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2007 Buick Lacrosse
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Discussion Starter · #1 ·
Good morning! (or afternoon, depending on your time zone)
I stumbled on this venue while doing a google search about slight coolant loss on my '07 Lacrosse and it looks like a good place to hang out, learn and even contribute. I've been working for GM Dealerships for over 40 years, mostly Buick and Pontiac, going back to the days when the factory fix on a 3.8 liter with the oil light flickering at idle was to replace the 10 psi. oil light sender with a 7 psi. replacement. For the recent past years, I've been with Chevrolet, so my 3800 exposure has been minimal.
My question concerns coolant loss on my '07 Lacrosse. A few months ago, one of the coolant elbows failed and I had an overheat condition until I could get it safely off the road (less than a mile). After replacing them with the aluminum ones, I ran straight water for a while, just to verify there were no other leaks. After I flushed and refilled the system with DexCool, I noticed it using about a pint of coolant per week in my normal commuting cycle. The oil fill cap had random spots of the dreaded foam, but none on the dipstick and no increase in oil level. No unusual smoke from the tailpipe and no coolant odor is noticed either, nor is there any loss of performance or idle quality.
I haven't had the opportunity to get it in the garage for coolant pressure and compression tests yet, but will ASAP.
Based on my searching here, I'm thinking lower intake gaskets are a likely area for leaks, as they would possibly leak into the lifter valley, rather than into the combustion chamber. I've never done a LIM removal before on a 3800, but it doesn't all that difficult, since I've done a few uppers in the plastic manifold days of 3800's and a bunch of Chevy intakes in all the years I wrenched on Winged Sprint Cars.
Obviously, some testing is in order before I start loosening bolts, but does it sound like I'm on the right track?
Thanks in advance for your input.

Bill
 

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If they're not upgraded to the aluminum gaskets AC Delco started using around 2012, it's most likely leaking. If you're not seeing it in the oil, mainly dipstick or during oil change draining (condensation when it's cold can sometimes put small amounts in the cap, so don't sweat that), it's probably getting sucked from the coolant passages into the intake ports at the LIM gasket.

Job is pretty common, and there's one or two guys with decent YouTube how-to's that you can familiarize with for ideas of what's in the process (RTV at valley corners, teflon on LIM bolts, etc.).
 

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2007 Buick Lacrosse
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Discussion Starter · #3 ·
Thanks for the reply, Dave.
I haven't had time to do any diagnostic testing yet, as I mentioned, but it will get done very soon. I'm glad you concur with my somewhat educated guess. I've been working on cars for 50 years, since high school, and achieved full ASE mechanics certification, but wrenching on an open header, push-start race car for over 20 years, when you can't take a test drive down your neighborhood street has taught me to think things through thoroughly before opening the tool cabinet.

Bill
 

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True, was on a crew for a couple Whelen Modifieds, and it's a pain to have to try covering all bases, make any improvements, and know it's only got one shot to work for many pieces that can't be serviced between practice/qualifying/feature in the same night.
 

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2007 Buick Lacrosse
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4 Posts
Discussion Starter · #6 ·
Just a follow-up to my original inquiry over a month ago, FWIW.
As I indicated in my original post, my coolant loss was less than a pint per week of normal commuting. Since it got extremely cold in the Western PA area, as in below 0 temps right before Christmas, I was hoping to postpone tearing the thing apart and I wasn't willing to put my garage queen El Camino into daily service in mid-winter, so I started research on additives, even though I don't feel that good mechanics come in cans.
I wound up adding a can of K-Seal Coolant Leak Repair, and within about a week of daily driving, the coolant level stabilized, and no foam ever appeared on the oil fill cap. I'm still a bit paranoid of trusting additives, so the coolant level line is marked on the reservoir and I check the level and the oil fill cap at least weekly.
I still don't trust any additive as a permanent solution, so the intake will be coming off once the weather moderates, but I'm happy I could postpone a legit repair for a while.
Thanks for all your help. I participate in a few forums and I just thought it was proper to do a progress report in the event it may help someone in the future.

Bill
 
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