93 3.8L Regal Coolant Leak

[Icekola]

Hi,
I have a 93 Buick Regal Limited, 3.8 Liter - Made in Canada (In kilometers it has about 260,000) -- It's been a pretty good car up untill EVERYTHING decided to break at once... Anyways... My concern is, the fact that my COOLANT is leaking from underneath the Throttlebody/Plenum -- I Took everything off, (the Upper plenum too...) and discovered that my Coolant leak is where the upper and lower sections join. I see no evidence of the water leaking into the ENGINE yet... It just leaks out the back side of the engine... The Problem is that the Plastic turned to mush... So I bought new rubber gaskets hoping this would solve the problem, but of course... 100 miles down the road, and I have a BIG puddle under the car.... Now... is this a common thing for this paticular engine? I have NOT seen any posts for this year, and am having a Very fun time finding a replacement part for this.. (The dealership wants $290, which i cant afford to spend... I am a knowledgable person, and have been working on my cars for years... I called a junkyard and they said they have one off of a PONTIAC Bonneville... Except it is Aluminum... Do you think that this part is interchangeable and would work??!? Also do you beleive I may have to replace the BOTTOM plenum as well, to get this leak to stop!? Also just for your info here's a little history on the cars cooling problems since I've owned it...

1) First Went the water Pump... Replaced -- No prob.
2) Then the heater core blew, and my floor ended up VERY wet... Replaced
3) Then of course the rubber hoses - Replaced
4) Then the Radiator sprung a LEAK - Replaced
5) NOW this Plenum thing!!

TOO Much pressure in the system or just really OLD!? hehe - hanks in advance!!
-Jason

[Ruley73]

You probably have a leak in your Lower intake manifold gaskets on the rear driver side. This engine is notorious for this. You just need to replaces those gaskets. I just replaced mine last weekend with 154k miles on my '95 Regal GS with the same engine. A friend of mind also had to have his gaskets replaced on his '94 Lesabre with 175K miles on it. Only the '93-'95 Buick Regals And Lesabres have the engine with the plastic plenum. The plenums are NOT interchangable mainly because the EGR valve is located on the front side (not the back) unlike the other VIN L 3800s. I hope this helps

[93rgeal87gn]

those plastic plenums are pricy but known to go bad!

[Ruley73]

The composite plenums rarely go bad on the '93-'95 VIN L 3800 TPI engines, The '95-up VIN K 3800 Series II is the engine that is notorious for this failure. The EGR gases cause the plenum to warp over time. When this happens a water jacket near the EGR passages leaks coolant into the engine.