Tag Archives: generator

Onan Marquis Gold 5500 Oil Change

I knew with the purchase of our new coach I would need to learn how to do some of the maintenance work or face many labor charges for simple tasks.

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I changed the oil on my first car, a 1967 Ford Mustang, once.   When I shimmed out from under the car covered in motor oil from both removing the drain plug and filter I swore I would never do it again, and I haven’t up till now.  But this is different right?  It’s just a little generator, not a big muscle car…

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With the cover off, the generator looks rather complicated, but the oil fill is right up front (the cap is already off in this shot) and the oil is very simple to drain with no drain plug to loose.  Simply turn the “T” handled pin that sits below and to the right of the oil fill.  The oil flows down a small rubber tube (how do you replace that when it rots out?) and out the bottom of the generator / RV.

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Easy right?  Once the oil was mostly drained out it was time to tackle the oil filter.  I purchased the proper cup style wrench from Napa when I bought the filter (a Napa #7398 filter) and used it to loosen the old filter.  Once loose, it spun right out and a bit more oil came with it.  This cool oil pan has a grid you can put the filter on to let it drain out and a spout for pouring the used oil back into the empty bottles).

Next, I installed the new filter.  I used some fresh oil to moisten the gasket, spun it on, and tightened it a 1/2 turn (or so) with the wrench.

The final step is to re-fill the oil tank,  My generator manual states to use 2 quarts of oil and has several different types you can use based on temperature.  I choose 15W-40 based on the rang of 10 F – 100 F.  We live in Florida and it never gets over 100 F here.  We are going to travel to Tennessee in a couple weeks and it could get cold so that is why I did not use the 30W option for hotter temps.

It’s a slow process to re-fill the generator.  There is a tiny reservoir so you have to go slow.

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With 2 quarts onboard it was time for a quick test.  I ran it for a couple minutes and then shut it down to check the levels.  Everything was registering full!  I put the cover back on and when in the coach to test it out with a load.

We have been having some surging issues with the generator.  Many posts I read said it was probably a gummed up carburetor but figured I would try this first.  Oh, and when I put the used oil into the empty bottle, there was less than a quart in the engine!!!  We just bought our coach used in August with 200 hrs on the generator.  I guess it has never been serviced!

After warming up for 10 minutes, I turned on 1 AC.  It took the load well.  After about 10 more minutes, I started up the back AC as well.  The surging began…  It surged about every 20-30 seconds for four or five minutes and then is smoothed out!  I ran it for another half hour with both ACs cranking and it was loving it!  So hopefully the surging problem is solved!!

That’s it…  Generator is ready for our first big trip which is only two weeks away.  Today I am going to try to get the TV area buttoned up.