1980 k-30 chevy

[ericlb]

ive got a few problems with the old truck, this is a 1980 chevy k-30, dually 53,000 miles from new in 1980, ive still got the window sticker on this one, 454 with 4 speed and 4;56 gears in the axles, [ thats why the mileage is so low, 6mpg is tough these days] anyway whats happening is 2 problems first the power steering pump, when cold it works just fine, but after the engine warms up [about 15 minutes of use] the pump howls like its low on fluid, it isnt low, and never has been, any option besides replacing it? second problem is the rear axle, its a locker, from the factory, the tires on this truck are mud and snow, 7;50 16's and i mean the tread looks like a tractors tires just about, this truck spends 90% of its time off road and i need to get a grip on the ground, where i go with it,usually into places a horse wouldnt go but the locker has lately taken to locking on dry ground during any kind of a turn which is not only hard on it, but its tough to turn when all 4 rear tires are locked side to side, ive heard of these problems before but its been a long time and i dont remember what the cure was, anybody remember?

 

[Grampy]

I"ll make a run at this - would check your hoses for deterioration or a restriction, especially the return side. Your truck may have a cooler on the return side ( should have one ) - check that too. Also could be old dirty fluid. I have a Dodge ( also uses Saginaw steering )that was squalling when cold, a fluid change pretty much solved that problem. I know the pump is worn but since it"s not used much any more, i"m getting by with it. Still works OK, but a little noisey. As far as the diff lock, what you probably have is the GM "gov-loc". I know it uses a mechanical linkage ( governor) to set the lock when a certain amount of wheel wheel speed difference happens, from what i"ve heard, usually they just won"t lock any more. I"m sure you will have to pull the diff. carrier out to find the problem. you will want a service manual,I have never worked on a gov-lov unit, only seen a couple of them. I should have a manual, will look - see if I can get some real info. on that locker. KEN

 

[ericlb]

thanks ken, i would appreciate anything you can find on the differential, im out in the country, i dont really mine changing out the ps pump if i cant get it to quiet down, but kind of hate to farm the differential out, most of the "mechanics" in this area wern't even born yet when this truck was new, kind of hate to send it to somebody who hasnt worked on one of these

 

[Grampy]

I'm in town today, most of my books are at the ranch, should be going out tomorrow AM. I'm assuming that your truck has the big 14 bolt rear diff. Some of the "young guns" should be familiar with it. GM used it for years, maybe still do. It was used in the 3/4 ton HD's and the 1 ton's. ( my '97 K2500 has it )

 

[JerryCPP (WA)]

Locking differentials that won't release? Be sure you are using an extreme pressure lubricant in them. You can buy EP additives that contain molydisulfide. A bottle of that in each one may loosen things up.

 

[Grampy]

Since I'm just goofing off this afternoon, I have always been amazed by what you can find on You Tube. Open that up and search "Eaton Mechanical Locking Differential" That video shows what your truck probably has - several videos there - some of them not too complimentary about that unit. Easy to see what really happened. LOL

 

[ericlb]

thanks for the help guys, i first plan to drai the differentials, flush then out and refill with the ep additive, i can use regular 85-90w gear lube with the additive right or do i need something else to see if i can get it working again correctly, i remember the old positraction units in the muscle cars used a special oil in them but his should be a whole different unit than those, the front differential does not have a locker, when i got this one my reasoning was if i cant get there with a 454 engine 4 speed manuel trans, rear locking diff, and 4x4 with 4;56 gears i probably needed to rethink just where it was i was trying to go , this is a working farm rig, not a rock climber , might be worth mentioning i may have set a record for bad gas milage though, it took 2 full tanks of gas to pull a stock trailer with 8 cattle in it to a town 70 miles away and come home , wife told me we wont be using that truck again for that will we

 

[Ron-MO]

You likely are on the right track with the additive used in old muscle cars. I had a 76 1/2 ton 4x4 which had the rear locker (12 bolt), and I had the same issue till I added the small bottle of additive, then problem went away. It is likley that your 80 has the type with clutches in it like my 76 did. I have a 2012 Silverado which has a mechanical locker and is a totally different animal, but won"t own another pickup without a locker of some type again as when I bought my 92 new they talked me into taking one without, and I would have to go to 4x4 on a slight hill in wet grass (spinning one rear tire). Try the additive and I think that problem will go away.

 

[ericlb]

update, well that seems to work, drained the rear end flushed it out and refilled with 85-90 and 1 bottle of additive it seems to be working as intended after a couple of weeks now