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What did you do with your GMT400 today...or yesterday....

the tools I found online use two gauges with a regulator. I can build something like that but it's being able to connect into the GP hole. I might try taking an old GP and seeing if I can drill through it and make some sort of adapter to connect it all up.

I had wanted to use the compression tester adapter but the quick connect is an odd one I have not seen before. If I know what it was I could possibly find the female side to make me up a gauge with regulator and air compressor chuck.
 
Get a leak down tester.
Bring the piston to TDC both valves closed.
Attach tester to cylinder like you would a compression tester. Add shop air and increase pressure slowly up to 100 psi.

Reading the second gauge losses:
0-10 psi is excellent
10-20 psi is ok (some gas engines 15-18 is limit)
20-30 psi loss means that sucker is worn out.
Anything over 30 psi loss means dont drive without comfortable hiking boots on.

The leaking air ideally should go into the crank case (oil pan, valve covers, etc.) as it has natural ring blow by.

Leaking into exhaust pipe means exhaust valve bad. Leaking into intake manifold means intake valve bad.
Leaking everywhere means way, way bad things.
 
Biggest problem I had with leak down tester was keeping the piston on TDC.
If the piston is not perfectly centered over TDC then the piston will be pushed to the bottom of the bore.
Best to have a socket and a breaker bar holding the cranking shaft from spinning.
 
Thank You @dbrannon79 for sending Me the power steering valve, spring and connector for the 1995 year truck.
Those parts with the new 95 pressure hose to the hydraulic brake booster got My truck switched from the EVO solenoid system to the standard old fashioned pressure type.
And, no leaks.
Filled the pump reservoir with Dex/Merc, fired up the engine, cranked the steer wheel forth to one side and back to the other zeveral times and all seems well and fine.
Might be later today, or within the next several days, I’ll get the truck out and give it a road test.
 
MrMarty51 said:
Thank You @dbrannon79 for sending Me the power steering valve, spring and connector for the 1995 year truck.
Those parts with the new 95 pressure hose to the hydraulic brake booster got My truck switched from the EVO solenoid system to the standard old fashioned pressure type.
And, no leaks.
Filled the pump reservoir with Dex/Merc, fired up the engine, cranked the steer wheel forth to one side and back to the other zeveral times and all seems well and fine.
Might be later today, or within the next several days, I’ll get the truck out and give it a road test.
Click to expand...
Glad I could help :)
 
Well folks, this 93 has been good to me over the past year I've owned it! but I think I have found the source to all my problems.....

anything look wrong here.... these are laying in the order they were removed bottom of the pic would be the front of the truck.

IMG_5736.jpg
 
All 7 have AC-DELCO stamped on them except for #8. it was stuck. all I did to remove was once the threads were clear from the head it spun easily with my fingers. I dropped the down pipe to get better access then grabbed it with a pair of plyers gently turning back n fourth and pulling straight back. it didn't take much effort but came out. I did not hear anything fall into the cylinder, I am thinking it's already ate the tip and spit it out, but I believe the damage has already been done and this might be what has caused all the blow by.

I will wipe them off better to get a good look and see if these are 60G's or what they are. I was under the impression it had Bosch duraterms as I saw a post here where they were installed at one time.
 
dbrannon79 said:
All 7 have AC-DELCO stamped on them except for #8. it was stuck. all I did to remove was once the threads were clear from the head it spun easily with my fingers. I dropped the down pipe to get better access then grabbed it with a pair of plyers gently turning back n fourth and pulling straight back. it didn't take much effort but came out. I did not hear anything fall into the cylinder, I am thinking it's already ate the tip and spit it out, but I believe the damage has already been done and this might be what has caused all the blow by.

I will wipe them off better to get a good look and see if these are 60G's or what they are. I was under the impression it had Bosch duraterms as I saw a post here where they were installed at one time.
Click to expand...

Yeah looks like it ate the tip like a Kardashian
 
I'm not sure I would be able to verify if that tip is still in the cylinder or not without pulling the head. I think I will just rotate the engine by hand a couple time and send it. I pulled them out due to the recent hard to start on cold mornings. I wanted to do a compression test and possibly a leak down test if I can fab up a homemade leak down tester.
 
On a side note, I can use the broken GP to try and make an adapter for a leak down tester. not sure how hard the metal is to hack off the remaining tip and drill though it. then attach an air compressor male quick coupler fitting
 
Just finished doing the compression test on the 93. not looking too good here.... when cranking it, I gave it extra cranks, counted about 9 compression strokes each.

1. 380
2. 250
3. 260
4. 270
5. 330
6. 350
7. 350
8. 270 (had broken GP)
 
I left it for the day. I still have some other things I can do on it. still need to check the voltage at the GP controller and amp draw. if all checks out I will bench test the 60g's and add one more good one to the mix. I can also increase the delay timer I have wired into the GP controller to run for 10 seconds instead of 8 seconds.

I thing what's adding to the hard starts too is the OEM style starter that's on it. I know last winter when I got the truck I gave that starter a good work out cranking on it to get it running. I bet it's also getting weak too.

I have my old starter that came off the 95. it's mounted on that 6.2 block and seemed to crank it over just fine when I was playing with it. I can try swapping them out and see if that helps.
 
If you been looking for an excuse to buy one of the $40 boroscopes on amazon- this is a good excuse. Pull the injector to see in there with the scope.


Do the tricks loosen any stuck rings. Beginning with fakey wmi treatment as the water misting will remove carbon from cylinders injector faces, and hopefully some carbon holding a ring or two stuck. (remember to undo pipe before cat/soot trap/muffler)
Then add the different liquids to try loosening the rings incase any are stuck. Long shot but a few hours and $20 could be worth it.

Then pour in the can of “Restore”. It can help clean up compression.
 
Well good news.. Started putting the 93 back together, bench tested the 60G's that came out. one did not work! so that left one bad 60g and the one broken. used a couple from the 6.2 block that were also 60G's installed them. then decided to pull the starter.

Glad I did pull the starter out, I found the bracket loose on the block! installed the starter I had pulled off the 95 and sinched up the rear bracket. gave it a once over and tried starting it up. hadn't changed anything on the delay relay, still the 8 seconds WTS. cranked over and it fired right up first try after it had been sitting for a week. still runs smooth so I think I will keep truckin her around till she blows LOL

Still have the inner fender to put back and a couple other things to tidy up but I was impressed she fired right up on the first try!
 
Got the 93 all buttoned up. started messing with the heater control motor since for some reason it decided to quit the last week. pulled it from the dash, tried actuating it hot to cold and it would go some and stop mid way. was going to go get a new one until I saw how much they were for this tiny thing.

pulled it apart seeing nothing wrong, had another I had gutted for the gears, tried it after swapping the gears out. same thing, it would travel some and stop, then messing with the control it started going again. swapped the gears back into the original one and for what ever reason it started working again!! I'm wondering if that digital control on the dash is going out. it's working for now so I put it all back together, pulled the truck out from the back yard to the front so I could drive it again.

cranked her a couple time and noticed that the starter I installed sounds much stronger than the one I pulled off. the only issue this starter had was it would click a couple times after it was hot on the 95. it will buy me some time to know if this truck is worthy of a powermaster, and to save up for one too.

I thought about putting a post out on some of the 6.5 FB groups looking for a used powermaster. I bet if I found one that needed a solenoid or something minor I could repair it to use on this truck.
 
Installed PowerMaster starter in the ‘94 K2500 Suburban and it works great.


Confirms the old starter was done. Had intermittent no start, until it finally would never start. No start happened after shutting down in front of my son’s house 2 blocks away the night before we were driving to Montana. He towed me home. I ordered the PowerMaster from Quadstar delivered to Montana (avoids CA sales tax).
 
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