Corrosive coolant

[fa35jsf]

So while tearing into my 802 to replace some leaking fuel hoses, I noticed that the top of the thermostat housing showed signs of leaking right at the hose. Well I took the hose off only to discover that the housing had been corroded away.

Now I need a new thermostat housing and thermostat. Anyone know part numbers for these two items. I can’t seem to find it in my manuals.

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[WWRD99]

I don't know the part numbers and obviously you have a paper copy of the tm and need parts 3,4 and 5...any chance you looked at the online tm available in this site? If you can't find it I can try to look them up in the tm online here...not sure if you have easy access or not. I'd check the lower hose outlet too or any coolant outlet plus add some grounds to slow electrolysis...maybe add some good water and fresh coolant.

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[fa35jsf]

Lower hose outlet looks ok. My father said this can happen if you have a bad mix of coolant. This stuff was super green. Looks like someone put straight concentrate in it at one point in time.

As far as the TM goes, I’ve looked everywhere for part numbers. Maybe I’ve got the wrong TM?


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[WWRD99]

Your dads right for sure...typically it's not the coolant but the water used to mix it...if you change coolant a lot it won't matter much but something that sits, like these gensets, with a charged up set of batteries wreaks havoc on aluminum parts...making sure you have good clean low resistance grounds helps and using distilled water to mix the coolant works. If you don't have one already the funnel attachment to fill the radiator makes it a bunch easier too...most come with a long pipe to mount the funnel to. The tm should have a parts list right after the page with the picture description...is a page missing? Idk, usually finding parts is the easier thing to do with a tm.

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[nextalcupfan]

MEP802A-MEP803A THERMOSTAT COVER Onan 186-6189 ⋆ Green Mountain Generators

MEP802A-MEP803A THERMOSTAT COVER Onan 186-6189

greenmountaingenerators.com

Tricky little bugger, it's in the parts manual for the ENGINE not the Genset.
I found the part # in TM-9-2815-253-24P (803a DN4M Parts Manual)

 

[nextalcupfan]

@fa35jsf Is the outlet Aluminum?

I ask because I've seen this before on my Dad's 1963 Pontiac Bonneville, only it was the cast Aluminum timing cover that went away.
I know you have to change coolant every so often (3-5 years or 100k miles seems to be an average) because they have corrosion inhibitors that degrade over time.

As a matter of fact I changed the coolant in my MEP-803a about 6 months after I got it. (Unit is a 2002 with no reset)

 

[69birdman]

So while tearing into my 802 to replace some leaking fuel hoses, I noticed that the top of the thermostat housing showed signs of leaking right at the hose. Well I took the hose off only to discover that the housing had been corroded away.

Now I need a new thermostat housing and thermostat. Anyone know part numbers for these two items. I can’t seem to find it in my manuals.

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A Murry Ultra 15358 180° thermostat and #2138 gasket will fit. There's a thermostat housing available on EBay with bolts.

 

[glcaines]

Make sure you dilute the coolant concentrate with deionized water if you use concentrate.

 

[fa35jsf]

A Murry Ultra 15358 180° thermostat and #2138 gasket will fit. There's a thermostat housing available on EBay with bolts.

Thank you for those part numbers!


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[fa35jsf]

Is there any reason why I could not use a thermostat inlet housing from an 803?


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[kloppk]

No reason you couldn't. Both use the same inlet housing 186-6189

 

[Kahles56]

Before you put new coolant in the unit I would flush out whole system and run a coolant cleaner for aluminum through system , flush out after you run at least two times plane h2o to get rig of any contamination.

Also for those of you that might be thinking of changing or not changing coolant , test coolant with a multi meter and see if there are any microvolts passing in the coolant. One probe in coolant one probe on block/ground. ANY microvolts means you need to change coolant.

PS you may need a new water pump as well.

 

[Guyfang]

Perhaps you need to download ALL the TM's for the set. Anything engine related is completely separated from gen set related, like Nextalcupfan wrote. All the TM's are in the TM forum for your use.

 

[nextalcupfan]

Is there any reason why I could not use a thermostat inlet housing from an 803?


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In case you missed it I put a link in my earlier post to a MEP 802a/803a thermostat housing on Green Mountain Generators.

 

[fa35jsf]

Perhaps you need to download ALL the TM's for the set. Anything engine related is completely separated from gen set related, like Nextalcupfan wrote. All the TM's are in the TM forum for your use.

Thanks. I had downloaded all the TMs but apparently forgot to print that one (I like paper best). Found the correct TM on my computer and printed it.


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[fa35jsf]

In case you missed it I put a link in my earlier post to a MEP 802a/803a thermostat housing on Green Mountain Generators.

Thanks. I just found a used but very good condition housing listed as 803 on eBay for like $28. That’s why I was asking. Man parts for these generators are expensive


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[fa35jsf]

Should I maybe switch to an extended life coolant or add some supplemental coolant additive (SCA) to the green stuff. I know a lot of other diesel applications need something extra in their coolant


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[nextalcupfan]

I bought Heavy Duty Diesel coolant and plan on changing it every few years.
The "waterless" coolant was a very appealing idea though.

 

[Guyfang]

It took my son 3 days to burn all my TM's when I stopped contracting. I know how you feel about paper. Sure wish I had kept some of those books. But where? I would have needed a very large room like the Army gave me for an office.