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Water in #8,7, maybe 6. Help with causes...

S

slauder

Regular Contributor
Only #8 plug was wet and hydro locked, others looked okay. With plugs out started turned engine over saw water spitting out #8, compression checked 1 145, 3 145, 5 135, 7 155 but tool came out wet white water mix... Started testing # 2 and she didn't want to turn much so removed tools and closed up for the day.

Looking at diagrams in manual before I replace risers that are 5.5 years old. I don't understand how a riser or elbo could be responsible for the water. What do I look for when I pull them.

other observations... Oil looks okay and I am missing antifreeze in heat exchanger
 
Lots of times, the bolts get loose at the elbow/riser/manifold gasket joint. 25ft-lbs and that is an easy fix. Still, the raw water iron needs to be replaced.
 
I have the risers and elbows but wanted to be sure of problem before I spend time fixing what might not be the root cause of the water. It appears to be raw water but not sure. Marina suggested turning off water at seacock and turning over to see of water still spits and when gone spray plug hole with wd40, plug and start.

I did just that (plus draining at heat exchanger) this AM and ran until 150 degrees then shut down. Engines sounded healthy.

I thought that proved that it was raw water, but then I noticed the antifreeze is low in heat exchange. I'm not sure if that invalidates the test. Anyway I think I can get the boat to my home marina on one engine and replace risers and look for evidence of breach.

Thanks for your help. Scott
 
You can put a pressure tester on the HX to see if the closed side has a leak.

I would NOT run the engine with the seacock closed; I'd close the seacock and remove the belt from the raw water pump....

The risers and elbows are raw water cooled. The raw water flows thru internally cast passages while the exhaust exits the inner most "hole". The typical failure mechanism is for corrosion to cause a void between the "water jacket" and the exhaust port. This allows the water to accumulate in the exhaust port...when #8 or #7 have there exhaust valve open with the engine stopped, they will accept the water once enough accumulates...quite common for this "void" to occur in the elbow which allows the water to "escape early" (not at elbow-hose joint)...

If your install permits, remove the exhaust hose-elbow connection and look into the exhaust port of the elbow...if the forward wall of that port is rusty, it is a good indicator the elbow has been leaking for a while.
 
Thanks again Mark. I will check for rust this weekend when I do the risers. 5.5 years on them and I thought with low hours and me being very busy last summer I could wait until this spring. Looks like I was wrong! I guess the sherwood raw water pump is you concern about running with seacock closed.

Question: if the risers are breached, would water in 7 and 8 mean that both sides are failed?
 
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Yes, no supply to the sherwood, when running, will annihilate the impeller...very quickly

Water in 7 & 8 means you have issues on both sides...likely to be the same root cause but could occur at different locations (riser on one side, elbow on the other)...

Age will drive cast iron's life around salt water...and frequest use usually adds to service life...
 
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