I replace my coolant elbows everytime I have the system drained. It'* always a crap shoot as to whether they will seal or not. Just put new ones in last month when I redid the UIM / LIM gaskets (again). They now leak every morning when I start the vehicle. This week is especially cold (single digits) and I produce a nice yellow pool on the ground. This is not acceptable for a variety of reasons (neighbors have dogs, environmentally irresponsible, don't want antifreeze dripping down my engine every morning). It is the elbow connecting the accessory bracket to the LIM. Is there any way to seal this, or to rig up an alternative? It eventually seals when the engine heats up. Can I use RTV or something around the joint? I don't want to spend every weekend draining my engine and replacing this thing. I cannot for the life of me figure out how GM thought that this was a viable way to connect two parts with 212 degree fluid running between them. A small hose with clamps would have worked. This L36 is a tinker toy job.

Ymmot04 has the same issue with his 03 SLE we changed them twice (once during a LIM/UIM job and once there after) we still have not to my knowledge figured out what is causing it

All that I've done I clean up the hole real good, make sure there are no crack. Then put a thin film of red RTV on the O ring. It slides in easy, then seals. Never had a leak. You also need to make sure the plastic is centered in the hole.

If the elbows have pressure on them, they will distort shape and leak.

Here'* my procedure that hasn't failed me, since I realized the pressure issue.

Clean both the tensioner and LIM with steel wool to ensure there is no ridge from prior elbow etc.
Lube the o-rings with vasoline/oil
Put the elbows into the tensioner and slide them in as the tensioner goes on.
As I tighten the bolts for the tensioner, continually wiggle the top elbow to ensure there'* no pressure on it.
Wiggle the top elbow into the 90 degree position after the tensioner is tightened.

Thanks for the info Bill, I'm going to have to take mine in for round three whenever I feel up to it. I'll bet if I wasn't constantly topping it off I'd drain the res in a month or a little more. Was very frustrating replacing them for a second time just to have them leak again.

I would really inspect things. If your having that many leaking problems you may have a crack in the LIM or tensioner. If that'* the case I do have a tensioner here. 2 of them in fact.

I'll take a better look at it this time, but I really don't think anythings cracked. It stops leaking once the car warms up, which makes sense if the elbow somehow got dis-formed. Also, when I start it I can see it leak out the openings like its just blowing past the elbow o-ring. I did grease the o-rings before putting them in and they are the ones that can't really roll out.

Make sure it'* the right tensioner Dan.. there'* 2-3 different designs, IIRC you mostly parted out W body stuff.

True, but I will soon have a extra H body engine.

What year?

From what I've seen, there'* a
97/98 W body that looks similar to 96-99 H body, but is slightly different
99+ W body that is the same as 00+ H body.

Lump whatever letter the Park Ave is, into the H body mount category. I think it'* a G for Ginormous