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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: HookedOnReefing on July 01, 2009, 10:52:42 pm
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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 :o. 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 :o 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
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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).
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Blue smoke = oil burning. Probably from the valve guides/seals.
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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.
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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
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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 :o 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).
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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.
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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?
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Truck will run fine with out it.
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In operation, it will recuce some NOx by injecting compressed air downstream of the combustion process to help burn off by-products.
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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.
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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
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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!!! ;D 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?
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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.
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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.
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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.
get a stubby 9/16 (think that is the size or its 5/8) and come from the carb side towards it.
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The oil pressure sending unit isn't to hard. I have done them with a pair of channel lock pliers before. They are not super tight. As far as the cap replacement you don't change the timing at all. I usually take the old cap off with plug wires still attached. Leave it laying right there, then replace the wires with the new ones onto the new cap in the same order. The firing order should be on top of the intake, and number 1 should be toward the car on the right front corner of the cap.
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plugs and wires are best done one at a time as to not get them mixed up. Get yourself a set that is made to fit(not universal) if you are looking to keep it simple. I 2nd what blazin says on the cap; just remove it with the wires attached. you will see just how easy it is to change the rotor when u get the cap off then change the wires with the new cap in place. have funwith it and if u get jammed up; just jump on here.
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you could take the dis out to mess with the sensor, me personly would do the who works. but you can take the cap off and do one wire at a time then change the rotor in case you get mixed up the firing order will be 1-8-4-3-6-5-7-2 your right(from inside the truck) side cylinders are | 2 4 6 8 | of | | your left side are(from inside the truck) | 1 3 5 7 | Distributor rotates clockwise number one wire should be pointing to number one piston.
if you take out the dis. make sure you remember which way the rotor is pointing it can only go in two ways the way you see it and 180 degrees out so as long at you get it close and watch the rotor as you pull the dis. out it will move slightly from the cam shaft
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Good point on the rotor, however, If u do remove the dist. make sure u mark the dist and engine block as it can be put back in slightly off. I bought an 82 that the distributor had been put in one spline off and run that way for 8 years before I got it. when i couldn't use a timing light to time it; I figured it out and it made a world of difference to put it in properly.
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In operation, it will recuce some NOx by injecting compressed air downstream of the combustion process to help burn off by-products.
AIR doesn't help NOx reduction, just HC and CO emission levels.
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Well, got the oil pressure sending unit out and put the new one in. What a pain to get to! But it's done and the oil pressure gauge is once again indicating something rather than just dancing across the dial :D
I've never had this truck with working gauges so have no real base as far as oil pressure and coolant temp is concerned. Oil pressure is consistently 15 PSI and it doesn't really matter weather it is running at idle or being driven. Coolant temperature runs consistently at 150*F. Are these acceptable/normal numbers?
I've not yet replaced the distributor cap and rotor as well as plugs and cables. But will play with it this week. You guy's have given me the confidence to do the job. If I screw up, I've got more trucks that I can drive while fixing this thing and will ask you for help ;D
I have been replacing some of the vacuum hoses. They're in bad shape. I've replaced the easy ones. Some of these seem to come together into some sort of "plug" that plugs into a "connector with pins". It kind of looks like a trailer pin connector to power your trailer lights/brakes etc. (Is this part of the TVS???) Rather than going ahead and pulling the hoses off, I thought I ask you guy's first. Can I pull out the hoses and put new hoses in place of the old vacuum hoses OR does the hole connector/plug need changed out???
The other question I have is regarding the Thermostatic Air Cleaner Motor. On the bottom of the air-snorkle, there is a hole (shut by the damper door). Below that on the exhaust manifold there is also a hole. Shouldn't there be something there that connects the 2 so that it can pull in warm air when needed like a hose or pipe?
What are some of the tell-tale signs that you have a vacuum leak? How does it affect the engine/performance?
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15 psi is fine for idle, however it should increase as the rpms increase. With a consistant 15lbs I would question the accuracy of the guage it should be higher when u 1st start the engine. 150 degrees is a bit cool but again your guage may not be real accurate. I would mainly watch the guages and worry if u drop oil pressure fromwhere u r at. and keep an eye on the coolant temp to make sure your are not getting too hot. For the vacuum hoses u can just replace the hoses. there should be a tube aprrox. 2" in diameter that connects the exhaust manifold to the air cleaner housing to pull in warm air for cold weather if this is not there I would not hookup the vacuum line to run the damper door. Their also should be a vacuum diagram under the hood in front of the engine on top of the radiator area on the header panel. this will show u where the vacuum lines go alsomake sure that they are routed correctly.