Converted NP203 grinding sound in 2WD

[AuroraGirl]

When filling a 205 transfer case this link is informative.

Help identifying

I have a picture of my transfer case identification tag, trying to figure out exactly what fluid to run, this is a 1988 square v30 454 4-speed, the Chilton's manual says for 86 to 87 k30 k35 refer to owner's manual, it's hard shifting in and out of 4high I'm thinking of fluid change would help...

www.gmsquarebody.com

The 203 Full time were listed for 10-30 or 10-40. Part timed many, but always used the new machined shaft kits on my stuff.
Never had any problems with oiling.
I still have the T400 and transfer case from my 1979 that spent 18 years pushing an 8.5' Western plow.

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are you just generally replying to the topic or was that answerr to someone ? Iguess im confused haha

 

[Dooley]

are you just generally replying to the topic or was that answerr to someone ? Iguess im confused haha

Just general info.
Over the years info from Chiltons isn't the most reliable when it comes to fluids.
In the linked thread there was info from Chiltons that was incorrect.
As for the 203 cases if you live in a warm climate most of the year straight 30 is ok.
If you live where it is/gets colder, using a 10-30 or 10-40 works great.
There were a great many updates in the 203 over the time it was used.
The early ones had a one piece tail housing and the oil drive gear was part of the machined output shaft.
The 2 piece tail and plastic drive gears came later.
Part way through the 1978 year they changed the size and pitch of the drive chain.
They narrowed it and put steeper pitch which helped eliminate slippage as the chains wore/stretched.
I have half dozen 203 and probably that many 208's in the back garage. Most of my 205 stuff used up or sold except a pair splined for T350's.

 

[coolpup32]

My thoughts were always that thinner oil would never hurt (aside from the 0w stuff). I live in the south east, my opinion may differ if I lived in Death Valley. I've ran 5w30 in the wife's civic for 18+ years and it calls for 10w40

 

[AuroraGirl]

Just general info.
Over the years info from Chiltons isn't the most reliable when it comes to fluids.
In the linked thread there was info from Chiltons that was incorrect.
As for the 203 cases if you live in a warm climate most of the year straight 30 is ok.
If you live where it is/gets colder, using a 10-30 or 10-40 works great.
There were a great many updates in the 203 over the time it was used.
The early ones had a one piece tail housing and the oil drive gear was part of the machined output shaft.
The 2 piece tail and plastic drive gears came later.
Part way through the 1978 year they changed the size and pitch of the drive chain.
They narrowed it and put steeper pitch which helped eliminate slippage as the chains wore/stretched.
I have half dozen 203 and probably that many 208's in the back garage. Most of my 205 stuff used up or sold except a pair splined for T350's.

this is a 1978 truck lol wonder which one it was, if its the deeper chain that honestly may be enough for me to choose that going forward as tcase for the truck.

Do you know what that pipe is about? the front axle has warn hubs from the era, the same kidn that manual hub 208 trucks got in the 80s(at on d44 axles/10 bolts) which is also purchaseable today but they are clearly that old themselves, so I think the truck stands good reason to believe had the part time done if it was still functional when it came into our family in 2000 ish and has sat since. The pipe is what makes me think its going to lubricate the thing back there but im unsure how it sends fluid with the factory insides, maybe they had pumps or something with part time conversion?

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also you seem super smart, is there anything big different between a 1977 np205 and a 1980 np205, I know there is a difference in mine specifically in the crossmembers , the adapters(one is short foot one is tall), and then the 1980 has a slip yoke rear while the 77 was fixed.

Just curious

 

[AuroraGirl]

My thoughts were always that thinner oil would never hurt (aside from the 0w stuff). I live in the south east, my opinion may differ if I lived in Death Valley. I've ran 5w30 in the wife's civic for 18+ years and it calls for 10w40

0w30 is as thin as 10w30 at normal outside temps like 70 degrees, for example, however, the properties of the 10w30 are going to handle the temperature of the unit better.

I believe for a chain, thats lubricated, an oil thats 0w30 would shear off easier/not serve as good at those forces trying to rotate and fling it off and then being between I may be wrong on this but its how i understood. the concept also works for small engines like snowblower i think. maybe.

 

[coolpup32]

@AuroraGirl all I see is a plug, no indication of a conversion.

 

[RaisedK5]

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[AuroraGirl]

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[coolpup32]

@AuroraGirl is that attached to the transfer case? I thought that was the pivot rod for the eBrakes

 

[coolpup32]

you can see on @Dooley photo, the pipe pretty clearly, you're looking from above the case. on yours all i see is a standard plug. the goal was to raise the oil level in a manner that the tail housing would hold oil, that's where the oil pump is

 

[Big red square]

I have a converted 203 in my 75 K25 - truck is fairly new to me, never been inside the transfer case. It has a piece of threaded pipe so you can overfill it for the part time conversion. The truck had been sitting for a while when I got it so I changed all the fluids, including the transfer case, with straight 30w. First couple of thousand miles all worked just fine. In the last couple of months it’s developed a nasty metallic buzz/grinding sound in 2wd high. I already checked the shifter adjustment to make sure it’s grabbing the correct gear and not drifting into neutral or something, and checked the fluid level. The sound comes and goes, I can go a whole day without hearing anything, and the next it sounds like a can of marbles every time I use anything but the lightest touch on the throttle. The sound when it’s particularly bad causes the shifter to visibly vibrate forward and backward at a high rate. If I shift into 4 lock it’s perfectly fine, no sound, either with or without the front hubs engaged. Does this sound like a problem with the part time kit and/or differential assembly in the tail housing? It’s my daily and I’m trying to get an idea of what I need or probably will need before I tear into it. I’m looking at a couple of two piece cast differential housings to possibly order in hopes that the problem lies with that crown gear engagement rings. Thanks in advance for anyone’s thoughts.

How do you fill the transfer case?