2004 Hunter 33 high temp alarm

Nov 4, 2018
6
Hunter 2004 33 Bedford basin
Hi everyone. We purchased a 2004 Hunter 33 recently. Here is the story so far. Picked up the boat in Toronto (Pickering) and everything seemed fine. We motored most of the way to Halifax which is about 1400 miles or so. The motor ran great. Side note I had installed a Flexofold 3 blade prop before leaving. Running the engine around 22 to 2400rpm which gave us 6.5kts. No problem until approx 150 hrs later I get high temp alarm.
I check through hull all seems good. Check water strainer, good. Check impeller, looks good but replace anyway. All hoses seemed fine. Start engine and water is coming out of exhaust, but exhaust sounds a bit throaty if you know what I mean.
Ran lower rpm for the rest of way to Halifax and no problem. Then it started again!
Weird how it’s fine for a long period then gets hot for no apparent reason.
I have heard that it could be the heat exchanger or something to do with coolant.
Anyone have this kind of problem?
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Check for weeping from the engine coolant pump. You may have a coolant leak which means the pump seal may be at the end of its life. Mine went bang after a period of intermittent high heat events. Coolant spewed everywhere. I replaced the pump and all has been well.
 
Jun 2, 2011
347
Hunter H33 Port Credit Harbour, ON.
There was an issue with the heat exchangers in the early YM engines. I don't recall the issue exactly but many were replaced. Mine is a 2006 so it was after the issue and I let it go. I also believe that it was more of a problem in warmer climates. The antifreeze to use is long life premixed. Mine is red.

The fact that your exhaust sound changes may indicate that there is insufficient flow through the heat exchanger. This could be caused by a blockage on the intake of the heat exchanger, (old failed impeller parts) or in the water supply to the exhaust. (possibly carbon buildup around the water injection) If the water flow is reduced there could be a reduction in the muffling of the exhaust. If the heat exchanger is the original design the lower flow could trip it into overheating. Check the actual coolant temperature with an infrared thermometer to make sure that it is actually running hot and not the temperature sensor malfunctioning.

Nice boat by the way. I am sure that you will enjoy it. I certainly enjoy mine.

Did you happen to track your fuel consumption on the trip? I think that I am averaging about 1.75ish liters per hour. I don't put a lot of engine hours on in a year. (about 20 L of fuel a season)

Good luck and have a good summer.
 
Nov 4, 2018
6
Hunter 2004 33 Bedford basin
Hi Jake, thanks for that. I will check the temp and perhaps get someone to have a look at the heat exchanger. And yes we do love the boat. I can’t believe how little fuel I burned from Toronto to Halifax, about $300 we think approximately 2 litres per hour. The three blade prop makes a big difference.
 
Nov 6, 2006
9,885
Hunter 34 Mandeville Louisiana
Another thing to look at carefully is the sea water strainer and all connections on the suction side of the pump.. any tiny leak can admit air into the system and cause low flow and ultimately overheating. My old Groco cork gaskets hardened up after many years and at higher RPM, air would enter and the engine would overheat.. slow down and everything OK.. Rebuilt the sea strainer and everything is good.. No drips were evident, but the clue was that there was some green corrosion on the outside of the bronze body at the screen port, where a very slight weep must have been the culprit..
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
Yes there was an issue with undersized heat exchangers with the early 3YM30's. They were changed out mid 2005. Yanmar only covered the fix under warranty if there were complaints. Boats, such as yours ( I'm assuming ) would only motor a short distance out of the marine, hoist sails and go for a few hour sail, fire up the engine and head back into the marina for the night and therefore never had the overheating problem. Ours was an early 2005 and came from Toronto. Up in Georgian Bay we motored considerably and had problems with overheating and I finally managed to get Yanmar to change out the heat exchanger after contacting Yanmar US and citing safety concerns.
 

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Oct 29, 2005
2,355
Hunter Marine 326 303 Singapore
Check the wear on the pump impeller cover. Too much wear will cause air trap. Just to confirm, turn the cover over and fit the flat side to the impeller.

KenY
 
Jul 24, 2012
53
Hunter H31 Saint John NB CA
The overheat temperature sensors are color coded on Yanmar. I had overheat alarms coming in after 15 minutes run time. Turns out the PO installed a sensor that was way too low. I never had an actual overheat problem at all, just the wrong sensor. Check online for the correct color code for your engine.
 
Jun 28, 2005
440
Hunter H33 2004 Mumford Cove,CT & Block Island
Check sea water strainer, check mixing elbow, for restriction, replace sea water impeller, check thru hull for blockage, check overtemp sensor for proper operation, or simply replace, can also add temperature sensor and gauge. Most important check pump belt for proper tension, inspect for wear, replace if necessary.
 

drm1

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Sep 13, 2020
107
Hunter 36 Bayport Yachting Center
Yes there was an issue with undersized heat exchangers with the early 3YM30's. They were changed out mid 2005. Yanmar only covered the fix under warranty if there were complaints. Boats, such as yours ( I'm assuming ) would only motor a short distance out of the marine, hoist sails and go for a few hour sail, fire up the engine and head back into the marina for the night and therefore never had the overheating problem. Ours was an early 2005 and came from Toronto. Up in Georgian Bay we motored considerably and had problems with overheating and I finally managed to get Yanmar to change out the heat exchanger after contacting Yanmar US and citing safety concerns.
I have a 2005 Hunter and have the overheating issue at >3000 rpm. Checked with the mechanic who serviced the boat til I bought it last year. He’s retired now. Says that he wasn’t aware of an overheating issue before I mentioned it to him last year (the previous owner never went far from the dock). did change antifreeze (it needed it), impeller, had a heat gun on it to verify overheating and bypassed the hot water tank (blockage in the hoses). my engine was one of the earlier ones built with the undersized heat exchanger.

3000 rpm is typically more than enough but it would be nice to have the extra rpm if I needed it to outrun a storm or some other safety related issue. I don’t imagine Yanmar will do anything on a 16 year old boat unless there is the upgraded heat exchanger that I can order as a replacement part.

any advice?
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
I have a 2005 Hunter and have the overheating issue at >3000 rpm. Checked with the mechanic who serviced the boat til I bought it last year. He’s retired now. Says that he wasn’t aware of an overheating issue before I mentioned it to him last year (the previous owner never went far from the dock). did change antifreeze (it needed it), impeller, had a heat gun on it to verify overheating and bypassed the hot water tank (blockage in the hoses). my engine was one of the earlier ones built with the undersized heat exchanger.

3000 rpm is typically more than enough but it would be nice to have the extra rpm if I needed it to outrun a storm or some other safety related issue. I don’t imagine Yanmar will do anything on a 16 year old boat unless there is the upgraded heat exchanger that I can order as a replacement part.

any advice?
I went to Yanmar US, which is the North American HQ. As we are in Georgian Bay with lots of areas where you can only motor and close to rocks, I cited safety concerns if the engine overheated. This was 14 years ago on a 2 or 3 yr. old boat. IMO it should have been a full recall. There are still plenty of boats out there, similar to yours, where the owner ony motors out of the marina and sets the sails, then motors back in to the marina after. Once these are sold and used more often this issue will crop up, such as your case.

Not sure where you're located, but check with a few of the dealers like Eastern Marine, Toronto Harbour or Bristol Marine Port Credit. They could most likely order the new larger heat exchanger tubes for you.

 

buddy0

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Sep 17, 2014
48
Hunter 33 Oriental, NC
Yanmar would not help with my 2005 in 2019, as expected - too much time had passed and I am the second owner. Most of the previous years the boat was kept in a lake by the original owner, so they didn't notice the problem.

For me, it ran fine at 2400 RPM (tested for an hour), but overheated after two minutes at 2800 RPM.

Buying from a Yanmar dealer was the only option I could find.
Replacing the original 38-tube heat exchanger core with a new 63-tube one completely fixed the problem for me.

-buddy
2005 Hunter 33
 

drm1

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Sep 13, 2020
107
Hunter 36 Bayport Yachting Center
Great info. Thanks!

Buddy or Scott, do you happen to have a part number?
 

drm1

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Sep 13, 2020
107
Hunter 36 Bayport Yachting Center
Looks like this was published in 2003. Wouldn’t that have the old number on there?
 

drm1

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Sep 13, 2020
107
Hunter 36 Bayport Yachting Center
Thank you!

Toad marine had the part listed for ~USD $2100.
Yikes
 
Oct 29, 2005
2,355
Hunter Marine 326 303 Singapore
Hi Jake, thanks for that. I will check the temp and perhaps get someone to have a look at the heat exchanger. And yes we do love the boat. I can’t believe how little fuel I burned from Toronto to Halifax, about $300 we think approximately 2 litres per hour. The three blade prop makes a big difference.
So what's the findings? Resolved?