86 305 Cylinders Full of Water

[jobrown]

Well. This isn't the first time.

​86 GM 305 Crate Motor in a 77 Cobalt 19CD

​Situation: Chilling at the dock for around an hour, boat has been running beautifully all day, went to crank it to motor it over to the trailer and it was hydro locked. Got it home and pulled the plugs and there's water in all of them. Pulled the oil plug and there's water in there as well.

​Background: Had this water in the cylinder problem last year, replaced the risers and resurfaced the heads. Apparently to no avail.

​First steps?

​Ive shot wd-40 in the cylinders to protect them and drained the oil from the motor. Anyone have this problem before? Time to get a 350?

 

[Bt Doctur]

What about the manifolds?

 

[jobrown]

What about the manifolds?

​I pulled them with the risers, tested them with acetone, no leaks, no cracks.

 

[alldodge]

When chilling at the dock was anyone sitting on the stern of the boat

 

[jobrown]

When chilling at the dock was anyone sitting on the stern of the boat

​Yes, a lot of people. You know how the ladies love the old teak! and she was full of fuel, 50 gallons, which the tank is situated on the back half of the boat. People were on the swim deck, and laying out on the stern, all four of us

 

[Rick Stephens]

Sounds like it might have immersed deeper than the risers. Shutters won't help that, they will only stop a sudden surge when you decelerate or a wave overtakes the stern. The only fix may be to put taller risers... after you dry out the motor, of course.

 

[alldodge]

Sounds like it might have immersed deeper than the risers. Shutters won't help that, they will only stop a sudden surge when you decelerate or a wave overtakes the stern. The only fix may be to put taller risers... after you dry out the motor, of course.

Yep, that is my thinking, you probably did it yourself. Its happened many times before

 

[jobrown]

Good!!! Drying her out now, going to throw in some new oil and see how she runs. I will keep you updated.

 

[alldodge]

Good!!! Drying her out now, going to throw in some new oil and see how she runs. I will keep you updated.

If you have room under the hatch, add some 3 to 4 inch risers which could keep it from happening again

 

[Scott Danforth]

My guess is in addition to the extra weight, your 40 year old boat may have water soaked foam.

Check the water / riser installation height

https://www.perfprotech.com/blog/articles/marine-exhaust-riser-height