Fuel Tank leaking

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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m270mlrs2
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Fuel Tank leaking

Post by m270mlrs2 » Sat Sep 21, 2019 9:57 am

Good Morning just a quick question on my M151a2 non emissions fuel tank, while i was preforming services to the vehicle, i noticed that fuel is coming out around one of the bolts that holds the fuel cap down. My question is is there a gasket for the fuel cap and also why would it be coming out the top? I haven driven the vehicle except to back it in and out of the garage to let it run to charge the batteries. I was wondering if it may be a pressure issue because sometimes the fuel drains right out of the in line fuel filter and some times it stays in the filter for a little while. The fording filler cap vent is switched to the open position so I am not sure what else to check. Thanks for any advice and if you have the gasket and also the bolts that hold the cap for sale let me know. Thanks again

Rickf
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Re: Fuel Tank leaking

Post by Rickf » Sat Sep 21, 2019 3:23 pm

There is a gasket under that plate, and it does not take a lot of movement to get the gas splashing around enough reach the top of the tank. As far as the filter goes the amount of gas remaining in the filter means nothing, it is just the nature of the beast with the filters. The inlet and outet are not exactly even with the ends of the filter so trapped air will stay in there and sometimes all fuel will run out due to evaporation in the carb or a leaky valve in the fuel pump.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Surveyor
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Re: Fuel Tank leaking

Post by Surveyor » Sat Sep 21, 2019 3:56 pm

You could buy one from one of the dealers such as

https://www.armyjeepparts.com/p-3202-m1 ... -1855.aspx or http://www.tnjmurray.com/militaryvehicl ... ED4F3B1E6C

or if you have a sharp knife, just make your own out of gasket material from your local auto parts store using the old one/lid as your template...

https://www.autozone.com/sealants-glues ... icle=false
1960 M151 Run #1 (Now runs and stops but still working on it...)

m270mlrs2
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Re: Fuel Tank leaking

Post by m270mlrs2 » Sat Sep 28, 2019 6:19 am

Ok ordered the new gasket should be in Monday. Should I apply any Permatex on the gasket and also should i drain the fuel tank its about half full. I am also going to replace the fuel gage sending unit and gasket. The Fuel gauge might be ok other than weathered. If i touch the sending unit on the tank while its on, the gauge jumps and reads a different level. I have those parts and might as well do it all at once and if that does not fix the gauge, I will buy a new one. Thanks for the info

Rickf
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Re: Fuel Tank leaking

Post by Rickf » Sat Sep 28, 2019 7:56 am

If you have the wherewithal to drain the tank it would be a safer job. If not you can do it with the gas in the tank just be sure to disconnect the batteries and tape up the battery terminal so there is no possible chance of it contacting the batteries. Do this no matter how you do it, gas in or out. Remember that even static electricity can produce enough spark to light gas fumes. Whenever I have to work over an open source of gasoline I just have a fan blowing over the area. Does not have to be a huge fan, just enough to keep the vapor from accumulating. Even if you drain the tank you are going to have vapor since you can't get it all out of there short of draining all the gas out and leaving the tank sit open for a week or more to dry out. Just use common sense and remember you are working with flammable material. Keep a large fire extinguisher nearby also just in case.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone


m270mlrs2
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Re: Fuel Tank leaking

Post by m270mlrs2 » Sat Sep 28, 2019 9:52 am

Thank you for the advice on the fan I am going to do it outside but will set a fan to keep the air moving and have my fire extinguishers ready last question do i need to remove any lines from the cap r should everything move enough to let me get the gasket on the tank? thanks again and I will let you know when the job is safely completed.

Rickf
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Re: Fuel Tank leaking

Post by Rickf » Sat Sep 28, 2019 11:05 am

You are going to have to remove the lines since you have to get the plate and the pickup all the way up out of the tank to get the gasket on. And as far as gasket sealant I would use Permatex #3 on the gasket. You do not need a lot, just a thin layer.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

m270mlrs2
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Re: Fuel Tank leaking

Post by m270mlrs2 » Wed Oct 09, 2019 5:05 am

Good morning I got the tank drained and everything apart so I decided to remove the tank to check for rust underneath. The tank and the Jeep body look great no rust holes or pitting. I wanted to ask should I put any type of undercoating on the bottom of the tank or on the Jeep body before I set the tank back in. I know water gets between the two from washing or rain. I just want to preserve it the best way possible since its in good shape. Thanks again for any advice

Rickf
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Re: Fuel Tank leaking

Post by Rickf » Wed Oct 09, 2019 8:10 am

If the paint is in good shape then leave it alone, if it is a bit rusty then sand it and repaint. Undercoating is just a way to hold water against the metal and then you do not see the rust until the metal is gone. With paint you will see the rust as soon as it starts and you can address it right away.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

m270mlrs2
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Re: Fuel Tank leaking

Post by m270mlrs2 » Tue Nov 05, 2019 9:28 am

Ok it’s all back together installed and filled up. Took it for a ride this morning, got back and there was fuel still leaking around the cap. I cleaned and installed a new cap gasket applied rev and let it set for a week. Maybe I should look for a new tank? Any suggestions I will snap a couple of pictures and send them in a second

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acudanut
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Re: Fuel Tank leaking

Post by acudanut » Wed Nov 06, 2019 5:13 pm

Did you use a gasket for the top tank top ? How much fuel is in the tank ? A new tank won't solve this issue. (my 2 Cents).
Overfilling the tank could cause problems too.

m270mlrs2
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Re: Fuel Tank leaking

Post by m270mlrs2 » Thu Nov 07, 2019 4:01 am

Good Morning yes i installed a new gasket and applied some rtv. I put about 9 gallons of fuel into the tank. I did notice that the fuel cap had an extra hole for another bolt but there was no hole in the tank for the bolt to go into so i put rtv in the blank hole. Is there a different fuel cap?
fuel tank.JPG
fuel tank.JPG (84.71 KiB) Viewed 180 times

Rickf
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Re: Fuel Tank leaking

Post by Rickf » Thu Nov 07, 2019 6:02 am

RTV is for use when you have no gasket and a gasket sealer is for use on gaskets. I had mentioned the Permatex #3 a couple posts up. I don't think that is the issue though, Are you sure you cleaned off all of the old gasket from both the tank and the plate? The missing bolt may be an issue but if the RTV was put on according to directions then it should seal. Did you check to see if there were any bends in the tank top or the plate? That plate is going to be very hard to bend so the tank might be the issue but with the RTV and all of the bolts it should not be leaking. How tight are the bolts? And is it leaking where that missing bolt is?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

m270mlrs2
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Re: Fuel Tank leaking

Post by m270mlrs2 » Thu Nov 07, 2019 6:39 am

I did use the Prematex #3. I didnt see any bends on the cap or bad pitting and corrosion. I was sure to get all the old gasket off I sanded it down to the metal. The bolts are pretty tight I had to clean the treads on the inside of the rim. I guess the ting that is bothering me is that 1 missing bolt and that there was no hole in the fuel tank rim. Here is the before picture with two missing bolts. The second missing bolt wasnt on tight and it was one of the threads I had to clean up to get the new bolt in.
tank 2.JPG
tank 2.JPG (121.89 KiB) Viewed 166 times

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