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Carvr 325 MY Transmission overheating
Posted: May 16th, 2019, 1:36 am
by Hepp325
Hello everyone. I am the proud owner of my first boat - a 1996 Carver 325 Motor Yacht. I love the boat but so far she does not love me. Last year we took the bought out, had an alarm which turned out to be an overheating starboard transmission. Had my marina replace the transmission and cooler with new during the winter. Just took the boat out for the first time this year. Had the same overheating problem with the starboard transmission. The engine is running well and not overheating. This tells me there is something wrong with the cooling circuit for the transmission. But what? The transmission manufacturer wants them to pull it out and send it back. The marina doesn't want to void the warranty. I don't think it is the transmission but in the cooling circuit, the transmission is a symptom not the cause. I am looking for suggestions on what possible problems could e occurring outside the transmission? I would appreciate any advice.
Re: Carvr 325 MY Transmission overheating
Posted: May 16th, 2019, 8:57 am
by km1125
How long does it take to overheat? They should be able to check line pressures to see if the clutches are slipping, which would generate a LOT of heat quickly. Could also measure propshaft RPMs and compare with engine to measure slip. Also can measure cooling line temperatures before and after heat exchanger to see if it's doing the job.
Re: Carvr 325 MY Transmission overheating
Posted: May 16th, 2019, 1:00 pm
by mjk1040
I'm thinking cooling flow? Maybe you should have the cooling system back flushed, raw water impellers checked? We dealing with closed or open cooling here? Does the exhaust water on both engines appear to be equal? Maybe a descaling on the starboard engine? Bad alarm sensor? Could be the replacement parts, but I'm doubting that at this point!
Re: Carvr 325 MY Transmission overheating
Posted: May 16th, 2019, 10:18 pm
by Viper
All the above are good points. Check your raw water flow and ensure that when you shift into gear, you are getting full travel of the shift lever on the transmission both forward and reverse, otherwise you'll take out the clutch pack and generate heat in the process.
What caused the original one to fail? It's important to find this out. All too often, most common with engine failures, efforts aren't made to determine the root cause of the failure. This can lead to the replacement failing soon after if the cause was a result of something external to the unit. Seen this all too often with replacement engine failures that were eventually determined to be a result of external influences such as a fuel delivery issue for example that took out the original engine, not diagnosed/caught, the root cause of the engine failure not determined that may have pointed in that direction, and as a result, the same issue still exists and takes out the replacement hardware. What happened to the old unit and why?
Re: Carvr 325 MY Transmission overheating
Posted: May 16th, 2019, 10:23 pm
by tomschauer
Hopefully this is not the issue but, you say last year you had a trans temp alarm and you replaced the trans. Did it actually fail? or was it replaced because a $25 temp sensor is bad and set off an alarm, and is doing the same think $xxxx later?