Mystery coolant loss

[Merkava_4]

I replaced my elbows last summer and the o rings dont hold up, just make sure you use blue rtv.

You can get the genuine GM o-rings from eBay. That's what I did and slathered them up with Dow Corning 111 grease. I applied 111 grease to the metal surfaces too.

GM Part Number: 25537068 (O RING) (0.674" I.D.)
GM Part Number: 24502846 (O-RING) (0.799" I.D.) (0.1.03 X-SECT DIA.)

You'll need one at 0.799" I.D. and three at 0.674" I.D.

 

[-Regal-]

Two factory plastic cooling elbows on the passenger side that go in and around the alternator did it for me on my series II 3800. Alternator needs to come apart to fix this. I would replace with HELP! brand metal replacements. Very common issue for series II 3800 motors. Couldn't find it for the longest time and it was still an issue even after replacing the radiator (which itself needed replacement anyways). Once those two things were replaced I only had slight coolant loss that I suspected was the original coolant level sensor not mating up with the new radiator very well. It was mostly curtailed with AC Delco coolant pellets.