Repairing Plastic Tank.

[George7941]

It is the power steering fluid reservoir on a Freightliner truck and has a crack at the filler neck, where the neck transitions to the body. The good thing is that there is no standing fluid at the crack, just splashed fluid when the truck is moving. The crack is not visible in this photo. The tank is made of a translucent white plastic and I don't know whether it is ABS or nylon or what other kind of plastic it is. I don't see any markings indicating type of plastic. I don't even know if it is themoplastic ot thermoset.

A new tank is $180, the cheapest used one is $150, hence my effort at repairing the existing tank.

The two options I am considering are
1) If thermoplastic, I can try welding with a soldering iron.
2) JB weld for plastic, after cleaning and sanding the surfaces.

Any suggestions are most welcome.

 

[SatinSilver]

Is it losing any measurable ps fluid? For that price I may live with it awhile.

 

[George7941]

It is not losing any fluid as long as I don't top up the fluid to the level where it is supposed to be. The truck was acquired used not too long ago and I found the crack when I topped up the fluid (atf) and the atf started leaking through the crack when the truck is driven.

My concern is about water leaking into the reservoir and contaminating the atf. If I cannot repair the crack properly then I will just spend the $180 and get a new tank.

 

[Pop_Rivit]

I'd first try a little JB Weld on it before replacing it. If that doesn't work then consider replacing it, but I've had good luck making similar repairs with JB Weld.

 

[Keith_Stone]

Lots of vibrations there? A repair might be tough. Might be best to go ahead and replace it. Plastic welding works pretty good, do a web search for some info. I've had some success with chainsaw gas tanks, but they're harder plastic(polystyrene?)

 

[901Memphis]

The JB weld should hold forever if you can prep the surface.

 

[Eddie]

I think it is POLYPROPYLENE which can't be glued. I think heat sealing is the only way to fix this. I had the same problem with windshield washer and radiator overflow bottles and heat sealing did the job. If you are not successful maybe a salvage yard is worth a look. Ed

 

[Blueskies123]

What about a good epoxy glue?

 

[Chris142]

A power steering leak is grounds for being red tagged at the scales or a road side inspection. Btdt and i had to wait 14 hrs until the repair guy was able to get the leak stopped! Id rather spend the $180 now than spend a day sitting on the side of hwy127 in death valley waiting for parts.

 

[eljefino]

Hate to say it but go new. Plastic gets brittle after time in the environment and eventually snaps when you look at it wrong. That used ones are unobtanium should say these blow out all the time.

And that's a poor design; that hose must pull on the cap which stresses it underneath.

 

[Errtt]

Plastic welding then a coat of epoxy on top until you get a new tank to replace it.

 

[George7941]

Originally Posted By: eljefino
And that's a poor design; that hose must pull on the cap which stresses it underneath.


Actually the filler neck is on the left, with no stress at all on it and that is the one that cracked. The return hose seen in the photo is clamped on to the truck frame close to the reservoir and thus does not unduly stress the reservoir.

I have decided to try plastic welding and if the results are not satisfactory I will just buy a new tank.

 

[zzyzzx]

I have not had much luck fixing broken plastic, but for something like that, it would be tempting to try clear silicone caulk type of thing from the outside. Any type of fix in only likely to buy you some time. I have never used Qbond, but heard good things about it. Also, if it were a beater car I would be more likely to try a repair it, but if you are making a living driving that truck I would just go ahead and buy a new one.

 

[Trav]

I used some stuff some years ago to repair plastics, it is amazing. The only problem is finding it in the US, maybe ebay?

Anyway this is the stuff, you just grind a V out with a dremel then put some of the powder in the V and put a few drops of the chemical on the powder.
You will never break it in that place again.
I repaired my motorcycle fairing with it and it was still fine after 10 years.

I will bring a few kits back with me this year, if anyone is interested.

http://www.motorradonline.de/rat-und-tat/so-gehts-kunststoff-verkleidungsreparatur/275935

http://www.hein-gericke.de/kunststoffklebe-bzw-reparatur-set.html

 

[Quest]

From a long-term reliability perspective: I don't trust any gluing repair.

In your case I'd cut the chase and buy a new tank instead.

Q.

 

[Wilhelm_D]

Originally Posted By: George7941
A new tank is $180, the cheapest used one is $150, hence my effort at repairing the existing tank.

The two options I am considering are
1) If thermoplastic, I can try welding with a soldering iron.
2) JB weld for plastic, after cleaning and sanding the surfaces.

Any suggestions are most welcome.

I believe what you've got is polypropylene.

The standard repair is speed welding. A plastic welder, similar to a soldering iron, is fitted with a feed tube for the plastic weld rod. The speed tip heats the rod and the substrate, while at the same time it presses the molten weld rod into position. A bead of softened plastic is laid into the joint, and the parts and weld rod fuse.

If there is not too much flex on the break, 3M does have something that might work:

Structural Plastic Adhesive

If it is not too difficult to get the piece off, another approach would be a "patch". Drill a hole through the center of the break and sandwich something like silicon between two pieces of an inert material like aluminum sheet with a nut, bolt, and lockwasher.

 

[strat81]

Short term fix with stuff you probably have in your toolbox: a layer of pipe dope covered by duct tape.

 

[wag123]

Originally Posted By: 901Memphis
The JB weld should hold forever if you can prep the surface.

^^
This!