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post #1 of (permalink) Old 08-04-2001, 01:57 PM
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TH400&NP208 Fluid Question

With a Turbo 400 and NP208 is the fluid a shared entity? I know that they both use ATF. BUT is it the same ATF. I.E. if my trans case is leaking will it show on the transmission dip stick?

Thanks,
Shane Bevel

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post #2 of (permalink) Old 08-04-2001, 02:33 PM
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Re: TH400&NP208 Fluid Question

I'm not sure about the TH400/NP208, but I do know firsthand the fluid IS a shared entity on the later model trucks. We had an Ethanol powered 99 Silverado with a Vortech on it..long story short, it ate 2nd gear in the trans. When we tore down the 4L60/NP246(?) the same nasty, burnt tranny fluid was also in the transfer case.

If you don't have an answer in a day or two, I'll ask my buddy with an 87 'Burban.

post #3 of (permalink) Old 08-04-2001, 03:57 PM
 
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Re: TH400&NP208 Fluid Question

Too late....I have an '87 Suburban w/ TH400 and NP208. I just recently installed a used T-case. The fliud is not shared. There is a seal on the input shaft of the T-case and a gasket is used between the two. I used RTV Black when I put the used one in because I didn't know about the gasket and once I had it apart, I had no way to get to a parts store anyway. I did do a fluid change on both while I was at it. I put a 50/50 mix of ATF and Lucas oil stabilizer in the T-case. It works good.


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post #4 of (permalink) Old 08-04-2001, 04:08 PM
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Re: TH400&NP208 Fluid Question

Thanks for the help!

Damnit man!

Anybody replaced the seal on the front output shaft of the 208 trans case? Mine is leaking.

Hoping I could buy some time by just toping it off, but hell If I am getting under there to top off the transcase every week!!

Thanks,
Shane Bevel

The Roanoke (VA) Times Photo Department
1986 3/4 ton 4x4 'Burban 5.7L Vortec Powered
2000 Specialized Rockhopper FSR
[img] http://people.unt.edu/~shaneb/front.jpg [/img]
post #5 of (permalink) Old 08-04-2001, 05:44 PM
 
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Re: TH400&NP208 Fluid Question

Not fer nuthin' but if the front seal is leaking, it's leaking into your trans. Does the dipstick show it overfilled? Too much fluid is just as bad as not enough in an automatic.
It's pretty easy to do. I didn't even use a floor jack. I took it out by hand and layed it on my chest. The seal is just like the output shaft seal or a grease seal on a front hub. Pry it out with a screwdriver and tap the new one in with a small hammer. Prolly less than $5 plus fluid.

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post #6 of (permalink) Old 08-04-2001, 06:57 PM
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Re: TH400&NP208 Fluid Question

Front output to the front. axle, not to the transmission. But thanks anyways.

Now that I look at it it looks as though it might be leaking from the pan somewhere and just being blown back onto the t-case.

Thanks,
Shane Bevel

The Roanoke (VA) Times Photo Department
1986 3/4 ton 4x4 'Burban 5.7L Vortec Powered
2000 Specialized Rockhopper FSR
[img] http://people.unt.edu/~shaneb/front.jpg [/img]
post #7 of (permalink) Old 08-04-2001, 07:08 PM
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Re: TH400&NP208 Fluid Question

Mine was leaking there also. Try to tighten the nut that holds the yoke to the case. mine was so loose i could turn it by hand.

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post #8 of (permalink) Old 08-06-2001, 08:40 AM
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Re: TH400&NP208 Fluid Question

It is very common for the rear seal to leak on the automatic transmissions, and the fluid will leak into the adapter, and then into the transfer case. This is why GM switched to using ATF in the later NP205s behind automatics. Better to have all ATF than a mixture of ATF and gear oil. This will also overfill the transfer case, causing it to leak.

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