MEP 803A Overheating

[mlaxton]

So I have navigated old threads to the best of my ability. I recently picked up an 803a with 500 hours. Last night I changed all filters and fluids, also replaced the temp gage that was broken. I fire it up and within a few short minutes (maybe 4/5 min) the temp was at 200 + degrees. It wasn’t idling high and there was no load on it. All the fluids were filled correctly and double checked. So I backed the throttle down and got it to stop rising at around 210. Gave it some time and it slowly started creeping back up so I shut it down. I reached in and put my hand on the radiator because it felt cool blowing out of the top, and it was cold. The top hose was pretty hot just felt saturated from the motor heat, but the bottom hose was very cool pretty much the ambient temp of outside. I’m thinking the thermostat is stuck, the unit was drained and I’m guessing it was for some time. So my questions would be if you agree with the diagnosis? If the thermostat I got works on the same ohms as the old one, it looks different but is made by the same company I got it off of eBay. Also I have read in other posts that a standard Chevy thermostat works “perfect”. I am a ford guy lol so what is standard? A small block Chevy thermostat? I will attempt to attach pics of the thermostats.

 

[Daybreak]

Howdy,
NOTE; run the generator at the required speed at all times. 120/240 and 60Hz. Do not run it slow, do not idle it down.

There are threads here with good info about which gage works well.

 

[mlaxton]

Howdy,
NOTE; run the generator at the required speed at all times. 120/240 and 60Hz. Do not run it slow, do not idle it down.

There are threads here with good info about which gage works well.

I did not slow it down until it overheated badly

 

[Zed254]

Here is some Faria / Beede info to help you trouble shoot.....

 

[mlaxton]

Here is some Faria / Beede info to help you trouble shoot.....

thank you

 

[Daybreak]

Howdy,
I would make sure you have the unit full of coolant. Put some coolant in, use the dead crank switch a little to move it around, and add some more. Keep putting coolant in. It needs to get al through the block. There also could be a issue with the water pump.
If you have a method to lift the side of the generator, that will help getting the coolant into the radiator.

 

[Dock Rocker]

Do you know for sure that the gauge is accurate? You should trust a military gauge like you would gas station sushi.

I would definitely confirm with a laser temp gun before I got to crazy with the diagnosis.


Sent from my iPhone using Tapatalk

 

[America]

I did not slow it down until it overheated badly

did you get a High coolant temp shut down? Did the get a red light?

 

[America]

So I have navigated old threads to the best of my ability. I recently picked up an 803a with 500 hours. Last night I changed all filters and fluids, also replaced the temp gage that was broken. I fire it up and within a few short minutes (maybe 4/5 min) the temp was at 200 + degrees. It wasn’t idling high and there was no load on it. All the fluids were filled correctly and double checked. So I backed the throttle down and got it to stop rising at around 210. Gave it some time and it slowly started creeping back up so I shut it down. I reached in and put my hand on the radiator because it felt cool blowing out of the top, and it was cold. The top hose was pretty hot just felt saturated from the motor heat, but the bottom hose was very cool pretty much the ambient temp of outside. I’m thinking the thermostat is stuck, the unit was drained and I’m guessing it was for some time. So my questions would be if you agree with the diagnosis? If the thermostat I got works on the same ohms as the old one, it looks different but is made by the same company I got it off of eBay. Also I have read in other posts that a standard Chevy thermostat works “perfect”. I am a ford guy lol so what is standard? A small block Chevy thermostat? I will attempt to attach pics of the thermostats.View attachment 794375View attachment 794376

Your oil pressure is to high to be that hot. No way you have that high of pressure during a over heat.

 

[mlaxton]

Howdy,
I would make sure you have the unit full of coolant. Put some coolant in, use the dead crank switch a little to move it around, and add some more. Keep putting coolant in. It needs to get al through the block. There also could be a issue with the water pump.
If you have a method to lift the side of the generator, that will help getting the coolant into the radiator.

I will give that a shot, are there any known problems with these water pumps? I did check the belt, when I fired it up for the first time I dad coolant ready, didn't drop very much though

 

[mlaxton]

Do you know for sure that the gauge is accurate? You should trust a military gauge like you would gas station sushi.

I would definitely confirm with a laser temp gun before I got to crazy with the diagnosis.


Sent from my iPhone using Tapatalk

where is the best spot to get a reading with the gun?

 

[mlaxton]

Your oil pressure is to high to be that hot. No way you have that high of pressure during a over heat.

What temp will they shut down at?

 

[America]

Do you know for sure that the gauge is accurate? You should trust a military gauge like you would gas station sushi.

I would definitely confirm with a laser temp gun before I got to crazy with the diagnosis.


Sent from my iPhone using Tapatalk

Also th

I did not slow it down until it overheated badly

did coolant leak out? Your not really overheated tell your coolant starts to boil and this will make it leak out of the cap because of high pressure, you may have a over flow/coolant drain line that runs out the bottoms of the genny did anything come out during the over heat?

 

[mlaxton]

Also th

did coolant leak out? Your not really overheated tell your coolant starts to boil and this will make it leak out of the cap because of high pressure, you may have a over flow/coolant drain line that runs out the bottoms of the genny did anything come out during the over heat?

No nothing leaked out, I stopped it when it hit about 225

 

[America]

What temp will they shut down at?

i just had a mep 803 that was overheating two days ago. It will shut down down around u

What temp will they shut down at?

 

[America]

Howdy,
I would make sure you have the unit full of coolant. Put some coolant in, use the dead crank switch a little to move it around, and add some more. Keep putting coolant in. It needs to get al through the block. There also could be a issue with the water pump.
If you have a method to lift the side of the generator, that will help getting the coolant into the radiator.

Also after you do the above remember that the last bit of coolant is added to this unit through the overflow bottle by letting the set warm up and cool down a few times while topping off from the overflow, it’s the only way. These units in fact will reintroduce air into the system the minute you open the radiator cap again unless the genny is Propped up at a angle.

 

[mlaxton]

Also after you do the above remember that the last bit of coolant is added to this unit through the overflow bottle by letting the set warm up and cool down a few times while topping off from the overflow, it’s the only way. These units in fact will reintroduce air into the system the minute you open the radiator cap again unless the genny is Propped up at a angle.

thank you I am going to perform an ohms test to confirm the gauge and check coolant level again ill report back

 

[America]

where is the best spot to get a reading with the gun?

At the temperature sensor. Make sure you basically Touch the gun on it so that all your picking up is tge metal right around the temperature sensor. If the wire coming off the coolant temperature sensor is in the view of the gun it will through it off.

 

[Zed254]

What temp will they shut down at?

If you don't have the TMs for the machine check out Guyfang's library here: https://www.steelsoldiers.com/threads/mep-803a-all-the-tms-you-need.175591/ . Lots of good information that will help you learn and troubleshoot.

 

[Ray70]

Out of curiosity, in case I missed it, did you change the temp sender to match the new gage? Your new gage is going to read incorrectly if you leave the old sender because the original is a 240* and new is 250* but both have the same full swing resistance.
So the new gage will read high.
Also, is that a 24V gage, or did you need to use the resistor conversion board?
I would say throw in a new 180* thermostat, fill it up and test the actual temp as others have suggested.
It sounds like it was not really as hot as you think.
If you check the temp on the side of the block, the coolant hose near the thermostat ( or thermostat housing itself ) or top of radiator all should be about 200* or slightly less.