Question about plastic gas tank replacement. - JeepForum.com
Reply
 
LinkBack Thread Tools
post #1 of 16 Old 05-15-2019, 12:17 AM Thread Starter
Daves86cj
Registered User
1986 CJ7 
 
Join Date: Mar 2014
Location: Grosse Pointe
Posts: 23
Question about plastic gas tank replacement.

I have a 1986 CJ7 which came with the optional 20 gallon plastic gas tank. It has sprung a leak. Can I replace it with an aftermarket 15 gallon metal tank? Do I need to replace anything else like the sending unit and mounting straps? If this is possible, is there anything else I should know before attempting this?

I ask because it seems as if a replacement plastic tank is not available.

Thanks very much!

Daves86cj is offline  
Sponsored Links
Advertisement
 
post #2 of 16 Old 05-15-2019, 12:42 AM
whollsee
Registered User
1982 CJ7 
 
Join Date: Jul 2014
Location: Sydney
Posts: 227
MTS do a plastic 21 gall for 78-86 but I think you will need with conversion kit and some $$.

http://www.mtscompany.com/jeep.htm

When ever I hear the word 'Jeep' I reach for my wallet.
whollsee is online now  
post #3 of 16 Old 05-15-2019, 01:09 AM
BagusJeep
Web Wheeler
 
BagusJeep's Avatar
1981 CJ7 
 
Join Date: Jul 2009
Location: Bali
Posts: 6,956
You would need the tank, sending unit, filler hoses and straps. The carrier is deeper on the plastic tanks, up to you whether you buy a new one or convert the old one to raise the tank to where the hoses can connect or do something with the hoses.

BagusJeep lives in Bali.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
BagusJeep is offline  
 
post #4 of 16 Old 05-15-2019, 05:58 AM
jeepdaddy2000
Registered User
 
jeepdaddy2000's Avatar
1971 CJ5 
 
Join Date: Jan 2002
Location: Eagle Point
Posts: 8,222
Is it a seam split or a hole? Small holes can sometimes be repaired with a larger diameter sheet metal screw.

The duty of a patriot is to protect his country from it's government
Thomas Payne
jeepdaddy2000 is offline  
post #5 of 16 Old 05-15-2019, 06:43 AM
walkerhoundvm
Registered User
 
walkerhoundvm's Avatar
1981 CJ8 
 
Join Date: Apr 2010
Location: The Big Cholla
Posts: 3,719
Poly tanks can be patched.
walkerhoundvm is offline  
post #6 of 16 Old 05-15-2019, 07:48 AM
only in a jeep cj
Registered User
1986 CJ7 
 
Join Date: Jun 2001
Location: Mobile
Posts: 5,953
Since we are here discussing this, almost every oem 20 gallon damaged / leaking tank that I have seen is due from someone over tightening the nut on the end of the strap. This will crush in the back top of the tank and put a fold in the plastic which later splits. A full or partially full tank will slosh fuel around and it will leak.
The strap is only supposed to be tightened enough to where it only puts light tension on the top of the tank.

Ed
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon
only in a jeep cj is offline  
post #7 of 16 Old 05-15-2019, 09:19 AM
caseypotts
Registered User
1980 CJ7 
 
Join Date: Nov 2003
Location: Prescott
Posts: 501
Some of my thoughts on 21 gallon MTS poly tank. It seems to be a decent tank, they don't however seem to spend a lot of time on cleaning them up at the end of the manufacturing process (it is however a gas tank). It will hang low. I'm not sure how much lower compared to a stock 20, but much lower then a stock 15 gallon tank. 5 inches doesn't sound like much on paper, but in application...yeah it is much lower. You will need the lowering kit.

My single complaint on this tank is that the bottom is flat, there is no reserve hole or baffle. For me with a pump and FI, when the tank is low on fuel (lets say 2 gallons or less) and I go around a corner...I'm out of gas NOW.
caseypotts is offline  
post #8 of 16 Old 05-15-2019, 10:41 AM
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert - Palmdale, Ca. U.S.A.
Posts: 7,091
Cj

OP-Where is it leaking from?
LG

Have'n you along, is like loose'n 2 good men
LumpyGrits is offline  
post #9 of 16 Old 05-16-2019, 01:47 PM Thread Starter
Daves86cj
Registered User
1986 CJ7 
 
Join Date: Mar 2014
Location: Grosse Pointe
Posts: 23
Follow up on original post

OK. Got a bit of a reprieve. When I first saw the leak, I had just filled up the tank after having not used the jeep in a long time. As usual, I topped it off by adding more gas after the pump had automatically shut off. Got maybe an extra 1/2-3/4 gallon in it. I noticed the leak when I got home. I crawled under and checked the filler hose and vent hose above it and didn’t see a leak but tightened them up anyway. It’s pretty hard to see up there but I couldn’t see or feel a leak.

I put a bucket under it and it continued to leak for about 14 hours and finally stopped. I lost maybe 1.5 gallons. The gas gauge is stiil pegged above the full mark. This is when I started to investigate replacing the tank and discovered that a direct replacement was probably not available. That was when I considered retrofitting a 15 gallon metal tank which is readily available and cheap.

So, either the tank itself is leaking way near the top or a hose or fitting is leaking.

Anyway, the leak having stopped, I now have time to investigate the problem. I pictured myself having 20 gallons of gas in buckets and wondering what to do with it. As long as I don’t keep the tank over 3/4 full I’ll be fine for now

Thanks for all your comments and I can see that if necessary I can replace the plastic tank with a 15 gallon steel one for under 200 bucks.
Daves86cj is offline  
post #10 of 16 Old 05-16-2019, 02:42 PM
Shadow86
Registered User
 
Shadow86's Avatar
1986 CJ7 
 
Join Date: Sep 2016
Location: New York
Posts: 184
Garage
Quote:
Originally Posted by Daves86cj View Post
OK. Got a bit of a reprieve. When I first saw the leak, I had just filled up the tank after having not used the jeep in a long time. As usual, I topped it off by adding more gas after the pump had automatically shut off. Got maybe an extra 1/2-3/4 gallon in it. I noticed the leak when I got home. I crawled under and checked the filler hose and vent hose above it and didn’t see a leak but tightened them up anyway. It’s pretty hard to see up there but I couldn’t see or feel a leak.

I put a bucket under it and it continued to leak for about 14 hours and finally stopped. I lost maybe 1.5 gallons. The gas gauge is stiil pegged above the full mark. This is when I started to investigate replacing the tank and discovered that a direct replacement was probably not available. That was when I considered retrofitting a 15 gallon metal tank which is readily available and cheap.

So, either the tank itself is leaking way near the top or a hose or fitting is leaking.

Anyway, the leak having stopped, I now have time to investigate the problem. I pictured myself having 20 gallons of gas in buckets and wondering what to do with it. As long as I don’t keep the tank over 3/4 full I’ll be fine for now

Thanks for all your comments and I can see that if necessary I can replace the plastic tank with a 15 gallon steel one for under 200 bucks.
So something similar happened to me a few summers ago. I filled my 20 gallon fuel tank full and then pulled the trigger one more time and got maybe .5 more gallons in it. I parked it at home and came out to a big puddle underneath of it that was clearly gasoline. Found it was pouring out from the gas cap. I foolishly removed the gas cap only to see fuel shoot several feet behind the jeep.

Long story short, it seems something closed (rollover check valve?) And the tank had no place else to vent but out the cap. I now only fill it till the gas pump shuts off once and I have never had the issue again. Perhaps your issue is similar?
Shadow86 is offline  
post #11 of 16 Old 05-16-2019, 02:44 PM
walkerhoundvm
Registered User
 
walkerhoundvm's Avatar
1981 CJ8 
 
Join Date: Apr 2010
Location: The Big Cholla
Posts: 3,719
Doesn't look like you've learned much from the thread. These poly tanks can be fixed, chances are if there's a leak it's up top by the strap, and it's probably not a good idea to drive around with a leaking gas tank or plugged check valves.
walkerhoundvm is offline  
post #12 of 16 Old 05-16-2019, 04:03 PM
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert - Palmdale, Ca. U.S.A.
Posts: 7,091
Cj

Replace the 'O' ring on the sender.
Get one certified for fuel.
LG

Have'n you along, is like loose'n 2 good men
LumpyGrits is offline  
post #13 of 16 Old 05-16-2019, 04:24 PM
ddawg16
Registered User
 
ddawg16's Avatar
1984 CJ7 
 
Join Date: Oct 2018
Location: South Bay
Posts: 601
Garage
You will obviously need to pull the tank to see what the issue is.

While you have it down....replace ALL of the rubber fuel lines. They are almost 40 years old.....if not bad now, they will be soon.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ddawg16 is offline  
post #14 of 16 Old 05-16-2019, 04:50 PM
StoneTower
Registered User
1985 CJ7 
 
Join Date: Jan 2015
Location: Fair Oaks
Posts: 1,269
Your take probably has around 18 gallons in it when it is full. Borrow a couple of plastic 5 gallon tanks from friends/family. Borrow a couple of metal boat tanks (outboard motors). Take off the fill hose from under the wheel well. Siphon all the gas you can out of the tank. Get a floor jack and a piece of 1/2-3/4" plywood cut to fit the skid plate and use a floor jack to support the tank. Remove the bolts and drop the tank. If you get all the gas out of the tank, you do not need the plywood or the floor jack.

LOOK before you spend any money. It could be the fill hoses that are leaking. Mine had a crack that was not obvious on the bent and it leaked when I filled the tank too full. It could be the overflow valve, it could be the O-ring on the sending unit. Get and O-ring that is made for the CJ7 20 gallon tank as it will be fuel safe and they only cost a few dollars. You don't want to replace it with a generic O-ring that is not fuel safe.

https://www.amazon.com/Omix-Ada-1773...y&sr=8-1-fkmr0

If you are happy with the clearance of the 20 gallon tank installed on your Jeep, and it turns out that your tank is split, look for a good used replacement (if it is not repairable). Jeeps rust apart in many states and that tank, if not abused, lasts a long time. I am sure thousands of those good poly tanks have been junked with rusted away Jeeps. Even in California where we have no rust to speak of, I see those tanks from time to time on Craigslist for $50.00.

I like the larger tank and would not want a smaller metal tank that can rust internally plugging up my fuel injection system.

If you want to try to repair the tank try this:

StoneTower is offline  
post #15 of 16 Old 05-17-2019, 01:25 AM
BagusJeep
Web Wheeler
 
BagusJeep's Avatar
1981 CJ7 
 
Join Date: Jul 2009
Location: Bali
Posts: 6,956
I repaired the tank on my J20, it had 5 large cracks in it and had probably been driven leaking gas for years. It was also unobtainable, no one makes them any more. To find one and ship to here, would have been pricey.

It is quite easy to fix, the polypropylene can be welded back together and then patched with more polypropylene as a filler, like you get in oil bottles. All you need is a soldering iron or a fancy pants hot air tool. A small roller and spatulas also help to smooth the melted material together. We had the hot air tool on site many years ago to patch PTFE coatings, it worked very well on plastics of different types.

I watched the video, the soldering iron was fine but he had no filler material or patches so the repair was weak. I have tried JB Weld as in video, it does not stick so well to polypropylene and is inferior to patching with polypropylene IMHO.

BagusJeep lives in Bali.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
BagusJeep is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
TJ Gas tank straps (OEM) tomk864 Free Parts 3 05-09-2019 07:56 PM
'74 CJ-6 Gas Tank Fuel Filler/Vent Hoses w/non-stock Setup Agar426 Jeep CJ Forum 2 09-16-2018 05:55 PM
Gas tank Michael333 YJ Wrangler Technical Forum 8 09-13-2018 05:18 AM
body mounts in front of the gas tank.... jonnygranada YJ Wrangler Technical Forum 3 03-28-2018 06:49 AM
Heater core hose replacement question. thekooties WJ Grand Cherokee Forum 6 11-29-2017 11:45 PM

Posting Rules  
You may post new threads
You may 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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome