95 SSEi power loss

1995 Bonneville SSEi Supercharged
155K miles. Engine rebuilt 80K ago (not by me).

Barely made the 1500 mi. trip to new home in Florida. It had VERY little power to climb even a slight grade. It would rev high and slow to a crawl.

Local mechanic (pretty good guy but limited experience and no supercharger experience) checked it out and found multiple and various problems that I thought were reasonable. He replaced the throttle position sensor and O2 sensor the water pump and the catalyst which was making lots of noise.

When I took it out to test it was quieter (exhaust noise) and idled better but didn't have the power of a 3.8 SC. I drove it 60 miles on the highway and it used about a third of a tank of gas! You could almost see the gage dropping. When I sat at idle for any length of time the temp. rose pretty high but not to the red.

The mechanic is out of ideas. His computer shows no problems.

The supercharger has been rattling for quite a while and I have learned from the forum that it is probably the sc coupler.

Could the coupler/supercharger be responsible for the power, mileage and overheating problem?

What else?

Thanks for your comments. This forum is a GREAT resource!

Ray.

Based on your description of symptoms I believe the problem is not with your engine at all but with the transmission. You stated that the engine would rev but you wouldn't go anywhere. This is a classic sign of a transmission going bad. The other item is the fuel mileage. If the transmission is slipping the engine must work harder to get you to the same place and uses more fuel. If you have 155K on the transmission I would expect it is time for a replacement. You can put in a used one or have that one rebuilt. You can even find them on e-bay. Just make sure you use the HD version for the supercharged engine.

Also, welcome to the forum!!!

Thanks for your speedy reply.

Your diagnosis certainly does click. Especially since the perform shift/normal shift switches haven't worked for a long time. The performance/touring ride also has been malfunctioning so I thought it was computer module-electrical more than anything serious.

Do you think the overheating while standing fits with the transmission diagnosis? Also, could it be as simple ($$$) as needing a new torque converter?

Thanks again.

Ray.

A slipping transmission can certainly cause excessive heat build-up and since the engine has to work harder then the engine could overheat as a result. But I would not suspect this while standing still. I would look more toward the fans not coming on at the appropriate time or not working at all. As long as you are moving the air flows through the radiator and keeps everything cool. Could be a bad relay or a bad fan assembly.

The torque convertor could certainly be the problem but I would think that you will find you will need a complete rebuild or replacement of the transmission. I base this on the fact that the car runs ok but it will not climb hills in the higher gears. A torque convertor is only about $300 but since you have to drop the transmission that will be about $650 to replace it. You can find a used transmission for a lot less and since you already have the tranny out for the torque convertor then it is logical to replace it as well and with 155K you got your money's worth out of that one.

Do a search on car-part.com for local wrecking yards in your area to see what kind of price you can get. I found several in the FL, GA, AL area for less than $600. One only had 61K miles.

Thanks again for your advice and helpful suggestions.

Ray.