Drained all fluids last night... fun surprises... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

redz 1970 K5 · 09-01-2004, 02:25 PM

No wonder why almost every seal of the transfer case is wet and/or leaking. Those seals of the NP205 were never meant to handle the thin ATF that was found inside.

So, no use in crying, I'll just let it drain and put in 80W90. I am thinking the leaks will probably slow down a bit too. Since I will not be redoing the seals right now, that is all I can hope for. I guess the ATF was clean.. It has been in the truck since I originally had it in 2002 and just repurchased it a few months back. So, 2+ years with ATF (Probably Dexron III) and a couple thousand miles. I am not too worried, just glad I finally drained it.

Rear diff fluid was relatively clean. The rear was a standard open, contradictory to the posi I was told it had (Never bothered to check previously) Front was extremely cloudy and wrought with fine metal particles. At least it does have the 4.56's as advertised.

TH350 was ok... Some particles in the strainer, say about 30% of the strainer surface had small particles. The tranny was rebuilt before I bought it, and they didn't do a fluid change again (or since).

Took all of the covers to the machine shop to dip, I'm too lazy to clean em!

So, what do you guys think? Trick shift or just Dexron III for the AT? Figure since I am not doing a full flush, I will just stick with Dexron for now.

cheyenne10 · 09-01-2004, 02:54 PM

Make sure your tranfercase to transmisson adapter seals are not leaking. This will allow transmission fluid to pass through to transfercase (then T-case has Trans fluid in it). Mine overfilled and leaked bad. Had seals replaced and works well now.

redz 1970 K5 · 09-01-2004, 02:55 PM

Will do, thanks!

2wdBlazer · 09-01-2004, 04:08 PM

Man. 4.56's on 33's. You gotta have some high RPM's!

redz 1970 K5 · 09-01-2004, 04:21 PM

I just take it easy... Using an online calculator, w/ 4.56's, 33's and the 1:1 ratio of the 3rd gear of the TH350, at 65MPH I am at 3,000RPM's. It's a little high, but well within the operational range of the 350.

It's all worth it off of the line though. WOW is all I can say.

redz 1970 K5 · 09-01-2004, 04:29 PM

Oh, just double checked. The 205 Xfer case final drive in high is 1:1 as well, so the RPM's are truly around 3,000.

That is only 350RPM's higher then a truck with 3.73's and 31's.

Guess it's time for the 700R4... Lower 1st and OD.

Dean · 09-02-2004, 06:40 AM

I bet you have a leak between the trans and transfer case....been there done that.

redz 1970 K5 · 09-02-2004, 10:28 AM

It wasn't a mixture of gear oil and ATF; it was 100% atf. Guess I am not convinced there is a leak there. I will find out tonight.

687980chevy · 09-03-2004, 03:24 AM

I remember in 1980 GM got the brite idea to put ATF in their transfer cases&4spds.>better gas mileage.You could have a 80 model T-case.My 79 had 90w.The 1980's also had a slip shaft yoke on the back of the transfer case(like a th350). My 79 has the yoke bolted to the case and a slip shaft driveshaft(np205).

bouncytruck · 09-03-2004, 11:54 AM

I've heard of guys running ATF in their 205's without any problem, but I'd run the proper stuff.

redz 1970 K5 · 09-03-2004, 12:52 PM

Quote:

Originally Posted by 687980chevy

I remember in 1980 GM got the brite idea to put ATF in their transfer cases&4spds.>better gas mileage.You could have a 80 model T-case.My 79 had 90w.The 1980's also had a slip shaft yoke on the back of the transfer case(like a th350). My 79 has the yoke bolted to the case and a slip shaft driveshaft(np205).

It's the original transfer case from good old 1971...

I here ya Bouncy... I am 100% that the ATF has not caused any problems. To me, it's a question of seals and leaks. ATF has found it's way out of almost all of the xfer case seals. Now, I bet the gear oil will slow down the leaks considerably. Not that it will make the seals any better, but just due to a much thicker viscosity, it will not leak as much. If the transfer case was bone dry, I would consider ATF again.

**Stocker** · 09-12-2004, 06:58 PM

Quote:

Originally Posted by 687980chevy

I remember in 1980 GM got the brite idea to put ATF in their transfer cases >better gas mileage.

I've heard this also, and not just GM. Though it appears quite thin, ATF is supposed to have excellent lubricating qualities, and should cause no problems in t-cases - or so I've heard.

Grim Reaper · 09-13-2004, 04:15 PM

Up north a lot of people will run ATF in below zero climates because the gear oil is like molases. I think the the 205's in the 80's were speced for ATF. Might make a little more chatter driving down the road but should be fine. 203 ran motor oil and pople did the same and ran ATF. To be hones it will stay cleaner with a detergent ATF.

09-01-2004, 02:25 PM	#1
redz 1970 K5 OBS guy Join Date: Jun 2004 Location: SoCal Posts: 1,060	Drained all fluids last night... fun surprises... No wonder why almost every seal of the transfer case is wet and/or leaking. Those seals of the NP205 were never meant to handle the thin ATF that was found inside. So, no use in crying, I'll just let it drain and put in 80W90. I am thinking the leaks will probably slow down a bit too. Since I will not be redoing the seals right now, that is all I can hope for. I guess the ATF was clean.. It has been in the truck since I originally had it in 2002 and just repurchased it a few months back. So, 2+ years with ATF (Probably Dexron III) and a couple thousand miles. I am not too worried, just glad I finally drained it. Rear diff fluid was relatively clean. The rear was a standard open, contradictory to the posi I was told it had (Never bothered to check previously) Front was extremely cloudy and wrought with fine metal particles. At least it does have the 4.56's as advertised. TH350 was ok... Some particles in the strainer, say about 30% of the strainer surface had small particles. The tranny was rebuilt before I bought it, and they didn't do a fluid change again (or since). Took all of the covers to the machine shop to dip, I'm too lazy to clean em! So, what do you guys think? Trick shift or just Dexron III for the AT? Figure since I am not doing a full flush, I will just stick with Dexron for now. __________________ 88 Suburban Goodies- Alpine, Auto Meter, BDS, Bilstein, B&M, BFG, Borgeson, Bushwhacker, Cowl hood, Flowmaster, Genuine Gear, Holley, Infinity, JVC, K&N, MB Wheels, MSD, Pioneer, Skyjacker, Sony, Thorley, Walker + more

09-01-2004, 02:54 PM	#2
cheyenne10 Senior Member Join Date: Apr 2000 Location: Oregon Posts: 2,512	seals leak Make sure your tranfercase to transmisson adapter seals are not leaking. This will allow transmission fluid to pass through to transfercase (then T-case has Trans fluid in it). Mine overfilled and leaked bad. Had seals replaced and works well now. __________________ Bob

09-01-2004, 02:55 PM	#3
redz 1970 K5 OBS guy Join Date: Jun 2004 Location: SoCal Posts: 1,060	Will do, thanks! __________________ 88 Suburban Goodies- Alpine, Auto Meter, BDS, Bilstein, B&M, BFG, Borgeson, Bushwhacker, Cowl hood, Flowmaster, Genuine Gear, Holley, Infinity, JVC, K&N, MB Wheels, MSD, Pioneer, Skyjacker, Sony, Thorley, Walker + more

09-01-2004, 04:08 PM	#4
2wdBlazer The Blazer King Join Date: Sep 2000 Location: Valrico, Fl (Tampa) Posts: 1,212	Man. 4.56's on 33's. You gotta have some high RPM's! __________________ 72 2wd Blazer. Its the superbichinest, megacoolinest, superflowinest.

09-01-2004, 04:21 PM	#5
redz 1970 K5 OBS guy Join Date: Jun 2004 Location: SoCal Posts: 1,060	I just take it easy... Using an online calculator, w/ 4.56's, 33's and the 1:1 ratio of the 3rd gear of the TH350, at 65MPH I am at 3,000RPM's. It's a little high, but well within the operational range of the 350. It's all worth it off of the line though. WOW is all I can say. __________________ 88 Suburban Goodies- Alpine, Auto Meter, BDS, Bilstein, B&M, BFG, Borgeson, Bushwhacker, Cowl hood, Flowmaster, Genuine Gear, Holley, Infinity, JVC, K&N, MB Wheels, MSD, Pioneer, Skyjacker, Sony, Thorley, Walker + more

09-01-2004, 04:29 PM	#6
redz 1970 K5 OBS guy Join Date: Jun 2004 Location: SoCal Posts: 1,060	Oh, just double checked. The 205 Xfer case final drive in high is 1:1 as well, so the RPM's are truly around 3,000. That is only 350RPM's higher then a truck with 3.73's and 31's. Guess it's time for the 700R4... Lower 1st and OD. __________________ 88 Suburban Goodies- Alpine, Auto Meter, BDS, Bilstein, B&M, BFG, Borgeson, Bushwhacker, Cowl hood, Flowmaster, Genuine Gear, Holley, Infinity, JVC, K&N, MB Wheels, MSD, Pioneer, Skyjacker, Sony, Thorley, Walker + more Last edited by redz 1970 K5; 09-01-2004 at 04:33 PM.

09-02-2004, 06:40 AM	#7
Dean Senior Member Join Date: Jan 2000 Location: Cincinnati, Ohio Posts: 1,492	I bet you have a leak between the trans and transfer case....been there done that.

09-02-2004, 10:28 AM	#8
redz 1970 K5 OBS guy Join Date: Jun 2004 Location: SoCal Posts: 1,060	It wasn't a mixture of gear oil and ATF; it was 100% atf. Guess I am not convinced there is a leak there. I will find out tonight. __________________ 88 Suburban Goodies- Alpine, Auto Meter, BDS, Bilstein, B&M, BFG, Borgeson, Bushwhacker, Cowl hood, Flowmaster, Genuine Gear, Holley, Infinity, JVC, K&N, MB Wheels, MSD, Pioneer, Skyjacker, Sony, Thorley, Walker + more

09-03-2004, 03:24 AM	#9
687980chevy Registered User Join Date: Feb 2004 Location: Hilly Southern Indiana! Posts: 201	I remember in 1980 GM got the brite idea to put ATF in their transfer cases&4spds.>better gas mileage.You could have a 80 model T-case.My 79 had 90w.The 1980's also had a slip shaft yoke on the back of the transfer case(like a th350). My 79 has the yoke bolted to the case and a slip shaft driveshaft(np205). __________________ 68 K-10,79 K-10,80 C-30 57 chevy convertible 79 Z28

09-03-2004, 11:54 AM	#10
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	I've heard of guys running ATF in their 205's without any problem, but I'd run the proper stuff. __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

09-13-2004, 04:15 PM	#13
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Up north a lot of people will run ATF in below zero climates because the gear oil is like molases. I think the the 205's in the 80's were speced for ATF. Might make a little more chatter driving down the road but should be fine. 203 ran motor oil and pople did the same and ran ATF. To be hones it will stay cleaner with a detergent ATF. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project



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