Re: 98 LeSabre Series II - Plastic Plenum

[newfangledcog]

We are working on a 98 LeSabre with the 3800 series II engine. It has multi-port injection, and the EGR has a tube that goes up into a port on the plenum. The problem here is that the hot gases have eaten a hole through on both sides of the port into the coolant jacket, allowing coolant to get into the intake. We also found that the port was empacted with carbon from the exhaust gases, and had to be cleaned out. I suspect that this may be the case with a lot of these cars. This condition undoubtedly diminishes the ability of the coolant circulating through the jacket around the port to draw heat away from the area. This in turn allows the heat from the exhaust to more rapidly deteriorate the plastic, and cause a leak. I think the Mfg. could easily have corrected this simply by casting a metal ( or some other heat resistant material) insert into the plenum, to line the port.

When we went to the dealer to get a replacement part, they told us they were not aware of any problem or condition with these plastic plenums, and that the plenums seem to last as long as any other part; however, the counter man didn't even have to look up the part on the computer, he simply went to the back and brought one out. Then he told us he was having a problem keeping a supply of them on the shelf. Draw your own conclusions. He said he was unaware of an upgrade, and the plenum he brought out was identical to the original. So, sooner or later, same problem again. The aftermarket parts dealers in our area were also unaware of any upgrade, so we just bought it from the dealer.

Just a note: While we had it apart, we thought it would be a good idea to put a pressure test on the cooling system. We wanted to be sure there were no additional leaks from the lower area of the intake. In order to do this, we cut a piece of aluminum plate 1/2" thick, cut a notch in it to clear the EGR tube, then drilled it to take two bolts for attachment. We then set two O-rings around the coolant jackets, and bolted it down. This allowed us to seal the ports, and perform the test.

[HotZ28]

I moved the post you attached to an older thread and started a new thread for you.
Please read: Posting in closed or outdated threads - LeSabre
Thanks

[imidazol97]

Originally Posted by newfangledcog

When we went to the dealer to get a replacement part, they told us they were not aware of any problem or condition with these plastic plenums, and that the plenums seem to last as long as any other part; however, the counter man didn't even have to look up the part on the computer, he simply went to the back and brought one out. .

Back in about 2001 the intake on our 98 went bad at 75K. No help from GM. They didn't know anything about the part problem. They still don't. But at the time our service manager tried to help. He told the dumb management trainee that finally contacted him on our behalf that he was replacing about 1 per week in their relatively small shop.

GM's inability to address the problem is because they use management trainees as troubleshooters in the call center. That's their training. The trainees don't care; and they're gone within a year to bigger and better mismanagement problems.

When I called again after months they finally agreed to a $500 coupon as settlement on a new car. But my wife had wanted a retirement car and we'd just bought a red Celebration model that she loved. Why would I want to buy another one; I considered that one my last new car from GM. I'll buy used after others have learned what goes bad (like sludge in toyotas and transmissions in toyota and transmissions and noises in hondas, etc., etc. They all have their problems despite what some owners say).

If I have to replace mine again, it'll be a Dorman which has adapted to some needed mods. The car now has 150K miles on it almost.

[GringoPete]

Originally Posted by imidazol97

I'll buy used after others have learned what goes bad (like sludge in toyotas and transmissions in toyota and transmissions and noises in hondas, etc., etc. They all have their problems despite what some owners say).

I agree with you 100% . Japanese cars break down as well. All machines are capable of breaking down or needing maintenance at some time or another. Best thing to do is keep up with your oil changes etc..... and your car will more than likely last longer.

I tend to baby my 98 lesabre for most of the part. I take it easy turning corners and go easy on acceleration as not to give the tranny a workout.