1999 Buick LeSabre

[joekingcorvette]

Look at how the car didn't rust from the filter area being wiped off after oil changes. I changed the oil on my moms car and was surprised at the lack of rust in this area. Only 88,000
miles on the car but it's getting rusty. Plus I had to add 3/4
of a gallon of anti freeze so I think the intake gaskets are getting bad.

 

[Jesse_NE]

If that has a 3800 V6 in it, coolant leaks from a bad intake gasket aren't uncommon. Considering the age of the vehicle, as long as the loss isn't severe, you could probably just monitor it.

 

[Dave9]

I wouldn't wait. Yes the 3800 commonly has intake manifold leaks and can hydrolock and ruin the engine. It's a solid engine otherwise and should still have 100K mi. of life left in it, if the body of the vehicle (or engine subframe) doesn't rust away first.

Replace the upper and lower intake manifold gaskets (along with new upper manifold, one of the common problems is the EGR pipe sits too close to the plastic upper manifold and makes it brittle and there's where a leak starts). Some people even plug off the coolant passage through the throttle body to reduce the chances it leaks there first.

I did this repair a few years back so I still have the parts list I used. Double check this list, I did this on a '97 not '99, but both should have the same series II 3800 in them.

Intake Manifold - I got a Dorman 615-180 but get some other brand, the Dorman is ill fitting and had to be modified, and it even ended up breaking a few months later, though at the MAP sensor mount, not where it was modified. Get one that includes the newer design lower diameter EGR tube insert, which insulates the plastic manifold from the EGR gas heat more.

Intake Manifold Gasket Set - Felpro MS 98014 T - this kit includes the RTV sealant you'll need

Dorman 47065HP Heater Hose Elbows - The originals are plastic and will probably break when you try to pull them off. These are metal.

Optional things you might also want to replace while you're at it are the coolant temperature sensor, ACDelco 213-815, and the thermostat, ACDelco 12TP4D.

No *special* tools are needed (as far as I can remember). Access is great in those, no need to remove the hood or anything.

 

[slacktide_bitog]

are those holes supposed to be there?

 

[Dave9]

I should have mentioned in my prior post, that just because the intake manifold/gaskets is an extremely common fault on those, like any other vehicle you could have a different problem like head gasket, warped or cracked head, or even a water pump, hose, or radiator leak, but if you don't see an external leak, then tearing it down to see where the problem lies, you will need at least the upper intake manifold gasket and once you're in that far you might as well replace the lower intake gasket too, and probably you'll find the leak without having to touch the heads.

Coolant system stop leak products aren't really effective for this problem because it tends to turn into a large leak very quickly once degraded enough, hence the risk of hydrolock.

 

[Chris142]

Originally Posted by slacktide_bitog
are those holes supposed to be there?

Ya. That's where the jig holds it to be welder together.

 

[joekingcorvette]

Originally Posted by Dave9
I should have mentioned in my prior post, that just because the intake manifold/gaskets is an extremely common fault on those, like any other vehicle you could have a different problem like head gasket, warped or cracked head, or even a water pump, hose, or radiator leak, but if you don't see an external leak, then tearing it down to see where the problem lies, you will need at least the upper intake manifold gasket and once you're in that far you might as well replace the lower intake gasket too, and probably you'll find the leak without having to touch the heads.

Coolant system stop leak products aren't really effective for this problem because it tends to turn into a large leak very quickly once degraded enough, hence the risk of hydrolock.


You have very good advice Dave9. I told my mom the possible solutions and she is going to think about getting it repaired. She is almost 90 and the car has been driven gently it's entire life and I believe the transmission and the rest of the car is in great shape. The motors purrs nicely and is very quiet. I personally believe its the intake gaskets and will probably have a competent mechanic repair the problem. It would surprise me if she doesn't have it repaired just due to the fact it could ruin the engine or starter if left unprepared. Thanks everyone for the good advice.