Hydrolock damage

[brplut40]

I have a 1993 Sea Ray 200 20' boat. the engine was replaced in 2006 with a new 4.3L merc v6. when the engine was replaced the cooling system was also converted to a full fresh water system. This means that the engine and the exhaust manifolds are cooled with coolant and the riser are raw water cooled. The fresh water system is a Seakamp system with Osco exhaust manifolds. The lower unit is a alpha, but I am not sure on which generation.

I just bought this boat 3 weeks ago and before purchasing it took it out for a test drive. The boat started and ran great. No weird noises while running or when shut off. I stored the boat in my driveway, fully covered for the last 3 weeks. I went to take it out the passed weekend and it would not start. the engine would not turn at all. I tried cranking it several times and it never moved. Took the boat out of the water and pulled the plugs, coolant came out of 2 of the 3 cylinders on one side. No coolant on the other side. I cranked the engine by hand and with the starter to push out the remaining fluid. I then did a compression check on the cylinders that had fluid in them and they were between 130 and 150. I can get exact readings if necessary. I am going to replace the gasket and block off plate between the riser and manifold as i think that is where the coolant leaked from.

My question is after i fix the leak, dry the cylinders out, change the oil, filter and plugs, if the engine starts and runs fine how worried should i be about other damage that may have occurred? Thanks for the help to a new person to the forum.

 

[fendersfender]

Re: Hydrolock damage

I personally would have that manifold pressure tested just to be sure...better safe than sorry....and if it is the riser gasket...wouldnt all the cylinders have water???

 

[Haut Medoc]

Re: Hydrolock damage

Welcome to iboats......
I would not worry to much about any corrosion issues from coolant, if it were salt water in there I would be....
I would drain the manifold & pressure test it....
It may be the joint between the manifold/riser (likely), but it may not.....
I'd look real hard at the mating surfaces, (there should be a good 1/4" of metal all around)....
A straight edge & a feeler gauge for truenss as well....
Gaskets usuall fail for a reason, corrosion, bad mating surface, etc....
Do the pressure test & you will know how to proceed.....
I guess what I am saying is don't just slap a new gasket on the & think all is well, it may or may not be.....​

 

[Haut Medoc]

Re: Hydrolock damage

I personally would have that manifold pressure tested just to be sure...better safe than sorry....and if it is the riser gasket...wouldnt all the cylinders have water???

Likely, but not always.....

 

[TilliamWe]

Re: Hydrolock damage

It's going to be a cracked exhaust manifold. Could be the gasket, but more likely the exhaust manifold is cracked/rusted through somewhere.

 

[HT32BSX115]

Re: Hydrolock damage

and if it is the riser gasket...wouldnt all the cylinders have water???

possibly not.

When I had my absolutely wonderful 460 King Cobra installed, I had a riser gasket leak on both sides. The water that leaked into the exhaust system only got into cyls that had open exhaust valves after shut down.




Were the manifolds, riser/elbows also replaced in 06' ?

Also, do the manifolds have riser extensions or are the elbows bolted directly to the exhaust manifolds?

 

[brplut40]

Re: Hydrolock damage

Were the manifolds, riser/elbows also replaced in 06' ?

Also, do the manifolds have riser extensions or are the elbows bolted directly to the exhaust manifolds?

I will have to verify if the risers and manifolds were replaced in 06, but am pretty sure they were.

The elbows are bolted directly to the manifold with 4 bolts. From what the previous owner told me there is a stainless steel block off plate with gaskets on both sides which prevents coolant from going into the riser and raw water from the riser into the manifold.

 

[Haut Medoc]

Re: Hydrolock damage

I will have to verify if the risers and manifolds were replaced in 06, but am pretty sure they were.

The elbows are bolted directly to the manifold with 4 bolts. From what the previous owner told me there is a stainless steel block off plate with gaskets on both sides which prevents coolant from going into the riser and raw water from the riser into the manifold.

True, but it can leak from either the raw water side or the closed side & that block off won't prevent water from entering the exhaust cavity.....
In your case the leak is on the closed side & you will need to determine where....
Somehow water is getting into the cylinders, & it is likely through open exhaust valves, like HT sez.....
2 year old manifolds risers should not leak, but you will have to test them......

 

[Bondo]

Re: Hydrolock damage

Ayuh,.......

It's a Closed system,.....

Drain it,+ pressurize it to 15lbs,+ Listen.......

You'll Hear where the Leak Is........


Btw,....... Welcome Aboard,....

If it Starts, Runs,+ Don't make any Funny Noises,......
You probably got Lucky.....

 

[brplut40]

Re: Hydrolock damage

may sound like a dumb question, but how do I go about pressurizing the system? Am I able to do this in the garage, or do I need to take parts into the shop?

 

[Haut Medoc]

Re: Hydrolock damage

Well, you need to have a compressor or a large bicycle pump, & a suitable fitting for introducing air & the means to block off the proper places.....​

 

[Bondo]

Re: Hydrolock damage

but how do I go about pressurizing the system?

Ayuh,..... Do to the fact you have a Closed system,...... It's Easy.....

Remove the Rad. Cap,+ hook up a Stant cooling system pressure tester......
Most any compendent Automotive Mechanic should have 1 in his box,...
Or,...
1 may be Rentable from an Automotive Tool Rental Shop.....

 

[brplut40]

Re: Hydrolock damage

good news on this one. Got a pressure tester and tested and it held pressure pretty well, but did slowly drop. Pulled the riser and manifold apart and you could see where the block off gasket had failed. Replaced the gasket, retested the pressure and everything looks good. Started it up and everything ran great. Even got it out on the water the day we fixed it. Thanks for all the help. looks like I avoided what could have been a costly problem