Crack repair in Thetford toilet

In an earlier thread I sought advice on how to repair a crack in the plastic surface beneath the Thetford toilet seat. A number of wise TM'ers pointed me in, what I believe, was the right direction. I wanted to share some detail about the repair outcome.

In the first photo you'll notice the crack in the cover beside the penny. The plastic material is thin and not very effectively reinforced (IMHO) so it is susceptible to breakage. So, don't let your seat (with its hard plastic pads) slam down unnecessarily on the cover & sit gently --especially if you're a +200 lb'er -- like me.

I took the cover to Philip's Plastics, a plastic fabrication & machining specialty shop, located at 3801 E Roeser Rd., Unit 18, Phoenix, AZ. 85040 (Ph 602 470-1808). It's a very high tech shop with computer guided milling machines, plastic cutting & welding, etc.. The work was performed by Matt Brewer, the General Manager. I share this in case anyone decides to ship a part of some kind for repair. Apparently, this shop gets stuff shipped to them all the time. They were a first class operation & I toured their facililty.

He tested the material and said that he did not believe that it was polyethylene. He believed it to be an ABS-based plastic. I know this contradicts what some were told by the thetford factory.

Anyway, the 2nd photo shows the reinforcement that he fabricated for the underside of the cover. This fits perfectly over the cracked area and I guess he used a bonding agent that reacts well with ABS-type material. I'm sorry that I didn't get the name of the bonding agent but he seemed pleased with the resulting bond. He also machined a mirror piece to reinforce the opposite (unbroken) section of the cover.

Then he cut a deep grove in the crack (from the top side of the cover -- where you saw the penny) which extended beyond the ends of the crack. He didn't cut through the entire depth of the crack -- but I'd guess that he went through more than half of the material's thickness.

Next he cut a strip of plastic off the backside of the cover -- where it abutts the trailer wall. You can see the photo of the back edge where he removed about a 10 inch strip.
He did this because he did not have an identical plastic match & he wanted to use the exact same material as a welding rod.

I watched him work a gas torch and simultaneously heat both the channel that he carved with his dremel and the plastic strip (now a welding rod) -- to an ideal temperature and consistency to promote welding of the plastics.

I probably would have ruined a dozen or more covers but he made it look easy. I'm sure that it took considerable skill.

Anyway, the weld produced a raised surface which he carefully ground down. I may go further and polish the surface with something or other -- but it really is unnecessary. The last photo is the final result.

I thank all of you for your input on this project. I will install softer bumpers on the underside of toilet seat as soon as I find some. I went to ACE hardware and was told that the bumpers that were recommended are no longer available (they checked on-line too).

Oh, I was charged $40 for repair and considered it a bargain.

Eric

[ShrimpBurrito]

Eric,

From the pictures, that looks like an excellent repair job. Please let us know how it holds up. Interesting that the tech thought it was an ABS-type material. If it ABS, I presume it could easily be glued with ABS cement. Who wants to give it a try?

Looks like you can buy the bumpers I suggested here:
http://www.acehardwareoutlet.com/pro...rce=GoogleBase

If you don't have luck there, let me know and I'll walk down to Ace I bought mine from and get you a few pairs. And don't forget to use stainless screws. You'll either put them in now, or in a few months.

Dave

[Wavery]

If it reacts to MEK (like ABS does), repair and reinforcement would be simple. If done from the underside, it wouldn't even have to be pretty.

Dave, I thought those bumpers were hard plastic (?), not hard rubber. I saw them at my local Ace. If they have some "give" -- they'll work fine.

And Dave, you're way too kind.

[ShrimpBurrito]

The ones pictured in the link above look like mine. They basically have the consistency of a pencil eraser. For that matter, you could also probably use a larger block-type pencil eraser instead of specific toilet bumpers. I'm not sure how easy it would be to drill a hole in them, but it might work. You'd need to not only drill a hole for the screw, but you'll also need to countersink it as the screw obviously needs to be completely recessed. But like I said, I can pick some up for you if you'd like. Not really worth alot of messing around with.

The hard plastic ones I linked to in the other thread (for the reference of others, post #2 in this thread) had some screw housings that protruded below the bumper, which would have had to fit into a countersunk hole in the seat. You do not want those.

Dave

[countrygirl]

I found this on the net and wondered if you all think it would work. I don't need it...just happened to run into the info:

Repairing RV plasticPosted by Russ and Tiña DeMaris Published in plastic repair Like the poor termite in the Shel Silverstein ditty sang,

“It’s plastic, good Lord, it’s plastic!

I know it ain’t no wood

And it can’t do me no good,

Because it’s plastic — and you can’t eat plastic,

Everything’s gonna be plastic by and by.”

And sure enough, seems like nearly everything is getting to be made of plastic. Plastic has its place, but it sure can be a headache for the RVer when a plastic part breaks and there’s no handy replacement. It would seem that there ought to be some good way of gluing broken plastic parts back together.

The first thing that comes to mind for many is good old super glue. We’ve found by bitter experience that most plastics just don’t respond to super glue. Some epoxies work–for some plastics. Read the label on the epoxy container first, and then be prepared for a mess. Sometimes a bit of sandpaper taken after the edges that are to be joined will help with an epoxy set.

Some swear by Amazing Household Goop, and the company touts its versatility. But beware, if you’re working with small repair areas, the big hole in the Goop tube can let a lot of goop out. It’s also somewhat flexible, which to us says if you have a part that needs to be solid, Goop might not be the choice.

We’ve stumbled onto a product from SureHold called “Plastic Surgery.” It’s a cyanoacrylate based adhesive, which may jog your memory to say, “Ah! Super glue!” Yep, it is fast acting like super glues, but unlike most of them, this one does stick to a broad range of plastics. Although we haven’t tried it yet, the stuff also claims to work on fiberglass.

What we’ve found to be really handy about Plastic Surgery is unlike the design of most super glue tubes, this one is good for multiple uses by design. The lid is equipped with a puncture tool which you simply poke down on first use. The tool stays right in the lid, so that after use it pokes back down the snoot of the tube, keeping it from gunking itself closed. With the lid open, project in hand, there’s an indented portion of the container where you squeeze, and the tube gives, allowing you to apply “just the right amount” of the adhesive to the work. Hold the pieces together tight for a few seconds (”5 - 15″ according the product card) and the work should hold. Slap the lid back on the tube and you’ve got plastic mender the next time you have need.

We bought ours in a small town hardware store for less than $2 for a 3 gram tube. Ace Hardware touts it on their web site, so it should be readily available nearly everywhere.

[Bill]

Following Eric's lead, I, too, took the top of my toilet to Philips for crack repair. Although the repair looks OK at this point, I would have been more pleased if it had been repaired like Eric's.

I took it in a week ago, talked with Matt (he remembered Eric's piece), and left it with him. He expected to have it in a week or so. After a week, I called for a progress report. The girl in the front office apparently mistook this for badgering, and since Matt was out of town for a few days, she gave it to another guy. She called me later the same day, and I went to pick it up. Biggest difference that I can see is that there was no reinforcing done. The repair guy apparently cleaned out the crack, but then simply ran a bead on both sides with a thermal welder, using some chips he scraped off the rear lip of the piece (just as was done with Eric's). The repair was ground and polished on top, and looks really good, but it lacks the reinforcing "plate" that shows in Eric's photo. We'll see how it holds up.

I asked the repair guy what the material was. He said that in spite of his 27 years of experience, he couldn't tell except that it was some kind of cross-linked polymer material. And they are notoriously hard to work with. None of the solvents they had - and they had many - would touch it. So the thermal weld is as much of an answer as there is going to be.

One other note. As can be seen in Eric's pictures, he brought in his unit with the bowl still attached, and Matt worked around it. I decided to remove the bowl. Since I was hand-carrying it in, rather than shipping it, I'm not sure that I should have. The screws on the underside that hold the bowl in place are shiny-new in Eric's photo's, but on mine they were so horribly rusted that the heads were deformed, and there was no way that a big Phillips screwdriver was going to get enough of a grip to do the job. To get them out, I had to grind a slot in the screw head with a Dremel tool - a hacksaw would have worked - and back them out with a big screwdriver. For reassembly I didn't want to use the same screws - too much metal gone - but I found that they can be replaced with simple #10 x 5/8 sheet metal screws. The thread pitch is slightly different from the originals, but they work.

Finally, I asked both the repair guy and the front office manager if they like this kind of one-off work, or if they consider it an annoyance. He agreed that it was not their major focus, but that they did a lot of one-off work and welcomed it. And sure enough, they had car mirrors, motorcycle gas tanks, and dozens of other similar plastic parts visible in the workshop. So if you need a toilet repair, I think you can ship the piece to them and expect good service. The price to me was the same as it was for Eric, $40 cash ($50 credit card).

By the way, there was a suggestion in an earlier thread that the toilet top material might be PVC. It's not. PVC cement doesn't touch it. Neither does paint thinner, denatured alcohol, MEK, PVC cleaner, SuperGlue cyanoacrylate, or epoxy for plastics. However, although I don't know what it is, I know that there really is a solvent or glue that is quite successful. On my unit, the rim of the bowl (deep blue) was glued to the underside of the toilet top at the back center. This glue patch was very hard to break apart.

Bottom line, if you take or send your piece in, I would suggest that you ask specifically for Matt to do the work, and allow time for him to get it into his schedule. Mention the reinforcing plate, and perhaps provide one of Eric's pictures to illustrate what you mean.

Bill

[Bill]

Originally Posted by Goodyear Travels

I will install softer bumpers on the underside of toilet seat as soon as I find some. I went to ACE hardware and was told that the bumpers that were recommended are no longer available (they checked on-line too).
Eric

Having just completed this same repair, I too went looking for bumpers. The long soft rubber bumpers used to be stocked at ACE as part number 40240. That part number is no longer available - I bought the last 3 that my local ACE had in the bin. However, part number 40203 appears to be identical, were stocked in quantity, and the ACE Owners' site said there are plenty in the local warehouse, and no notice of discontinuation for them. So I bought 4 of those (they come in pairs) at a different ACE.

These bumpers are longer than the OEM bumpers - 2 1/2 inches as opposed to 1 3/4 inches. This will bring the user's weight close to the edge of the toilet top, where the top is stronger, as opposed to centering it on the gap, where the crack occurs. And they are soft rubber, as opposed to the hard plastic of the OEM bumpers. This will reduce point-stress loading, which contributed to the cracking of the toilet top.

I have posted bumper pix below. This may be more than you wanted to know about toilet seats, but here it is. First pic shows the original 4 bumpers, with one removed. They are simple press-in bumpers that fit predrilled holes in the underside of the seat. Removing it reveals that the toilet seat is plastic coated wood, so it will hold screws. Picture 2 shows the difference in size between the old bumpers and the new one (center). Pic three shows where I mounted the seven bumpers I bought. The existing holes have been filled with RTV.

BTW, part number 40203 was the one recommended by Dave / Shrimp Burrito in his earlier post. However, his linked source seemed to be a specialty source - I found them to be available at any old ACE Hardware.

Bill

[ShrimpBurrito]

Eric & Bill -

Thanks very much for your writeups. We went camping this weekend, where we experienced a non-stop downpour for 36+ hours, and I realized that my crack like yours has gotten bigger. So I'm going to give Matt a call tomorrow and see about shipping him my toilet top for repair. I'm sure there are places here in LA that will do it, but for the $15 in shipping costs to get it there and back, it's not worth tracking one down, especially since you guys have had good experiences with them.

Dave

[ShrimpBurrito]

Just wanted to report back on our toilet repair. Following Eric & Bill's lead, I sent the toilet to Philip's Plastics for repair. I think my cracks were a little worse than Eric's, but I am happy with the results. I can post pics if anyone is interested, but it basically mirrors Eric's results (with the braces). My cost was $50, as I paid with a credit card over the phone.

Dave