Oil Cooler Adapter Rebuild

[gdbeckst]

Hi everyone,

I'm getting the engine ready to paint and have been mounting all the external components (timing cover, water pump, valve covers, etc). Now the last thing to mount is the oil filter/cooler adapter.

From my reading and previous experience with MG's, I knew there was a rubber o-ring between the block adapter and the cooler adapter. My hunch was that it was never replaced and so was probably a petrified chunk of rubber bound to start leaking soon.

Upon disassembly, I was right. So I've purchased the Dorman o-ring kit mentioned somewhere on the GMC MotorHome photos site.

It looks like a mechanic had worked on the lines previously, as they were 1/2" copper tubing (lol) and all the fittings had an obscene amount of teflon tape on them. The tape job was looking a bit sad so I decided to do a complete rebuild and remove/reseal all the plugs and fittings. I've also purchased SS oil cooler lines so the line connectors had to be changed out anyways.

Anyways, to my question:

Underneath one of the plugs was a spring. There is also what appears to be a poppet at the bottom of the bore. I'm assuming this is a pressure relief valve in case the cooler lines become plugged or something.

I'm not sure why this is required, as there is already a pressure relief valve in the block filter adapter.

I'm wondering if anyone knows exactly what this is and if there's a procedure for setting the appropriate relief pressure by torquing the plug or something? I'd hate to cause issues because I didn't set the proper spring tension on this valve.

I haven't seen any other posts mentioning the relief valve in the cooler adapter. My cooler adapter may not be OEM (this engine has been rebuilt, possibly replaced, several times). It has the words "Thermo Chem500 Pat #3463317" cast into it. The patent also makes no mention of a pressure relief valve.

See attached pictures. The first one shows the disassembled oil cooler adapter, along with the spring and plugs. The second picture attempts to show the poppet valve in the plug bore that the spring came from.

 

[tmsnyder]

I don't believe mine had that on it, it's a 76. The filters can have a pressure relief built in though.

What does the o-ring look like that came with your Dorman kit? I used a square oring from an oil gasket and it's too fat I think. It works, but not like an oring should, there's still a gap between the two metal surfaces, i"d rather see them clamp together hard and squish the oring the proper amount.

 

[gdbeckst]

I haven’t actually picked up the kit yet. The kit I ordered is Dorman 917-036.

I’m thinking I might just order a new oil cooler adapter to avoid issues with the pressure relief. One of the aluminum inlet/outlet ports has some threads missing anyways. The oring is $7, a new cooler is about $35 ($50 w/ shipping and tax).

Can anyone recommend a new oil cooler adapter that would work on a GMC with a 455 and Doug’s D755Y headers?

I’m looking at this one:

https://www.summitracing.com/parts/HDA-211

It’s got the correct 13/16”-16 nipple and one of the only ones I can find with 1/2” NPT ports (as my current one does) rather tha.n 3/8” NPT. It looks a bit thicker than my current one but I don’t think clearance will be an issue based on what I remember with the oil filter location.

 

[Matt Colie]

GD,
Many of us just buy a Fram filter, peel the seal ring and toss the filter before it has done any harm.
Matt

 

[tmsnyder]

GD,
Many of us just buy a Fram filter, peel the seal ring and toss the filter before it has done any harm.
Matt

You trust the Fram seal ring? LOL

Seriously though, I found the seal to be too thick. When torqued properly, I want the rubber seal to be squished properly and metal on metal contact maintaining the proper squish, the way a proper o-ring seal is designed.

 

[LarryW]

You trust the Fram seal ring? LOL

Seriously though, I found the seal to be too thick. When torqued properly, I want the rubber seal to be squished properly and metal on metal contact maintaining the proper squish, the way a proper o-ring seal is designed.

I have been using the Fram type seal on the oil filter/cooler adapter since 2005 with leak issues very early in my oil change experiences. I was talking to the late great Bob Drews about the seal on the adapter and noticing that it seemed to be squashed and deformed in some spots and leaking. He reminded me that the seal used on an oil filter was designed to be screwed on. So, oil was needed to allow it to slip as you turn it down hand tight. The seal at the adapter is not a turning type of contact. As you tighten the bolt that holds the adapter in place, the adapter does not turn/screw, it tightens straight. The seal on the adapter should be dry. So I started using the Fram type seal dry. My leak and deformity issues went away. Then, never had a leak until I tried the "O" ring specified for this application on my adapter. It just was not thick enough to get enough "squash" to make a good seal. Tried it...didn't work...actually leaked...went back to the Fram type seal. Actually, I have found that the seal from a Wix filter is also a perfect fit. About every third oil change I will use the seal from the filter I'm throwing away and put it on the adapter. I clean it up and put it on dry. No leaks, no deformity. Just what I've noticed.