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Discussion Starter · #1 ·
hey guys... i'm new here, usually post on clubGP but thought i'd check this out too... Here's my problem... My mom's got a 97 lesabre with the series II 3800... the other day the plastic intake finally cracked, leaking antifreeze into the cylinders and clouds upon clouds of smoke out the exhaust... we fixed it to the tune of about $400 for just parts, lucky my dad's a mechanic... I know this is a common problem on these engines, and AllData has it as a safety recall item... i contacted buick and they said this one was not under recall... anyone else have dealings with this issue?
 

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yes I run a Pontiac, buick shop....I've seem it many times, the plastic around where the EGR tube gets bad from heat and starts to leak, then you end up with coolant getting into the intake and into the cylinders.......Note: putting in the throttle body coolant plug takes the problem away
 

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There is a modified aftermarket plenum available for those engines. Usually available on Ebay.
 

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I'm curious if the plenum itself cracked or whether it just suffered the leak around the EGR pipe?
If there is an actual crack in the plastic UIM I think that's caused from a faulty Fuel Pressure Regulator.
Otherwise GM did make a reinforced manifold and there is also the Dorman manifold that is available.
 

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Discussion Starter · #5 ·
we couldnt tell if the intake itself was cracked, but you could see on the gasket where it was leaking throught... it was very close to the air intake... in fact, when we removed it, there was coolant in the rubber air intake tube... my guess is the gasket gave way, and quite possibly the intake itself could have been salvaged... but we were'nt about to take that chance... im not sure if i can post pics on this forum but im gonna try to show u guys what we saw... only good thing that came of this is the pistons got a good steam cleaning and are probably as clean as they'll ever be
 

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fast_redgt said:
Note: putting in the throttle body coolant plug takes the problem away
I wrote http://www.zzperformance.com/ and was told plugging it doesn't work... You've actually plugged it and know that it works? If that's true it's a 15 dollar fix worth every penny!
 

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I know this post is almost a year old, but I recently bought a high mileage 95 LeSabre with the plastic intake and want to know if there is any way to prevent the intake from leaking anti-freeze into the engine. Maybe a cooler t-stat? Removing the EGR all together and plugging the hole? All help is appreciated, thanks!
 

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Replacing it comes to mind. The coolant temp is not what causes the leaking, it's the EGR gasses eroding the plastic.
 

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I thought it was the heat that was generated from the hot exhaust gases that caused the plastic to melt and fail? I just thought if I put in a cooler t-stat that maybe the exhaust temps might go down a little? Why would exhaust gases alone erode the intake? So my question would be, is it the heat or gases that cause the failure? Thanks for the help, keep them coming guys!
 

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95 LeSabre said:
I thought it was the heat that was generated from the hot exhaust gases that caused the plastic to melt and fail? I just thought if I put in a cooler t-stat that maybe the exhaust temps might go down a little? Why would exhaust gases alone erode the intake? So my question would be, is it the heat or gases that cause the failure? Thanks for the help, keep them coming guys!
both the EGR does generate more heat then the intake can handle and they heat warp around the coolant passages. also a leaking fuel pressure regulator left unchecked/repaired can cause excess fuel vapor/liquid to pool in intake a misfire/backfire has blown many an intake to little bitty pieces [first hand repaired several for detonation]

if you can get your hands on a steel one all the better. other than that wait for the leak and replace then.
 
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