Transmission fluid loss

[medion42]

I have a 96 blazer 4X4 with a automatic transmission. I can not find any leaks and no fluid on the ground but I seem to lose transmission fluid. Is there any thing I can check for this problem. I any vacum lines going to it ? Or could it be burning it up in the exaust? Thank Medion42

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[4lowlife]

It could be getting introduced into the radiator if there is a leak. Does the tranny dipstick look foamy when you pull it out? Keep adding fluid if it needs it.

Look into the radiator for any discoloration of the coolant.

[medion42]

Thanks did check radaitor but does not seem to have tranmission fluid . Tested it and was 25 below. Is there any way that the fluid could be getting in to the engine? Thanks Dan

[swartlkk]

How much fluid have you lost from the transmission? 1qt, 2qts, a gallon??? And over what time frame will it lose this amount?

Hanr3 has mentioned that if the rear seal goes bad on the transmission (between the transmission and the transfer case, that you could be filling up the transfer case with additional ATF. If you pull the fill plug off of the transfer case and fluid pours out, then you've got a rear seal leaking on the transmission.

Only other places for ATF to go are on the ground via an external seal/gasket/hose leak or into the radiator as Scott (4lowlife) has stated already.

[medion42]

Thanks for the input. When I bought the blazer it had 117m on it . I never check it until the check engine light went on code said transmission slip. At that time which was this summer it took 3 qts to bring it up. It has 119,700 now and it took about little over 1qt this time. I think about 1500 miles since the last time I added oil. Will check the level in transfer case. Thanks for all the help Dan

[medion42]

OK checked the transfercase and it was over full . Is their a good additive that might help the seal. Dan

[4lowlife]

OK checked the transfercase and it was over full . Is their a good additive that might help the seal. Dan

(in reply to medion42)

Nope. you need to drain the T case. (Get two quarts of t case fluid from the dealer first!. It's about $6.00 a qt.) The transfer case must be removed. Then you will have to replace the rear tranny seal.

Might as well drop the tranny oil pan and add a drain plug kit. Reinstall the pan and fill it up wil the correct atf. Start by adding 4 qts, to the tranny dipstick tube,then replenish as necessary.

[medion42]

Thank you all for all the help I will do what you have said. Dan

[swartlkk]

I do not think there is any difference between this Automatic Transfer Case Fluid and normal Auto Transmission Fluid... Please if someone else knows, let us know if there is a difference.

*EDIT* - Sorta found an answer atleast for my t-case (NVG 136)...

If you have the AWD (RPO NP4) option (Safari/Astro/Bravada), then you need the Auto-Trak II fluid (blue stuff) P/N 12378508 (Canadian P/N 10953626). Should be right around $6 at the dealership as Scott stated.

I still think that in the non-AWD t-case, that normal Dextron III fluid is fine. The difference between the AWD t-case (NVG 136) and the other two (NVG 233 & NVG 236) is that the AWD has a viscous coupling between the front and rear axles where the other two are direct coupled.

**EDIT** - Here's some more info:

GM switched to improved light-blue Autotrak II active-transfer case fluid (PN 12378508) on all 4wd 1998-2000 pickups and SUVs and 1999-2000 Cadillac Escalades, Olds Bravadas and Chevy Astros/GMC Safaris. This fluid replaces the old red version, which can be topped off with the blue. Technical Service Bulletin (TSB) 99-04-21-006.

[medion42]

OK fellows the seal was real bad. Now I notice that vacum switch had atf in the hose. What is its purpose and will that stop when the transfer case is at normal level? Thanks Dan