Onan 8k Quiet Diesel coolant flush w/pics

[Bob86ZZ4]

This info is probably here somewhere but I sure couldn't find it searching. I did find good text info but not any pictures. So, I figured I'd take some pics along the way and post for others. I've got about 750 hrs on my generator. I bought the rig used last year off a lot and have no history so decided I better flush out the coolant on it today. Hopefully I can get the pictures to work here. I don't know how to put the text under each picture. So, hopefully the pictures will speak for themselves. That cover above the starter button is held on with one bolt just above the start switch. After taking that bolt out it's kind of tricky to lift up on the lower edge of the plate and slide it down to get the plate to clear the start switch (I bumped mine with it and it started trying to start). Once you get it down far enough for the tab on the upper edge of the plate to clear you can work the whole thing out to bring the radiator fill tube out. That filler neck on the right of the switch plate is just into the overflow tank so filling that up doesn't actually put any coolant into the radiator I think. Now, once you get the filler tube assembly out you need to remove it from that cover access plate. It slides down into a bracket on the back of that plate. I turned the cap open to the first vent position and that allowed me to slide the whole thing up out of the bracket and move that bracket out of the way. That's shown in picture 2 I hope. You'll probably want to do this with it cooled down since that system could be under pressure if it's hot. The underneath shots show where the drain is located. The first one shows it's near where the exhaust pipe comes down. Looking up there you should see it. Mine was directly on top of a frame member which wouldn't allow the drain cap to be removed. That white plastic fitting has the drain cap and the radiator hoses attached to it. There is a bolt that secures it to the generator. I couldn't get a shot of it but if you put your finger around that plastic hose fitting you'll feel it. A socket made short work of removal. Sorry, I didn't note the size but it's the same size as the head on the bolt holding the access cover on the switch panel. Maybe 10mm? Once I had the bolt out I could manuever the drain fitting a bit and allow it to be pulled down some so I could get a slip joint pliers around it and unscrew it. It's just a standard hose type cover/plug. Drain the coolant. I then put the cap back on and filled it with water and ran the gen for a bit to circulate and help flush it out. Drain it. I'm going to stop at the hardware and get a new rubber ring to put in the cap before putting it back on. I need to go buy some Prestone coolant and distilled water, as well as that rubber ring. I'm going to do another flush or two with distiiled water before putting 1/2 gallon of coolant in and topping up with distilled water (my 8K has a 1 gallon capacity). It's hard to pour from a gallon jug into that filler neck since the underside of my camper is right above it. I'm going to use a large water bottle to put the fluids in and pour from that into the neck.

Okay, I'm sure I've missed something so others can help me out.

Thank you.

[Norm4015]

Pour the distilled water / coolant in very slowly and let the air bubbles work out. If you pour in too quickly you may get a lot of air bubbles. When it is full to the neck leave the pressure cap off and start the generator. The air bubbles will work their way out and it may even stall once with a 33 code (low coolant). Just start it up again and let it run about 5 minutes.

After you are through flushing and filling add a couple of inches in the overflow bottle. Put the radiator cap back on and run the generator until it is completely warmed up then shut it off. Let it completley cool and like the next day, check the level again at the radiator cap and overflow bottle and top up if necessary.

[Bob86ZZ4]

Good tip, I forgot to put that in about leaving the cap off and running it. That's how I always do my car too. Once the thermostat opens up and it's warm the coolant level will likely drop and you can add some more. I think it's important when doing it this way (flushing a couple times with water) that when you begin to fill up you first add the proper amount of coolant (full strength type not that pre-mixed, 1/2 of the system capacity), that way you can add the water to top off. Otherwise you won't be able to get the proper 50/50 mix since there's sure to be some water in the engine that won't drain out. At least a car motor does and I don't know about these motors but they might hold some water.

[squeak]

Bob also you need to clean the fins on the radator under the gen. look up at it and you will see lots of stuff in the fins

[Bob86ZZ4]

I'll look again, I kind of glanced up there and didn't notice anything but I'll check it. Thanks. Got the 1/2 gallon of Peak antifreeze in today and then managed to get about 1/4 gallon of distilled water in with that. Ran if for a bit with the cap in off and it took a slight bit more. Shut it down and left if for awhile. I used a 1 liter Aquafina plastic bottle to pour the coolant and distilled water in. It worked well since there is not enough clearance above my generator for the gallon jugs to fit.

[Barlow46]

"Use a funnel when filling the cooling system through the fill opening to prevent coolant from entering the vent hose and blocking the escape of air as the system fills. The system will seem full when it actually is not if the air cannot escape through the vent hose If the vent hose does get blocked, pinch the overflow hose and blow the vent hose clear. Coolant trapped in the vent hose will prevent the system from filling to its capacity, which can lead to serious engine damage." This is a quote from Supplement 981-1049. From what I understand is that if air gets trapped, the overheat sensor does not come in contact with liquid coolant and will not shut down when the engine overheats resulting in a cracked head or worse.