Recommended Posts

Fairly new with motohome experiences. I have a question and as dumb as it may sound, I don't want to make a costly mistake.

I have a 2006 Fleetwood Excursion with Onan 7500 diesel generator. The manual says to run it 2 hours a month even if I don't use it. I have noticed that there are two filler caps -- oil and coolant -- right next to each other. However, I can not see clearly if any coolant/water is in the tank.

I put a small piece of clean bamboo in the tank to see if any liquid was present, but it came out clean. The tank shows a max and min level mark, but it is difficult to see any liquid present near these marks. Does anyone have any suggestions? I am not clear since the coolant and oil fillers are within 2 to 3 inches, and I can't see clearly if there are separate tanks for each one. I don't want to fill either with the wrong product. Help!

Share this post

Link to post
Share on other sites

Welcome to the FMCA Forum.

Best advice is to pull out your Generator Owners Manual.

Second best is to give Onan a call on Monday/go to Onan's website. Too easy for us to do an inadequate job of describing their location and lead you to a REALLY BIG problem.

Brett Wolfe

Share this post

Link to post
Share on other sites

Hi jimsreyes,

Welcome to the FMCA forum. I think we have the same generator. Mine is the Onan Quiet Diesel 7500. Brett's advice to call the manufacturer is always the best way to get an answer. In addition to the Max/Min marks on the side, there should be, across the top above the two caps a label telling which one is which. Since we do seem to have the same unit, I'll take a try to answer your questions.

1. I do run my generator one hour a month if there is no use during the month (rare). I will put both HVAC units on to let it have some exercise. If the unit has been used that month, there is no need for an additional exercise period.

2. Your description of the coolant and oil filler caps is the same as my unit.

3. If you remove the oil filler cap (yellow) it is connected to the cable that goes into the oil reservoir. It is for checking the level of the oil for the engine. There is a tube the cable passes through. It is in the same area as the coolant tank. With a clean cloth handy, remove the cap and pull out the cable. At the end of the cable is the measurement end. There should be oil on the measurement end between the add and fill marks.

4. When you remove the coolant filler cap (white), it is just that, a cap with rubber grommet(s). There is no tube, the filler leads directly into the coolant tank.

5. You are correct, the min/max indicators are kind of useless. Like you, I can not determine if there is coolant between these marks. I use a metal coat hanger to determine the coolant level. The rod you used should also work fine. The objective is to use something stiff so a measurement can be taken.

The difference is that I have a coolant level mark on my coat hanger. It is about 1 inch below the MAX mark. Gut feel says you may be low on coolant.

The challenge now is to understand what coolant is in the generator. I do not know if Onan or Fleetwood would be the initial fillers of the generator fluids. Gut feel says it would have been Fleetwood. See if there are any labels or the documentation mentions what coolant is in the unit.

If it were me and I could not determine what coolant was in the generator, I'd do a complete maintenance of fluids and filters on the unit. If the coolant turns out to be green in color, you were about do for a coolant change anyway. If you do a maintenance cycle on the unit, you'll now have a record of what is in the unit.

Lastly, if you do do a maintenance cycle, consider putting the long life coolant (red) in the generator. The change out cycle goes from 3 to 6 years. Good luck and please post what you find and what your final solution is.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now