Onan 7.5kw MDJE operating temps?

[Redhook98]

What should I be reading on my Onan 7.5kw MDJE with a laser thermometer? I see temps in excess of 240 degrees directly under the injectors. Is that normal? Do the injector areas get hot (yes, I realize that is the combustion area). Typically I see temps around 160-190 in the rest of the readings taken around the generator.



These are taken under about a 60% load (best I can do right now). Water flow is great.

 

[rslifkin]

Right around the injectors is probably one of the hottest parts of the cylinder head. If you're shooting areas with coolant passages and not seeing over 190, it's probably cooling fine.

The service manual lists a few thermostats, but doesn't say which you're likely to have. Assuming closed cooling, I'd guess it's the 180* one (next step down is 160*). That means anything under 200 - 210* coolant temp is normal.

 

[DavidM]

Remember, it is coolant temps that you are trying to indirectly measure with an IR gun.

The place to check engine temps is at the thermostat housing. It is away from really hot places like the cylinder head and is representative (although probably 5 deg lower) of coolant temps.

Sounds like your generator is doing fine.

David

 

[Redhook98]

Thanks guys. The PO was worried that that area was getting to hot. I saw the higher temps and wanted to check. This is the first time I have had it reliably running. Switched from an iffy mechanical fuel pump to electric. Big difference. No surging or coughing. At 60% (appx 4400 watts) load it gets down to 115 VAC and about 57 Hz. Both acceptable in my book for a 40 year old gen.

 

[rslifkin]

I'd go through the governor adjustment procedure. You should be able to keep it within 62 - 58 hz from no load to full load ideally. 63 - 57 is acceptable, but I'd get it as tight as you can without causing it to surge / hunt.

 

[Tator]

I have new oil and fuel filters as well as new pump parts that were for my old MDJE 7.5. Easily over $100 in parts that I'm willing to give to a good home for shipping costs. Let me know if interested.

Tator

 

[Redhook98]

I have new oil and fuel filters as well as new pump parts that were for my old MDJE 7.5. Easily over $100 in parts that I'm willing to give to a good home for shipping costs. Let me know if interested.

Tator

Definitely interested! Thanks!