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79' GMC C15 - Spruce Caboose

79 GMC 1500
I found some rust free fenders, ordered the exterior cab pannel patches , rear quarter wheel arch pannels. Found an oem hood and grill as well.

Been chasing a shuttery misfire type idle since I got this thing. Changed plugs, wires , cap and rotor.Still there... Ohmed out the coil.. it's good... hmm

And then read through my Chilton's a bit more and saw the timing chain section.. followed the test procedures and found about 8-10 degrees of timing chain slack.. so hopefully that's the culprit of the issue. It's one of them atleast. Motor has 184k km also so it makes sense it hasn't been done yet as it seems pretty bone stock.

Rene gave me some solid advice and I got a niece one piece oil pan gasket that includes part of the timing chain gasket as well. Came with all new hardware and aligning keeper doodads. Gonna take it to our little shop at work on Sunday and getter all done.

I also got a new water pump and thermostat aswell.

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One thing I never got to work on in my blazer was the motor. Which isn't a bad thing that's for sure, but I'm probably more excited than most that have to change a timing chain haha.
 
One thing I never got to work on in my blazer was the motor. Which isn't a bad thing that's for sure, but I'm probably more excited than most that have to change a timing chain haha.

It’s always fun to learn new skills!
 
The timing chain, and sprocket swap went over well. The one piece oil pan gasket came with 4 screw in dowels with tabs on them so you can hang your gasket tight to the bottom of the block and then put your pan up and its all aligned. Great idea... however if you a pull a me and snap one of them off by accident, fishing a sheared plastic thread out of your engine block while working around an exposed oil pick up, is a real... :flipoff8:. Once that fight was over and the pan was back up, i installed the cover back on and said gaskets, it was really nice that the bottom timing cover gasket was a part of the oil pan and no rtv bullshit was needed.

Also threw a new water pump on since I had one available for free. Ive known by the temp gauge that the thermostat was probably stuck open since i bought it, as the temp just fluctuates with your driving, changed it with a stock 195. Fired it up anddddd over heating.. hmm thats odd. Triple check water pump PN# to ensure its a clockwise rotating model for my truck, checked out. Air lock... hmm maybe but should work itself out with the rad cap off, nope just overheating again...Ok, well the pump was free so maybe its just not working.. took the thermostat out of truck, and with the rad cap off ran it. Doesnt overheat, and i can see movement in the coolant, so the pump is working... I tried two different thermostats and tested them both with a torch and a heat gun to check their functinality in terms of opening. I shot my IR gauge at the manifold where the thermostat is, and then shot the IR gun at the temp sender location ( between cyl 1-3 ). The manifold temp was about 185 ish and the heads temp was around 230. At that temp, my gauge is pretty much getting to the overheated area and i shut off the engine everytime to let it cool down. Online research showed average temp is about 210, not sure where or how thats measured though.

For now im just running it with the fail safed failed thermostat in the housing as that way the engine runs a little cold but its better than warped heads..
Also got that aftermarket black trim off the truck!


Im hoping to find an aftermarket temp gauge thatll give me accurate reading in numbers.

First question is, what are the tabs on the temp gauge as per temperatures?

If my gauge isnt faulty, which it could be or the sending unit ( the unit is a month old ) what would cause the engine to overheat before the thermostat is opening, or is that even possible?

could trapped air really cause these issues. I ran the truck multiple times with the cap off but without the thermostat opening im assuming air wouldnt get out anyway. People recommend drilling two small holes in the thermostat to allow air to pass?

With no higher point than the filler,is there a good way to ensure no air trapped?. ive always had a second point to open usually

Took some photos of the underside of the truck as i was inspecting it further. Its in ALOT better shape than the blazer was. theres still original black paint under the truck. Should be good once i get the few cancer spots all fixed up this summer and then if i tackjle the surface rust i should be ahead of some problem areas.
 
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Also have that spare rad laying around. Gonna see if I can clean it out. I've heard of guys using Cascade and hot water to Clean out crap from them sitting. Incase my rad is the issue..
 
That engine looks nice and grimy inside! One suggestion would be on your next few oil changes toss in a qt of atf and run it around for a little right before changing your oil. It will help to clean out all the soot and buildup. It's basically like putting that motor flush stuff in except cheaper and usually everyone has some atf laying around.
 
That engine looks nice and grimy inside! One suggestion would be on your next few oil changes toss in a qt of atf and run it around for a little right before changing your oil. It will help to clean out all the soot and buildup. It's basically like putting that motor flush stuff in except cheaper and usually everyone has some atf laying around.

Awesome man, will do. Always got some laying around like you said. I imagine this motor sat for a long time on the farm before my buddy rescued it, also who knows how it was treated. I wish I would known that right before I changed out this oil but maybe I'll just do some un needed but needed oil changes in the near future and do a few cycles to clean some gunk out. With 115k miles on it it should be good still. Fingers crossed. Valve covers will be coming off this weekend as I have a tick that could be a loose rocker, also want to take a closer look at the possible gunk build up
 
Hey Nick just thinking....

Was overheating a problem before you did the chain? If not maybe the timing is out? Not saying it is but unless the new pump is bad there isn’t much else to go wrong.
 
Hey Nick just thinking....

Was overheating a problem before you did the chain? If not maybe the timing is out? Not saying it is but unless the new pump is bad there isn’t much else to go wrong.
That's what I was thinking but didn't dare say it
 
If it was a farm truck that would explain the gunk. Possibly alot of idle time or like most farmers I know it probably didn't get a lot of miles put on it so they probably just rarely changed the oil. I change oil on everything from my vehicles to farm equipment to everything at work once a year no matter what.
 
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If it was a farm truck that would explain the gunk. Possibly alot of idle time or like most farmers I know it probably didn't get a lot of miles put on it so they probably just rarely changed the oil. I change oil on everything from my vehicles to farm equipment to everything at work once a year no matter what.
I do that too except with conventional oil if it is used once and got to operating temperature it should be changed at 3 months
 
Hey Nick just thinking....

Was overheating a problem before you did the chain? If not maybe the timing is out? Not saying it is but unless the new pump is bad there isn’t much else to go wrong.


It wasn't overheating before but the thermostat was failed open. The motor was at tdc of cylinder one when I pulled the chain n sprokets, and the timing is set at 8 degrees of advance without vacuum. To get it to not overheat I put the old open thermostat back in so it's acting exactly how It did when I got it. The pump is pushing coolant through the rad but maybe just not good enough, I may just clean this spare rad out and change it?
 
It's not running hot at all this way but it is running cool , which I believe is making it run a bit rich,a it's not vaporizing the fuel properly, if I got that correct?
 
Ok that all makes sense.
Definitely try the other rad.
.

Okay, wasn't sure if maybe I was missing something obvious.

The spare rad is a bit cruddy and I priced out a new one at 200$ , might just splurge on a new one. Some guys have suggested running a dirty rad with just water and dish washer stuff in it and then flushing a few times but all that work for a rad that might be shit,doesn't sit to well with me. If I can get this motor a bit less cruddy inside I think it'll live long enough to deserve a new rad.. I did run into a guy that has a 454 with forged internals and th400 for sale so maybe I'll just buy a big rad in preparation... :whistle:
 
Most of that "flush" stuff doesn't really work. If anything I would lay i down flat and fill it with vinegar for a day or two to try to clean out any hard water/scale. Then you could flush it out and see how it is. Might could try CLR(Calcium Lime and Rust) cleaner in it also.
 
Most of that "flush" stuff doesn't really work. If anything I would lay i down flat and fill it with vinegar for a day or two to try to clean out any hard water/scale. Then you could flush it out and see how it is. Might could try CLR(Calcium Lime and Rust) cleaner in it also.

After taking another look at it I'm realizing why it probably fell my way.. better than what I got but still cruddy and the old core system. I'll still try those two methods and see if I can just keep it as a backup. . I decided to just suck it up, and pick up a new rad from the parts store. I normally don't splurge as easily, buut I do have some money left over from the Blazer, and it's all for this c15 so why not.

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Sad to see the blazer go but, it bought me this c15 and paying to fix it up some, paid off some credit card debt and also treated myself to something I've wanted for a long time and also something that'll help this c15. Got the red metal work bench from work. its pretty sturdy at 3/16ths thick, and the no price was right.

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Actually being able to learn how to weld will be the next step in my abilities, I'm going to start practicing as much as possible with anything I can find.. I might even sacrifice a door to learning to patch body pannels, as i have a set laying around. They are 3500 square doors with all sorts of big mirror bracket holes and riveted metal skins to them already..
 
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