reading/commenting.

I inherited the boat from my aunts/uncles and they did not take give it the care it deserved. We have little service history to work off of because the marina they used to service it did not keep any records (seriously?) so this is what we've got.

I'll post in here what the tech finds out on Thursday, i'm not holding my breath for it though...

[Jonny Quest]

+1 on what Jeff said. That smoke that you see is from your electrical wiring or starter getting hot. If your starter is fried (and it may very well be) you can put a large socket with the break-bar on the harmonic balancer and spin the motor over by hand. Pull plugs first. That will give you a sense for if the motor is spinning freely or not. If the motor does not spin freely then you most likely have much more serious problems.

JQ

[shag]

Jeff beat us to it. Most likely smoke from the starter being forced to try and crank a possibly hydro locked motor? Or maybe even an old vapor lock (probably not)?
Batteries good? Battery cables replaced in the last few years? As above, it could be any number of things. But removing the spark plugs to see if it rolls over is a start. Best of luck!

[WLskinautique]

shag JonnyQuest NautiqueJeff Scooter G

Gentleman,

Thank you again for posting your theories on the issue. A PCM tech was able to take a look at it and said she's hydrolocked and water came out of the plugs. Visible rust on the block/manifolds where some bolts are disintegrated, likely needs a new long block and engine rebuild.

I'm chalking this up to the marina that my aunts/uncles brought it to for winterizing, when you decide to go with cost over quality - this is what you get. When I asked the marina for service records, he said he "doesn't use a service management software and throws away the papers that are older than 2 years". Sounds like he doesn't want to keep a trail of all his team's mistakes.

Do you know anyone looking for a 1996 Ski Nautique (open bow) 906 hours with a hydrolocked engine?!? If so, send them my way!

Thanks again Planet Nautique!

[Scooter G]

Excellent team called diagnosis from a 10 second video, not bad.
But definitely bad news on the reality, sorry to hear, dang man.

[NautiqueJeff]

Well, I am glad we were able to diagnose it correctly, but I feel really bad that we were right and the engine is ruined.

WLskinautique If you are serious about wanting to sell it, I would like to see some pictures. I don't mind a project boat. The problem is that I just bought two other project Ski Nautiques. Let's see how far my wife will let me go...

[workky]

i will say something unpopular. i had a 84 Ski Nautique 2001 that had a 5.8 pcm. it had an external crack that ran down the side of the head and squirted a small stream of water at you when you lifted the engine cover. We never shut it off after we started on the lake because it would hydro lock. when it did occur, we would pull the plugs, pump the water out with the starter , put new plugs in and keep riding. i always kept spares.
i was not dirt poor at the time, but i certainly was young and dumb

This boat ran this way for 4 years, i finally fixed it.

i don’t trust mechanics, lawyers, politicians, some doctors, or people