I have one of the Mr. cool replacement heat exchangers, copper nickel. The good thing about these is that you can service both ends as they have removable caps at each end. Is it theoretically possible to remove the cap at the far end and run the engine and flush the water into a bucket thus cleaning out any debris that way or is that a crazy idea? (I am thinking that if I don’t get consistently good water out the exhaust next time I go out, I would take a hard look at the heat exchanger and the possibility of debris.)
Overheat adventure on 1985 Universal M12
- Thread starter odaydokay
- Start date
Some think it impedes electrical continuity between the anode and the HX. Others say the threads will cut the tape enough to make electrical contact.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 24,641
As you state, “It needs a proper ground from its threads to the exchanger”
The threads provide that electrical link as the exchanger should be connected to the engine, and thus to ground.
Teflon tape is there to reduce the chance of leaking. If there is no leak (and there should not be based on the type of threads used for the zincs and exchanger), then no need for the tape. If there is a leak, check and clean the threads.
Fun Fact: Teflon is used on some electrical wires as electrical insulation. It helps to reduce the smoke should a wire overheat.
The threads provide that electrical link as the exchanger should be connected to the engine, and thus to ground.
Teflon tape is there to reduce the chance of leaking. If there is no leak (and there should not be based on the type of threads used for the zincs and exchanger), then no need for the tape. If there is a leak, check and clean the threads.
Fun Fact: Teflon is used on some electrical wires as electrical insulation. It helps to reduce the smoke should a wire overheat.
Irrespective if there are breaks in the threads, it will always have greater electrical isolation between the anode and the threaded hole. You do not want that in this application. @sailme88 is spot on - do not use Teflon tape.
dj
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Sorry that I am late to this party.
The thermostat has nothing to do with this.
I have had a similar problem after the first run of my engine (M25) after the launch of my boat. The problem is that you can get a stubborn air bubble in the raw water circuit. It can be stubborn enough that the vanes in the raw water pump cannot develop enough suction to get the pump primed. What you did in opening the pump, LUBRICATING IT (I use dishwashing liquid soap - I coat each vane, then use the bottle to give the pump a squirt), and then closing the pump back up, solved the problem. Hopefully, you are running the "new" style Oberdorfer pump that has an O-ring, rather than the old type that used a gasket.
Also, be careful if you ream out the old H/X. Some of the holes/pipes DO NOT GO ALL THE WAY THROUGH the H/X. If you push it, you will cause a leak in the H/X, and have to find a boiler repair shop (yeah - good luck with that), or buy a new Heat Exchanger.
Also, the 3" x 13" long H/X is ALWAYS an upgrade to the 2" x 16" L heat exchanger. The 3" has removable end caps, and the 2" does not. I once sold someone a perfectly good 2" x 16" heat exchanger to replace the M12 - a 2" x 12"L spec'd for the M12. The guy returned it, and I gave him his money back, because he stated that it wasn't "supported" which it technically wasn't. It was 4 inches longer, and provided extra cooling capacity compared to the 12". The guy felt that the engine would run too cool, which was incorrect. The engine temperature should be controlled by the thermostat.
The thermostat has nothing to do with this.
I have had a similar problem after the first run of my engine (M25) after the launch of my boat. The problem is that you can get a stubborn air bubble in the raw water circuit. It can be stubborn enough that the vanes in the raw water pump cannot develop enough suction to get the pump primed. What you did in opening the pump, LUBRICATING IT (I use dishwashing liquid soap - I coat each vane, then use the bottle to give the pump a squirt), and then closing the pump back up, solved the problem. Hopefully, you are running the "new" style Oberdorfer pump that has an O-ring, rather than the old type that used a gasket.
Also, be careful if you ream out the old H/X. Some of the holes/pipes DO NOT GO ALL THE WAY THROUGH the H/X. If you push it, you will cause a leak in the H/X, and have to find a boiler repair shop (yeah - good luck with that), or buy a new Heat Exchanger.
Also, the 3" x 13" long H/X is ALWAYS an upgrade to the 2" x 16" L heat exchanger. The 3" has removable end caps, and the 2" does not. I once sold someone a perfectly good 2" x 16" heat exchanger to replace the M12 - a 2" x 12"L spec'd for the M12. The guy returned it, and I gave him his money back, because he stated that it wasn't "supported" which it technically wasn't. It was 4 inches longer, and provided extra cooling capacity compared to the 12". The guy felt that the engine would run too cool, which was incorrect. The engine temperature should be controlled by the thermostat.
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I have now done a few more things and no joy on getting the issue fixed. She’s running close to 200 and not even a full throttle which is not correct at all of course. I am going to now replace the thermostat. The service manual calls for an adhesive on the cover side of the thermostat flange. Does anyone know what kind of adhesive they would be talking about; something like a permit gasket seal maybe? Also, I am very worried about sharing off the two hex bolts. I know from experience it sometimes applying some heat is a good thing to do when you suspect something is frozen. Also tightening a tiny bit before loosening is another trick. Anyone got any experience with this? To heat it I could simply run the engine up I would think, loosen the two bolts, shut the engine down until it cools and do the change out then but again, any advice would be helpful.
You could also use PBBlaster or Kroil on those beforehand when cool and let sit for a day. If you just 'think" they may be frozen, why not try to see first? Planning always helps, worrying unnecessarily never does.
I've replaced thermostats on my M25 a number of times, never used anything but the proper gasket, no adhesive. A liquid type gasket is NOT an adhesive anyway, it is a sealant. The last thing you want is an adhesive, because it is something you will eventually want to remove.
If it were my boat, first thing I would do is take a thermocouple and check the accuracy of the gauge that is giving you the 200F signal. It could be the gauge.
Perma gasket is a decent sealant - although I typically don't like sealants there, it depends upon the mating surfaces. If the surfaces are nice and flat and in good condition I'll just put the gasket it. That's on a case by case situation.
To get the bolts out, I would get a six point socket or wrench depending on what you have and then apply torque to see if the bolts move or not. I may work it back and forth depending on what it feels like. If no joy, I might soak it in a penetrant like PB Blaster for a day. Then try the removal process again. Still no joy, I might use a torch to heat the area of the threads but that is very much dependant on access and what things look like. I would not heat up the whole engine as that just gets everything hot and tends to make it more difficult to remove those bolts.
dj
Perma gasket is a decent sealant - although I typically don't like sealants there, it depends upon the mating surfaces. If the surfaces are nice and flat and in good condition I'll just put the gasket it. That's on a case by case situation.
To get the bolts out, I would get a six point socket or wrench depending on what you have and then apply torque to see if the bolts move or not. I may work it back and forth depending on what it feels like. If no joy, I might soak it in a penetrant like PB Blaster for a day. Then try the removal process again. Still no joy, I might use a torch to heat the area of the threads but that is very much dependant on access and what things look like. I would not heat up the whole engine as that just gets everything hot and tends to make it more difficult to remove those bolts.
dj
I have a rebuilt universal diesel 5411 in 1983 Catalina C30 mk1.
When my ignition key is off and the engine is running the temperature gauge is off and will show the temperature about 190 to 200 degrees.
I don’t know why I turned the key off that day. Must’ve been a short between the headphones.
There is a small hole in the thermostat housing that allows a small amount of water to flow through the exhaust outlet until the engine reaches 135 and opens the thermostat. Until then, the water flows through and back into the cooling water pump and not out the exhaust system.
I know you said you have an M12 and I don’t really know the difference so I don’t know if this really helps.
When my ignition key is off and the engine is running the temperature gauge is off and will show the temperature about 190 to 200 degrees.
I don’t know why I turned the key off that day. Must’ve been a short between the headphones.
There is a small hole in the thermostat housing that allows a small amount of water to flow through the exhaust outlet until the engine reaches 135 and opens the thermostat. Until then, the water flows through and back into the cooling water pump and not out the exhaust system.
I know you said you have an M12 and I don’t really know the difference so I don’t know if this really helps.
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When the engine is off (after being warmed up and/or used to where the T is at operating temperature) when the power to the gauges is disconnected the T will stay at its last reading until the ignition switch is turned on, and if the engine is cooled, the T will start at cool/cold. This is NORMAL.
When you turn the ignition switch off when the engine is running, it disrupts power to the gauges as well as disconnecting power to the field wire to the regulator of the alternator. This does not hurt the alternator. Only disrupting the alternator output when the engine is running and the alternator is charging will damage the alternator.
When you turn the ignition switch off when the engine is running, it disrupts power to the gauges as well as disconnecting power to the field wire to the regulator of the alternator. This does not hurt the alternator. Only disrupting the alternator output when the engine is running and the alternator is charging will damage the alternator.
Stu,
Thanks, that is great information.
I thinking what I did was flipped up the gauge cover to check the temperature and tuned off the key accidentally, seeing the T was high, killed the engine with the throttle and went forward to check the hoses and they were normal temp. Started it back up and went out for a sail.
My engine gauge panel still has some issues after the previous owner swapped out the engine. This is a much more complicated system than I thought at first.
Luckily my alternator seems to be OK. No internal diodes issues yet.
Hope for the best and plan for the worst.
Thanks, that is great information.
I thinking what I did was flipped up the gauge cover to check the temperature and tuned off the key accidentally, seeing the T was high, killed the engine with the throttle and went forward to check the hoses and they were normal temp. Started it back up and went out for a sail.
My engine gauge panel still has some issues after the previous owner swapped out the engine. This is a much more complicated system than I thought at first.
Luckily my alternator seems to be OK. No internal diodes issues yet.
Hope for the best and plan for the worst.
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Reagan said, " Trust, but verify".... I say VERIFY first.. Before you jump in and accept the 200º number verify it to be correct. Laser heat guns are inexpensive. Get one, start up and verify the heat at the gooseneck.. IF the gun reads normal, you could be looking at a sending unit replacement. As for your fear of shearing, check around the tool rental places in your area for an induction bolt heater..