Onan 7500 Coolant Change question

[AlexP]

Doing this procedure. I used prestone flush in through the cap and then filled the rest of way with water and also filled reservoir with water. Ran for a while. Drained. Filled with distilled. Ran for a while drained. But when I drain reservoir doesn't seem to drain. Now it is mostly full of water.

The spec in my manual says 4.2 qt for coolant including reservoir. But doesn't seem like they mix. Is there some clever trick to drain reservoir?

I had hoped to just drain it all and put 2.1Q of AF in and top off with distilled, but seems like that is going to be a problem as reservoir is now full and doesn't seem to drain or mix.

??????

Thanks
Alex

[RV Wizard]

You need to access the actual radiator coolant pressure cap and fill the radiator through it. To gain access, remove the 10 mm bolt holding the cover above the start/stop switch on the generator and pull out the connected radiator cap and fully extend the hose. This is where you will fill the radiator. You could siphon off the reservoir and fill with 50/50 antifreeze and water. Good luck and keep us posted.

[AlexP]

Thanks Mike,
I actually did find the real cap under the plate and did my flushing and such through it. But doing it, I realized that the reservoir was not participating.

So siphoning out the reservoir....... Hadn't thought of that.

Off for some siphoning tubing.
Alex

[Steve N Sal]

Yup, siphoning it out would have been my suggestion too.

[OLYLEN]

Remember it's a diesel, so diesel AF just like the pusher motor. My son, diesel man(manages a fleet) says the biggest diesel major fail is coolant rot.

LEN

[AlexP]

Thanks everyone. Siphon worked fine. Stuff was yucky. 8 year old rig new to me, but under the radiator cap was....not so nice. I put in 5 year stuff. Should I believe the label?

[Mr_D]

Originally Posted by OLYLEN

Remember it's a diesel, so diesel AF just like the pusher motor. My son, diesel man(manages a fleet) says the biggest diesel major fail is coolant rot.

LEN

Liner perforation caused by cavitation, that's what the SCA additives are for IF your engine has liners. Some (Cummins ISB) don't have liners so don't require the additives. Our diesel gen has a Kubota diesel engine, it doesn't require the SCA additive. For Cummins it's DCA that you check for and add if needed.
Some coolants don't require any additives and last 6 years or so.

The approved coolants for a Cummins are:
Fleet Charge by Old World
Detroit Diesel Power Cool
Fleetguard Fleetcool
Fleetguard ES Compleat EG
Fleetguard Fleetcool EX
Shell Diesel Ready
Needs to be ASTM D6210
NOT contain sodium 2-ethyl hexonate