SailNet Community banner

1 - 8 of 8 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter #1
Sorry if this is double post, ran out of cell service. My W30 sailboat engine worked fine when I put it to bed last fall. In June I used the boat for the first time and a few bad things happened. First, the water temp gauge didn’t work. I wasn’t unduly concerned as I’d never had cooling issues. However, the engine overheated after about half an hour of motoring... Murphy’s Law. I shut it down as soon as the coolant cap popped and got a tow home.
I pulled the end cap off the heat exchanger and it looked terrible - maybe 80% plugged. Aha, I thought: problem solved. Removed and sent the HX out for refurb and cleaning.
This week I reinstalled it and filled up coolant, engine started easily and ran well.
I replaced the gauge (Faria) with an SW (which was available). I was told that the Faria temp sender would work with the new SW gauge. Started engine and temp ran up really fast to 220F where it seemed to stabilize. Hmm, gauge-sender mismatch maybe? Engine is almost 40 and sender may be original so I replaced it (Faria sender as that’s what was available). No change in temp reading.
I replaced the thermostat as it’s cheap and easy but this did not help.
because the temp went up so fast I wondered about the belt driven coolant pump. I loosened off the belt and could easily turn the pulley by hand. I pulled the pump and it does make a squeaking sound when I turn the shaft, not sure if this is normal or not. the pulley was definitely turning and the pump is just a pulley and impeller on a shaft so I don’t know it could NOT work.
I have a hot water heater in the cooling circuit between thermostat and reservoir, I disconnected both supply and return and was able to blow the coolant out of the loop easily just by blowing into one of the hoses. I pulled the fittings where the 1-1/4” rad hose bushes down to 3/4” Heater hose hoping to find an obstruction but everything looked clean as a whistle, zero scale or corrosion.
Any suggestions? Starting to lose faith I will ever fix this.
 

·
Registered
Joined
·
3,193 Posts
So the engine started and ran well after reinstalling the Heat exchanger? What's the water flow like out the exhaust? Are you sure the Thermostat opens? Did you change out the impeller while you were at it? Do you have an infrared thermometer by any chance? My water pump gave up the ghost after 32 years, but I'd just double check
the easy stuff 1st.
 

·
Registered
Joined
·
4,609 Posts
How's the flow at the transom?Pull the hose from the elbow. Good flow into bilge? Careful it can be pretty hot Gauge shows temp drop? Elbow is plugged. No flow ? Look at obstruction upstream .Impeller blades ,Plastic bag sucked into inlet. a clam growing in the thru hull. ? Ask me how I can list these so easily.
 

·
Registered
Joined
·
21,800 Posts
Vapor lock in the coolant circuit, after refilling? Can you see coolant being pumped back into the reservoir (if there is one)?

How long was “really fast” for the new gauge to get to 220? If almost immediate, it may not be correct.
 

·
Master Mariner
Joined
·
8,391 Posts
It sounds like a mismatch between sender and gauge to me, if the temp goes up ridiculously fast. It would take a diesel at least a few minutes to overheat if there was no cooling. Don't believe everything a salesman tells you. If I remember, the Faria series of gauges will not work with any other sender and vice versa.
If you have plenty of water going out the stern, your problem it isn't in the seawater system. You can completely remove the thermostat if necessary, it is only really necessary if the water is cold.
You should see water in the fresh water circulating if you take the cap off. Put a thermometer in. It shouldn't be anywhere near 212 even if the gauge says it is, shortly after starting. You could check the fresh water circulation pump by removing a hose higher than the pump in the system.
With a 40 year old diesel it is possible that some of the water passages could be restricted with scale from rust. There are probably cleaners available, though may require an acid bath, which means removal. But that could be a good thing as you could rebuild the engine and have a virtually new engine for less than a new one.
 

·
Registered
Joined
·
20 Posts
Discussion Starter #7 (Edited)
So, some clarifications. Tons of water out of the raw water circuit on the transom. No blockages there. Raw water pump impeller is new. Both old and new sender units were Faria, I'm inclined to burn $35 and just buy a Faria gauge and see if it works. I don't think I have any cooling issue, I think more and more it's a gauge issue.

I pulled the fresh water cooling pump because when I was in there opening up the vent on top of the thermostat housing to eliminate vapor lock as a potential cause, I noted that there was steam coming from somewhere around the water pump. Steam visible with flashlight above pump, none visible below pump. Took off belt and pulley, looked to be gently steaming from pump shaft seal. Tough to say for sure but the steam was coming from somewhere. There was a squealing sound before the engine overheated, maybe from this pump, there's a bit of squeak/binding when you turn it but no grating sound or feel. I'm going to pull the trigger on a new one, it's a PITA to get to this stuff and it's off now.

Is it feasable for me to have the old pump rebuilt with new shaft seals? Can't imagine the seals cost much - new pump is just under $500 CDN so curious if it would be cost effective to rebuild vs. replace. Who would do this type of work?
 

·
Registered
Joined
·
21,800 Posts
If the raw water pumps seals are just leaking, it’s very unlikely that’s causing your overheating indication. You may we’ll be right that it’s the gauge, especially if it shows high temps long before the engine could have reached them. I think you said “really fast”.

I’ve had little luck rebuilding pumps. Never lasts as long as the original. Consider buying a new one. They are a wear item.
 
1 - 8 of 8 Posts
Top