Chevy Express Transmission Issues

[DavidInWilmNC]

I use my van ('98 Chevy Express 3500 with 4L80E transmission) for towing our boat, but only for short distances. This weekend, I had it on a 700 mile trip (not towing). When I reached my destination, I noticed 'mess' on the rear doors and windows and figured it was just road grime or something similar. I stopped for gas on the way home and noticed more. This time I could see it was red fluid, so I checked the transmission. Sure enough, it was low - barely on the dipstick. I looked under the van and it was covered with transmission fluid. I didn't see any obvious leaks. The transmission shifted flawlessly, as always. Has anybody had any experience with this sort of leak? I know this transmission was used on many Chevy and GMC 2500 and 3500 trucks and vans and is supposed to be one of the best that GM built. Thanks for any input or suggestions!

 

[Rickairmedic]

Re: Chevy Express Transmission Issues

Dave I dont have any bad experiance but have heard stories . I drive a 2002 Express 1500 and will be watching this thread as it is my tow vehicle for the boat . The only thing I have really heard is not to tow in OD but to drop it down to third for towing otherwise I will be watching to see what others say.


Rick

 

[180shabah]

Re: Chevy Express Transmission Issues

Rick - The 1/2ton vans have a different transmission.

David - best place to start is to clean everything and then run it to see where it is leaking from. You've got two cooling lines(from trans to cooler and back), a front seal and a rear seal. I would check each of those. Could be pan gasket or plug(if equiped) but the quantity you describe leads me to the others.

 

[jakebrake]

Re: Chevy Express Transmission Issues

does the vehicle have a transmission cooler?

 

[180shabah]

Re: Chevy Express Transmission Issues

does the vehicle have a transmission cooler?

Yes, all the 3/4 and 1 tons have them. Can't speak for the 1/2 tons, never had one.

 

[DavidInWilmNC]

Re: Chevy Express Transmission Issues

Rick - The 1/2ton vans have a different transmission.

David - best place to start is to clean everything and then run it to see where it is leaking from. You've got two cooling lines(from trans to cooler and back), a front seal and a rear seal. I would check each of those. Could be pan gasket or plug(if equiped) but the quantity you describe leads me to the others.

In fact, if this van hadn't had the 4L80E, I wouldn't have bought it! That wasn't the only reason, but I have a couple friends who tow with the 'lesser' transmission in 1/2 ton trucks and vans and have had lots of problems.

The two cooling lines look good (dry). There is some fluid at the front of the transmission, which would be unlikely with a rear seal leak. It looks like some might be coming from the front of the transmission. Perhaps removing the torque converter cover would help in locating the leak if it's in the front. I ran the engine with the transmission in neutral and didn't see any fluid leaking. I agree with cleaning everything, driving the van (not on the interstate with high speeds throwing all that fluid around), and checking for leak location again. It's got 155,000 miles on it, so it wouldn't surprise me to find a very small leak or two besides the current big leak. Thanks for the input.

 

[dodgeramsst2003]

Re: Chevy Express Transmission Issues

I had a blazer with the 4l80E in it and when I was towing I would have the same problem. I towed two skis about 350 miles on vacation and noticed the trans fluid on the front of them when I stopped for gas. Go to a chevy forum and do a search. It seems to be a fairly common problem with them. They get hot, trans fluid expands, and then due to design it comes out of the vent tube. I only made the one long trip with mine, made sure the fluid was still full, and drove it another 40,000 miles before I sold it without any problems. I had a friend with an S10 same trans, and he had the same problem.

 

[DavidInWilmNC]

Re: Chevy Express Transmission Issues

I had a blazer with the 4l80E in it and when I was towing I would have the same problem. I towed two skis about 350 miles on vacation and noticed the trans fluid on the front of them when I stopped for gas. Go to a chevy forum and do a search. It seems to be a fairly common problem with them. They get hot, trans fluid expands, and then due to design it comes out of the vent tube. I only made the one long trip with mine, made sure the fluid was still full, and drove it another 40,000 miles before I sold it without any problems. I had a friend with an S10 same trans, and he had the same problem.

Well, I wasn't towing anything this time. The only thing I can think of offhand is a while back, the ECM had problems. It was causing the van's speed to read double. This resulted in a lot of weird behavior including causing the trans to lock up in OD at around 22mph. I shifted it manually to prevent this and drove it around 15 miles total until it was repaired. It seems like there was a very small leak after that started (I checked the speed sensor before replacing the ECM).

 

[allen6634]

Re: Chevy Express Transmission Issues

i din't personaly own a chevy.but i am a professial mechanic.if i was you i would instal aaftermarket trans cooler get the biggest one you can make fit.this will extend the life of all transmissions.

 

[180shabah]

Re: Chevy Express Transmission Issues

Blazer, Envoy, S10, camaro, impala, astro etc all used the 4L70(E), which was just a new version of the old 700R4.

This 1 ton van has the 4L80E - a totaly different beast.

 

[DavidInWilmNC]

Re: Chevy Express Transmission Issues

It's got a pretty decently sized trans. cooler from the factory. It also has what looks like a power steering cooler... it has Hydroboost brakes which use the power steering pump for power brake assist.

Actually, the 'lesser' transmission was the 4L60E. The 4L80E was an electronically controlled TH400 with a lockup torque converter. Jaguar and Isuzu also used this in certain models of their cars / trucks.

My thoughts are to clean it up and see if I can find the leak. If not, I suppose I'll change the fluid and filter and do a lot of positive thinking!

 

[bruceb58]

Re: Chevy Express Transmission Issues

Could you have possibly overfilled the tranny at some point? Getting it hot caused the fluid to expand and blow out the vent possibly.

 

[Mkos1980]

Re: Chevy Express Transmission Issues

You have the dipstick seal on the passenger side up of the tranny up front. Front seal which sometimes goes, servo seal, VSS seal (Vehicle speed sensor) and rear seal. I'm betting on the front seal or dipstick seal.

Theres no such thing as a 4L70E.

 

[briguy2817]

Re: Chevy Express Transmission Issues

You have the dipstick seal on the passenger side up of the tranny up front. Front seal which sometimes goes, servo seal, VSS seal (Vehicle speed sensor) and rear seal. I'm betting on the front seal or dipstick seal.

Theres no such thing as a 4L70E.

I'll second the dipstick tube seal at the case. Very, very common spot for leaks to develop, especially if you've had work done on the engine and the mechanic forced the tube out of the way to get to a component.

Brian

 

[180shabah]

Re: Chevy Express Transmission Issues

Actually, the 'lesser' transmission was the 4L60E.

Theres no such thing as a 4L70E.

"7" was a typo - probably shouldn't do this from work, just too many distractions

 

[DavidInWilmNC]

Re: Chevy Express Transmission Issues

You have the dipstick seal on the passenger side up of the tranny up front. Front seal which sometimes goes, servo seal, VSS seal (Vehicle speed sensor) and rear seal. I'm betting on the front seal or dipstick seal.

Theres no such thing as a 4L70E.

It sounds like the dipstick seal is the thing to check next. The VSS and rear seal areas look ok. I don't think there's much I can do myself with the front seal, and I'll have to look for the servo seal (whatever that is). I'll take it to the (manual) carwash tonight and clean underneath and let it dry for a bit. I'll drive it around the block in a day or two and look for fresh leaks. Thanks for the info!

 

[allen6634]

Re: Chevy Express Transmission Issues

It's got a pretty decently sized trans. cooler from the factory. It also has what looks like a power steering cooler... it has Hydroboost brakes which use the power steering pump for power brake assist.

Actually, the 'lesser' transmission was the 4L60E. The 4L80E was an electronically controlled TH400 with a lockup torque converter. Jaguar and Isuzu also used this in certain models of their cars / trucks.

My thoughts are to clean it up and see if I can find the leak. If not, I suppose I'll change the fluid and filter and do a lot of positive thinking!

one other thought. chevy trucks have a small o ring seal in the tail.the front yoke of the drive shaft should have a small hole in it .(the way chevy made them?) fill your tranny and park it on a hill with the front pointing up.place a clean piece cardboard under the front yoke and see it a leak is there

 

[dolluper]

Re: Chevy Express Transmission Issues

Overheated blew the pump seal ....have to pull the trannie to replace ...the beauty of computers s-crewing up