Monday, December 15, 2008
GM 3.8L Plastic Composite Intake Manifold
When car manufacturers decide to do something goofy, like using plastic intake manifolds, we in the repair business do not get happy feet anticipating a stream of big repair invoices. The customers many times see us as somehow connected to these breakdown time-bombs, wondering why we didn’t anticipate trouble, and force the manufacturers back on the proper path of metallic parts more resistant to problems. In actuality, we in the repair business love maintenance work, and would like nothing better than to service vehicles for our customers with all potential fiascos handled before they strand our clients. We are not always given this option, either because the manufacturers don’t broadcast their engineering snafus, or the customer ignores our warnings, which brings me to the pictures above of a GM 3.8L plastic upper intake manifold.
A metal tube routed up through the lower metal intake manifold from the Exhaust Gas Recirculation Valve burns holes in the plastic manifold it extends into, allowing coolant to be mixed into the crankcase engine oil and combustion chambers. Unfortunately, the signs don’t always become obvious until the coolant contaminated engine oil destroys the engine. This plastic manifold was used on most 3.8L GM engines from 1995 thru 2005. The fix, involving replacement of the upper plastic (composite) intake manifold, gaskets, and peripherals is costly; but much less expensive than replacing the engine, which will have to be done if this repair is not completed.
I had three of these in the last week, which is how things go wrong in auto repair: in threes. The first engine was already ruined. The second made lifter noise in the morning, and was salvageable, as was the third. The first customer had driven the
from back East, which is much harder on the manifolds due to extremes in temperature. He said he had experienced no sign of failure until the vehicle simply quit on him. I figured if I put this out on the blog, it might get picked up in the search engine, as was my Honda Balance Shaft seal blog, and save some engines. When the hood is opened on one of these, you will not see this manifold. There is a plastic cover over the entire engine, which says 3.8L on it. It can be removed by unscrewing the oil filler cap and tube (counterclockwise). This allows the engine cover to be slightly tilted and freed from the rear fixture. Then the plastic intake manifold will be visible. Pontiac
That’s all for this update from Nilson Brothers Garage, but if you’re appreciative of the information, here is a link to my new novel COLD BLOODED for Nook and Kindle. If you’re kind enough to read it and like it, please review it on the site you purchase it from. Thank You! Every little bit helps my writing gig. :)