I am almost finished with the rebuild of the UIM and LIM due to the typical problems the Bonnie has. I followed the excellent advice posted on many of these threads and replaced the coolant elbow, etc. Almost done, filling up the radiator and I keep hearing drip, drip drip. Come to find out it is leaking from the coolant elbow where it is seated in the lower intake manifold.

Option 1 : take it all apart again. No thanks.
Option 2 : cut the elbow and get creative with some tubing and clamps.
Option 3 : ask you guys if you have a solution that doesn't involve removing half my engine again. Any thoughts?

I think when I installed the elbow, I pushed it in too far then pulled it back out. When pulling it out, it must not have seated correctly or cracked, dunno. I've managed to pry the elbow out a bit from the LIM which slowed the drip, but has not completely fixed the problem.

3:00 am . . . I thought I was going to finish this tonight, maybe tomorrow.

Thanks, Lance

no known options besides taken it back apart.... i'm running a prototype elbow on my car, but yea once you took it off once, it goes way faster the second time!

willwren ran into the same problem with a replacement elbow when he did a series II UIM/LIM last month. Turns out it was a defective (new) o-ring. You might get by for a while by draining the coolant and sealing the elbow with rtv silicone, but that should only be until you have the time to fix the problem correctly. I don't think you have to tear down the UIM and LIM to change the elbow. I think you can remove the alternator, and the tensioner assembly from the front of the engine to remove the elbow. You will want to replace the other o-ring (o-rings) for the casting (or elbow)that connects the tensioner assembly to the water pump if you remove the tensioner assembly.

You could have a hard deposit, corrosion, or a casting defect in the bore on the LIM or the tensioner assembly that is damaging the o-ring or preventing it from sealing. When you have it apart, inspect the areas where the o-ring seats looking for problems that might prevent a good seal. If the bore is pitted, with the LIM dry, and the elbow out, you may be able to get a seal with careful cleaning and rtv silicone. If the LIM bore is really bad, you will have to tear it back down to either install a sleeve to repair the bore, or replace the LIM with a good used one from a junkyard. If the LIM elbow bore is not pitted and you can get it nice and clean, use new o-rings on the elbow (inspect them carefully before you install them), and add a little silicone grease to them to help push them in smoothly without tearing them. Some use rtv silicone to help them slide in, but it is not necessary with good bores and good o-rings.

If you do have to change out the LIM, if you are careful disassembling it, you will not have to purchase new gaskets for the LIM or UIM. And, it really does go more quickly and easily the second time.

You have it back together, start it up, build some heat into it, and wiggle the elbow around. The heat and the coolant pressure may just seat it for you.
Its worth a try.

I had an issue with an elbow recently.

Don't take off the entire intake again. You can put a new elbow in by removing the alternator bracket. And ...incidentally..you will have easy access to check your power steering fluid.

Things to be careful of are the other elbow (or o ring in most cases as the other elbow is part of that accessory bracket) In resealing my elbow..I used a little RTV, same as WillWren. It'* not supposed to be needed.

I agree with the Bills. If you can't get it to seal properly, take the alternator and tensioner bracket off, and take care of it that way. If you have a 99 or newer, change the other elbow also. If not, then the O-rings. Clean things up...as always, the cleaner the better, put some silicone grease (what I use) or RTV on it, button her up, and hopefully the leak is gone.

mine leaks too....been less than a year since it was replaced

I would go with RTV, and if that doesn't work, try the tensioner assembly.

I got a new elbow today at the dealer so I'm ready to get into this again. Any one have a good diagram of the bolts on the tensioner assembly? I think this (as recommended) is the way to go. I'm going to get into this today and don't like searching for bolts.

Thanks,
Lance

My son'* Bonneville has the same problem.
I just went to the dealer to get a new elbow but he doesn't list that part at all!
Does anyone know the part number for the elbow.
Vehicle info is;
'95 Bonneville (the low end model SE I think).
3.8L
VIN with a "K"

Lance... I remember 2.. maybe a third.

Remove belt from tensioner
Remove alternator
I was able to feel both bolts.. they are in reasonable places and you might be able to see both easily.

cboland.. Every GM dealer in the world should stock the 3.8 coolant elbow for a Series 2 and know it by heart. Call the parts dept .. I bet you were talking to a newbie