Fuel Tank Installation for Pilot-House Express and Chassis Cab Trucks

[JBNeal]

While removing photobucket pics from posts on here and replacing them with pictures stored in gallery albums, I noticed on several threads issues with mounting fuel tanks, with the mounting hardware, with tank to cab seals, and with replacing with the Tanks, Inc. W-series reproduction as it is quite a bit cheaper than the B-series reproduction or using the Gas Tank Renu service.  So I consulted the parts manual, which raised more questions as to what that book said and what contributors on here said (including myself).  Now that I have a better understanding of what's going on, I figured that I should document my findings for future information searches done on this subject so that there is little ambiguity on this subject.  Special thanks to Brent for verifying the B-4-D-126 tank mounting ?

 

According to the factory parts manual, there are several variations on fuel tanks for B-series trucks, but I'm only going to focus on B, C, and D express and chassis cab models.  Panels, chassis and cowl, and export models have different part numbers than the express and chassis cab models, and I do not know what the differences are other than that.  Basically, there are 4 different rear mounting brackets used on 2 different tanks with 5 different mounting configurations for the 9 different frame designs.  The parts manual, as usual, only shows one configuration (B-1) as a general guide for parts replacement.

 

FRONT MOUNT

On B-1, B-2, and B-3 models, the front of the fuel tank mounts to the crossmember, with bolts threading into weldnuts on the fuel tank.  Shown is a fix that I did when the weldnuts stripped out and/or broke off, leaving just a hole in the tank mounting flange to run a bolt through before the tank went off to be Renu'd.

additional information - B-series fuel tank comparison

 

On B-4 models, the frame and fuel tank were redesigned so that the mounting bolts with the frame flex springs were located on the front of the tank.  These springs are slightly different than the rear springs used on earlier models and have different part numbers in the parts manual.  However, the parts manual appears to have an error that lists the bolt spacer as 15/16", when these appear to be somewhat shorter.  But this a minor issue that can be dealt with at any well stocked hardware store or an online source if replacements are required.

 

 

REAR MOUNT

On B-1 and early B-2 models with 108" and 126" wheelbase, mounting bracket 589572 is used with frame flex springs.

 

On later B-2 and all B-3 models with 108" and 126" wheelbase, mounting bracket 1269979 is used with frame flex springs, as there was a change to the frame design.

 

On B-4 models with 108" and 126" wheelbase, the fuel tank was mounted directly to the crossmember.  The parts manual notes that mounting bracket 1269979 is used, but I believe this to be in error as the profiles do not match up.

 

On B-1, B-2, and B-3 models with 116" wheelbase, mounting bracket 589571 is used with frame flex springs.  (yellow line added to highlight bracket profile at frame)

 

On B-4 models with 116" wheelbase, mounting bracket 1393998 is used.  (yellow line added to highlight bracket profile at frame)

Note the two larger holes in the foreground crossmember; these are the mounting holes that are used on the 108" and 126" frames, as this crossmember is located closer to the transmission.

 

Tanks, Inc. has offered their W-series replacement tank since about 2012, and in recent years has provided some support with making this work in the B-series.  moparpro has recently offered a replacement B-series tank that is based on the original design, but apparently with modern metal surface treatments to resist oxidation.

 

There has been some debate about the installation of frame flex springs, both in usage and material composition.  Modern zinc plating alternatives are cost effective improvements over the original unplated springs and hardware; deviation from that is a personal choice as performance gains here can be negligible period.  Removing the springs can be done if truck is under light duty on improved roads, but I have a parts truck without these springs and that metal tank has an oil-canned surface from presumably a rough service life...skip this little design element at your own peril.

Sealing the cab at the tank filler neck took several forms in the B-series, with 3 part numbers listed in the parts manual.  B-1s used a foam rubber piece on top of the tank; early B-2s used a different style; and later B-2s, B-3s, and B-4s used a simple piece of rubber over the filler neck inside the cab.  Since few people will see this detail, use whatever remedy you feel comfortable with to keep out the dust and critters, I won't tell the nitpickers