NP 205 questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Kiss My SS · 11-29-2002, 02:16 AM

ok, here's the deal. My dad and I went for a test drive in the Jimmy tonight. We tested the four wheel drive for the first time and found that it is not working. It shifts into 4wheel hi and low and you can feel the gear reduction in low. The problem is that the front driveshaft isn't turning. It drives the rear wheels fine in 2 and 4 wheel. As much as I can figure, the front drive gear isn't engaging. Anyway, I figured I would check the level of lube in the t-case. Now there are two plugs on the back of the case. I assumed the top was to check the fluid level and the bottom was to drain the case. So I took out the top one and a lot of fluid came out. That seems strange. If the fluid level was supposed to be higher than the plug, then where do you fill it? I just copied the pictures from the magazine article about the 205 rebuild from and earlier post. Hopefully this might help me figure out what is wrong with my t-case. Also, what type of oil do you use in this case? Some have told me 90 weight gear oil where others have told me 30 weight. The stuff that came out looked more like gear oil. If you have any suggestions about any of these questions, I would be much appreciative. Thanks.

Beast388 · 11-29-2002, 11:01 AM

How did you determine that the front driveshaft wasn't turning?

An easy test is to make sure the hubs are unlocked and the transfer case is in either 4hi and/or 4lo. With engine off and tranny in park, or clutch engaged, climb under the truck and see if the front driveshaft will turn. If it does then you have a problem.

I have always put 80w/90 gear oil in my NP205. That is what all of my book recommend, including the owners manual. And yes, the fluid level should be high enough so that you can stick a finger into the top hole and feel the fluid. Good Luck!

chevypete396 · 11-30-2002, 03:20 AM

Might just have a busted hub. Or it might just be your transfercase linkage.

I am not sure why alot of fluid came out of the top plug. It's not supose to if it was checked / filled on level ground. You are right, that top plug is where you check and fill the t-case. and the bottom one is the drain.

I had a situation once with the 205 and 4 speed on my 68 "making oil". The oil was passing from the tranny through the 4 speed adapter into the 205 causing it to over fill the transfercase and under fill the tranny. It caused the rear seal to blow out of the transfercase at the rear drive shaft on the hiway from the heat. Your Jimmy probobly has an auto tranny so I don't think that the adapter seal could be a problem in your case.

If you do have a standard tranny: On level ground, drian off the excess or fill it to the proper level. Check it in a few days then in a few weeks then months. Keep an eye on it and see if it over fills again.

Like said, use SAE 80/90wt "gear lube" for the 205 T-Case... Pete

mkmiller1 · 11-30-2002, 05:32 PM

As far as too much fluid, I've heard of backing the rear wheels onto ramps then filling the transfer case full. this allows the fluid to run to the front of the case so you can put more in. I've mainly heard of this with NP203 transfers with part-time kits, but you never know.
Matthew

Rod · 12-01-2002, 02:04 AM

An automatic can push tranny fluid into the transfer case also if there are bad seals.

GMCJON · 12-01-2002, 08:28 PM

Don't know about the rest of you, but I don't find it a rareity to have excess oil come out of the fill/check plug on most any drivetrain components. I have checked more than my fair share of "boxes" on trucks, and I'd say about a third of the time excess oil comes out of the rearend, transfercase, or tranny. Even on new rigs this happens all of the time. I would not worry about it at all. I know that when I fill up my boxes, I quit pumpin in the 80/90w when some of the fluid comes out, and then insert the plug. Not once have I heard of it causing a problem. Anyway, my post kind of contradicts the rest of the reply's, so I dont know if it will help or just confuse the heck out of you.

chevypete396 · 12-01-2002, 11:32 PM

I have seen over filling a lot as well but In SMALL amounts. The type of over filling your talking about probably causes very little or no problems. He didn't say "a little" he said "a lot of fluid came out" thats why I gave him the advise I did...

When it blew the real seal out of my transfer case on the highway, it was over filling by a lot from the tranny. Probably as full as it could get. When I pulled over to see where all the smoke and oil was coming from I couldn’t even touch the T-Case it was so hot. This type of over filling creates to much heat and can cause damage and a huge mess. I would caution anyone against backing the rear wheels onto ramps then filling the transfer case full with an NP205. Nothing can be gained by doing this.

ROD:

Thanks for your reply, I didn't know that. I thought the auto trannys were sealed better in the rear and the transfer case/ tranny adapter was a completely different type of design... Pete.

**D.PASSMORE** · 12-03-2002, 08:19 AM

IF YOUR FRONT DRIVE IS NOT TURNING, THEN IT IS A MECHANICAL PROBLEM, NOT FLUID. CHECK YOUR LINKAGE, THEN YOU MIGHT HAVE TO PULL IT AND GO THROUGH IT. 4X4 HEAVEN 1-800-800-1679 HAS ALL THE PARTS.

mkmiller1 · 12-04-2002, 12:39 AM

thanks for clearing that up on the transfer case. I DO NOT promote jacking up the rear wheels to get more fluid in the case. As you said, nothing would be gained.
Thanks,
Matthew

Duallie · 12-29-2002, 01:46 AM

Drain it and replace the fluid. It could've been driven through a creek or something and filled with water. The water would go to the bottom and displace the gearoil upward, and when you drained it through the top plug, you coulda just let the oil out and left the water.

OLDCHEV4X4 · 12-29-2002, 11:30 AM

Kissmyss...is it auto or manual?
Are the hubs engaging?
Check the drivshaft like posted earlier.
Only fill it with 90w gear lube to the level of the top plug
Randy

ckhd · 01-07-2003, 10:20 AM

Definitely check the linkage. There are two rails on the 205, one that controls the high/neutral/low, and one that controls when the front driveshaft turns. Crawl up under, and have someone cycle the shifter through it's range. Make sure both shafts move clear in and clear out. The swivel points in the shift linkage tend to wear out and not move the rails as far as intended.

Overfilling shouldn't make the t-case not shift into 4 wheel drive.

As far as I can see, overfilling is from one of the three things mentioned:
1) someone putting too much fluid in.
2) water in the t-case.
3) leaky transmission seal.

In any case, I'd drain the fluid, and put fresh 80w-90 in. Check it in a couple of weeks to see if maybe it's the tranny pushing fluid in.

11-29-2002, 02:16 AM	#1
Kiss My SS Registered User Join Date: Nov 2002 Location: Omaha/Grand Island, NE Posts: 229	NP 205 questions ok, here's the deal. My dad and I went for a test drive in the Jimmy tonight. We tested the four wheel drive for the first time and found that it is not working. It shifts into 4wheel hi and low and you can feel the gear reduction in low. The problem is that the front driveshaft isn't turning. It drives the rear wheels fine in 2 and 4 wheel. As much as I can figure, the front drive gear isn't engaging. Anyway, I figured I would check the level of lube in the t-case. Now there are two plugs on the back of the case. I assumed the top was to check the fluid level and the bottom was to drain the case. So I took out the top one and a lot of fluid came out. That seems strange. If the fluid level was supposed to be higher than the plug, then where do you fill it? I just copied the pictures from the magazine article about the 205 rebuild from and earlier post. Hopefully this might help me figure out what is wrong with my t-case. Also, what type of oil do you use in this case? Some have told me 90 weight gear oil where others have told me 30 weight. The stuff that came out looked more like gear oil. If you have any suggestions about any of these questions, I would be much appreciative. Thanks. __________________ 1972 GMC Jimmy 4x4 1985 Chevy Monte Carlo SS 1996 Saturn SC-2 1996 Ford Explorer XLT -Wife's rig

11-29-2002, 11:01 AM	#2
Beast388 Suburbans RULE! Join Date: Jan 2000 Location: Clinton, IA 52732 Posts: 689	How did you determine that the front driveshaft wasn't turning? An easy test is to make sure the hubs are unlocked and the transfer case is in either 4hi and/or 4lo. With engine off and tranny in park, or clutch engaged, climb under the truck and see if the front driveshaft will turn. If it does then you have a problem. I have always put 80w/90 gear oil in my NP205. That is what all of my book recommend, including the owners manual. And yes, the fluid level should be high enough so that you can stick a finger into the top hole and feel the fluid. Good Luck! __________________ --Ben 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, TH350, NP205, 8-lug D44, 14BFF w/ Detroit, 4.10:1 gears, 4-Wheel Disks 4" Lift, 35" MT/R's.

11-30-2002, 03:20 AM	#3
chevypete396 Registered User Join Date: Mar 2002 Location: Fernley, Nevada, USA Posts: 540	Might just have a busted hub. Or it might just be your transfercase linkage. I am not sure why alot of fluid came out of the top plug. It's not supose to if it was checked / filled on level ground. You are right, that top plug is where you check and fill the t-case. and the bottom one is the drain. I had a situation once with the 205 and 4 speed on my 68 "making oil". The oil was passing from the tranny through the 4 speed adapter into the 205 causing it to over fill the transfercase and under fill the tranny. It caused the rear seal to blow out of the transfercase at the rear drive shaft on the hiway from the heat. Your Jimmy probobly has an auto tranny so I don't think that the adapter seal could be a problem in your case. If you do have a standard tranny: On level ground, drian off the excess or fill it to the proper level. Check it in a few days then in a few weeks then months. Keep an eye on it and see if it over fills again. Like said, use SAE 80/90wt "gear lube" for the 205 T-Case... Pete __________________ 1968 Chevy - 3/4 Ton - 4X4 - Longbed - 383ci - TH350 - NP205 Building the motor, painting the engine bay, rewireing everything... (775)-527-1199 / ryanspeterson@msn.com

11-30-2002, 05:32 PM	#4
mkmiller1 Senior Member Join Date: Dec 2000 Location: Magnolia, Arkansas Posts: 1,091	fluid As far as too much fluid, I've heard of backing the rear wheels onto ramps then filling the transfer case full. this allows the fluid to run to the front of the case so you can put more in. I've mainly heard of this with NP203 transfers with part-time kits, but you never know. Matthew __________________ GOD is good...All the time! '71 swb custom10 barn find-68K original miles 72 K5 CST rust bucket, but runs and drives 84K miles

12-01-2002, 02:04 AM	#5
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	An automatic can push tranny fluid into the transfer case also if there are bad seals. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

12-01-2002, 08:28 PM	#6
GMCJON Registered User Join Date: Aug 2002 Location: Hood River, OR Posts: 16	Don't know about the rest of you, but I don't find it a rareity to have excess oil come out of the fill/check plug on most any drivetrain components. I have checked more than my fair share of "boxes" on trucks, and I'd say about a third of the time excess oil comes out of the rearend, transfercase, or tranny. Even on new rigs this happens all of the time. I would not worry about it at all. I know that when I fill up my boxes, I quit pumpin in the 80/90w when some of the fluid comes out, and then insert the plug. Not once have I heard of it causing a problem. Anyway, my post kind of contradicts the rest of the reply's, so I dont know if it will help or just confuse the heck out of you. __________________ Proud third owner of a 1967 GMC 4x4. Only 72,000 original miles and I am VERY proud to say my parents didn't buy it for me.

12-01-2002, 11:32 PM	#7
chevypete396 Registered User Join Date: Mar 2002 Location: Fernley, Nevada, USA Posts: 540	GMCJON... I have seen over filling a lot as well but In SMALL amounts. The type of over filling your talking about probably causes very little or no problems. He didn't say "a little" he said "a lot of fluid came out" thats why I gave him the advise I did... When it blew the real seal out of my transfer case on the highway, it was over filling by a lot from the tranny. Probably as full as it could get. When I pulled over to see where all the smoke and oil was coming from I couldn’t even touch the T-Case it was so hot. This type of over filling creates to much heat and can cause damage and a huge mess. I would caution anyone against backing the rear wheels onto ramps then filling the transfer case full with an NP205. Nothing can be gained by doing this. ROD: Thanks for your reply, I didn't know that. I thought the auto trannys were sealed better in the rear and the transfer case/ tranny adapter was a completely different type of design... Pete. __________________ 1968 Chevy - 3/4 Ton - 4X4 - Longbed - 383ci - TH350 - NP205 Building the motor, painting the engine bay, rewireing everything... (775)-527-1199 / ryanspeterson@msn.com

12-03-2002, 08:19 AM	#8
D.PASSMORE One of the First Join Date: Jan 2000 Location: St. Augustine,FL. Posts: 4,060	T-CASE IF YOUR FRONT DRIVE IS NOT TURNING, THEN IT IS A MECHANICAL PROBLEM, NOT FLUID. CHECK YOUR LINKAGE, THEN YOU MIGHT HAVE TO PULL IT AND GO THROUGH IT. 4X4 HEAVEN 1-800-800-1679 HAS ALL THE PARTS. __________________ DAVID PASSMORE ST AUGUSTINE ,FL ZIP 32084 '71 SWB K/10 CUSTOM DELUXE (Chili) '72 BLAZER K/5 Muscle Truck (Mule) '72 LWB K/20 CHEYENNE (Blackie)

12-04-2002, 12:39 AM	#9
mkmiller1 Senior Member Join Date: Dec 2000 Location: Magnolia, Arkansas Posts: 1,091	thanks chevypete! thanks for clearing that up on the transfer case. I DO NOT promote jacking up the rear wheels to get more fluid in the case. As you said, nothing would be gained. Thanks, Matthew __________________ GOD is good...All the time! '71 swb custom10 barn find-68K original miles 72 K5 CST rust bucket, but runs and drives 84K miles

12-29-2002, 01:46 AM	#10
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	Drain it and replace the fluid. It could've been driven through a creek or something and filled with water. The water would go to the bottom and displace the gearoil upward, and when you drained it through the top plug, you coulda just let the oil out and left the water. __________________ Just as if I knew what I was doin'

12-29-2002, 11:30 AM	#11
OLDCHEV4X4 Registered User Join Date: Apr 2000 Location: Chester County PA, USA Posts: 1,228	Kissmyss...is it auto or manual? Are the hubs engaging? Check the drivshaft like posted earlier. Only fill it with 90w gear lube to the level of the top plug Randy __________________ 72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania

01-07-2003, 10:20 AM	#12
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	Definitely check the linkage. There are two rails on the 205, one that controls the high/neutral/low, and one that controls when the front driveshaft turns. Crawl up under, and have someone cycle the shifter through it's range. Make sure both shafts move clear in and clear out. The swivel points in the shift linkage tend to wear out and not move the rails as far as intended. Overfilling shouldn't make the t-case not shift into 4 wheel drive. As far as I can see, overfilling is from one of the three things mentioned: 1) someone putting too much fluid in. 2) water in the t-case. 3) leaky transmission seal. In any case, I'd drain the fluid, and put fresh 80w-90 in. Check it in a couple of weeks to see if maybe it's the tranny pushing fluid in. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans?



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