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Discussion Starter · #1 ·
Had an issue at the end of last year with the diesel engine on my Catalina 30. Literally as we were pulling into the harbor on the last trip of the year, we experienced a fairly sudden loss of power (50% or so drop) and the engine ran slightly louder when usual. Had been a long trip (6+ hrs) and we were not actively watching the temperature gauge, so it seems likely that it was an overheat. Started up the alright next morning, but still experienced the low power and the temp gauge was climbing super fast.

After having her on the hard all winter, we are trying to diagnose the issue now. But the word from the mechanic is that he cannot do much while the boat is on the hard because he needs to see the engine under strain. That makes sense to me in terms of diagnosing why it is heating up so fast now, but would that be the same for the low power? And would any potential engine damage be visible on the hard?

And on a related note, I could use some advice on dealing with these engine troubles when trying to sell the boat. At the moment it seems my two options are to 1) advertise her on the hard with engine issues that can't be diagnosed or fixed until she is in the water, or 2) get her into the water and have the mechanic work on her and then try to sell. Not sure what to do here because with #1, it will be a hard sell and I will surely take a huge hit on the price. #2 does have the upside of potentially getting things fixed, but on the flip side I could also launch and find a mooring and have the mechanic work on her, only to find that the issue still persists, but now I'm deeper in the hole. Any advice appreciated.
 

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What have you attempted to troubleshoot up to this point? Have you pulled the Raw water impeller to look at it? I think that's where I might start. If it's lost vanes, then you'll have to look downstream in the exchanger for them. Might want to do that anyway. If not the Impeller I'd check the thermostat. Regarding low power, have you done the basics? Fuel Filters, etc. Check the pick-up tube? is there a clogged screen at the end? is the fuel tank vent blocked?

I think I'd replace the obvious maintenence items and then get it in the water, and solve any issues that remain. It may be simple. But, I think you still need to resolve it one way or the other. As a Buyer, I wouldn't spend the money to survey and launch a boat that had an unknown engine problem, from over heating, unless the price and the hull etc were worth the risk of a re-power or re-build. I like Catalinas but there's enough of them out there that I'd probably move on to the next one for sale. Good luck with it, Hoping it's something simple.
 

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Discussion Starter · #3 ·
Thanks for the response. Mechanic is going through this week and changing the impeller, fuel filter, and doing basic maintenance. Going to try to see if he can do a compression test on the hard as well.

Yeah, maybe the plan is to see what the mechanic says, but try and launch it and hope it's a simple fix. I'm just worried about sinking more money into it if it turns out to be a difficult issue to resolve.
 

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It may help to know what engine it is. Someone else may have had exactly this problem.

My first impression based on the engine running louder is that raw water stopped entering the exhaust. A simple impeller failure wouldn't account for the power loss though. If you were running hot for a long time and the head or head gasket failed, that would account for both.
 

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Had an issue at the end of last year with the diesel engine on my Catalina 30. Literally as we were pulling into the harbor on the last trip of the year, we experienced a fairly sudden loss of power (50% or so drop) and the engine ran slightly louder when usual. Had been a long trip (6+ hrs) and we were not actively watching the temperature gauge, so it seems likely that it was an overheat. Started up the alright next morning, but still experienced the low power and the temp gauge was climbing super fast.

After having her on the hard all winter, we are trying to diagnose the issue now. But the word from the mechanic is that he cannot do much while the boat is on the hard because he needs to see the engine under strain. That makes sense to me in terms of diagnosing why it is heating up so fast now, but would that be the same for the low power? And would any potential engine damage be visible on the hard?

And on a related note, I could use some advice on dealing with these engine troubles when trying to sell the boat. At the moment it seems my two options are to 1) advertise her on the hard with engine issues that can't be diagnosed or fixed until she is in the water, or 2) get her into the water and have the mechanic work on her and then try to sell. Not sure what to do here because with #1, it will be a hard sell and I will surely take a huge hit on the price. #2 does have the upside of potentially getting things fixed, but on the flip side I could also launch and find a mooring and have the mechanic work on her, only to find that the issue still persists, but now I'm deeper in the hole. Any advice appreciated.
It is not unusual for an engine to lose power when it overheats. (It is a precursor to seizing up, which is what will happen if it over heats too much!) So the two problems are likely related.

If you were buying a boat which one would you buy, the one that has unknown engine issues or the one that has recently been serviced by a mechanic and is running fine?


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Discussion Starter · #6 ·
If you were running hot for a long time and the head or head gasket failed, that would account for both.
Yes, this is what I am afraid of. It is my understanding that a compression test could be use to figure out if there was a cracked head or a head gasket failure. Is it possible to do a compression test on the hard?
 

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Discussion Starter · #8 · (Edited)
It is not unusual for an engine to lose power when it overheats. (It is a precursor to seizing up, which is what will happen if it over heats too much!) So the two problems are likely related.
Is the loss of power usually related to a cracked head or blown head gasket? Or are there other causes?

A buddy of mine mentioned that running hot could cause clogs in the heat exchanger and/exhaust elbow. Does anyone know if either of those would lead to a loss of power in the engine?
 

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I would start by checking the tension on the belt that runs the cooling pump. That will take 10 minutes and cost nothing.

Then move onto impeller.

Loose belts account for quite a few overheating problems.
 

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Boy oh boy. There is a lot of room for possibilities. I'm guessing that you have the 5411 or M18? Regardless, your alarms aren't working or you would have mentioned the alarm going off, which may have helped prevent a failure if it were in fact an overheat or oil pressure drop. It certainly sounds like the head gasket has failed and a compression test will confirm or discount it. It seems like everybody is helping you diagnose the overheat issue when what you need to do is find out what happened to your horse power. You can do it on the hard and if you do it in the water, have the seacock shut regardless.
 

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Checking the raw water filter is the first step of debugging a cooling problem, as those can routinely collect debris and become blocked.
 

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Just went through a similar situation with my Catalina 28. Engine overheating, white smoke, and little to no water coming out of the exhaust. The impeller was fine, as was the vent loop and mixing elbow. Turns out the heat exchanger was clogged. The yard ran a chemical through it for a couple of hours, it completely fixed the problem. Saved me the trouble of taking the thing apart and cleaning it.
 

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The yard ran a chemical through it for a couple of hours, it completely fixed the problem. Saved me the trouble of taking the thing apart and cleaning it.
I honestly don't know why anyone bothers to disassemble anymore. This method is so simple, less likely to damage anything and gets every little bit, throughout the whole raw water circuit, if you set it up at both ends.
 
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