salt water in single cylinder

beruken · Jul 16, 2025

water breached a cylinder apparently from riser gasket. It was only there about 12 hours before I cleaned it out. other cylinders on starboard looked fine. I vacuumed out water and attempted to dry with q-tips

and a torch but concerned with potential rust on valves. Going to do compression test now. Any thoughts on how to prevent rust, spray a little wd-40 in there?

Thanks

cyclops222 · Jul 16, 2025

Good luck on a baddie.

kenny nunez · Jul 16, 2025

Be sure to spray some rust penetrant into the cylinder and exhaust port. Do not test the compression until the engine has ran and warmed up. I am sure that there is no damage as you caught it right away. It is normal to get small amounts of rust on the valves and seats from not fogging before storage. Most times the rust will clear after some runtime. Automobiles get rust build up from being parked for long periods.

beruken · Jul 16, 2025

cyclops222 said:
baddie

kenny nunez said:
Be sure to spray some rust penetrant into the cylinder and exhaust port. Do not test the compression until the engine has ran and warmed up. I am sure that there is no damage as you caught it right away. It is normal to get small amounts of rust on the valves and seats from not fogging before storage. Most times the rust will clear after some runtime. Automobiles get rust build up from being parked for long periods.

Thank you!

beruken · Jul 16, 2025

beruken said:
Thank you!

So, did compression test anyway bc i did not mention the engine was running at wot when the alarm kicked on.
0 pressure in cyl 6
100 in 4
135 in 2
valve stems look fine so not that. I assume the ring is shot but no noise from crank.

Bondo · Jul 16, 2025

beruken said:
water breached a cylinder apparently from riser gasket. It was only there about 12 hours before I cleaned it out. other cylinders on starboard looked fine. I vacuumed out water and attempted to dry with q-tips and a torch but concerned with potential rust on valves. Going to do compression test now. Any thoughts on how to prevent rust, spray a little wd-40 in there?

Thanks

Ayuh,...... The best way is to start it up, 'n run it,.....

Bondo · Jul 16, 2025

beruken said:
So, did compression test anyway bc i did not mention the engine was running at wot when the alarm kicked on.
0 pressure in cyl 6
100 in 4
135 in 2
valve stems look fine so not that. I assume the ring is shot but no noise from crank.

Ayuh,...... Have you run the motor yet,..?? If not, do so, then test the compression,.....

If the test is the same, pressurize the cylinders with compressed air, at each cylinder's Tdc, 'n listen for where it's leaking,.....
Intake valves will hiss through the carb, exhaust valves through the exhaust, or the rings will hiss from the oil cap,......

Scott Danforth · Jul 16, 2025

all on the same bank of the motor points to a failed exhaust port. as stated, run the motor a bit, then take compression readings. from there, do a leakdown test. from there, fix what is broken, then fix the cause

beruken · Jul 16, 2025

Thanks guys. Appreciate the feedback. Thought I was in need of a total rebuild but will verify.

beruken · Jul 20, 2025

So finally got the engine cleaned out of moisture in the oil in the top of the heads, removed the rest of the oil that was a milky grey. I think it mostly came from steam being forced thru the engine. There was smoke or steam coming from the carb. Anyhow, waiting on a new riser gasket set and want to flush the engine with some old oil, or maybe a cheap car oil as a one time use to determine the issue at hand. Then if it doesn't need a tear down, fill with new 25w. Sound reasonable?

beruken · Wednesday at 3:54 PM

So quick update. Engine started right up, a little rough while on choke as usual. Once it kicked off it smoothed out and sounded pretty good while revving it, however, I noticed when it got up to temp I was still not getting water flowing out the proper ports, but it seemed like an increase in steam coming out the exhaust (block water jacket was full of soot after the initial event happened). Shut it down and pulled the #6 plug and it looked fine but then felt a little slick with oil, all around the threads too. Did another compression test and a big fat zero again. I did notice an odd sound, coming from the carb, cyclical and not consistent like how I would expect. I guess it is time to look for a pressurizing valve for the spark plug hole.

Mc Tool · Wednesday at 5:47 PM

sounds like a blown head gasket .Symptoms being , water in only one pot , water in oil and no compression in that pot . Maybe head gasket #6 cylinder blown thru water jacket on intake side and into lifter valley or push rod hole .

beruken · Thursday at 12:58 PM

Mc Tool said:
sounds like a blown head gasket .Symptoms being , water in only one pot , water in oil and no compression in that pot . Maybe head gasket #6 cylinder blown thru water jacket on intake side and into lifter valley or push rod hole .

Yeah, just did leak test and it is pushing water out the exhaust and air out the intake and #4 spark plug hole. I was thinking a cracked exhaust manifold that was causing the water to get in in the first place but pretty sure it was just the gasket.

Lou C · Thursday at 6:19 PM

Given salt water use it's also possible that one head rotted through behind the valve seat area. How many seasons in the salt does this one have on it? If you get 15+ you're doing well, 20 is unusual.

beruken · Thursday at 6:39 PM

I bought a 1999 in 2013. I don't know if it was exclusive to salt but likely being one owner. It sat for 3 during covid. I was getting worried the manifold was going to break through around the thermo housing, I've taken so much rust out of there. That's dishearting but I had been shopping around for some bigger fresh water boats. Trying to understand how to remove the distributor now so I can just drop back in hopefully without turn the crank at all.

Scott Danforth · Friday at 3:20 AM

beruken said:
Trying to understand how to remove the distributor now so I can just drop back in hopefully without turn the crank at all.

you have to turn the crank to TDC on cylinder #1 to install the distributor.

from there, depends on which distributor/ignition system you have. if you have an MPI, you align the marks on the rotor with the distributor when you drop it in (follow the factory manual). if you have a carbed motor, you point the distributor to plug #1 tower when you drop it in, then you set timing

Lou C · Friday at 7:13 AM

I know that some will dispute this but after running my present boat in Long Island salt water (23 seasons) I have seen that winterizing using proper antifreeze (PG but with corrosion inhibitors) seems to prolong the life of certain components…for example after 23 seasons in the salt I have changed the thermostat housing a few times but still have the original intake and I do pull the stat housing to check the inner passage in the intake when I winterize. Otherwise I found that the cyl head cooling passages were getting eroded after about 15 years and some seepage around the head gaskets was already happening before my overheat back in 2016. How do I know that? Oil analysis. It showed up way back in 2011, and after in 2015. Nothing showed on the dipstick till the head gaskets let water in a cyl (2013). Replaced cyl heads due to cracks from overheat. Exhaust has been replaced on schedule every 6/7 years. I had 3 sets of OMC batwings & converted to the later 2 piece when I replaced the heads.

Lou C · Friday at 7:29 AM

So the moral of the story is that oil analyses help to avoid problems or catch them while they are small!
I do 3 things at end of each season:
Oil analysis
Compression test
Scope exhaust elbows with inspection camera

Lou C · Friday at 8:19 AM

o

88 Horizon oil report 12-2024 redacted.png

oil analyses 2011-2024, see the elevated sodium in 2011 and 2015? and associated high wear levels of Al and Fe, and how they gradually dropped after the repairs were done in 2017?
I used the Fel/Pro marine head gaskets they seemed to seal well....
I think anybody running a raw water cooled engine in salt water should do a yearly analysis....
it also tells you if the oil you use actually stays in grade...

Mc Tool · Friday at 2:01 PM

I gotta admit I am stunned that so many peeps are happy to pump salt water thru their engine, I know outboards are stuck with that but they are easily flushed. Why dont peeps use heat exchangers and run proper coolant in the engine and maybe use the salt water from after the heat exchanger to cool the exhausts, and doesnt anybody make decent stainless manifolds.
I thought that my series of boats would end with a stern drive......never had much to do with them but after reading of all the issues that seem to go with them I think I will stick with my outboard or a jet ( we have a shallow bar at our estuary ......some one just got their picture all over the local news parked on the bar .....in full view of the whole town

). Damn shame as the guy up the road has offered me his 20'boat with a 350 chev and some Mercury stern leg for bugger all , poor bastard ,felt a bit covidy ,went to the quack and has got cancer everywhere and a few months to live . I dont really want the boat as I feel like Im picking over his bones before he has even gone .

salt water in single cylinder

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