Weird oil in np205

[JayDubBlazer]

Ive been hearing a weird low whine when i let off my accerator. I checked the oil level and first found it to be way over filled and second i found the below oil. It has the viscosity of 10 weight, has a slight pinkish hue, and smells vaguely like 80w90. Thoughts? Im guessing it was filled with trans fluid after draining gear oil. Also would having it too full cause it to whine? The whining is in 2hi havent tried 4hi or low yet.

Thanks

[vectorit]

Looks like ATF?
I've heard people like to use ATF in manual transmissions, but personally I wouldn't put that kind of oil in my MT.

Or someone could have used Motul MC oil?
I know guys that run Motul in their HD transmission, and it looks and fits your description of what you have.

[JayDubBlazer]

Sorry I meant it was in my transfer case.
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[vectorit]

Do you have an automatic trans in that truck?

[JayDubBlazer]

700r4
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[vectorit]

I'd then be concerned that your ATF from the transmission is getting into your Tcase.

[GASoline71]

Yup... Unless it's a divorced unit, I'd check to make sure the tranny isn't leaking into the T-case.

Later model T-cases use ATF in them.

But the ol' NP205 is a gear oil only T-case as far as I know. I've had 3 of them in different rigs, and they all used 80w90wt gear oil.

Gary

[JayDubBlazer]

Does this mean I have a bad seal in the transfer case or the transmission? The transmission has less than 500 miles on it.
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[GASoline71]

Are they mated together? With an adapter? The 700R4 and the 205 never came mounted together in a factory rig.

Gary

[JayDubBlazer]

They are mated together, I got the trans from bowtie. Ill get some pictures when I get home.
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[GASoline71]

Just an observation... the NP205 is a cast iron monstrosity that is bomb proof. There is no chain inside... it's all gear driven. It has a tendency to buck a little in low gear and sounds like a gravel crusher. One of the main reasons cats building mud trucks and pullers use the NP205's is for their strength and durability.

Nowthen... mate that heavy cast iron T-case to a light duty 700R4, and it might be a little much for that tranny. I don't know of any apllications where the NP205 came behind an auto tranny. GM used the NP203 and NP208 behind the slush boxes of the day. The NP205 found itself behind the big granny low 4 speeds. Through my experiences with GM truck T-cases... that's what I have seen and used.

I would hate to see a crack in the tranny where it is mated to the NP205 and letting ATF in the T-case.

Gary

[franken]

Originally Posted by GASoline71

It has a tendency to buck a little in low gear and sounds like a gravel crusher.

These are features...

Originally Posted by GASoline71

I don't know of any apllications where the NP205 came behind an auto tranny. GM used the NP203 and NP208 behind the slush boxes of the day. The NP205 found itself behind the big granny low 4 speeds.

I seem to recall the 205 started in 69 and was used behind the TH350, and TH400.

The 203 was used for a while when the thinking that full time 4WD was a good idea. Those trucks ate front driveshafts and gas like crazy.

The 208 came after the 203 but 1 tons of the same era used the 205 behind the TH400.

Searching for a round pattern 32 spline 205 and a 32 spline 203 teaches you stuff

[willett]

Originally Posted by GASoline71

Just an observation... the NP205 is a cast iron monstrosity that is bomb proof. There is no chain inside... it's all gear driven. It has a tendency to buck a little in low gear and sounds like a gravel crusher. One of the main reasons cats building mud trucks and pullers use the NP205's is for their strength and durability.

Nowthen... mate that heavy cast iron T-case to a light duty 700R4, and it might be a little much for that tranny. I don't know of any apllications where the NP205 came behind an auto tranny. GM used the NP203 and NP208 behind the slush boxes of the day. The NP205 found itself behind the big granny low 4 speeds. Through my experiences with GM truck T-cases... that's what I have seen and used.

I would hate to see a crack in the tranny where it is mated to the NP205 and letting ATF in the T-case.

Gary

205's came behind th400's on 80's 1 tons
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[Mr. 250r]

Its pretty well known about the whole atf vs gear oil.... the new 89 i just bought has atf which im leaving in it because it calls for that, me personally if i ran an auto i would put atf in it and if i ran a manual like in my 87 i would put whatever i could find faster in it which would be gear oil. I have an 85 book that ill look in and see what it calls for but i think they switched it to atf around 88

just google search np205 atf and you will find endless amounts knowledge lol

[turp mcspray]

There are seals in the trans to transfer case adapter. Very common to leak, especially after being disturbed, such as installing a new trans. If you have tranny fluid in your 205, and it was over full, I would bet money they are bad.

[Stocker]

Originally Posted by GASoline71

I don't know of any apllications where the NP205 came behind an auto tranny.

My '72 has a TH350 and NP205, factory stock.

Originally Posted by turp mcspray

If you have tranny fluid in your 205, and it was over full, I would bet money they are bad.

I agree..... mine developed bad seals and I had to occasionally add ATF to the trans and drain the excess from the t-case.

[vectorit]

Check out this thread, and the latest few posts to it.
They are discussing the seals you are asking about.

http://67-72chevytrucks.com/vboard/s...84#post6157184

[JayDubBlazer]

Does anyone have some exploded views ofmthe seals? I very well could have missed these seals when installing the transmission.

[FRENCHBLUE72]

Jaydub I have my case and adapter out on the bench right now.. Let me know what if any pictures you may need of the seals as I just replaced mine..

part number for the seals is national 471424

[V30 mongo]

Just for your information: I have a 1988 V30 CC. I bought it new in 88. The NP205 transfer case was filled with ATF at the factory. The owners manual calls for ATF in all 1988 transfer cases, NP208 and NP205. Why? Maybe it is to make things simpler. But this does not make sence because the SM465 transmission calls for 80W90. Anyway, I replaced the ATF with 80W90 and it has been good now for over 25 years.... And by the way, if your NP205 is equiped with a PTO unit, it is a verry good idea to overfill the transfer case as to allow a oil level to reach inside of the PTO unit. The normal fill level is below the PTO outlet. This is ok if neutral in transfer case is not used, but the neutral position is used, such as with PTO use, it is possible that the PTO unit and the matching transfer case gear will not get enough lubercation.

[JayDubBlazer]

Originally Posted by FRENCHBLUE72

Jaydub I have my case and adapter out on the bench right now.. Let me know what if any pictures you may need of the seals as I just replaced mine..

part number for the seals is national 471424

French that would be great. Those seals look like they go over the spline on either side. Are there any gaskets or o-rings that go on the flat mating surfaces?

Thanks
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[GASoline71]

Good info here. I learned something new as well. Never new the 205 was ever mated to an auto tranny from the factory. I had 3 trucks with a 205 and they all were granny low 4 speeds.

Gary

[snj8198]

Originally Posted by GASoline71

Good info here. I learned something new as well. Never new the 205 was ever mated to an auto tranny from the factory. I had 3 trucks with a 205 and they all were granny low 4 speeds.

Gary

ya, it's chatted about here and there Gary, I bet you passed over a read and didn't realize. The 205 could be found behind the TH400 with 32 spline, TH350 with 27 spline (this is the critter that is used for a 700r4 swap), and as you know, the SM465 with 10 spline.

The seal in question is a double lipped one but the part number escapes me. I'll remember it a month after you figure it out

[burnin oil]

Originally Posted by GASoline71

Good info here. I learned something new as well. Never new the 205 was ever mated to an auto tranny from the factory. I had 3 trucks with a 205 and they all were granny low 4 speeds.

Gary

Have the factory adapter for a 4spd to 203 transfer case. Nice setup in the winter. That is a rare! 205s with autos were very common in 3/4 and 1 ton trucks.

[GASoline71]

Not to derail too much... but I heered through the interwebs that there was an aluminum case NP205 that came out in some MOPAR trucks in the 70's. Anybody hear of one of those animals?

Gary