Chevy Express Transmission

occhionero

I have a 1999 chevy express 1500 conversion van. When the engine and transmission are hot due to long idles and hot outside temps the transmission shifts hard and jerking when in drive. If I shut off the engine and wait for 5 minutes and restart the problem goes away.

1320jon

When the engine computer sences high temps in the transmission it is commanded to shift hard to save things. The harder it shifts the less wear on internal "soft" parts like clutches and bands. If its happening , you have a problem. I d look at the trans cooler, trans cooler lines, fuild, filter, etc....

On a side note, I do not belive in oils at all, but I only use amsoil in transmissions I like, and the operating temp of amsoil is much broader and higher then the cheaper dextron 3 fluids available.

Most good scan tools, "scanners" can plug into your aldl connector under the dash and read the actual trans temp (in some pcm's) and see line pressures in the trans. A good trans shop should be able to do it.

If the engine is also running hot, that is causing the trans to heat up. The trans is cooled by engine coolant in a seperate cooler in the radiator. If your engine is running hot, look at the pump, the thermostate (low temp thermostats are available), and the fan, radiator blockage.

tireman9

I have a Class C Motorhome on an Express 3500 chassis. Am really pleased so far. I am looking for an aftermarket pan for the auto trans but the one I got from Summit was too deep to clear the exhaust cross pipe that runs under the back couple inches of the Trans pan.
Does anyone make a pan that is deeper but only in the front half?

1320jon

Derale makes some pretty cool pans. They put tubes in the bottom, with a fin inthe tube to "hopefully" get air flow and help cooling. They ussually sell a standard pan and a deep pan. The standard pan I think is alittle deeper then oem due to the addition of the tubes. Might be worth investigating.

newsie23

Use the 'new' Dextron vi fluid - it is backward compatible, and will soon be the 'only' Dextron. Consider a friction modifier. I use Tufoil. I believe the main reason they are not 'recommended' is they would fail the emission, warmup test. When I used it the first time in a high mileage vehicle, I had to block the radiator to get enough heat from the heater, at cold temperatures.

tireman9

The deep pan will not work as it only leaves about 1/4" clearance to the exhaust pipe that runs under the rear of the pan. Derale only makes a deep 4" pan for the 4L80L.