MAJOR Tune-Up questions for a neglected Farm Truck

[HookedOnReefing]

I'm giving my 85 GMC Sierra 2500HD manual transmission 350 V8 4BBL 2WD Farm Truck a well deserved MAJOR tune-up. I don't think the previous owner cared too much or at all . Changed the oil, oil filter, air cleaner filter, breather filter, tranny fluid, differential fluid.

Couple of issues I like to resolve. Don't want to spend a bunch of $ on the GMC as it is run on and around the farm. The 82 Chevy C20 BBC is a different story, that thing is my baby.

Questions:

1) While pulling out the old PCV valve, the rubber grommet just fell apart. So now the new PCV valve is hooked up but not secured with a tight fitting new grommet in the cover. Did an internet search and there seem to be several PCV grommets available in slightly different sizes for my make, model and engine combo. Not sure if that's correct. Which size should fit?

2) Drained and replaced all manual transmission fluid. While it shifts, it is sometimes still hard to move between gears. Is this maybe the linkage instead?

3) Occasionally there is a clicking/ticking sound coming from the front of the truck. It goes completely away when I push in the clutch. Any ideas?

4) Almost every time when the truck is started, a blue smoke cloud comes out of the exhaust. After running a few seconds, smoke clears and disapeers for as long as it's running.

5) Exhaust fumes smell verrrrry rich however, no black smoke indicating a too rich fuel mixture?

6) While driving, the truck can sometimes be hesitant in accelerating/holds back and kind of make a very fast put-put-put noise that can be felt as well. It's is not backfiring.

Tomorrow I'll be flushing the coolant system as it contains all water now Will also change out the little fuel filter located at the carburetor and change spark plugs/wires. Should I also change the distributer cap, rotor and contact points? Or can I just change out plugs and wires? Will also start replacing all vacuum hoses one by one as they seem VERY brittle.

Anything else that I should do/check?

Sorry for all the questions guy's!

Alex

[1980c10]

I always start a project like this by replacing what i know is bad or what i am going to replace anyway. Then i see what problems still remain. As far as the cap and rotor go i would take the cap off and see if they look alright. As far as the pcv grommet i would check a local store or see and match them up with the pcv and truck. Shifting-I would start by checking linkage. Blue smoke=fuel; tune up may fix this(quicker starts).

[TexasRed]

Blue smoke = oil burning. Probably from the valve guides/seals.

[HookedOnReefing]

Blue smoke = oil
Black smoke = fuel
Hard to see what color it actually is.

If it is oil, wouldn't it constantly blow blue smoke? It only does it on start-up.

[VileZambonie]

It's either worn valve guides or valve guide seals or both. You can try just replacing the seals and see what happens without pulling the heads

[HookedOnReefing]

Thanks. I'll try that and see what happens.

Run into another problem. Checking over everything I noticed that there are supposed to be 3 drive belts. This truck only has 2 in use When standing in front of the truck, there is supposed to be a drive belt going from the radiator fan to a pulley on the right. Is that the water pump

I know it has operated without that belt for at least a year from talking to the previous owner (a construction company).

[ccz145a]

Water pump is in the center on the top. Crank pulley below that.

Just so you know, directions are always in reference to someone sitting in the driver's seat. So left is driver's side and passenger side on right.

'83 v8 ought to be like this:

power steering is mounted lower left side of the block
a/c compressor upper left
alternator upper right
a.i.r. pump lower right

I think the a.i.r. pump is the one you are talking about... it will have hoses that eventually tap into the exaust manifolds. Truck will run fine with out it.

[HookedOnReefing]

Thank you! It is indeed the A.I.R. pump. Just read that it is part of the emission system. As you say, you can run the truck without it and it has been. Are there any adverse effects from not operating the AIR pump?

[Lt.Del]

Truck will run fine with out it.

[ccz145a]

In operation, it will recuce some NOx by injecting compressed air downstream of the combustion process to help burn off by-products.

[Blazin]

As far as the hard shifting goes, I am assuming you have an SM456 being a 3/4 ton, and you said it was manual. There is no linkage. The shifter goes directly into the top cover, and moves the shift rails there.

[1980c10]

when I mentioned linkage in my above post; I did mean the clutch linkage. U would just want to make sure that the clutch is fully releasing. also 1st and reverse usually shift a little hard due to how the syncros are set up. good luck

[HookedOnReefing]

Thanks!

All this info has really helped out.

Yesterday I finished the coolant flush, put on a new radiator cap, re-installed the new PCV valve with a new PCV grommet and fuel filter at the carburetor. Changed some of the obvious bad vacuum hoses and installed a new coolant temperature sending unit. I'm surprised at how cool the truck runs. Yesterday wasn't hot outside at 70*F and the truck ran at approx. 150*F (between 100 and 210) at the gauge. After shut down it would indicate somewhat higher in the 170*F range.

Thus far I Changed: engine oil, oil filter, air cleaner filter, breather filter, tranny fluid, differential fluid, PCV Valve, PCV grommet, Coolant flush, Coolant Temperature Sending Unit and some of the Vacuum Hoses. Also had the tires rotated/balanced. I know all this is basic stuff but I've never really done this before and feel pretty good about it!!! I guess if you don't try and start somewhere, you never learn.


Still need to replace all spark plug wires and spark plugs and will do this my self. Will let my local mechanic mess with the distributor cap, rotor and points and have him also adjust the timing as well as idling settings on the carburetor  as I don't feel comfortable working on it my self yet. Also don't have the tools.

Next up is my oil pressure gauge. I have a mechanical gauge, not a dummy light. Gauge fluctuates around. Bought a new oil pressure sending unit yesterday. It's a bell shaped kind of deal. Using the search function on this forum, as my manual wasn't helpful at all, I found where it's located. I think it's located on/near the firewall just below and almost right behind the distributor. What a PAIN to get too!  Any suggestions short of having to move the distributor out of the way? Which wrenches should I or can I use to make the job relatively easy?

[Blazin]

On a scale of 1 to 10, the dist cap, and rotor are easier than all the spark plugs to change. As far as points, an 85 is electronic, no points. All you need for tools to change the cap and rotor are a medium to short phillips screw driver, a 1/4 drive ratchet, with a might be wrong on the size but I if I remember correctly a 1/4 socket to swap the coil over into the new cap.
The oil pressure sending unit is electrical not mechanical if its a stock 85 piece. It is threaded into the top of the engine block to the left of the distributor. They are pretty simple to change as well. Make sure you use pipe dope or teflon tape on the threads.

[HookedOnReefing]

Thanks Blazin!

The oil pressure sending unit is indeed electrical looking at the part. It threads into the engine and then it looks like a single wire will clamp onto the top of the unit. I'm still at a loss as to how to change out the old unit for the new one. I don't see how you can work in that small a space

I might just do the distributor my self as well. Do I need to take the hole distributor of or just unplug all the wires, mark which wire it is and where the go on the cap. Take the cap off, take the rotor out. Put the new rotor in and new cap and attach all the wires? If that's all it is, I can do it, but IF I need to reset the timing, mess with setting the No. 1 Cyl @ TDC, I'm at a loss.

While I'm at the distributor, it's probably easy to put the new oil pressure sending unit in as well.