Fuel Preasure Switch temp fix

[3dubs]

This is not a permanent fix!

I went to pick my son up from school and when I stopped diesel was poring out of my truck. I drove it home and opened the hood. Diesel was coming out of the fuel filter. I swapped the filter out but it kept leaking. I could see it was coming out about the middle. I quickly figured out it was the fuel pressure switch. I printed out the TM page with the part numbers and went on the hunt. Finding it was impossible to get I reluctantly found a spin on filter that everyone says is so much better. But I kept searching the internet and found the part was still made. The part is only on military CUCV but it is also an aircraft part. But it would be next week before I could get it. I need my truck so I went to looking at the extra fuel filter bracket trying to figure out how to plug the hole in the bracket but so I could put the switch in when I got it. My wife (who knows nothing about mechanics) said she knew I could do it with only string, bubble gum, and a paperclip. Then she added duct tape because every crazy red neck uses duct tape. She was almost right.

I got my son's plastic gold coins and a rubber glove for parts. For tools I used a flat head screwdriver, leather glove, and a paperclip.

The coins were the perfect size to fill spot the switch goes in. I used the leather glove to hold the paperclip on the stove burner. I used the hot paperclip to put a hole in each coin. So I can use a screw to get them out later.

Then I used the flat head screwdriver to get the old switch out. Then I put about five coins in the rubber glove(I have a box of them for working on the truck but they suck). pulled the rubber tight around the coins and stuck them in the hole.

Ran the flat head screwdriver inside the hole to cut off the extra rubber glove.

Put the metal clip back on and the filter. Just like any good red neck there is no leak now. I just hope the rubber holds up to the diesel.

 

[3dubs]

Well the fix got me home. But the glove can't take the diesel and I have a small leak. So now the bubble gum and duct tape. I will just put some silicone into the old fuel pressure switch to plug it up. This is why I ordered two switches!

 

[tshermankb]

hahaha! nice work man! that sensor actually is non essential on these trucks. I had the same problem and pressed a 35mm freeze plug into the housing it has worked beautifully.

 

[3dubs]

I know it is not essential. But I did not have a freeze plug. The fix worked until the part came in. Owens Export Services rocks. Once I found them they had the part shipped out the same day. Now I am going to take the O-ring down and get the size. Then I will get better O-ring because I hear they are the weak point.

 

[owensexport]

The switch kit I have has the updated silicone o-ring that will
not rot out.

If your switch is leaking air, it is through the switch itself and
not the o-ring!

 

[Stonepicker1]

The switch kit I have has the updated silicone o-ring that will
not rot out.

If your switch is leaking air, it is through the switch itself and
not the o-ring!

What is the price of the kit. I have two that are leaking and one is only a year old.

I bought two complete assy off ebay, they don't have the pressure switch but got me up and running again. Just want to fix the other two for back-ups.

 

[acmunro]

I wouldn't mind the info either. Thanks

 

[owensexport]

Call me at 818-772-0806 after 10a Pacific time
or steve@militaryjeep.com

 

[NMC_EXP]

The switch kit I have has the updated silicone o-ring that will not rot out.

I spent about 30 years in the rubber R&D, engineering and manufacturing business. In my last assignment at Caterpillar I had design control for o-rings.

Silicone is not a good choice for diesel fuel. Reason it that it will swell up and eventually double in volume, and become very soft in the process.

If it is in a low pressure system and there are no sharp edges to cut the o-ring as it swells it may seal OK even though it swelled to twice it's original size. It will certainly not be reusable if the unit is disassembled.

This link goes to a Dow Corning Silastic (Dow makes Silastic silicone rubber) data sheet on silicone rubber fluid compatability. See page 14 for the effect of soaking silicone rubber in diesel fuel for 7 days at room temp. These are standard ASTM tests.

http://www.siliconelms.com/DC LSR Compatibility Guide.pdf

Caterpillar used to be fanatical about quality. The only place we used silicone rubber was for parts which had to work at extremely low temp, that it where silicone really shines. CAT had optional "arctic packages" for it's machines and these included several silicone seals.

If a seal or o-ring is going to be replaced during regular maint (like fuel filter change) nitrile rubber (aka Buna N) is OK so long as the temp is less than 120 deg F. If the seal/o-ring is not replaced regularly or the temp is over 120 F Viton is the best choice for diesel and pretty much any other petroleum based fluid.

Regards

Jim

 

[owensexport]

Here is my corrected statement, sorry for starting a science discussion:


The switch kit I have has the updated o-rings designed by Standyne that will not rot out.

 

[kentuckycucv]

I took my pressue switch out. got a 1/4 tap... threaded the hole and put in a 1/4 in short screw with lock tight.... Not a drop has leaked since... Be sure to shop vac the little bits of metal from threading , to keep your ip and injectors clean.

 

[3dubs]

Replacing the switch again! Does anybody know what size the O-ring is? What is the best material to use? I am bout to do some research. But I want an O-ring that can take high temps and diesel I would like it to be good for bio-diesel too. I have never used bio but I might. I am guessing Viton is good but I would like to have a few choices for the O-ring shop.

 

[NMC_EXP]

Replacing the switch again! Does anybody know what size the O-ring is? What is the best material to use? I am bout to do some research. But I want an O-ring that can take high temps and diesel I would like it to be good for bio-diesel too. I have never used bio but I might. I am guessing Viton is good but I would like to have a few choices for the O-ring shop.

3dubs

Can't help you with the size. I'd like to know the sizes of all the o-rings in the factory fuel filter myself. Mine oozes fuel from every joint.

Regarding biodiesel - I checked the Parker O-Ring Handbook. It does not specifically list "biodiesel". This is no surprise as a national standard for biodiesel has not been established. Might be 10%, 15% or 20% vegetable oil plus diesel fuel and the vegetable oil might be soybean, canola or who knows what. This fact is driving the fuel system and engine folks at Caterpillar crazy.

Anyway, Parker recommends Nitrile rubber (a.k.a. Buna N) or Viton for both straight diesel and straight vegetable oils. So the same should apply to diesel/veg oil blends.

Viton really shines where high temp is involved (greater than 250 deg F). It will outlast Nitrile in almost any application because even at less than 250 F nitrile eventually thermally degrades and gets rock hard.

Downside to Viton is that at low temps it stiffens up. This can result in some minor seepage during cold weather starts until the system warms up and the rubber thaws out.

Since this is a low pressure system, I'd recommend a fairly low durometer hardness, say 60 durometer. 70 is probably OK if thats all they have but I would not use 90 durometer.

BTW - Here in the soybean belt it's hard to find anything but biodiesel. Found a Shell station that sells straight diesel and I believe my M1009 likes it better than biodiesel.

Regards

Jim