Mep802a coolent

Waterhouse

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Marianna, fl
I just bought a Mep802a. I was going over it and fixing a few things. I decided to drain and flush the coolent. I pulled both hoses and ran water through the rad both ways till clear. Then I attempted to do the same on the engine. It would not allow water through either way. I got thinking maybe the thermostat won't allow water through.

So I put the hoses back on and and filled it with water. I started the motor and left it run. After awhile the coolent temp gradually went up to 230-240. (No load) The motor never shut down by the fault code. I opened the door and felt the rad and hoses. Everything was just Luke warm. I pointed a digital temp gauge at the waterpump and it read 140. The manifold that the exhaust pipe bolts on was only about 250.

What do you guys think? Thermostat? Maybe the gauge is bad? What about not getting water through the pump? Is that normal?

I never drained the block petcock because it's kind of hard to get to. I figured I would just run it a few times with water. Now I'm wondering how you refill the block if you can't get any water in the hose.

Are the thermostat and pump readily available?
 

jamawieb

Well-known member
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Ripley/TN
You would need to run water in the top hose and have the radiator cap off. You will have a steady stream coming from the thermostat housing. Sounds like the gauge or sending unit is bad if it showed 240 because it shuts down at 220. The TM shows how to test the sending unit. Yes the thermostat and water pump are available, water pump on ebay and thermostat from parts store. Several post on the thermostat, the old number is murray 15358. Its been updated but I cant remember the number.
 

Zed254

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I think I was able to get an OEM thermostat on Ebay when I changed one out. My notes on Thermostat say....

Thermostat – Murray Ultra 15358 , Gasket – CST-2138 (2 Inventory)... Stant 45358, Gasket 25138. Gates 33008S, Gasket Gates 33624 these from cross ref chart.....ACDELCO 12TP1D, MOTORAD 2000180 these from Rockauto.
 

Waterhouse

Member
60
18
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Location
Marianna, fl
Thankyou. Do I need a gasket or will the make-a-gasket stuff work here? As far as testing the gauge, is it just a matter of sticking it in boiling water and see what it reads?
 

Zed254

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I used a gasket and Permatex Indian Head Gasket Shellac when I change out mine.

Testing the gauge will require a sender to provide resistance as temperature changes if you use hot water. I would check the connections on the gauge first. TM might have some troubleshooting tips. Lots of good stuff in those TMs......

ARMY TM 9-6115-641-24
2-92. COOLANT TEMPERATURE SENDER.
2-92-1.

Testing.
Shut down generator set.
Open left side engine access door.
Disconnect and tag electrical lead from coolant temperature sender (4, Figure 2-25).
Set multimeter for ohms and connect to coolant temperature sender terminal and casing. Muitimeter indication
-should be greater than 300 ohms.
Start generator set and observe multimeter.
As engine operates and coolant temperature rises, multimeter indication should decrease.
Shut down generator set.
Replace coolant temperature sender if indications are other than above.
Connect electrical lead, remove tag, and close left side engine access door.

2-40. COOLANT TEMP. INDICATOR.
240-1.
Inspection.
a. Shut down generator set.
b. Release control panel by turning two fasteners and lower control panel slowly.
c. Inspect COOLANT TEMP. indicator for cracked lens, loose mounting, corrosion, and other damage.
d. Raise and secure control panel.
2-40-2. Testing
Shut down generator set.
Open left side engine access door and disconnect negative battery cable.
Release control panel by turning two fasteners and lower control panel slowly.
Isolate generator set VOLTAGE potentiometer by disconnecting wire 156A at terminal 1 and wire 157B at -terminal 2 of AC voltage regulator.
Set multimeter for ohms and connect between terminals L and R of generator set VOLTAGE adjust
-potentiometer.
Adjust potentiometer until multimeter indicates 117 to 143 ohms resistance.
Disconnect multimeter but do not disturb potentiometer setting.
Disconnect and isolate electrical lead from terminal S of COOLANT TEMP. indicator.
Connect jumper wire between disconnected wire 156A and terminal S of COOLANT TEMP. indicator.
Connect jumper wire between disconnected wire 157B and terminal G of COOLANT TEMP. indicator.
Connect negative battery cable and move generator set MASTER SWITCH to PRIME & RUN position.
COOLANT TEMP. indicator should Indicate 116 to 164°F.
Move MASTER SWITCH to OFF position and disconnect negative battery cable.
Repeat steps e thru g, setting potentiometer between 58.5 and 71.5 ohms
Connect negative battery cable and move MASTER SWITCH to PRIME & RUN positron.
COOLANT TEMP. indicator should indicate 156 to 204°F.
Move MASTER SWITCH to OFF position and disconnect negative battery cable.
Replace COOLANT TEMP. indicator if Indications are other than above.
Remove jumper wires and connect electrical leads to AC voltage regulator and COOLANT TEMP. indicator.
Raise and secure control panel.
Connect negative battery cable and close left side engine access door.
 
Last edited:

Farmitall

Active member
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Eubank, KY
Thankyou. Do I need a gasket or will the make-a-gasket stuff work here? As far as testing the gauge, is it just a matter of sticking it in boiling water and see what it reads?
You should use a gasket and a very thin coat of Indianhead gasket shellac on each side of it just to fill any machining marks and make a good seal.

Avoid using for a gasket silicone products.
 

Waterhouse

Member
60
18
8
Location
Marianna, fl
Thankyou all,

So I tested the temp sensor and it seems to be accurate. I believe the thermostat is stuck. I will get one soon. The other problem is the "hightemp shut down" sensor. It appears it doesn't work. If I touch the two leads together, it gives the red light up front and the generator won't crank.

Is it a fact that it should shut it down at 220F? Where can I get one of those sensors?
 

America

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Location
USA
Thankyou all,

So I tested the temp sensor and it seems to be accurate. I believe the thermostat is stuck. I will get one soon. The other problem is the "hightemp shut down" sensor. It appears it doesn't work. If I touch the two leads together, it gives the red light up front and the generator won't crank.

Is it a fact that it should shut it down at 220F? Where can I get one of those sensors?
I would test the thermostat with hot water.
 

Waterhouse

Member
60
18
8
Location
Marianna, fl
I will test the thermostat with hot water, but I'm going to have another on hand before I remove it. The gauge seems to indicate correct at boiling water. (In a pan) The hoses/radiator never got hot when the gauge read 240. So that leads me to believe it's the thermostat. Maybe the pump, but it's not leaking.

I ran the generator for about 5-10 minutes with no load to get to 240 on the gauge. I could still touch the thermostat housing without getting burned.
 

America

Member
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Location
USA
I will test the thermostat with hot water, but I'm going to have another on hand before I remove it. The gauge seems to indicate correct at boiling water. (In a pan) The hoses/radiator never got hot when the gauge read 240. So that leads me to believe it's the thermostat. Maybe the pump, but it's not leaking.

I ran the generator for about 5-10 minutes with no load to get to 240 on the gauge. I could still touch the thermostat housing without getting burned.
Might as well replace it even if it still works while your in there.
 

Chainbreaker

Well-known member
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Oregon
Might as well replace it even if it still works while your in there.
Agree 100%! When your depending on a generator to keep you powered up during an outage you want to proactively "do the right things" to help facilitate reliability. Since your already investing the work to remove the thermostat, go ahead & install the new one and keep the used "known-good" one as your spare. If the new one ever fails later, you still have a used working spare to get you through until you can replace with a new one.

In general, when doing PM's I always install the best newest parts on the generator & keep any used known good parts (air filters, hoses, belts, etc.) as working used spares on the shelf. Anyway, that's my "make it better" approach when it comes to servicing, dismantling & testing routine "consumable parts".
 

Waterhouse

Member
60
18
8
Location
Marianna, fl
Yea, I like keeping good used spares. In the case of thermostats, I don't know if new is better. It is the one item I have bought new over the years that has been defective more than any other. Now I am in the habit of testing the new one before installing.

Ps, how do you guys quote someone? I don't see a button for it.
 

Waterhouse

Member
60
18
8
Location
Marianna, fl
Ok, I got a new thermostat and gasket. I figured I would remove the top hose to make it easy to work on. This is what I found.



I've heard if you mix the new orange coolent with green, you could get a gel. This stuff was like wax with crystals in it.



There wasn't as much in the thermostat or underneath it.



So on to the next question. I removed the thermostat and tested it and the new one in a pan. Both worked. The old one has a small hole in the edge. Not sure if it needs it.

While I had it out, I noticed the water was level with the thermostat housing. Just for fun, I hit the test crank switch and the motor turned over quickly. Should I expect water to come shooting out the thermostat hole? None came out. Do you think my pump is shot or clogged?
 

Guyfang

Well-known member
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Location
Burgkunstadt, Germany
I think you need to flush out your coolest system. Use some sort of cleaning agent. I would do it twice, if not three times. THEN you can try and figure out if your water pump is bad. Or if you need a thermostat. Or if your gage and sending unit is bad.
 

America

Member
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35
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Location
USA
If that stuff doesn’t dissolve easy, I would think the motor needs to be rebuilt if you expect it to be reliable. I would try to get it to dissolve without scrubbing that way you know the other areas You can’t scrub or see are dissolving as well.
 

America

Member
75
35
18
Location
USA
Thankyou. Do I need a gasket or will the make-a-gasket stuff work here? As far as testing the gauge, is it just a matter of sticking it in boiling water and see what it reads?
Gasket maker is something everyone should have in their tool box, but I only use it when i can’t get factory made gaskets. Also the gasket maker is only as good as the person applying it.

Do you mind if a ask what the plans are for this set?
 
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