Hot Rods HVAC plastic crack, what kind of glue?

Hi All,
1965 Impala. One of the plastic pieces for the under-dash HVAC system is cracked. What glue or silicone or RTV or ???? can I use that will withstand both A/C and heater?
Any suggestions or help would be appreciated. Thanks!

 

I have repaired a plastic heat exchanger housing for a generator at work with 3M 5200. Withstood being run a few hours at temp.

 

J-B Weld ....To quote a hot sauce commercial.....I put that **** on everything.

 

Would a 2 part epoxy work on that?

 

If its black plastic, it's possible ABS plastic, if so go to the hardware store and get some ABS glue in the plumbing aisle. The glue needs to melt the plastic for a good weld, think model car glue.

 

Crazy glue or 2 part epoxy have always done me well on those lonely nights at sea .

 

There are some plastics that glue doesn't work on. You might have to look into plastic welding.

 

weld it back together with a soldering gun . you won't have to worry about what kind of glue, etc will work

 

I wonder if that glue that harden's (sp) with the ultra violet light works????....

 

@wraymen said it, JB has plastic adhesive.
Then wrap it with Flex Tape. The stuff is strong and would almost work without the glue.

 

Not all the ac parts are plastic. Some are some kind of Fiberglas. I think JB is the safest way. Picture would help

 

I had a broken fender on my quad. Went to HF and bought their plastic welder. Basically a soldering iron with a paddle on it. Comes with ss mesh. I melted the mesh in, then added some plastic filler over it. Works great. That quad takes a beating. IIRC it was $16.

 

The method I use is to put a toothpick tip sized dab of both ABS and PVC cement somewhere on the plastic where it can't be seen, and see which of them dissolves the plastic. That's the cement I'll use.

If neither dissolves the plastic I normally go with epoxy.

 

Thank you for all of the replies!! Here are some pictures:

I think I also need to fill the big hole at the end of the crack.

 

LOL I could not have said that any better. You're the man my friend.

we used to use a lot of 2 part epoxy when I was still working in the HVAC industry for patching and running. I liked the stuff that cam on a 2 colored ribbon you just tore it off needed it and smushed it in place like putty.

 

If I were you I’d go with the plastic welding advice.
I’d have that repaired in the time it took you to read all the responses.
Most of the other methods involving glues and epoxys are liable to be messy failures mainly due to the fact that very few plastics with the exception of ABS and PVC are friendly to glue.
And those plastics are joined using a solvent cement that melts the surfaces and causes a bond.

Take a good close look at your plastic piece.
Most plastic parts will have a circular spot or something like that identifies the type of plastic it’s made of.
If you like I can post a picture of what that looks like later on.
It will say something like ABS or PP (Polypropylene) or?
Being able to identify the material is a big help

 

I agree 3m is great stuff, I've used it on wood boat projects multiple times. However, it creates a damn lot of heat while it cures, which could melt plastic, so try a spot first if possible. It also runs all over the place unless you add thickener, so heads up on that. Good luck!

 

I don’t think that SPI started labeling products until the 80s. I’m not sure that a 65 piece will be marked.

 

Beano, I even fixed a cracked plastic gas tank on an auger with it. Took two tries but it stopped leaking. The trick was surface prep and cleaning. I was in a hurry the first time.

 

Another vote for JB Weld. Non conductive, used in electronics ***emblies. Some youtube videos it's ridiculous how strong and durable it is for the cost of 2 little tubes. It's my go to non-weld sticker-toer. A standing lamp broke off the thing the shade fastens to. Filed the groove a little nicer and stuck them together. Even used them to fix a OT motorcycle intake housing. probably the same type of plastic. just smeared it on all the joining parts and held everything together with masking tape until it set. No failures.

Even fixed my boys engine. There was a casting defect on the block and it was leaking oil. Cleaned it well, cut a piece of a soda can as a patch backing and stuck it on with duct tape to hold it until it fully cured. Still not leaking.

 

I used it to limp my bike from New York (or close to there) to Missouri once. Crack was on the bottom of the tank and I could not get it as clean as it needed to be so I had to redo it a couple of times. But it got me there.

We screwed a 440 together in the late '70s. The heads were pitted on the mounting surface, pretty bad pitted. We used the JB weld that was iron/steel specific. We had the heads off about 10 years ago and they were still fine and they went back on. granted the car don't get driven much but it gets driven as much as what most of ours get driven.

 

Never have had much luck bonding plastic . What I have had luck with is sheetmetal strips shaped to bridge the break , pop riveted in place to provide support , then use an epoxy . It may or may not chemically bond , but it'll somewhat seal the crack . Its too bad the tweakers couldn't keep their noses out of the old " airplane glue" that would melt the plastic , that stuff worked !

 

Hi All,
Thanks for your replies!!
OK --> JB Weld....lots of recommendations for JB Weld....but there are a bunch of JB Weld products --> which one?
https://www.jbweld.com/products

 

None of them!

Oh the pain of giving good advice and having it ignored.
Someone even mentioned a HF plastic welding kit. That’s probably affordable.

You know what they say, you can lead the horse to water but you can’t make him drink

 

^^^^^^^^No to JB weld. Get the plastic solder gun and affix it back together.

 

Hello,

ULTRA VIOLET LIGHT: Don't waste your money or time. It looks nice, it applies fine, and the light is cool to use, but it is not a strong bond and the slightest amount of force will crack the compound. We used this on a plastic piece in the trunk wall and opening the panel, using the normal handle, caused area to crack, again.

We also used it on our fibergl*** boat on a small plastic vent cover. It did fine, but the next accidental rub in our constant, crossover, ****pit movements, cracked the joint that was fused together by the ultraviolet light.

Jnaki

If you do decide to get one and use it, you will have to have an umbrella as the hot daylight sun will start solidifying the solution you just put on the joint. YRMV... but one of those was enough of an experiment for us.

If the product that split is white, then 3m 5200 is a killer cement to use for an almost permanent fix. Don't get the 5200 on anything else as it is hard to get off of any surrounding surface. I suppose you could add the 5200 and a thin piece of plastic on the inside of the crack, so the black A/C pipe or flat surface area will not show the white glue joint.

We have tried the two part epoxy and the smelly JB Weld. They are sloppy and not worth the constant applications. They do work, but whew, it just killed my senses in an enclosed area. Again, YRMV

 

I have used the first one and the marine one with good results. The quick set one is a little too quick for me. Starts setting up before I’m finished applying.

 

Just a question. Don’t you have to know what type of plastic it is to get decent results? I don’t know how well 60 year old plastic is going to “weld”. Might do more damage than good. Again, I’ve never used them so I might be way off.

 

I’ve used plain old soldering iron then JB on top of that. Even added some little pieces of nails to help hold all together.

 

*Dorothy Parker...responding to the challenge."use the word horticulture in a sentence"