MEP-803 overheated first time under load

[cstumpf750]

So I got a couple of 5000 watt heaters off Amazon to load test my generator. I put one of it just to see how things went with a partial load. Well, it overheated in short order. I shut it down before it did it via the sensor. seemed like the thermostat never opened. I found a forum post where the same thing happened and after it cooled down they pulled the thermostat and it worked when tested, so they put it back together and it worked fine. So I tried again today and this time the thermostat opened and closed repeated while under a 5000 watt load. I watched the gauge move back and forth several times before shutting it down. I still need to do a full load test, so I’ll keep an eye on it, but I think it should be OK.

I’ll get a spare so I have one if I need it. Does anyone know of a cross reference to a thermostat and gasket from an auto parts store?

 

[FarmingSmallKubota]

So I got a couple of 5000 watt heaters off Amazon to load test my generator. I put one of it just to see how things went with a partial load. Well, it overheated in short order. I shut it down before it did it via the sensor. seemed like the thermostat never opened. I found a forum post where the same thing happened and after it cooled down they pulled the thermostat and it worked when tested, so they put it back together and it worked fine. So I tried again today and this time the thermostat opened and closed repeated while under a 5000 watt load. I watched the gauge move back and forth several times before shutting it down. I still need to do a full load test, so I’ll keep an eye on it, but I think it should be OK.

I’ll get a spare so I have one if I need it. Does anyone know of a cross reference to a thermostat and gasket from an auto parts store?

MEP803A Thermostat

My MEP803A (2012 Letterkenny Reset with 53 hrs) overheated and shut down during a 105% PF run a few weeks ago so I changed out the thermostat. I bought a new Onan Thermostat on the auction site with the correct NSN # (6685-01-360-9653) and part # (186-6193). It is rated at 74C (165F). All...

www.steelsoldiers.com

Here you go

Also cheap ebay https://www.ebay.com/itm/196206324395

 

[kloppk]

According to my notes...

Murray Ultra 15358 and the gasket is a 2138

 

[cstumpf750]

There are different temp thermostats. Mine currently seems to have the 190 degree version. I think 165 is a bit cool, especially for a diesel. Thanks for the cross reference.

 

[2Pbfeet]

@cstumpf750 The 15358 should be a 180F open thermostat.

 

[Toolslinger]

So, just out of curiosity... Where are you finding a Murry 15358? I went through every Murray thermostat on the O'Reilly site, and did not find that number.

I did find a 15358 at AutoZone, but not a Murray brand.

The only references to Murray having that number I find are here on Steelsoldiers, and then there's something in a Ram forum, but no manufacturer, or actual sales links.
That's not to say anyone is wrong... My opinion of search engine results has gone right in the toilet over the last several years...

 

[Ray70]

Assuming your thermostat was installed correctly ( spring towards the engine ) I'd say you may have had an air pocket under the thermostat, preventing it from opening correctly.
Some thermostats have a small 1/8" hole drilled in the flat body with a little brass ball that acts like a check ball almost. It will let air bleed out but blocks the flow of water. If I get a thermostat without the hole I almost always drill a small 1/8" hole in it to help bleed the system. The 1/8" hole doesn't flow enough water to affect the operation of the thermostat at all, but it will allow air to bleed out easily.

 

[2Pbfeet]

Assuming your thermostat was installed correctly ( spring towards the engine ) I'd say you may have had an air pocket under the thermostat, preventing it from opening correctly.
Some thermostats have a small 1/8" hole drilled in the flat body with a little brass ball that acts like a check ball almost. It will let air bleed out but blocks the flow of water. If I get a thermostat without the hole I almost always drill a small 1/8" hole in it to help bleed the system. The 1/8" hole doesn't flow enough water to affect the operation of the thermostat at all, but it will allow air to bleed out easily.

I've heard the gizmo called a jiggler. I know some newer thermostat designs have grooves cut in them to allow air to by pass the thermostat.

I've heard of the 1/8" hole trick before, though I have never needed to use it to get air to bypass a thermostat because in the past I had been able to find thermostats with jigglers for engines that needed them.

All the best,

BG

 

[Ray70]

Jiggler! That's the term I was looking for.