Changing Hydraulic System Oil

[vito.a]

I changed the hydraulic oil over the weekend. Our coach uses 50-55 quarts (12.5-13.75 gal) of Dexron III and a Parker IN HC 5720 (10 micron) filter. The filter is located very low just behind the engine and in front of the trailer hitch, so it’s a perfect place to drain the system.

I purchased 12 gallons of Dexron III from Walmart for $12.15 per gallon. I checked around and with shipping, this was the least expensive I could find.
I ran the engine and used the air ride system to raise the coach all the way up on the air bags. I was then able to fit a 5 gal bucket under the filter. I loosened the filter approx 2 turns and let the fluid run out into the bucket. Make sure you have a large filter wrench as this is a large diameter filter.

The trick here is not to remove the filter until you are done draining the system. When the 5 gal bucket is near full, tighten the filter back onto the housing to stop the flow. Change the bucket out and loosen the filter again. I used three 5 gal buckets and drained about 12 gal of fluid. After the fluid was done draining I then removed the old filter. The new filter came with two rubber gaskets. My system used the smaller gasket. Be careful here as the gasket stays on the filter housing, not on the filter. I removed the old gasket from the housing and lubed the new gasket with Dexron and pressed it into the groove then reinstalled the new filter. Tighten it ¾ turn after the gasket makes contact.

Then I had to pour 12 gal of fluid back in through a fairly small opening that my funnel would not fit. I ran the engine again and then rechecked the fluid level. Overall this was much easier than I expected.

[10Boomer]

Originally Posted by vito.a

I changed the hydraulic oil over the weekend. Our coach uses 50-55 quarts (12.5-13.75 gal) of Dexron III and a Parker IN HC 5720 (10 micron) filter. The filter is located very low just behind the engine and in front of the trailer hitch, so it’s a perfect place to drain the system.

I purchased 12 gallons of Dexron III from Walmart for $12.15 per gallon. I checked around and with shipping, this was the least expensive I could find.
I ran the engine and used the air ride system to raise the coach all the way up on the air bags. I was then able to fit a 5 gal bucket under the filter. I loosened the filter approx 2 turns and let the fluid run out into the bucket. Make sure you have a large filter wrench as this is a large diameter filter.

The trick here is not to remove the filter until you are done draining the system. When the 5 gal bucket is near full, tighten the filter back onto the housing to stop the flow. Change the bucket out and loosen the filter again. I used three 5 gal buckets and drained about 12 gal of fluid. After the fluid was done draining I then removed the old filter. The new filter came with two rubber gaskets. My system used the smaller gasket. Be careful here as the gasket stays on the filter housing, not on the filter. I removed the old gasket from the housing and lubed the new gasket with Dexron and pressed it into the groove then reinstalled the new filter. Tighten it ¾ turn after the gasket makes contact.

Then I had to pour 12 gal of fluid back in through a fairly small opening that my funnel would not fit. I ran the engine again and then rechecked the fluid level. Overall this was much easier than I expected.

Vito good write up, think my 08 ISL might be a little different it used AW46. I have one spin filter, and a internal filter in reservoir.
Did you cycle your steering to purge through guild and remove air, or do you not need to do that step?

[CountryB]

Why not install an in-line shut off so next filter change will be less messy and time consuming? Is the line from your reservoir to filter 1-1/2"?

[vito.a]

Perry, I haven't checked the steering. I don't think it will be a problem.

Mike, I just don't think the shut off is necessary. The oil runs down the rear half of the filter and I used a blue paper towel over my hand to spin the filter back and forth. It was very easy this way.
How often should the hydraulic oil be changed?

[CountryB]

Originally Posted by vito.a

How often should the hydraulic oil be changed?

Good point.
Probably once in the life of the coach - however the manual states "filter and fluid change should be done every 12 months or 15,000 miles".

[BigLar368]

I am going to change ours before our big trip later this year. All I have is the internal filter. Also there is no drain plug. Gonna have to crack a line and let it seep out....lol. The city is gonna think I am working as a mechanic out of our home....lol.

[tc914-8]

Hi Vito, thanks for the info and write up, that sure seems like a lot of fluid. My reservoir looks like about 1gal Max. I will have to check the capacity chart to see how much my system holds. I did change the internal filter and definitely did not see any other filters other than engine oil, 2 fuel filters. I had my local shop do the trans filter and fluid change after I first took ownership last year.

[96 Wideglide]

Originally Posted by 10Boomer

Vito good write up, think my 08 ISL might be a little different it used AW46. I have one spin filter, and a internal filter in reservoir.
Did you cycle your steering to purge through guild and remove air, or do you not need to do that step?

Perry, what color was your fluid that you removed? I know the manual said AW46, mine did as well.
Also, did your coach come with the TRW steering box?

[96 Wideglide]

Tony, little larger fluid tank on side radiator coaches, as the fan is also run by hydraulic motor.

[10Boomer]

Originally Posted by 96 Wideglide

Perry, what color was your fluid that you removed? I know the manual said AW46, mine did as well.

Also, did your coach come with the TRW steering box?

Yes my coach has a TRW box, I bought all the hydraulic filters, internal and spin. I checked oil, looks like tranny fluid but also dirty AW46. Sent out last November for final analysis have seen the report as I’m in WA building new home and RV garage. What did you have?

[96 Wideglide]

Don't know, but speculate it's ATF, despite what the manual say's.

Looked at TRW'S website once, and ATF is the only fluid they want in their steering box.