Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 06-24-2014, 01:23 PM   #1
Junior Member
Join Date: Jun 2014
Posts: 3
1990 Mobile Traveler

Hello my name is Redds and this is my first post. I am looking to buy an RV. It's a 1990 MT. It has a 7.3 engine installed and the guy said it is only getting 7 mpg. He also told me the last owner replaced the gas for the diesel engine. Being a retired diesel mechanic my thoughts went right to the transmission as the cause. If the old trans was used then it's holding the engine back. He said it takes some time for the RV to get to 65 on the highway so I think it needs another trans to take care of this problem. I was in class 8 semi's so I know little of this class of what will work. From what I read John Deere did this unit. I know the 7.3 IH engine are good but it needs help. Any help would be great as to what trans it will need.
Thank you

Redds is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 06-24-2014, 02:44 PM   #2
Senior Member
Jim_HiTek's Avatar
Join Date: Nov 2011
Location: Full time RV'er
Posts: 1,760
I don't know what a MT is. I'm assuming a Class A. An engine swap would be, what?, $20,000 to $30,000? Doesn't seem likely that someone would do that. If it's a rear engine Class A, then it undoubtedly came with a diesel...and the current tranni.

Many Class A's, depending on length and weight, only get 7.5MPG to 9.5MPG with the average being 8.5MPG. As far as the previous owner only getting 7MPG, maybe he's a lead foot. You're pushing a large box down the road, and if you treat it like it's a hot rod, you'll probably only get 7MPG.

Maybe you should drive it like you drive your trucks for the greatest economy...I'll bet you get better then that 7MPG. 55MPH uses a lot less fuel then 65MPH.

'02 Winnebago Journey DL, DSDP, 36' of fun.

Visit my RV Travel & Repair Blog at : http://chaos.goblinbox.com
Jim_HiTek is offline   Reply With Quote
Old 06-24-2014, 08:39 PM   #3
Join Date: Jan 2010
Posts: 48
Diesel run at lower RPM then gas, might need overdrive. What RPM is it turning at 60 MPH ?
National Dolphin 35Ft. 1995 slide Ford 460
Banks SYSTEM Best thing I did. 6.5 MPG at 65MPH with toad.
gary peterso is offline   Reply With Quote
Old 06-25-2014, 05:30 AM   #4
Junior Member
Join Date: Jun 2014
Posts: 3
Thanks. The RV is a 1990 Mobile Traveler that came with a 454 Chevy engine was by John Deere and the last year for this company. I was just hoping someone knew of a trans that would go on that engine.
Redds is offline   Reply With Quote
Old 06-25-2014, 01:57 PM   #5
Senior Member
Nick-B's Avatar
Forest River Owners Club
Ford Super Duty Owner
Join Date: Aug 2009
Location: Vaughn, WA
Posts: 1,377
I'm pretty sure a 1990 (or 1989) John Deere gasser chassis would have originally come with a Ford 460 engine and the Ford 4-speed OD trans. If it originally had a 454 Chev then it is a Chev chassis and the '89 & '90 models would have still had the old TH400 non-OD trans which would definitely lower the MPG.

Peek under the front end of the coach. If it has a solid front axle, then it will be a JD/Ford chassis. If it has independent suspension with A-arms, then it is a Chevy chassis.

I'm thinking if it is a Ford OD trans and the gas engine got switched to diesel then computer controls are probably not all hooked up so the tranny will not know to shift into OD and/or lock up the converter. That would have the diesel engine spinning way too fast at highway speeds.
1995 Coachmen Santara 360MB 36' w/slide.
Ford F53/460 chassis, 1997 Jeep Grand Cherokee "toad"
Nick-B is offline   Reply With Quote
Old 06-25-2014, 02:24 PM   #6
Moderator Emeritus
Gary RVRoamer's Avatar

Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,632
I agree with Nick-B. The John Deere chassis typically had a 460 Ford. I don't recall if the Chevy 454 was an option, but Nick identified the transmission that was used with it in heavier rigs.

You say it has a 7.3L Ford diesel now? If so, it was likely a Ford gas engine originally. Ford used the same tranny with the gas engine and 7.3 diesel, so that part may be ok. Not positive if the trannys had the exact same gearing, though.

What about the rear axle ratio? I think the diesel used a different rear end.recaRear axle ration
Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote
Old 06-26-2014, 05:19 AM   #7
Junior Member
Join Date: Jun 2014
Posts: 3
What a world of thanks on what to look for, I hope to see it Friday or Sat. But the guy told me it had a 7.3L International Harvester Diesel engine in it. He also said it was by John Deere and was gas converted to diesel. As for the trans it was my first thought on the slow power problem, I never thought of the electronic part of it I never was a car nut always Class 8 trucks. I was also trying to research this RV and seam to see parts are very hard to come by. Guess might need to install an Allison Trans. I have been looking for other conversions but most used the Cummins engine with the AT452 trans.

Redds is offline   Reply With Quote


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
1990 1/2 Bounder-GFCI reset? jewelzee44 Vintage RV's 6 06-21-2014 08:14 PM
1990 Sun Clipper. Voltage Regulator HazelTodd Class A Motorhome Discussions 1 05-21-2014 12:31 AM
1990 Pace Arrow opportunity AaronJ Vintage RV's 3 04-25-2014 12:02 PM
Plumbing diagram for 1990 34' Pace Arrow Tecelote Fleetwood Products Owner's Forum 7 04-07-2014 03:35 PM
1990 Bounder 34s Ford fuel pump madjack Vintage RV's 3 12-30-2013 03:13 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:41 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.