Trans oil cooler in C6 radiator

[ohmygosuness]

Hi guys,

I'm having trouble finding a plug for the auto trans cooler that's built into radiator. So far, every plug I found online, the flange is way too small to cover the plastic part of radiator. The closest thing I found is this connector:

https://www.amazon.com/GM-Genuine-12603782-Engine-Indicator/dp/B0013FXUVM/ref=sr_1_4?crid=2XTAJWG2IRCPT&dib=eyJ2IjoiMSJ9.8jzSrl0LzIgNPVTr7bsE_MHY-OHPSF7RHies3VMP0KCjsKgxlJ8ydoZ9dSHDc1FLAGO2CDjxCWM 0KjXzmW3ZopI1Y31P1AcQvmA8g_iWHnE__WKKfgSiSaLbLnOzh dHe-Kid3B2FKOcfp9aO2tS4AI1C_knOyTGNVKnkKL5VHUvG199nQyg ttOpV9b6-VkmyvLzeQccjFzj4yF6UJDj1ldQ2l3ztjsYQCFspqa0dl-Y.g3ZP7XpRxV6lkkBExtGnvym4c8v887kt0U6pigeYZGo&dib_tag=se&keywords=gm+transmission+cooler+connector&qid=1748910209&sprefix=gm+transmission+cooler+connector%2Caps%2C2 80&sr=8-4

I'm trying to either plug this oil cooler up or loop the inlet/outlet to itself so it won't be used for now. If I can't find a plug for it, I'll loop it. Unless someone has other suggestions. I know the thread is 9/16-18.

Can someone tell me what kind of line connects to the unthreaded part of this connector (the side with a metal clip)?

Here's a pic of the oil cooler:
214538

[crash]

If you don't mind spending some $$ to solve this problem, you can probably find what you need here...

https://www.anplumbing.com/

They pretty much have anything and everything and are super helpful if you don't see what you need on their website.

My guess is that you need a straight thread to AN adapter, and then an AN cap to just keep the dirt out.

[ohmygosuness]

If you don't mind spending some $$ to solve this problem, you can probably find what you need here...

https://www.anplumbing.com/

They pretty much have anything and everything and are super helpful if you don't see what you need on their website.

My guess is that you need a straight thread to AN adapter, and then an AN cap to just keep the dirt out.

Thanks, Crash. I'll give them a call. I don't mind spending a few bucks. Straight thread to AN adaptor isn't hard to find but I feel like the flange width needs to be custom-made to be way bigger since the application is rather unique. I don't think putting a bolt/washer would be a good enough seal either.

[Presdough]

What about a bolt and a rubber drain plug washer? You're not keeping fluid in, you're keeping dirt out.

[ohmygosuness]

What about a bolt and a rubber drain plug washer? You're not keeping fluid in, you're keeping dirt out.

I haven't filled up my radiator fluid yet but this trans radiator is loosely placed inside the engine radiator. It's not sealed around the edges to prevent engine radiator fluid from coming out. So, I do need a flange large enough to press against the black plastic area so engine radiator fluid won't spill out.

[VRaptor SpeedWorks, LLC]

I haven't filled up my radiator fluid yet but this trans radiator is loosely placed inside the engine radiator. It's not sealed around the edges to prevent engine radiator fluid from coming out. So, I do need a flange large enough to press against the black plastic area so engine radiator fluid won't spill out.

So the fittings are both sealing the coolant from leaking out of the radiator AND sealing the trans cooler lines? That doesn't sound right.....? That sounds like a recipe for either coolant to leak into your transmission.....or trans fluid to leak into your coolant if something doesn't seal inside the fitting? For what you'd spend on AN fittings to seal them up, you could probably just replace the radiator with a C5 unit and forget it.

[ohmygosuness]

So the fittings are both sealing the coolant from leaking out of the radiator AND sealing the trans cooler lines? That doesn't sound right.....? That sounds like a recipe for either coolant to leak into your transmission.....or trans fluid to leak into your coolant if something doesn't seal inside the fitting? For what you'd spend on AN fittings to seal them up, you could probably just replace the radiator with a C5 unit and forget it.

I guess I'll find out after filling it up with radiator fluid. I'm not having any luck finding the right plug for this. I might weld a big washer to a 9/16-18 thread bolt and seal it up with an O-ring. I also don't mind using this trans cooler for my future Mendeola, if it works well.

[crash]

So the fittings are both sealing the coolant from leaking out of the radiator AND sealing the trans cooler lines? That doesn't sound right.....? That sounds like a recipe for either coolant to leak into your transmission.....or trans fluid to leak into your coolant if something doesn't seal inside the fitting? For what you'd spend on AN fittings to seal them up, you could probably just replace the radiator with a C5 unit and forget it.

Yes the AN deal is not cheap...and I was also thinking last night that something doesn't seem right here. I don't have a stock Vette radiator to look at because we always ran the all aluminum radiators, and then I switched to the larger truck radiator a year or so ago, but I was thinking maybe an OEM fitting that goes into the cooler threads and seals to the plastic tank is missing? I can't imagine a radiator needing a fitting like this and it not being provided with the radiator. I HAVE installed radiators with plastic tanks before on street vehicles and they always have a barbed fitting or a threaded fitting specific for a tube nut on the coolers. Again, maybe something is missing from the OEM setup?

EDIT: I zoomed in on your picture and something definitely does not look correct. The cooler threaded hole is not even in the center of the tank hole. It looks to me like something is definitely missing from that assembly. What does the other connection point look like? Is the cooler loose inside the tank?

[ohmygosuness]

Yes the AN deal is not cheap...and I was also thinking last night that something doesn't seem right here. I don't have a stock Vette radiator to look at because we always ran the all aluminum radiators, and then I switched to the larger truck radiator a year or so ago, but I was thinking maybe an OEM fitting that goes into the cooler threads and seals to the plastic tank is missing? I can't imagine a radiator needing a fitting like this and it not being provided with the radiator. I HAVE installed radiators with plastic tanks before on street vehicles and they always have a barbed fitting or a threaded fitting specific for a tube nut on the coolers. Again, maybe something is missing from the OEM setup?

EDIT: I zoomed in on your picture and something definitely does not look correct. The cooler threaded hole is not even in the center of the tank hole. It looks to me like something is definitely missing from that assembly. What does the other connection point look like? Is the cooler loose inside the tank?

Yes, the oil cooler is loose inside the radiator. I had to prop it up in the first pic so I can show you guys. When this was being disassembled, if I remember correctly, what kept these holes sealed was 2 lines coming from the trans going into these threads. Here's another pic with the cooler loosely sitting inside:
214642

Unfortunately I threw away these OEM lines since I didn't think I'd be using them again.

It used a fitting like this with a wide flange:
214643

I believe the end with a metal clip snaps into a barb like this:
214644

I may just get these fittings to try them out. Then loop its inlet to outlet.

[ohmygosuness]

This is how I have plugged for now. These OEM type clip-on barb fittings do seem a bit sketchy. If I end up using this cooler, I'll run lines to it. But I think this will work.

214803