# Using sealant on a sending unit gasket?



## dieselboy01 (Jan 18, 2011)

In june i replaced the front tank, lock ring and gasket in my 95 F350. I was filling up yesterday and diesel started dripping out where the sending unit is. When I got home I tapped the lock ring a little tighter. I topped the tank off again and fuel is still seeping out. 

Today I bought a new lock ring and gasket. 

I was wondering if I could put a light coat of sealant (either a fuel safe RTV or anaerobic gasket maker) on both sides of the O ring? 

Your thoughts?


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## xgiovannix12 (Dec 8, 2012)

i think the gasket should be plenty to seal unless the tank is damaged where the lock ring goes


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## Randall Ave (Oct 29, 2014)

Make sure everything is clean. Put it together with a new gasket. My opinion is no sealant, but If you use sealant. Let it sit for a day before you fuel up.


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## FredG (Oct 15, 2012)

Sealant would work I seen guys Cobb them up. It's only a bandage.


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## Walleye Hunter (Aug 13, 2017)

I once replaced the sending unit on my E-350 with a Dorman unit from the local parts store. It turned out that the Dorman unit did not seat properly in the recess and I had to pay extra attention to keeping it centered during installation. I try not to use RTV when it's not necessary because it's a PITA to remove next time but you could use it without hurting anything, just leave it set up before use like mentioned above.


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## Randall Ave (Oct 29, 2014)

Walleye Hunter said:


> I once replaced the sending unit on my E-350 with a Dorman unit from the local parts store. It turned out that the Dorman unit did not seat properly in the recess and I had to pay extra attention to keeping it centered during installation. I try not to use RTV when it's not necessary because it's a PITA to remove next time but you could use it without hurting anything, just leave it set up before use like mentioned above.


That's the problem I've seen with aftermarket parts, they almost kinda fit.


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## TJS (Oct 22, 2003)

On all fuel pumps and sending units I have done over the years I always put grease on the "O" ring. Not sure if your set up used the "O" ring or not.


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## FredG (Oct 15, 2012)

TJS said:


> On all fuel pumps and sending units I have done over the years I always put grease on the "O" ring. Not sure if your set up used the "O" ring or not.


Good place for grease anyway.


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## dieselboy01 (Jan 18, 2011)

It uses a square O ring on the sending unit. I put a light coat of Loctite #2 gasket sealant on the O ring. It says its rated for diesel fuels.


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## dieselboy01 (Jan 18, 2011)

After every cured for a few days I filled the truck up and diesel started pouring out of the gas tank vent. After a long search I found out the style of vent I have was only used on cab and chassis trucks. The part was discontinued years ago and my only hope was a junk yard.

I'm not a fan of installing 20 year old used parts so I made my own vent.


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## dieselboy01 (Jan 18, 2011)




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## dieselboy01 (Jan 18, 2011)

So far this tank is leak free. Hopefully its water tight now too.


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