Case 470 Gas Tank Pressure

Not sure if anyone can help with this or not...
This is a question about a Case 470 Tractor. (Gas)


I have it partially restored for use so it's not a show tractor.
The problem involves a pressurized gas tank.
While bush-hogging I often smell gas. It is hot in the pasture and the grass is thick so the engine is working hard, but no problem with the water temp.
Every time I added gas I noticed that air would BLOW out the fuel cap when I opened it.
This is a new cap supposed to be for this tractor. It has a cork gasket but I do not know if it's vented correctly or not.

While mowing I started screwing the cap off every 3 minutes and every time it would blow out pressure.
After I shut it off yesterday I loosened the cap and that thing was practically blowing out air as if the gas was boiling inside.
It was just a constant flow of hot air. Continued for 3 or 4 minutes..
This fuel tank sits right behind the engine/tail pipe, so it HAS to get hot.


It seems to run fine with the pressure in the tank:beatsme
Should I run it under pressure or try to remove that cork gasket?

My buddy's Ford 9N did the same thing, the location of his gas tank is right above the engine and exhaust. I took some sheet steel and made a heat shield for the exhaust manifold, that took care of his problem. Is there some way to make a heat shield for yours that would clamp on the exhaust elbow by tank? Good luck with it. Clyde P.S. my little 129 IH cub lawn tractor does this on real hot days too.

Gas gets hot on most of these old machines because of the tank location, but gas boiling out for 3-4 minutes doesn't sound good. Modern gas is crap, especially if it has ethanol added. A heat shield is in order, or a very thick layer of insulating material on the tank. I'm surprised you aren't getting vapor lock problems. Probably only because the tank is building pressure prevents the vapor lock. BTW, nice tractor. what year is it. Looks very similar to my 420b.

ManicACMechanic said:

BTW, nice tractor. what year is it. Looks very similar to my 420b.

Click to expand...

It's a 1970 year model. It's a work in progress. I still have several things to work on.
I may try to come up with some form of heat shield there between the tank and exhaust.
It runs good and shows 2013 hours.

And I use only 100% gas mostly because of my lawn mowers.

4th gear in the transmission is clearly worn but I have not jumped on this yet, I use the tractor quiet a lot.

I have not used these materials personally, but have been told this type of insulation helps reflect heat. There are different sizes available, the links are just for reference of the materials. One is self adhesive and the other is applied with spray-on adhesive.

You might want to eventually fabricate something in metal to for appearance reasons, but my thought would be to try something like this to see if it solves the issue, then go from there.

http://www.summitracing.com/parts/DEI-050508/

http://www.summitracing.com/parts/the-14125

That gas line appears to be awful close to the exhaust pipe. It is hard to tell in the photo. Perhaps you could make a new line with a half moon shaped loop to give it more clearance where it crosses the exhaust pipe.

fpgm04 said:

... have been told this type of insulation helps reflect heat. There are different sizes available, the links are just for reference of the materials. One is self adhesive and the other is applied with spray-on adhesive.

Click to expand...

The 2nd link looks interesting. I wish I had a 2 feet square pc of it. I do wish it came in Case Flambeau Red
It claims to block 90% of heat and rated up to 2000 degrees. That' impressive....

Tinkerer the gas line IS maybe 4" from the exhaust but this is a hard pipe and is all original.
The carburetor itself is not far from the tail pipe
One version of this tractor has the exhaust straight up thru the hood with a rain flapper.

One day I need to replace the rusty exhaust pipe and I might try to get one made with a heat shield around it somehow.
It does not leak exhaust and the muffler is back under the rear axle.

I may need to get a heat gun on the tank and see how hot it's really getting when in use.
It was hot enough to float the cap when I unscrewed it. It just started puffing/bouncing the cap up and down with the engine off.

Before.


Later


It's a LOT of work to do all this. Cleaning is probably the hardest part.
In 43 years an old tractor that leaks oil in places will sure attract dust dirt and hard grime that is not easy to get off.
I cleaned, sanded, primed and sprayed it all never using a brush. Using hardener in the paint seems to help with more shine in the finish.
I had already installed part of the parts in this picture, but it does show basically what I took off to paint the front frame.
I still like all the rear section; wheels, lift arms etc.


This is a G148B engine and I think similar to some of the old 580B backhoes.

Yes, In general, this chassis looks very similar to the 420b backhoe frame. Now you have the gear driven power steering pump like mine, but my tractor originally had a belt drive pump so I imagine the motor may have been changed at one time. What are those hydraulic pipes that run back over the top of the engine? Does it have a steering vavle mounted on the column like an old Massey?

ManicACMechanic said:

What are those hydraulic pipes that run back over the top of the engine? Does it have a steering valve mounted on the column like an old Massey?

Click to expand...

Yes it's the power steering valve and lines.

Case Gas Tank Pressure

I have a model 430 1974. Looks basically the same... Original gas cap...I have never had any pressure build up in my tank.....I would definitely change out the cap or like you said remove the cork gasket...this is not right and could prove to be dangerous.....Here is a picture of me and my son working to clear out from the blizzard last February....it's a great tractor. I'm on the early 310 backhoe and he is working the Case....