2006 3800 engine water in cylinders, back pressure in radiator, water in oil pan. UIM or head gasket?

Tom Simpson

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Hey guys. My parents overheated their 2006 LaCrosse with series III 3800 engine. I first noticed that plastic overflow tank was full of coolant. So once the motor cooled down I removed radiator cap and an enormous amount of pressure was released and then the water from tank flowed into radiator. I then cranked motor with radiator cap off and water gushed out or radiator in buckets. I suspected a blown head gasket pumping back pressure into water system. Then I removed two of the front spark plugs to check compression and water pumped out of cylinders when cranked. I then drained oil and water came out of oil pan. Oil wasn't emulsified yet.

I started tearing down motor expecting a head gasket replacement job. But then I started reading from here and other places that it is a common problem was the UIM gasket leaking on the plastic ones up to 2004. Was told something about the EGR valve getting hot and burning through plastic housing? This would allow water to dump into cylinders and would most likely be my problem.

Few questions before I go further:
My UIM is aluminum. Is this a common problem with these?
How do you inspect a blown gasket? I don't see any observable problems? I have attached pics...
How would an UIM gasket cause pressure to pump water out of radiator? Is this normal?
Water in oil pan. Would a blown UIM gasket cause this? Wouldn't the water be burned an emitted as steam out the exhaust? How would water get past rings and be in oil pan?
Does my symptoms point to a blown head gasket or cracked block?

I am attaching some photos of gasket. Can you guys tell me what to inspect? I'm a backyard mechanic and ignorant of this. Thanks
 

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2007LucerneCXL

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It's a series 3 so some of what you may read only applies to the series 2 UIM. What you may want to confirm or look at would be the lower intake manifold, but not really sure on why or how long it overheating. As MelsRegal mentioned the compression test, but it would also be good to find the reason for the problem in the first place, stuck thermostat, water pump, intake gasket etc.
 

Tom Simpson

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Thanks...and here is an update:
Pulled the intake off completely and the gasket looks bad to me but maybe I damaged it pulling it off? Not exactly sure but the square holes looked "warped" or out of square. I have attached pics of both gaskets (each side).
Now...#4 cylinder is still full water. It's at the top of the head where the IM mates. As far as the other ones...I don't see any water BUT I had already pulled the front two plugs out (#1 and #5) and they pumped water when turning motor checking compression.
I never finished the compression check because once I saw #5 and #1 cylinder with water, I assumed I would be doing a head gasket job. So I guess I screwed up by not performing a compression check on all cylinders before removing intake manifold?
As far as past overheating...who knows. I know it has a few times in the past because I had to change the cooling elbows a couple years ago that leaked. The plastic ones that are famous for cracking. Other than that...I am not sure. Remember...it's my parents car and my father is 80 years old. He forgets things and won't tell me of problems until it is a crisis.
Let me ask...since water is in both sides of the engine, I was going to order a IM gasket set and assemble back together. I have a hard time thinking both head gaskets blew...right? Wouldn't it more likely be the IM gasket? Is there a way to confirm with my intake off now or is it too late?

Thanks guys and let me know if I need to answer anymore questions.
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MelsRegal

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Unless you disassembled something related to the valve train, why can't you do a complete compression test?
 

Tom Simpson

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You saying to hook it up to battery, fill crankcase with oil and turn over engine to do a compression test with the intake off? Can I do that without damaging anything?

Also...another area of concern was that there was oil in intake was I removed the upper part. It was puddled in the lower parts cavities that covered two bolt heads. Is that normal? Is oil leaking past valve seals or something else wrong?
 
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Mad_Coachman

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You saying to hook it up to battery, fill crankcase with oil and turn over engine to do a compression test with the intake off? Can I do that without damaging anything?

Also...another area of concern was that there was oil in intake was I removed the upper part. It was puddled in the lower parts cavities that covered two bolt heads. Is that normal? Is oil leaking past valve seals or something else wrong?
That's normal. It's due to how the PCV valve is located in the upper intake manifold.
 

2007LucerneCXL

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Pull the fuel pump fuse/relay. All plugs are out and maybe a good time to shoot WD40 in the wet cylinders. Toss a couple of quarts of oil in as it's only turning over not running so just enough oil to keep the pickup covered, put on a cheap oil filter that will only be used for cranking and pitched along with oil after combustion testing. Assuming serpentine has already been removed and move plug wires out of the way. Not sure if anything else needs to be done to test. Also while it's apart valve cover gasket may be considered if not already off.
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Tom Simpson

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Hmmmm.......yes....everything is as you described it. Only thing I haven't done is removed the oil filter. I left that on when I drained the oil. I'll just leave it on since I am only cranking the motor.
I'll do that tomorrow and see what it reads.
Thanks for the info!
 

Tom Simpson

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Ok....I did the compression on front 3 because after the readings I figured a head job was in order and didn't go through the hassle of pulling the back 3 plugs yet.
Anyway:
#1 - 60# psi
#3 - 75# psi
#5 - 140# psi

Does this verify that I at least need to pull heads and inspect?
 

2007LucerneCXL

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It appears that would be the next step. Another option is to do wet compression test but it would be more for checking rings vs heads. The other item that can influence those numbers would be if a valve was not fully seated. Maybe others have addtional suggestions if there are any other steps before pulling the heads.
 

Tom Simpson

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It appears that would be the next step. Another option is to do wet compression test but it would be more for checking rings vs heads. The other item that can influence those numbers would be if a valve was not fully seated. Maybe others have addtional suggestions if there are any other steps before pulling the heads.
Yeah....I also keep going back to my original reasoning of blown head gasket which was compression in coolant. Remember...my radiator shoots out water when the cap is off and I turn the motor over. There was enough pressure that the overflow tank wouldn't drain into radiator. Backpressure in my coolant system was my first indication.
OTOH....I can't imagine both head gaskets being blown at same time. I haven't checked the back 3 cylinders yet but I know # 4 is full of water. On top of that my engine isn't firing either.

I can only logically conclude that one head gasket blew during an overheatat some time. Then they kept driving it and maybe overheated it a few other times causing the the IM gaskets to blow and frying the Crankcase Position Sensor killing my ignition. Don't know...

I will go now and fight like hell to check the compression on rear three cylinders and will report back.
Thanks!
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2007LucerneCXL

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I guess a small blessing, if you call it that, is they didn't hydrolock it. I know the feeling all to well when asking the folks on problems and the reply is "awhile" which the range could be yesterday or some time over the last calendar year. While doing both heads is a pain it may be preventive maintenance on the unknown of the rear IMO.
 

Tom Simpson

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OK...I checked compression on 2 of the rear cylinders and stopped.
#2 - 135 psi
#4 - 65 psi

Damn...what a PIA it is to get to the rear plugs. After reading two of the three, then I said, screw it. I will have to pull it anyway.

After I pull the heads, would you go the extra step and send the heads off for a rework? Is there a way for a backyard mechanic to inspect heads? I hate to put money into a 15 year old car that is driven by an 80 year old who probably should not be driving anyway.
 

niceguypmp3

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luckily the 3800 has good reliable and strong cast iron heads and block. While it's not impossible that the overheating could have cracked the heads, it's more unlikely than with aluminum heads. Back when I used to rebuild and repair engines, then if a head gasket was blown due to overheating, then we'd remove the heads and clean the underside where the gasket goes. also, take a wire wheel brush on a drill and clean between the valves and check for cracks. between the valves is usually where heads will crack when overheated, if they crack. but also check between all of the holes and openings where the gasket seals. look for cracks there too. More than likely though, it just blew the head gaskets and the heads are probably fine. You could send the heads in and they will check them for cracks for you and can find them even if you can't see them.
 

Tom Simpson

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I removed front head. Take a look at these pics and see if anything sticks out at you that would indicate head failure? As a reminder...the two cylinders on the left had bad compression.
Thanks guys
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FD611V

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Cannot believe the experts on this forum didn't recognize the problem... engine over-heating due to bad head gaskets. The head gasket appears to be a faulty one. Three out of the four water jackets holes look to be "non functional" for cooling the head and pistons. In fact never seen a head gasket that only appears to have 1/4" dia. coolant holes, and three somehow managed to swell to just a "tiny" pin hole for the coolant to flow from heads to engine block.
Might as well replace both head gaskets, and with some good $80.00 gaskets instead of those $30.00 ones that Buick love to install. That means my 2006 Lacrosse with the series lll 3.8 V-6 probably has the same gaskets. I would guess there where and are many hundred or thousand Buick owners that have/had the same over-heating due to these small coolant holes in the gasket. BTW: When you buy the replacement ones, take a 1/2" hole punch and make those coolant hoes half-inch dia.
 

2007LucerneCXL

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I suspect that means all the engineers are wrong who designed the engine and gaskets, good to know.
 

FD611V

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I suspect that means all the engineers are wrong who designed the engine and gaskets, good to know.
For once you got something right. With the recalls that are made on automobiles, who do you think causes the problem for the recalls....engineers. Gosh! Some nut cases need to be in straight jackets. You fit that to a "T"
 

2007LucerneCXL

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As always insightful, I'm sure your doctorate degree in automotive engineering and design is hanging proudly on your garage wall. Expect a call from GM on your findings so you can help re-engineer the V6 from 1962 to present day models.
 
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