After launch this season I notice the engine only gets to 140 degrees. In the past, if I remember correctly, I would tap on the thermostat housing and it all would then run hotter -160 or above. Not so this year. Any more tapping from my hammer and I will break the housing. So I guess I have to finally change the thermostat? It doesn't look like it has ever been changed. I don't think this is a false reading either as my water from the faucets only gets luke warm. Looks like this a easy change right? Two bolts to remove and replace the thermostat and gasket, maybe use some gasket sealant too?
Engine runs cool
- Thread starter Pat T
- Start date
Diesel like to run pretty warm. Is that a Universal? IIRC it should run 175-180. A thermostat is a pretty simple change as you said. Drain the coolant from the heat exchanger first. (at least down to the thermostat level)
The biggest errors I saw, when working in the Chemical Industry, was errors in judgement made by believing solely on ONE sensor measurement.
Just like a good detective does...
Get TWO confirmed Sources
and make sure they are not lying.
I suggest Laser Temperature measures on Coolant and exit water temperatur on the exchanger.
Jim...
PS: Calibrate by shooting an ice cube and boiling water. The Lie detector.
Just like a good detective does...
Get TWO confirmed Sources
and make sure they are not lying.
I suggest Laser Temperature measures on Coolant and exit water temperatur on the exchanger.
Jim...
PS: Calibrate by shooting an ice cube and boiling water. The Lie detector.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 24,519
On your idea of laser temping (infrared temp) the various parts of the engine. There is sometimes a disconnect between the sender (lower Voltage) and the gauge for some units. The gauge says 140 but the sender is actually reading 160.. Who would think that could happen.
If historically when he taps the housing the temp climbs to standard, then it's fantastically obvious that the thermostat or sender is stuck.
They may just need a cleaning.
And yes, for thermostat replacement, rem bolts, clean or replace stat, replace cap. Put a towel to catch any coolant that comes out of the housing. It won't be much if any. Open the air bleed on top first. BTW you may need crack that air bleed with engine running after all is done, to eliminate any pockets. Just open it till it spews.
Clean/scrape off old gasket, use new one. Pliable gasket sealer won't hurt it, but if installed correctly then won't need. Don't get any in the coolant.
This is as easy a task as it gets.
Use the factory temp spec. Do not install higher temp. Many reasons. The manufacturer knows what their engine temp should be.
Edit: if you have a remote expansion tank above the water heater, you should drain the coolant down some before opening the housing. And refill and bleed of course after.
They may just need a cleaning.
And yes, for thermostat replacement, rem bolts, clean or replace stat, replace cap. Put a towel to catch any coolant that comes out of the housing. It won't be much if any. Open the air bleed on top first. BTW you may need crack that air bleed with engine running after all is done, to eliminate any pockets. Just open it till it spews.
Clean/scrape off old gasket, use new one. Pliable gasket sealer won't hurt it, but if installed correctly then won't need. Don't get any in the coolant.
This is as easy a task as it gets.
Use the factory temp spec. Do not install higher temp. Many reasons. The manufacturer knows what their engine temp should be.
Edit: if you have a remote expansion tank above the water heater, you should drain the coolant down some before opening the housing. And refill and bleed of course after.
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Just a word of caution. When I removed the thermostat housing on a Universal M25 that was 20 years old at the time, the two bolts had apparently seized in the aluminum threaded holes and pulled the threads out with them. You could end up not being able to put it back together. A fix is a helicoil, and should be pretty easy to get at with drill, etc. (I ended up drilling out oversize and making internally and externally threaded bushings on the lathe; loctite on the outside, never seize on the inside.)
Most temp gauges on sailboats are not all that accurate. As above I'd take readings at the sender with a temp gun before hammering on anything. There are many things to consider here, like did you recently change the impeller? Did you work on or replace the riser? Change the cooling water? Add antifreeze? Clean out the sea strainer (which might just be a byproduct of a haul out)?
Or perhaps the sender or gauge is just failing. Put your hammer away and test the thermostat. Put it in a pot of water on the stove with a thermometer and see at what temp it opens; easy peasy.
If you determine there is a fault with the accuracy of the sender/meter then remember it is any change from the norm that should concern you, not the actual numbers. If it always shows 140, but one day creeps up to around 160, then take note. Otherwise, assume the 140 (after heat gunning the engine) is really 180 and all is OK.
Some engines will get hotter the more load they have on them, and this is not normal. Maybe it indicates a bad thermostat, insufficient coolant flow (restricted passages in the engine) or even a warning that the fresh water cooling pump may be close to failing? Honestly, I just can't remember, so perhaps someone could help with that.
Or perhaps the sender or gauge is just failing. Put your hammer away and test the thermostat. Put it in a pot of water on the stove with a thermometer and see at what temp it opens; easy peasy.
If you determine there is a fault with the accuracy of the sender/meter then remember it is any change from the norm that should concern you, not the actual numbers. If it always shows 140, but one day creeps up to around 160, then take note. Otherwise, assume the 140 (after heat gunning the engine) is really 180 and all is OK.
Some engines will get hotter the more load they have on them, and this is not normal. Maybe it indicates a bad thermostat, insufficient coolant flow (restricted passages in the engine) or even a warning that the fresh water cooling pump may be close to failing? Honestly, I just can't remember, so perhaps someone could help with that.
Agree with the others on trying to get a second reading, probably from a laser. But also, what's the water temperature in Illinois this time of year? That could also affect the time it takes to get up to running temp and maybe the high end temp.
It hasn’t been said yet but antisieze is the best friend the next person who tears into the stat could have.
Les
Les
Thanks all. My second indicator that all is not well is the temp of my faucet water which is heated by the engine and its not getting warm as before even though I have given ample time to run this Universal to warm up. ( I think temp in the harbor was about 65 Deg F) So tomorrow I will attempt to change out the thermostat. I have been carrying a spare for a few years now anyway and what the heck, the boat is 23 years old. I just worry about those simple jobs that end up not so easy as jviss speaks of. We shall see.
Well the maintenance gods had mercy on my poor soul and the bolts came out rather easily. You could see the anti-seize on the threads yet. Thank-you Mr. Kubota. The new thermostat made a little difference and I could get the gauge to read about 150 F now and this is at the dock while at idle. FYI, 160 F was the recommended replacement and that's what the old one was also. I feel better now. I know the thermostat is not at fault. Only thing to check now is will the engine run a little hotter under load and what will an infrared thermometer read in comparison to the panel gauge.