Generator Oil Leak

[EvenSteven]

Just got back from our first trip in the HR to Lake Powell, and the Onan 8k generator has developed a good sized oil leak.

We've only had this coach for a couple months (05 Endeavor 36 SKT). It wasn't leaking when we drove it home from back east, but developed a small generator oil leak about a week after getting it home. The oil is dripping from the drain plug, but it looks like it might be coming down to the plug from above. It leaks during operation, and when at rest. After a week sitting on the launch ramp while we were on the houseboat, there was about a half quart sized stain on the pavement.

The oil and filter were replaced by the dealer before we picked it up. I guess I'll start with checking the oil filter to make sure it's sealing properly.

I'm prepared to pull the generator to get to the bottom of this problem if I have to. Before I do that, though, I wanted to ask for any similar experiences any of you have had. Is there a way to remove the sheetmetal from around the generator to look for the source of the leak without having to completely remove the generator?

Perhaps, like an old VW engine, it might be easier to remove it and work with it on the bench?

[rex]

Well if you even think you may need to remove it, start now putting PB Blaster on the mounting bolts. If you don't, they may twist off while trying to remove them. Then you have to drill them out and that is not fun.

If you have a generator slide it will be easier to remove, and/or work on. If on a slide or not the front hood must be removed to pull the generator out completely.

To access the interior you will need to remove the screws in the top, sides, and back but not the front. Note the length of all screws on the top as 3 of them may be a different length where the antifreeze tank is mounted ( may be on the corner nearest the start switch ).

[EvenSteven]

Great tips, Rex!

This gennie is on a slide, so I think I'll pull the sheetmetal first and see if I can identify the leak while it's still sitting in the coach.

I've got to remove the fiberglass nose piece from the generator slide anyway; the mounting holes on one side are stripped out. That's another project...

[TEDDE]

I just had my onan 7500 watt genny apart to change oil. With the driverside sheet metal and the top removed you look right at the oil filter and the area all around it. I am glad I did this as I changed my antifreeze and went to pour the new coolant in, it would not allow antifreeze to go down the filler tube that the rad cap is attached to. That is when I decided to pull off the sheet metal and take a look. The rubber hose that allows the rad to be filled by removing the rad cap was kinked in two places. It must have been there since factory as no antifreeze could be added through this tube. All top ups are made through the over flow bottle anyway. I cut 8 inches of hose out of the line and all is well now. If I never had pulled the sheet metal off the genny I would never have seen the kinked hose. That is when you change the oil filter because you are looking right at it, as compared to removing the filter through the little access door on the bottom. It takes a little longer but you then see everything. Who knows what you will find....You will find your oil leak for sure..you can even run the genny with the sheet metal removed so you see everything..
Hope this helps

Ted

[2fasttoon]

While your under ther check the fuel lines, If its a diesel pay attention to the return line to the tank.

[Mr_D]

Originally Posted by TEDDE

I am glad I did this as I changed my antifreeze and went to pour the new coolant in, it would not allow antifreeze to go down the filler tube that the rad cap is attached to. That is when I decided to pull off the sheet metal and take a look. The rubber hose that allows the rad to be filled by removing the rad cap was kinked in two places.

Ted

Kind of the same with our 8.0 KW Power Tech, except mine was easier to fix! The filler tube is almost level when the rig is level and my parking spot slopes down in front. I just backed the rig out almost to the street so the back end was down and filled it up.
Also, just because your gen is on a slide out doesn't mean it'll be easy to service!! On mine the slideout sides are high and very close to the gen case. I need an open end or box wrench and even then it's close. Guess I need to buy a ratcheting box end set next.

[EvenSteven]

Thanks for the tips, everyone!

I'll pull the sheetmetal this weekend and see where all that oil is coming from. Sounds like a good opportunity to inspect the cooling system and everything else that's been hiding down inside those shiny green covers.

I do a lot of technical offroading, and we're regularly under our rigs tightening and inspecting things. Sounds like I should be treating the HR to the same level of attention. As smooth as this coach rides, evidently travelling along the highway helps you identify all your loose fasteners and weak links.

Funny story: Just before leaving our place in Havasu, heading for Lake Powell, I was going to check the oil level in the gennie and just about pulled the entire fiberglass front cover off trying to pull out the gen slide. Seems our well-maintained California highways had vibrated all the right side fasteners out, and was beginning to affect the left side ones as well.

I'll post up when done with what I've found in the generator.

Thanks again!

[Barlow46]

Originally Posted by TEDDE

I just had my onan 7500 watt genny apart to change oil. With the driverside sheet metal and the top removed you look right at the oil filter and the area all around it. I am glad I did this as I changed my antifreeze and went to pour the new coolant in, it would not allow antifreeze to go down the filler tube that the rad cap is attached to. That is when I decided to pull off the sheet metal and take a look. The rubber hose that allows the rad to be filled by removing the rad cap was kinked in two places. It must have been there since factory as no antifreeze could be added through this tube. All top ups are made through the over flow bottle anyway. I cut 8 inches of hose out of the line and all is well now. If I never had pulled the sheet metal off the genny I would never have seen the kinked hose. That is when you change the oil filter because you are looking right at it, as compared to removing the filter through the little access door on the bottom. It takes a little longer but you then see everything. Who knows what you will find....You will find your oil leak for sure..you can even run the genny with the sheet metal removed so you see everything..
Hope this helps

Ted

Ted, hate to tell you this but the tube is supposed to have that kink/bend in it. You need to put your hand on the metal radiator cap and remove the hose from its holder. Then it straightens out and you add the coolant. This method allows you to "burp" the coolant and get the air of out the system when you change the coolant. I am not sure if you have created an additional problem or not but it would be good to talk to someone who knows, just in case.

[Mike Canter]

Something else to add on that kinked radiator hose whicc is normal. onan has a warning notice out about filling the system with coolant. On that small black plastic fitting that the radiator cap goes onto are two small hoses aswell as the larger radiator hose. One of the small hoses goes to the plastic expansion tank and the other one goes to the thermostat housing to bleed air out of the system. Onan wants you to use a funnel that will get past those two small hoses so when you pour in the coolant you do not pour it into that small hose that goes to the thermostat housing. If you pour coolant into that small hose you will block the air from escaping and cause an air pocket in the engine which will cause it to overheat.

[RonNBama]

Evensteven, also take note of the 10mm bolt lenghts as you remove them from the panels. There two different lengths and Onan makes a point that the coolant tank can be damaged by using the wrong bolt at that location. Be sure to turn off the 12V power to the genny too. The "front" panel (Onan's term) can make contact with the terminals if you fumble a bit. I have a paper copy of the Onan instructions.

While were on the subject, does anyone have the engine manual for the HDKAJ (7500W) unit? A local shop was kind enough to print me off the first 11-sections today but the really good info (valves, belts, etc) seems to be in sections 12-18 (engine manual). Found one on FleaBay but haven't closed the deal due to an aversion to PayPal on my part.

[Norm4015]

I would start with checking the oil filter. Is it loose? When the dealer replaced the oil filter did the old gasket come off with the filter or did it stay on the generator and now it has two gaskets that aren't sealing?