Advice on 3.8 w/ coolant leak?

Messages
39
Location
Texas
Hey everyone, need some advice. My girlfriends '91 Buick Lesabre with the 3.8 is leaking coolant internally. You can't tell by looking at the dipstick or when you change the oil though, so I had an UOA done. It shows 222 on sodium and 72 on potassium, so it confirms what I suspected. This car has just over 200K on it, and she really needs it to last another year. I thought this year 3.8 was a first generation and didn't suffer from the notorious intake leak? So maybe it's a head gasket, not sure. I'm not afraid of doing the intake gaskets, but really don't want to mess with head gaskets. So my questions are: Does this motor suffer from the intake problem? Is the S and K on the UOA really that bad? Think it would last another year or so without touching it? Thanks in advance for any info!
 
Messages
701
Location
Northern IL
To be sure where its coming from I would pressure test it and watch where the coolant leaks out. My money would be on the intakes but no sense in doing those and having it be the head.
 

JRed

Site Donor 2021
Messages
2,323
Location
Virginia
Could try some of those famous GM coolant "conditioner" (stop leak) tablets. Or some Subaru "coolant conditioner" (also stop leak). Worth $5, and the Subaru stuff seems harmless for the most part - plenty of Subarus running around using the stuff every single coolant change. But yes - the Na and K in the UOA may seem harmless for the moment (if it's not shedding metals) but you could prevent a larger problem down the road by spending a little now to fix it. Honestly, I'd give the stop leak a try. My beater has a leaking heater core - I plan to give the Subaru stuff a shot first.
 
Messages
122
Location
Memphis, TN
They have the same kind of lower intake gaskets that the series II 3800 have they're plastic,nylon to be technical, also and eventually go bad.
 
Messages
10,008
Location
Upstate NY
The lower intake manifold gaskets on the Series I 3800's do go bad over time. More from age than acid attack, though. I'm betting those are the original gaskets. 20 years on the original LIM gaskets is pretty good in my eyes. On the Series I, doing the LIM gaskets is pretty cheap. The gaskets cost about $60 for the good ones ($30 for nylon ones that'll last a year easily), then a gallon of coolant, RTV silicone sealant, and some blue Loctite for the LIM bolts. So about $80-100 for everything, including an oil change. Just fix it. It's cheap/easy enough if you're moderately mechanically inclined and have a good tool set.
 

womcat

Thread starter
Messages
39
Location
Texas
Thanks a bunch everyone! I think I'm going to just fix it. I added some of the GM type stop leak tabs when I did the water pump about a month ago, and it's still losing coolant so I guess I'm out of options. The motor is for sure all original, so if those intake gaskets leak too, that's probably what it is. I think this issue has been caught early enough, the UOA didn't show any high metals and the oil was still barely in grade. Thanks again!
 
Messages
881
Location
NC
Fix it soon! My neighbor had a 1998 Buick LeSabre. He was losing some coolant, but not a lot, and kept adding coolant. Not sure if this came OEM with DexCool, but he was adding regular coolant. One day on the way downtown, the gasket opened up and locked the engine....toast.
 

womcat

Thread starter
Messages
39
Location
Texas
Well I went ahead and replaced the IMG yesterday, took all afternoon but it wasn't too terrible. I could see a couple places around the coolant passages where the gasket was broke, and most of the bolts were super loose. I'm pretty sure this should fix the problem. Guess I'll find out soon. Thanks again for the advice!
 
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