Anyone here experience Intake Plenum Explosion on a GM 3.8 L?

[drphilsauto]

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[Joe Marconi]

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[FROGFINDER]

YEP.

[TheTrustedMechanic]

Just curious if anyone else has run across a GM 3.8 naturally asperartated engine...where the plastic plenum has turned into shrapnel. I came across the car in this condition after the customer said they tried to jump start a very weak battery.

 

After cranking the engine a few times the plenum exploded after a huge backfire in the intake.

 

She was very lucky the car did not catch on fire as a result

 

Doing a quick Google search on the condition resulted in other cases like this, when owners tried to jump start their cars in this manner. The destruction of the type of backfire is beyond belief. I wish I would have took pics of it.

 

Anyone else with similar experience?

I have never personally seen the devastation you describe but I do remember reading a tsb, tech-tip or some such info about it as a possibility. As we all know backfires can be quite violent and given the reduced structural integrity of the plastic intake manifolds this type of failure is not out of the question. I think the info I read was more along the lines of possible cracking and vacuum leaks because of it as opposed to catastrophic failure. I have seen a MAF damaged by a backfire as well as a Chevy 4.3 or 5.7 (I don't remember which, the gaskets are very similar) that blew out one valve cover gasket after a backfire.

[Type S Zero]

i'm in canada with cold harsh winters, so battery boosting is quite common around here, and yes i've witnessed another tech boosting a 3.8 GM (i was actually in a new car waiting for its engine to heat up so i could put the blower at work for the interior to get at a normal temperature before entering the shop to install a remote starter....because at -15°C plastic trims are very fragile + entering the shop with a car that cold, the humidity from the wash bay condenses on all interior surface and then freezes....so you get a layer of ice everywhere inside ! )

 

.... so he tried cranking but battery was completely dead (a trade-in that was left standing for a long time), he came back with a booster pack, cranked it (took a while but not too long either) and then the gunfire sound with plastic parts flying !

 

we ordered the intake manifold from the junkyard, replaced it and car ran fine.

Edited August 27, 2012 by Type S Zero