How To: Repair Cracked Washer Fluid Bottle

[Mark D]

This issue came up in a different thread so rather than derail the conversation over there I figured I'd start fresh. There is a pretty simple fix to what seems to be a common problem: cracked windshield washer fluid bottles. To complicate the issue replacement bottles are no longer available from DMCH.

Long story short, when I bought my car I knew it had a cracked washer bottle and the previous owner tried without any luck to fix the crack using glue. The washer bottle material is high density polyethylene (HDPE) which is a tough material to get glue to stick to. Luckily it can easily be repaired by melt welding instead.

Step 1. To fix a cracked/leaking washer bottle the first thing you need to do is get the bottle out of the car by removing the black plastic bucket that holds it in place at the DS front trunk area. This can be a little tricky since there are eight M5 bolts holding the damn thing in there and like all of the other threaded inserts in the front you're bound to have a couple that have the bolts rusted in solid.



Step 2: Assuming you were able to get the black retaining bucket removed, do yourself a favor and drill a few holes in the bottom to let water and other debris escape. Mine was full dirt that had collected over the years... Trapped water (and leaking washer fluid) also collected and seeped into the pump at the base of the washer bottle causing the electric motor to fail. Note that in these pictures I've got the bucket completely removed, but you can just let it hang by the electrical harness that is routed through the large round opening in the top lip of the bucket.


Step 3. Next clean up any dried washer fluid residue and glue from previous repair attempts by you or previous owners. Make sure the the washer bottle is super clean around the cracked area to ensure a good repair.




Step 4. Find yourself an old milk jug made of HDPE. It's the translucent/clear plastic, not the opaque white plastic. Cut out a section of milk jug material slightly larger than the cracked area on your washer bottle and clean both sides of the patch section well. One nice thing is that milk jugs have all kinds of curves and contoured areas that you can find to match the shape of the washer bottle. The piece I cut was near the jug handle and fit perfectly in the little corner recess of the washer bottle.



Step 5. Using a heat gun warm up the washer bottle around the cracked area until it starts to get soft. Don't get it too hot or the plastic will blow out around the crack and you'll have a nice big hole instead of a hairline crack.


Step 6. Once the bottle is warmed up a little bit place your patch section of milk jug over the crack and heat it up until it's nice and melty. The thinner milk jug material will soften quicker than the thick plasic bottle so be careful. You can press down slightly on the patch to help create the bond between the two pieces of plastic.



Step 7. Check for leaks and reheat if needed to get a complete seal.

Step 8. Reassemble the bottle and retaining bucket back on the car being careful not to crush the harness or plastic tubing to the bottle as you tighten everything down.

Step 9. Drink beer in celebration.

[Spittybug]

When I pull mine out, I sincerely hope to find an equally easy crack to fix. I'm hoping it isn't along a long seam or at one of the nipple areas......

[SS Spoiler]

Good write up, nice pictures.

Paul Cerny

[Dangermouse]

Is the original bottle material thick enough that you could just re-seal the crack by using a putty knife to "melt" the two edges together when the bottle is warm enough?

[Mark D]

I don't recall the exact thickness of the bottle in that area but I'd guess somewhere between 1/16" to 3/32". The thickness varies in different spots bottle because I think they were blow molded.

You could probably get away with heating up the bottle in the cracked area and using some type of flat edge to fuse it back together. Or a hot soldering iron tip might do the job once you heat everything up and start to work the edge closed. I figured another layer of solid material over the crack was a good insurance policy that I wouldn't be going back in there again a few months later to make another repair. It wasn't much additional work to add the patch and it gave it some additional strength vs the original part in that weak corner area.

However, I'm pretty sure that my bottle cracked because the PO had to go in there and change out the original washer pump. When he reinstalled everything the bottle was not seated correctly and compressed and flexed in that corner as the bolts were tightened. If you are careful reinstalling everything there should be no compressive load on the bottle and there should be no reason for it to suddenly crack.

[Spittybug]

No luck. My crack is on the other side of the bottle, right in one of the compound corners....very challenging. I tried the milk jug trick and the bond just wasn't all that good despite a good cleaning and softening of both plastics. I tried a few times. I also tried simple melting/blending with a hot screwdriver. Still it leaks. The more I try, the more I'm stressing the surrounding plastic too. This isn't surprising after 31 years or so; despite popular perception plastic does indeed degrade and start to breakdown. I think we'll be seeing more and more of this.

Rather than patching the outside and fighting hydraulic pressure, I'm thinking I could line the interior of the bottle to seal the leak and help prevent others. I either need to be able to inflate something like a balloon inside, or more likely, pour in some kind of liquid polymer and form an interior skin. But what?

Other than that, has anyone found any other bottles that fit the space? How about an IV bag type of setup (flexible)?

[Dangermouse]

I almost hate to suggest it but what about that "as seen on TV" black Flex Seal stuff. If it actually works then you could coat the outside of the bottle.

Why not test it out on a plastic milk carton that you cut an slit opening with a knife to simulate a crack. Spray the stuff on, follow the instructions and see if it still leaks in 6 months?

[Spittybug]

Interesting idea...

Just tried again with more patching, more melting...nope. The original plastic has lost a lot of its elasticity and is more brittle. Consequently it doesn't really melt back to itself very well and the patch never really integrates to it. Just kind of sits on top and can't stop seepage.

[Bitsyncmaster]

There is a gas tank sealer used for fiberglass gas tanks that may work. You just pour it in and slosh it around and let it dry. That was used on a lot of experimental (home built) airplanes.

[Citizen]

Rather than patching the outside and fighting hydraulic pressure, I'm thinking I could line the interior of the bottle to seal the leak and help prevent others. I either need to be able to inflate something like a balloon inside, or more likely, pour in some kind of liquid polymer and form an interior skin. But what?

How about fiberglass resin? Make sure the crack area is at the bottom, so that gravity causes it to fill the crack....

I dunno, just the first idea that popped into my head.

Or maybe POR-15?

Thomas

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