Hi all. Mechanical relative newbie here. I bought a 1987 Catalina 30 MK II late last year. Recently discovered that the Oberdorfer raw water pump was weeping - bad seal. Removed hoses, undid the four bolts, installed a brand new pump with the appropriate gasket. (Didn’t trust myself to do a good job of rebuilding the pump myself; opted to have that done when the shop can get to it, and then I’ll have a spare.) All tight, no leaks, engine runs, cooling water spurting out with the exhaust as it should. My first marine diesel repair job.
I can’t see how the above could relate to my new issue, but since I know squat and that pump replacement was the most recent change, I thought I should mention it.
New issue: while I was running the engine the next day to double check all was well after my pump replacement, the engine quickly overheated - at 1,000 rpm, then at idle. Never even put it under load. Climbed up to 220+ degrees, cabin smelled like hot coolant, had to shut it down.
What gives? Owner of a local mechanic shop that works with universal diesels assured me that if water is going out the exhaust then the seawater side is good. He added, maybe the coolant is not filled and vented properly. So it would seem like this overheating is a separate issue.
Thermostat faulty? The gent from whom I bought the boat (who’s been a big help in getting me oriented) says that the thermostat is pretty new - when the engine was rebuilt a year ago they installed new thermostat, starter and alternator. I need to learn how to confirm whether it’s kicking on when it should.
One likely relevant detail: I’ve been noticing small drips of coolant in the bilge under the engine. I thought I had it tracked down earlier, a hose clamp needed retightening one one end of the short hose between block and heat exchanger. But yesterday after I had to shut down due to overheating, I saw a bit of coolant, maybe a spoonful, had come out of a hose labeled pressure release.
Only other detail I can provide is that the coolant reservoir bottle shows just a hair (1/8”) below the Full line. Now I think of it, I don’t recall that changing at all while the engine was running. Could that be an indication that it’s after all just a sticky thermostat?
Well, that’s where the situation lies for now. Any troubleshooting help would be hugely appreciated. I’ve read some posts here and there that talk about possibly needing to “burp” the coolant lines, not sure whether that’s my issue or how it’s done.
I can’t see how the above could relate to my new issue, but since I know squat and that pump replacement was the most recent change, I thought I should mention it.
New issue: while I was running the engine the next day to double check all was well after my pump replacement, the engine quickly overheated - at 1,000 rpm, then at idle. Never even put it under load. Climbed up to 220+ degrees, cabin smelled like hot coolant, had to shut it down.
What gives? Owner of a local mechanic shop that works with universal diesels assured me that if water is going out the exhaust then the seawater side is good. He added, maybe the coolant is not filled and vented properly. So it would seem like this overheating is a separate issue.
Thermostat faulty? The gent from whom I bought the boat (who’s been a big help in getting me oriented) says that the thermostat is pretty new - when the engine was rebuilt a year ago they installed new thermostat, starter and alternator. I need to learn how to confirm whether it’s kicking on when it should.
One likely relevant detail: I’ve been noticing small drips of coolant in the bilge under the engine. I thought I had it tracked down earlier, a hose clamp needed retightening one one end of the short hose between block and heat exchanger. But yesterday after I had to shut down due to overheating, I saw a bit of coolant, maybe a spoonful, had come out of a hose labeled pressure release.
Only other detail I can provide is that the coolant reservoir bottle shows just a hair (1/8”) below the Full line. Now I think of it, I don’t recall that changing at all while the engine was running. Could that be an indication that it’s after all just a sticky thermostat?
Well, that’s where the situation lies for now. Any troubleshooting help would be hugely appreciated. I’ve read some posts here and there that talk about possibly needing to “burp” the coolant lines, not sure whether that’s my issue or how it’s done.
