dleefsu

Hi all and thanks in advance for any input. A few years ago an AC friend and I replaced the evaporator but instantly had a leak, very bad leak. All this time I thought we simply got a bad evaporator and was kicking myself for not testing it... Today I was reading and heard stories of having issues getting the expansion valve to seal so a light went off and especially when I read that could service the expansion valve pretty easily (well covered in other threads). So took it apart and geeze, good thing he's now an ex-friend as he used the wrong size seals, doubled up on the seals, stripped the threads out of the new expansion valve...

The current issue/question is the back bracket that secures the evaporator tubes to the expansion valve was also stripped out but I also read that other folks had to tighten those bolts down crazy tight before they could get a seal. The questions are:

1) My bracket is slightly bent which I'm assuming it's supposed to be straight and this very well could be causing some of the issues trying to get it to seal.
2) I searched for a while and all the usual part sources and no luck, has anyone made an aftermarket steel version and if not, would there be any issue it being made out of steel versus aluminum? Actually I couldn't even find the original one. If necessary I guess I'll straighten the one I have, drill out the threads and use washers but I have a metal shop that could make a new bracket as well.
3) Are there any other tips and tricks to get it to seal?

Thanks!
David
91 964 C2

griffiths

There are both steel and aluminum versions, none is better than the other because the amount of torque required usually does not strip out the thread in either type.

You can fabricate a steel one easily (.125" thick) with common DIY tools: hack saw, band saw, file, drill, etc. For example, to fashion the half moon openings for the two evap tubes you can measure the center point or radius of where you want them, drill it out and then cut into that with a hack saw, etc. clean things up with a file, drill and tap the hole for the fastener and so on.

When you mount the TEV with its new o-rings (lightly lubricated with refrigerant oil) try to square up the top plane of the TEV so its level and flat as you tighten the retaining allen screw in the TEV.

Many issues with poor o-ring sealing are related to either wrong o-ring size (I believe you need a #6 and a #10), failure to lubricate or not inserting the evaporator's inlet and outlet tubes square and center into the back of the TEV; you can scratch the mating surface where the o-ring sits in the TEV.

If you have more issues drop a PM.

Griff

dleefsu

Thanks for the response. Perhaps I'll contact the metal supplier we use in my biz and see about making a supply of them in case others need them. In reality they could make 20, 50 or 100 almost as easily as 1 or 2 as I'm guessing they would cut them on a cnc waterjet or laser cutter. The only debate is material as I'm guessing you see extreme temp variations meaning metals expanding and contracting at different rates. Perhaps create one piece that would be more of an aluminum spacer with a steel back piece that is then threaded and wouldn't bend or strip out.

I think the bottom line is that as a DIY project, don't try to tackle replacing the evaporator in a single day. I'm guessing we pushed it and in putting it back together my friend just got impatient and most certainly is why he didn't come back to finish putting everything back together...

griffiths

Here are 3 examples of the TEV (aka TXV or expansion valve) backside securing bracket. The top 2 are steel and the bottom is aluminum. The top 2 are respectively 5 and 6 mm thick and the lower aluminum is 6.5 mm thick.

Griffiths currently uses the 5 mm thick steel version in yellow zinc plate on its Kuehl High Performance 964/993 Evaporator (evaporator is shipped with new TEV pre-attached).

Either of the 3 versions works if your do things properly. The key to not having issues is using the correct size o-rings, lubricated (evaporator side connections are o-ring size 8 and 10 and the front side hose connections are 6 and 10), insuring the threads in the bracket as well as your fasteners threads are clean. You don’t need loctite. When you attach the refrigerant lines insure they are inserted 'true' (if you are replacing a TEV ditto, do not scratch the inside of the TEV's o-ring contact surface), no debris on o-rings, no corrosion on tubes, proper torque.

There are 2 5mm allen bolts that secure the TEV to the back side bracket. Suggested torque is 4.3 ft lbs and if you torque them evenly things will be flush. When connecting the refrigerant lines to the front side of the TEV the 6 mm bolt suggested torque is 6.5 ft lbs.

If you wish to make your bracket because your’s broke you could but I don’t see a need for something “new”. If you need a good used TEV backside bracket just ask anyone whom has replaced their evaporator on the forum here and they probably have a spare bracket hanging around (new evaporators are typically shipped with a new bracket to secure the temporary shipping dust plug).

dleefsu

Thanks for the additional information. I'm heading out now to get a few parts as I'm hoping to get it sealed at least temporarily to see if there's any other leaks and I've dodged a bullet and don't need to take the evaporator back out. She's going into the shop next week for a top end job and I've been debating on towing the car back home while they do the engine work and I'd thinker on things like this while she's laid up. My temp plan is to straighten the bracket and great info that folks probably have some laying around as I definitely didn't see anyone has them for sale. I'll get some longer allen bolts so I can nut the back and probably slightly drill the back of the bracket so the nut can seat itself a little.

I'm guessing with a straight bracket and good threads then I can go with proper torque.

I think a big note to others that may read this and are having issues getting it sealed, check that bracket to ensure it's straight because without question a little bend changes the angles and it won't seal properly. For reassembly and unless I can grow a 3rd arm, I think I'll try zip ties to hold it in place as it is not a favorable space to work in and that way can check and double check with hands out of the way... Oh yeah, also good info on the locktite as I was wondering about that.

540964

I have one, pm your address and I'll send it to you.
Cheers.

dleefsu

Update: After trying everything I could think of to at least temporarily get the lines to seal to the expansion valve, I had no luck. I bent back the back bracket best I could but will be happy to receive a perfectly straight one (thanks for that, PM sent) but I actually did get the back lines to seal (evap to EV). I also had to tap the threats on that bracket which wasn't bad if switch to american standard as 1/4 is just slightly larger. Also did the same for the single bolt on the other side (threads into the EV which were stripped out when I got to it). The one line couldn't get to seal is the smaller of the two and now I'm guessing something is out of round or simply isn't seating right for some technical reason. I tried various methods in putting it together (seems there's only one way but I would try snugging it, holding lines in various angles, wiggling them slightly to try to get a good seat... Tried various o-rings and kept refreshing to new so went through quite a few as I tried various scenarios including different torques, leaving fairly loose and tightening while holding the freon detector to the leaking area... I'm going to pick up a new expansion valve tomorrow and hope that's the problem as that should be easier to replace than the lines and then I can get back to standard/correct threads...

dleefsu

Another update which should conclude my issue. I tried to get a good picture but just didn't expose the issue well enough. I got another expansion valve today and low and behold, the issue appears pretty obvious. You could noticeably see a difference in the milling where the o-rings seat in the valve. On my old one the lip is very slight, the new one you can tell it makes much more contact with the o-ring and undoubtedly will seal much better. By 'old' it was replaced a few years ago when we did the evaporator. I handed someone else the two and asked if they could see the difference and took him about 8 seconds to see it too. i don't know what brand the old one is but obviously if having issues sealing the expansion valve it's worth a look. I'm usually OK with aftermarket as long as it's not the cheapest of the cheap but will definitely watch out for things like this in the future. This probably explains why seen a few folks with issues but not a huge number.

I guess I'll confirm once receive the new bracket and have it all back together and tested that everything went smooth from this point.