Hydrolocked engine 5.7 0m643181

[golfwins]

Before I let the temp come up, I decided to turn the engine off to make sure I had put enough oil. When I went to start it back up, I heard a little ting like I heard when it was hydrolocking. It was just one little "ting", and the engine started up after that. It's a sound you don't want to hear so I'm pretty sure there water got in the cylinders during that short start-up period.

I decided to let it warm up to about 160 on the dash. This may be telling or may it's not, but with a laser temp gun, the starboard side manifold was reading 160F and the "bad"/port side was reading 140F. I'm going for a walk with the wife and will try to check the cylinders for water when I get back.

[mmwjr]

To pressure test the coolant system you’ll need to block off all connections and one with a schrader valve to add pressurized air to about 10 psi. This test is basically just the engine and not the exhaust were I suspect your issue is. Since your compression tests results are good I doubt you have a leaking head gasket and the only other way to get water in the oil would be a leaking intake manifold but since the water jackets are only in the front it’s only possible to get water in the front cylinders.

[golfwins]

Thanks Mike. So you think I should probably start by pulling the riser and work my way down?

I was planning on pulling the riser after work tomorrow after today's issues.

[mmwjr]

Yes I would remove the riser and look for signs of water intrusion in the exhaust passage.

[golfwins]

Not a lot of progress today. Busy at work and then Valentines dinner after work. Here are a few pics.

This first pic is just showing water in the manifold after I took the riser off.



I don't know if this pic tells anything. Just throwing it in.



This is the most interesting pic to me. The view is looking into the riser and the far end is where the exhaust would coming from. It seems to be a pinhole leak at the seam. You can see 3-4 water drop lets and it kind of looks like it's spraying back towards the manifold/cylinders. Maybe there are more pinholes? Thoughts?



This red circle is where I was trying to find a crack or pinhole. It's not noticeable to me if it's there.

[mmwjr]

There is a fair amount of corrosion in the exhaust passage so water has been getting in there for some time. If it was salt water instead of freshwater it would be significantly worse. On the last picture the three passages around the circumference is where the raw water is injected into the exhaust stream to cool the gasses before going overboard. The leak is upstream from this. I would replace the exhaust components, except to pay a boat buck $1K.

[golfwins]

I just pulled the manifold off. The manifold bolts seemed to be lightly torqued. I'm not sure if they were torqued correctly or not, but I noticed what appears to be signs of an exhaust leak. Let me know what you think. If it is, could this cause water to be pulled into the cylinders? Probably wishful thinking since nothing so far has been pointing in a good direction for me, but worth a thought. I'm going to setup a pressure test for this manifold today or tomorrow. Thanks for your help!

[mmwjr]

No a exhaust leak at this point will not result in water intrusion. It can suck fresh air in raising exhaust temperatures and burn the exhaust valve.

[donald]

I see rust in all of the ports on the manifold.
Just my 2c but I would recommend replacing both manifolds
, elbows, and risers.
Don

[golfwins]

Thanks for the feedback Donald. They seem really solid but I haven't pressure tested them yet. I have contacted a vendor for quotes.

Mike, I came across a message on another forum and that's the only reason I thought that could be an issue. I may have misinterpreted the information.

[mmwjr]

Having trouble reading the attachment. I’ve never heard of a leak at the cylinder head exhaust port causing water being sucked in. Note as the engine moves past the exhaust stroke there is some back pressure as the exhaust valve is still open as the piston starts going down. If you have a leak allowing water in the exhaust it can be drawn into the cylinder, this is what you are experiencing.

[golfwins]

I'll see if I can fix that attachment for anyone else that ever comes across this, it basically says.

"Those exhaust will draw water with any exhaust leak. If it's at the manifold and tail ,I believe 3&5 would have water If it's leaking at the manifold port the velocity is going to be higher pulling the water in to those two cylinders that are leaking, thoughts coming from intake port design and flow."

It caught my attention since I was getting water in 1,3, and 5.

[mmwjr]

I guess you could try reassembling with new gaskets to see if this post is correct but I’ve not heard of this before, not that I’m an expert.

[donald]

Originally Posted by mmwjr

I guess you could try reassembling with new gaskets to see if this post is correct but I’ve not heard of this before, not that I’m an expert.

I too have never heard of something like that happening.
Don

[golfwins]

Thanks Mike and Don. I'm sure I was just trying to twist it my favor. I think I have some good news. There is a crack in the manifold. Here is a video. I barely tap the trigger and get bubbles.

https://youtu.be/SOokfTE2ffo

I was going to post a pic from my camera scope, but it doesn't tell the story. I can see it thru the #3 cylinder exhaust port. Makes sense since 1,3, and 5 were the cylinders getting water.

Do I need to stick with Mercury or can I go with Barr? The guys at Michegan Motorz said that I would be fine with Barr especially in fresh water. Thoughts?

Thanks for all of your help!!

[mmwjr]

The Mercruiser ones come fully painted while most aftermarket are either bare or just a poor primer. But for freshwater any are fine but not all are the same quality. I prefer Mercruiser, Sierra, and Osco.

[golfwins]

Mike, without looking back, I'm pretty sure you helped me with this boat when I first bought it. I bought it cheap because it would either not, or struggle to get on plane. I can't help but wonder if this has been the issue the whole time. This is me again trying to twist things in my favor, but maybe this crack existed when I bought the boat and was killing power to at least one cylinder and has finally gotten bad enough to hydrolock. I guess I will know ince I put the new exhaust on. Just a thought. Thanks again!

[mmwjr]

May be, how does the spark plugs look?

[golfwins]

Here is a pic of the spark plugs. Furthest to the left is cylinder 7, then 5,3,1.




Here is a picture of the adapters I used for anyone wondering how I setup my manifold pressure test. I used a blue rubber gasket to cap off the manifold from the riser. I used the three adapters shown and two 1\4" air tool fittings.

[mmwjr]

Plugs don’t look bad but the gaps seem big from the picture.