GM V6 and Coolant Loss

I saw this issue once again on an auto forum and thought I'd address it here to avoid retyping the information again. It pertains, specifically, to the plastic intake on an Oldsmobile 88 (eighty eight) Royale and, generally, to Buicks, Pontiacs and whatever other body it may have been stuffed into. The 3800 engine from GM was, in fact, widely hailed as an excellent engine. It made it onto Ward's 10 Best Engines of the 20th Century list and no doubt deserves the acclaim. It does, however, have a fairly serious Achilles heel (In the Series II incarnation) in the form of a melting plastic intake manifold. Making it more of a pain is the fact that the symptoms can often mimic those of a leaking head gasket, leading to expensive repairs that may not be necessary.

Directly past the throttle body, within the throat of the intake, there lies an approximately 2 cm wide circular passage through which hot exhaust gases pass back into the combustion cycle. This is quite normal and a part of the EGR system. What was unforeseen at design time (We can hope it was just an oversight!) was the eventual decomposition and melting of the plastic composite around this passage. During this process, perforations are formed through to the coolant passages that run right next to this EGR port. Catastrophic failure is not usually immediate and can be signified by the slow loss of coolant, unexplained by any other means (There are many ways you can lose antifreeze! Check them all FIRST.).

In personal experience, the car produced little to no white smoke once warmed up and driven but there may be some during warm up that is most pronounced on cold days. Thus, it is easily written off as simple condensation in the exhaust. (This may not always be the case, however, it may pour white smoke constantly.) Eventually the engine died on the freeway for no obvious reason. It's death was preceded by a lack of throttle response and no one bothered to look out the back window to check for smoke. It ended up hydrolocked, with very clean spark plugs and two cylinders completely full of water. After the autopsy, more water was discovered on top of the lower intake, which would have been impossible in the case of a 'blown' headgasket. At first only the intake gaskets themselves were suspect but after cleanup of the plastic upper, the holes burnt through by the hot exhaust inlet were discovered.

In addition to the other potential difficulties, burning antifreeze can accelerate the demise of the catalytic converter (After which a distinct sulfur/rotten egg smell is noticeable) and will most likely damage the oxygen sensor. The intake will usually require replacement and GM recommends replacing both the upper (plastic) and lower (metal) sections. Yes, they are very aware of the situation and have not issued any recalls regarding it. Nor, at this late date, are they likely to do so. This operation generally runs upwards of eight hundred dollars and usually occurs after the warranty period has expired**.

Now, since we've found this out too late and have no recourse but to repair the problem or ditch the car, what's to be done? Why, a copper pipe and some JB weld, of course!

Quick fix to repair the intake can be found Here
**(Most accounts have this occurring at 75-100,000 miles, although some have reported it as early as 35,000)