86 GMC Sierra Classic 2500 questions

[gmcnoob]

Hey guys. I'm still learning and am not an experienced mechanic by any means. Just curious if I took my truck to the shop how much should I expect to pay to have the brakes completely redone. Worst case scenario or most likely scenario. I actually think the brakes just need to be bled properly. I have the worst luck trying to fix things but I'm trying and learning a lot. I tried to bench bleed the master cylinder and bleed the brakes starting with the right rear and could not get any fluid to come out. I assume it must be my error so I'll have AAA tow it to my local shop. Just curious as to what I might expect.

Also as winter will be coming up soon I want to get the heat working again. It just stopped one day for an unknown reason. Are there a few simple things I could check first like a fuse? I looked at the fuse box and some of the descriptions were obvious and some of them I have no idea what they mean. Where should I start to diagnose this problem?

Thanks for any advise.

[jsavage977]

you will probably be lookng at half a hour to a hour for a shop to bleed your brakes, so whatever their labor rate is. Ours is $90 and we would get it done in half a hour easy so you would be into it $45. If you wanted a complete brake replacement we would replace brake pads, rotors, drums, shoes and most likely rear wheel cylinders for around $500. So whatever you would need would most likely be somewhere between those. If you where to do just pads and shoes alone and your rotors and drums are fine it would be significantly cheaper, around $200 probably.
For your heater im assuming that the fan stopped blowing? Is so look for a fuse labled blower. Or heater or something like that. If that doesnt work there is a wire that plugs into the fan itself that likes to fall off. Maybe you just need a new fan? They are pretty cheap, probably under $30. If the fan does work and there is no heat output you might be looking at a coolant issue. 90% of the time the issue is a stuck thermostat. Dont worry, they are easy to change (pull two bolts out, clean surface, add silicone and put bolts back in) and very cheap $5-$15.
GOOD LUCK

[Your41Plague12]

More than likely for your heat, either you blew a fuse for the blower motor or the resistor on the firewall housing finally bit the dust. The resistor is no more than $10, so I would change that anyway.

[Just call me Sean]

Blower motor is on a fusible link.

[gmcnoob]

Thanks for your valuable input. Still working on this beast and learning a lot. I have few more questions for anyone who doesn't mind sharing their knowledge. In the attached picture there is a bolt missing in what I think is the exhaust manifold. Exhaust leaks out of it like crazy and makes a bunch of noise. I put the end of a screwdriver over the hole and it sounds great. Is this something that is easily fixable?

Next, I seem to have a rare rim size. They are 16.5"x9.75 Western Cyclone Hurricane. I love them but the tires that I need are on national back order according to at least 5 tire shops that I contacted. Whaaaaat???? I need that specific tire (BF Goodrich) because it has to match one I replaced several month back when I got a flat. But the point is I am trying to replace the wheel center caps because the old ones are rusted and literally breaking apart. I took measurements and ordered the 5.10" diameter ones because that is the size of the hole on these rims... They do not fit and the other available sizes seem like they would be way too small. Info on these rims is almost zero. Did I measure the wrong thing?

On a side note can anyone tell me any details about the motor. I'm just assuming that it is not the the original 5.7 liter V8 that it says on the service tag but could be wrong.

[Keith Seymore]

Originally Posted by gmcnoob

On a side note can anyone tell me any details about the motor. I'm just assuming that it is not the the original 5.7 liter V8 that it says on the service tag but could be wrong.

Welcome;

Interesting SPID - some observations:

a) St Louis built truck; 1986 model year, GMC nameplate
b) The options are not quite in "reverse alphabetical order" - and jumping around a bit at that. Usually they are in alphabetical order so that was interesting to note. Do you mind if I post this, or could you post this over in the SPID thread?
c) Looks like a fairly early in the model year build. My guess is GMC started at 500001 so your VIN of 506422 would make it the 6422nd GMC produced (Chevy's would be mixed in there, too).

K

[gmcnoob]

I'll go ahead and post it over there.

[Keith Seymore]

Thank you;

that thread happens to be specific to '67-'72. We squarebody guys have our own SPID thread here:

http://67-72chevytrucks.com/vboard/s...highlight=SPID

I can stick it there if you like or you can. 'Preciate the effort.

K

[jetmech85]

The missing bolt in the exhaust manifold looks more like a missing AIR tube fitting. It is directly into the exhaust, and should be plugged. The manifolds turn down and have AIR ports on each cylinder. All my '86 trucks have the manifolds that turn up and one large AIR port at the front of each manifold. In MHO the ones that turn down lets you get to the spark plugs a little easier and tend not to cook the valve cover gaskets. From looking at your pic it is hard to tell if it is an original motor. Numbers on the right front of the block could tell you and from my experience the '86 engines had perimeter valve cover bolts, like yours and a one piece rear crankshaft seal. You can see the seal retainer between the flex plate and block from under the truck.

[gmcnoob]

That is great information jetmech85. I'm about to take it to a mechanic because I am just not experienced enough to mess with these things. Is the plug you speak of called an expansion plug? Maybe you could point me in the right direction on that one.

I went ahead and took a look at the block and all I can find is Edelbrock Performer EPS, no numbers. On the side of the carb it says Rochester Quadrajet and man is this thing dirty. Would you recommend having it replaced? See pictures. I'll admit it has been sitting around for a long time but I fire it up regularly and let it run. It's time to get it back on the road.

[jetmech85]

The intake manifold is an aftermarket item that is made by Edelbrock. I use these on some of my trucks. Not sure of any performance gains but it is lighter. The Quadrajet is the original type of carb that came on the truck and when working properly are great carbs. I have good luck with Edelbrock carbs so that is what I use. The motor number is on the block and there should be plenty of web sites showing the location on the block. The plug is, I think, a pipe thread plug and not an expansion plug. Others here may be more precise on the size and thread type. The problem is in getting the old fitting out. I have seen some welded closed and that may be your best option for now. It could get costly taking it to a mechanic for the issues that you will face trying to keep these trucks on the road and sometimes that is your only way but gain as much knowledge as you can and it can be a lot of fun and pride owning one.

[csdineley]

SBC block I'd location.

[gmcnoob]

I have taken all of the advice above and thanks to jetmech85's advice I plugged the exhaust leak with a 1/4" brass hex nut. Believe it or not it screwed right in snugly. No more clunky engine noise. Thank you!

I replaced the resistor thanks to the advice above and what do you know, the heat works again. For some reason it only seems to be blowing through the floor vent. Any suggestions on this one? I read it may have something to do with the truck not having the A/C hooked up. Any suggestions?

If anyone knows where to find the dang center caps that fit 16.5"x9.75" Hurricane rims I would be eternally grateful.... Going to get the new tires on soon and want to install those while the wheels are off. Nothing I have tried fits.

[motornut]

check your vac lines they control the vents

[gmcnoob]

After doing some electrical work under the dash I realized that the air flow tubes to the upper vents were removed at some point. Oh well, no big deal. The floor vent gets the cab warm enough to melt the ice on the windshield.

I got her running smooth and I'm feeling pretty proud thanks to you guys. Now I just have an issue where I have little power going uphill. It doesn't want to go much over 30 MPH going up a steep grade. Any suggestions on what I can look for on this issue would be greatly appreciated.

And still not one tire company I have spoken to can find the BFGoodrich All-Terrain T A KO Tire, 33x12.50R16.5/D 118R tires that I desperately need. Did they just stop making them?

[jetmech85]

I would look at the engine timing, take a reading on your spark plugs, condition of plug wires, and all rubber lines under the hood. When you can only do 30 mph uphill is the engine lugging down or is there slipping in the transmission? Go online to try to find the tires you need. If they are available online then someone locally should be able to get them for you. I think any 16.5 is going to be hard to find and probably pricey.

[gmcnoob]

Originally Posted by jetmech85

I would look at the engine timing, take a reading on your spark plugs, condition of plug wires, and all rubber lines under the hood. When you can only do 30 mph uphill is the engine lugging down or is there slipping in the transmission? Go online to try to find the tires you need. If they are available online then someone locally should be able to get them for you. I think any 16.5 is going to be hard to find and probably pricey.

Engine timing is getting into something I know nothing about but thank you. I'll do some research and try to figure out what you mean. Spark plugs and wires I can do.

There is no transmission slipping, I just have to really jam the gas to get it to downshift and even then the motor sounds great but it's like watching a turtle taking a walk.

On the tires it would be way too much to pay with shipping. One tire dealer told me they are on national back order and should be available mid October. He can get them for $198 each. Online I think it was $260 or so plus $200+ shipping or something ridiculous like that. I hope the guy I spoke to is right on the availability this month. Why is this size so rare?

[motornut]

is the tranny vac line hooked up?
it runs intake to valve on tranny....

[gmcnoob]

Originally Posted by motornut

is the tranny vac line hooked up?
it runs intake to valve on tranny....

That's a very interesting question.

Sorry for my ignorance but where exactly should I look? I have been trying to figure out this hissing sound that seems to come from behind the carburetor.... Could this be it?

[gmcnoob]

Hmmm... I suppose I should start here and follow it right? If I'm not mistaken this is the transmission vacuum modulator.... I'm not with the truck right now.

[motornut]

look at the orange one intake,little fitting behind the carb area
joins to rubber bit,then steel line (down behind block)to rubber bit again to tranny valve

[jetmech85]

The aftermarket intake you have does not have an EGR and that is fairly common. It is likely your engine had one at one time. I still suggest reading the spark plugs and doing a compression test. Do you have catalytic converter on this engine?

[csdineley]

Most aftermarket intakes don't have an egr valve. So you had one from the factory but when that intake was installed. They removed it. Also from your pictures you have an open vacuum port on the front of your carb. If I remember right, it should be hooked to your pcv valve.

"The distributor cap, wires and plugs have not been changed since I got the truck 4 years ago and I have no idea when they were changed previously. Should I go ahead and give that a try?" = YES

[gmcnoob]

I do not believe there is a catalytic converter. The PCV is hose is going to a port below the fuel filter..... Is this incorrect? Damn I feel like a moron.

[jetmech85]

I have an "85 "M" code 3/4 ton. Does not have EGR, cat., charcoal canister, and able to run leaded gas, manual transmission, all from the factory. Point is that its most likely motor causing my problem. Runs good at idle and under no load. Compression check showed 160-170 on seven holes but 90 on number 5. Backed off both valves and applied shop air to that cylinder and it blew out of the exhaust port. Applied air to a good cylinder and it moved the piston to the bottom of the stroke. A compression tester is fairly inexpensive and can give you a good idea of your engine condition.
The port below your fuel filter looks like its an adapter for a spread bore(Quadrajet) to a square bore manifold so that is not the factory PCV port. I will have to look at my '85 to see where it goes. It may be fine where it is but is it capped off at the original location?