05 4L80E and other Chevy 3500 Advice

[wander2039]

Just picked up our new addition last night, 05 Chevy 3500 28ft RV. Only has 26k so shouldn't have to do much drive train wise but putting a plan in place. The transmission fluid which should be Dex VI? is still cherry red but the dipstick is fairly dark not sure what caused it. Thinking of pulling the return line and letting it pump out the 4 or 5 quarts and replace, probably every 2 years since I'll put less than 5k a year, using Dex VI (Castrol or Coastal).

Also on the 2 year schedule will use the Mityvac and replace the PS and brake reservoirs, have to find the special PS fluid. Does the rear axle come from the factory with synthetics? Not touching the Dexcool till the 10 year mark or 15. How many grease zerks should I look for? I've heard there's 7 or 8 and plan on using moly grease.

I'll admit normally I stick to Ford's so Chevy's is a bit different fluid wise. Anything I should use or do differently?

 

[redhat]

Nice! I thought GMs took the generic PS fluid that covers GM, Chrysler, Toyota...

Thought only special one was the Honda/Acura?

Yes trans should be Dexron VI. How about cracking the rear diff or do others concur its probably fine?

 

[EricF]

Last I checked, Toyota used Dexron 3, Chrysler's used either ATF 3/4 and some use mineral oil ps fluid, and all GM's use P/S fluid.

There's nothing special about the fluid for your chevy.

 

[229]

Touch the Dexcool now. Have you checked the price of the waterpump?

 

[SteveSRT8]

I'd flush and install new Dexcool just because you don't know the history. Waterpumps on our 3500 6.0 service vans last a minimum of 150-200k miles and we NEVER touch the cooling system until component failure on the advice of a GM G team engineer who consults with our aftermarket upfitter.

We like Dex VI here and use the Castrol blended product. We used to have all 4L80E's, it's a great slushbox that can last forever. Check its operating temp with an infrared thermometer the pan should not be over 200-220 or it needs more cooling. I have one with half a MILLION miles up for sale right now! Still runs and drives great.

 

[wander2039]

Don't know about any others but typically in Ford's I use the same Mercon V in the PS as the trans. Looks like GM calls for PS fluid which may be the same as others. Forgot to mention I'll probably put a couple bottles of Lubeguard Red in the trans.

I'm surprised by the Dexcool comments! I know it's frowned upon but it's still a clear light red color looks almost new. Guess I change it nothing looks difficult to get to.

 

[dnewton3]

Are you 100% sure that the transmission in your RV is a 4L80E?

If you have a 8.1L Vortec or Dmax engine, then you probably have an Allison 1000 series transmission. The Allison in 2005 was a 5-spd; they did not introduce the 6-spd Ally until 2006 MY. If you can count the gear shifts, and be 100% certain of your transmission model, that would be very important in this topic! Do NOT put DEX VI in a 2005 Allison; there are seal compatibility issues that do no react well over time with the mandated DEX VI chem package. Allison has established a serial number cut-off that shows where DEX VI is acceptable for use in 2006 models. Being a 2005 vehicle, if you have an Allison, there is no way DEX VI would be a good idea!


As long as you're confident that you've got a 4L80E, then DEX VI will be fine. But the only way you'd have that transmission is if you had a 6.0L gasser Vortec engine, IIRC.

Regardless of the transmission, if the RV is a 2005 model, that vehicle (I presume it's a cab-n-chassis) never came with DEX VI from the factory, because DEX VI was not introduced until 2006, in varying stages of the GM vehicle line throughout the year. I suspect you've got DEX III(h) in there.

In short:
- If you have a 4L80E, then DEX VI will work just fine and would be a good choice. Or any DEX/Merc product would also be OK.
- If you have an Allison, stick with a DEX3/Merc product; many good ones to choose from. Stay away from DEX VI for your 2005 model year.

 

[wander2039]

Yes it's the 4L80E. I could be wrong but I think the 8.1 is only used in the workhorse chassis (Kodiak, 4500). So it came with DEX III that probably explains the dark varnish.

 

[dnewton3]

That being the case, a 4L80E would be fine with DEX VI. A good choice as it has excellent oxidation resistence and vis retention. Easily found in many brands, including a licensed product in Walmart ST blue; excellent buy for the money.

 

[wander2039]

Drove it around today to get licensed etc. It appears that it's weeping transmission fluid in the front and back on the transmission. Nothing major just looks like from setting too much and not being used. Would you still use Dex VI or should I put in a HM? I knew it looked like it was leaking at but 26k should be correctable.

 

[229]

quote Jasper Remanufacturers: " NOTE: VEHICLES PRODUCED AFTER APRIL 1, 2005 MUST USE DEXRON VI FLUID
OR WARRANTY WILL BE VOID."

 

[SteveSRT8]

Originally Posted By: Eric Smith
Drove it around today to get licensed etc. It appears that it's weeping transmission fluid in the front and back on the transmission. Nothing major just looks like from setting too much and not being used. Would you still use Dex VI or should I put in a HM? I knew it looked like it was leaking at but 26k should be correctable.


The rear seal is relatively easy to replace. You can also try an additive/HM fluid but you must be very cautious as the trans is sensitive to anything not OEM.

A few miles with new fluid may swell it back up and there won't be an issue. The front seal is likely to be more problematic.

 

[wander2039]

Build date is 2004 a bit before that. I was thinking Maxlife Dex/Merc. Funny you mention it the front seal is weeping also. I was hoping after a bit of driving it would clear up. Putting 500 miles on it next week so time will tell.

 

[wander2039]

Originally Posted By: SteveSRT8
Originally Posted By: Eric Smith
Drove it around today to get licensed etc. It appears that it's weeping transmission fluid in the front and back on the transmission. Nothing major just looks like from setting too much and not being used. Would you still use Dex VI or should I put in a HM? I knew it looked like it was leaking at but 26k should be correctable.


The rear seal is relatively easy to replace. You can also try an additive/HM fluid but you must be very cautious as the trans is sensitive to anything not OEM.

A few miles with new fluid may swell it back up and there won't be an issue. The front seal is likely to be more problematic.


Just a update. The rear seal is leaking rather badly.. bad enough to throw fluid on the diff. Going to cut the return hose right under the radiator. The line goes from metal to rubber to metal right in that area. Figured I'd drain out 4 quarts and replace with Maxlife. Adding a magnetic filter right there. See what it looks like next spring. I guess a bit of rust proofing till then. Doesn't look bad to replace the front isn't leaking that bad.

The PS was whining rather loudly the first 200 or 300 miles. Siphoned out twice replaced with Mercon V since that's all I had. Quiet as a can be now. Wonder how it'll hold up long term.

Going to dump the radiator before the next trip. It runs 195 on the highway but any slow climbs jumps up to 225. There is a bit of crud floating on top - nothing like my parents 00 Impala though. Maybe normal not used to the Chevy gauges.

Another hurdle is the rear diff. Want to put synthetic in it, what grade? Also need to replace the cover the only rust on the chassis. One of the owner I think backed a boat in salt water regularly.

I knew better than to buy a RV with low mileage!

 

[MolaKule]

Quote:
The rear seal is leaking rather badly..


If it is the tailshaft seal it is not difficult to replace it.

Anytime you buy a used vehicle, you have to catch up with the maintenance not done by the previous owner.

I would use a 75W110 or a 75W140 differential lube.