15th Nov 2009, 03:16

How can you tell that the exhaust leak is a "slow leak"?

23rd Apr 2010, 08:41

Original poster of the review here. To the above commenter, a slow leak for example is one that you know is there but is hard to find. Mine has a leaking A.I.R. emissions tube and valve on the passenger side of the motor. If you sit long enough, engine running while parked, the inside of the car will start smelling of exhaust. It also makes a tick-tick-tick noise at moderate to hard acceleration, which is easily mistaken by some for sticky valves/lifters or bad/loose main bearings. So that is my "slow exhaust leak."

I did a complete transmission service a couple weeks ago, which included a flush, filter and replacing the Lockup Converter Clutch Solenoid, which was causing my original transmission problems. The old fluid was still clean and fruity smelling.

For anyone with a 200R4 or 700R4 transmission on a GM car or truck, it is a common problem as these vehicles age. The transmission gets tiny fine metal particles floating around after a while, no matter how well cared for it it. Old gunky dirty fluid only makes matters worse. It causes the solenoid to clog and malfunction, locking up the torque converter at low speeds in 2nd gear, which causes very sluggish acceleration. It mimic an early shift when accelerating, and causes a big drop in highway fuel economy. When I fixed mine my highway fuel economy jumped from 18/19 to about 21-24.

And when coming to a stop it will stay locked and try to hold second gear, usually making the car stall. This simple fix has caused many people to do rebuilds when not needed, or send a perfectly good transmission to the junkyard. After a rebuild the solenoid will still malfunction if it isn't replaced.

These transmissions weren't built the greatest from the factory, giving them a bad reputation. There are, however, excellent rebuild kits for them. If done correctly and by a professional, the 200R4 can be made to handle as much torque as the older 350/375/400 models. Some people have even put them behind big blocks and they hold up well if built properly. They are actually becoming very popular as racing transmissions.

The 350/400 models are still a little more durable and less complex, but it's nice to have an overdrive 4th gear in an old muscle car. It's a lot more pleasant to sip fuel at 70 MPH at a low RPM than have your engine screaming at 3000 RPM's with a 3 speed automatic.

20th Dec 2012, 23:18

I have an 82 Park Ave and an 85 LeSabre.

Except for the PA's 350 4bbl, they are twins.

19th May 2014, 06:51

The 1982 Park Avenue did not come available with a 350 4-barrel

7th Jun 2015, 11:25

I have an 85 LeSabre that had the same problem as described with the transmission. After several garages told me it needed overhauled, a young guy at the 4th place disconnected an economize sensor... and the problem went away.

8th Jun 2015, 02:52

In reply to 7th June 2015 11:25. There was no economize sensor in that transmission. That shop just disconnected the torque converter solenoid, which permanently disabled the torque converter. They rigged your transmission to pacify you. The proper fix was to replace the torque converter solenoid, which was a common failure on the 200-4R.

9th Jun 2015, 16:31

I once had the same issue with the THM200-4R on my 1988 Cadillac Brougham. It was indeed the TCC solenoid. I wouldn't even bother going to a garage, as it's an easy fix. The job is messy though, as you have to drop the pan.

10th Jun 2015, 02:21

If you race or want performance, I like a M-21 4 speed even better than a Tremec. I don't do expressway driving in my muscle cars. I like the torque and power driving to a cruise night. I am bored to death with automatics unless it's a luxury car.