Mechanics

CUSTOM COOLANT LEAK

2000 Buick Lesabre

Engine Cooling problem
2000 Buick Lesabre 6 cyl Front Wheel Drive Automatic 138000 miles

So about a week and a half ago my Buick LeSabre started shaking while idling. When I tried to start moving the car, the vibration increased to the point where it was obvious that something was wrong and the check engine light came on.

After checking with a computer, the error message was Cylinder 5 misfire detected. So I went and towed my car home and checked spark plugs and all. As soon as I pulled them off, anti-freeze started leaking out, so the next step would have been to replace head gaskets. As a mechanic friend of mine recommended, though he also did suggest to swap the cables and spark plugs while at it, which I did.

After taking the upper intake manifold off, I saw that the entire upper part of the engine was flooded with coolant. Anti-freeze in this case. First thought that occurred was that the upper intake manifold gasket was bad and that's why it was leaking coolant there. Replaced it, changed the oil and put the engine back together. Car ran fine until today. When I tried to start it again, the vibration returned and when checking the coolant level, it was way under the level I had left it at the previous day, which was at full cold. Additionally, white smoke was coming out of the exhaust. Wondering if this would be a head gasket issue or something else at this point. Even though I haven't replaced the head gasket, it still seems a bit fishy for coolant to be leaking in the upper intake manifold and not the cylinder itself, which would be the case if it were a head gasket issue.

Looking at a repair manual for the make and model gives even more options from a broken cylinder to just spark plugs, though a head gasket isn't even mentioned there as a possible cause. Any advice on the matter will be appreciated.
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Eldarrion
November 23, 2009.




Hello,

Yes, it is either a Blown Head Gasket and/or a Cracked Head and the only way to find out if it is a cracked head is to pull the heads of and have the Magnafluxed. If after pulling heads you can see for sure that the head gasket has failed and damaged then I would say that it would be just a blown head gasket.

Also, is most cases when you pull the intake coolant will end up in the valley under it, coolant flows throught it also.

.

Obxautomedic
Nov 23, 2009.
Hi
Unfortunate you did not replace lower intake gasket that is the most likely cause of coolant leak. Can have coolant tested for traces of co2 or HC that would indicate headgasket.
Hope this helps
Thanks for donate

Docfixit
Nov 23, 2009.
Let me start this message by saying thank you to both people that replied. It did give me a bit of insight about the situation, but here is what I came up with yesterday evening: Well, I did start taking it apart yesterday, though this time didn't pull the upper intake manifold off, instead I went and removed the throttle body directly. Looking in through the hole there, once again there's coolant between the upper and lower manifold. I guess I may not be explaining the issue correctly, so. There seems to be coolant where the cylinders pull air for ignition from, and that's where its getting into the cylinders from. In addition, now the fifth cylinder and all the other cylinders on the same side are empty, as when I pulled the spark plugs on that side, they were almost dry and definitely didn't seem like there was anti-freeze on them. Now the other side seems to be having issues, which leads me to believe that the anti-freeze is getting in there from the top, rather than from a blown head gasket, otherwise both sides would be full.

One thing I didn't consider originally was the situation where the upper intake plastic could be cracked and the coolant would be leaking from there rather than the gasket between the two manifolds. Would that be a possibility or am I just hoping that I wouldn't have to take the entire engine apart for naught?

Tiny
Eldarrion
Nov 24, 2009.
Yes that is possible for plastic to crack but more likely throttle body or gasket is issue. Wonder why just cylinder 5 think all would be effected? Maybde crack is from water passage into cyl. 5 runner so when you had it off and on retorquing might have sealed but heat and vibration opened it up again.

Docfixit
Nov 24, 2009.
First time it was Cylinder 5. This time, it's one of the rear ones (2, 4 or 6), didn't hook computer reader up, because the first time I was borrowing one from a friend.

Which is essentially what makes me think it is not a head gasket or cylinder issue. If it were, it would be hitting the same cylinder over and over. Strangely enough, the first time I swapped the upper intake manifold gasket, it worked fine for about a week then it was suddenly back to the old condition again, only this time it's another cylinder.

And still, the coolant wouldn't be popping up between the two manifolds rather than being inside one of the cylinder tubes only. At least that's what my logical thinking tells me. I might be wrong though.

Tiny
Eldarrion
Nov 24, 2009.
I agree not headgasket it is in manifold? Is where
O.K. Water enters throttle body then exits out I believe a heater hose connection, so what about sealing off one and use compressed air to pressurize. Maybe crack, leak will show

Docfixit
Nov 24, 2009.
Yes, that's what I was thinking myself too. Going to try that tonight. Thanks again for all your help and assistance offered.
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Tiny
Eldarrion
Nov 24, 2009.
Wow is all I can say. Under a closer inspection of the upper intake manifold, the problem pretty much smacked me in the forehead. A hole, probably about half a centimeter in diameter that was right where the coolant goes to the drive throttle. A more interesting thing was that it was covered up with something sticky. At first I thought that that's how it was supposed to look, but afterward, after giving it a little thought, I figured it might be a gasket of sorts, so I pulled it out and apparently someone had done a pretty louse patch-up job. Either with duct tape or something else along those lines. Probably the previous owner had this kind of issue and took it to a repair shop that wasn't exactly reputable or tried to fix it himself without paying up the $150-300 for a new upper intake.

All in all, lovely, but the car is fixed now and purring like a kitten. Thanks to all that helped.

Tiny
Eldarrion
Nov 30, 2009.
That's Great and a weird one but you thought it out and had to be intake. And you where right. Glad all is well can't imagine what it would have cost if taken to a shop? $$$$$

Docfixit
Nov 30, 2009.
I've seen several of these that melt where the EGR tube enters the upper intake (don't remember if the problem was corrected in 2000). It can quickly seize the engine (hydro-lock, pull the plugs and try cranking again in the event of coolant loss with a seized engine). Good insurance replacing the upper intake when any problem is noted.

Tiny
Jesse777
Dec 1, 2009.

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