My 2006 Lacrosse (3.8 series 3 with 150k miles) has a slow coolant leak that I can’t seem to place. I have to add a splash (probably under a half cup) just once every couple of weeks to keep the recovery tank on full. Here’s the story:
I bought it a year and a half ago, and I don’t think it used any then. A year ago, with the suggestion of this community, I cleaned my throttle body (has coolant running through it). I reused the gasket, since I didn’t have time to special order one. I think this is when it started leaking, but I’m not positive. Over the past year, I’d guess I’ve put in 2-3 quarts or less. A month or two ago, I tore back into the throttle body, to replace the gasket in hopes that it was the culprit. It was in bad shape and melted. I replaced it with a new Fel-Pro gasket and put it back together. It still is using the same amount (maybe 1/4 inch on the reservoir per 2 weeks or so.) I also changed the coolant, replaced the reservoir, and replaced the radiator cap. I also pressure tested the cooling system, with “normal” results- drop of a couple PSI over 20-30 minutes.
The three things I think it might be are:
Intake manifold gasket (some say that the Series 3 fixed the problem, some disagree)- there is no coolant that I can see in the oil fill and just a bit of what seems to be normal condensation/emulsion from short trip driving. No “milkshake”.
“Coolant elbows” under alternator- I can’t see a leak there but it’s hard to see in that area. These are apparently a common problem.
Throttle body mounting gasket (again)- torque specs are 89 in-lbs. I bought a torque wrench that had in-lbs but it was really just a foot-lbs one that had markings for in-lbs. It was inaccurate and didn’t even go that low. So I just snugged the bolts up.
Any thoughts? I’d like to get this sorted out, and I appreciate your help!