Super Pissed at the Z71 - Cylinders 7 & 5 not firing

Take the valve cover off and make sure the rocker arms on #7 are moving up and down about the same amount as the other cylinders.

Next look at the valves on #7 and see if they are moving up/down like the other cylinders in the same bank. There could be a hole worn through a rocker end,

If everything looks good then rotate the crank so both the exhaust and intake valves on #7 are fully closed. Ideally #7 will be at TDC (top dead center)

Now pressurize (or attempt to pressurize) the #7 cylinder through the spark plug hole with compressed air. You can either rig up something to screw into the spark plug hole or even put a rubber washer on the end of a blow gun and just jam it against the spark plug hole.

If you hear the air escaping into the crankcase then you probably have a hole in the piston.

If there are bubbles in the radiator then its probably a blown gasket from the cylinder to a water passage.

If you hear air in the exhaust then its a bad/bent/burned exhaust valve.

If air is escaping back into the intake manifold then its an intake valve problem. Listen at the throttle body.

As a side note, if you tried the above procedure with cylinders that held pressure and had the spark plugs out then you also need to be sure the cylinder you are testing at Top Dead Center (TDC). Otherwise the compressed air will rotate the crank and shove the piston to the bottom of the cylinder and possibly have a valve open in the cylinder you are testing and get false readings.

Let us know what you find.

On the other cylinder you can still have a rounded off exhaust lobe on the camshaft. Compression will still look good because it can still suck in on the intake stroke. However if you look closely at valve movement you would notice very little movement wherever you have a rounded off cam lobe.

I have had personal experience with rounded off exhaust lobes on older 350 chevy's. They were almost round when I pulled the cam. Only 1 lobe was bad each time.Everything ran fine below about 50 MPH then it began popping back through the intake.

Good luck.
 
jrraw23 said:
No, no, you don't realize how much I wish I could . . . . still got a year and a half before i get outta college and get a job making enough money to where I can start making payments on one, till then im stuck
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you could have EASILY bought something with all the money you've wasted on that stupid truck. for example, i recently picked up a 2500 454/4l80e suburban for $2k in really good condition. it was cheaper than putting a transmission in my f350.:flipoff2:

it doesn't pass many gas stations, but it tows its ass off otherwise.
 
RufusTheRam said:
you could have EASILY bought something with all the money you've wasted on that stupid truck. for example, i recently picked up a 2500 454/4l80e suburban for $2k in really good condition. it was cheaper than putting a transmission in my f350.:flipoff2:
it doesn't pass many gas stations, but it tows its ass off otherwise.
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I think the lowest I've ever seen a decent tow rig was like $3800 for a f350 with a rebuilt 460 but at the time i didnt have the $$.

Tru if you add up everything I've spent on the Z71 I might coulda got something, not anything decent but something, but I don't have that much $$ sitting around at once, its just as I go I spend on it here and there, which I'm sure I would be doing on any other vehicle i bought.

Thats why I'm just going to wait then when I get out and get a job lease a brand new off the shelf truck for a couple years then trade it back in for a new one, rinse, repeat. Just so that I never have to lift a finger toward it again, I'm so sick of fixin broken stuff I'm willing to never actually own my own truck just so I can have a warranty. And in the mean time I refuse to buy another tow rig that I can "afford" and end up spending just as much on it in upkeep as I do my Z71 now, tru it wont be as modded and likely to break, but give me a break we all know how things break all the time regardless of how new or good of shape its in, thats why when I finnaly do take the step up I'll let someone else have to deal with my broken junk.

Course I say all this about waitin and buying new for the warranty but if I did find something for a real good deal I'd probably buy it just cause im a cheapskate . . . :shaking:
 
i don't know where you're looking, but i see good tow rigs pretty frequently on here and craigslist for $2-3k. case in point: http://nc4x4.com/forums/showthread.php?t=32241 it's a diesel to boot.

as for the money, just don't go spending every dollar you get on something. save a little. or, a small personal loan for $2k would be a negligible monthly payment. how much do you think you're going to spend on that motor?
 
As far as that truck goes IMO I don't want to buy a towrig that nots turbo'd already plus don't really want anything that old either, I would consider like a cummins 94+ or a Chevy 6.5 turbo'd 95+ but I still don't want to drop the $$ on a rig that I'm gonna have to end up fixin all the time, unless like I said above i find one for a ridiculous good deal.

Not sure how much on the 350, gotta get it apart and see what all's wrong with it. But I def will not spend more than a grand on it. Hopefully its just the cam and the valves that are messed up if so I can put a performance intake cam and chip on it for a good bit less than a grand. Not sure bout how much a vavle job costs thou . . .

But if the bottom ends messed up I'm not sure weather i'll keep that motor or not.
 
A reman SBC from AA or AZP would only run 7-800 and give you a 12 month unlimited mile warranty....

No way Id tear into that motor with your luck. Everything you fix will lead to the next problem.
 
SkyHiK5 said:
A reman SBC from AA or AZP would only run 7-800 and give you a 12 month unlimited mile warranty.....
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Last time I checked, they were ALOT more than that...
 
i wouldn't put a AA motor in one my trucks if you paid me and paid for it. the only option on a SBC is a chevy crate motor in my opinion i think i bought the last one for less than $1400 100k 3year warranty and its brand new from chevy. not rebuilt. you can't beat that.
 
sbc short blocks are so damn cheap... if you've got the 3/4 ton running gear anyway (brakes, suspension), go ahead and give it more juice while you're working on it so you can have an overall better tow rig.
 
Rich said:
Last time I checked, they were ALOT more than that...
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Ive bought two in the past 12 months
1 was 695 long block with core
Other was 775 long block with core

1 was ?69-77? other was a ?78-87?

My years may be off there a bit but there is a new and old pre-efi config. Both with perimeter bolt VCs

Honestly AA motors are hit and miss.
I will not install one without mic'ing every cylinder to ensure even bores as I have seen single cylinder punches. Then ill go through the entire engine and retorque everything.

Doing those two things, Ive never had a problem. Now I have taken 2 motors back without installing. 1 with 7-.030 and 1 -.120....uhhh yeah

The other the crank snout had been heli-coiled, poorly. Just didnt trust a miss centered damper.

I will agree hough. that if it was goin in my truck it would be a bowtie new motor.

Rickie, there is no way it will be economical to go inside that motor of yours, IMHO
 
Sell that POS and use the money to getcha a Schwinn. At least that will be reliable. You're learning exactly why I don't like GM products. Just out of curiosity, how many miles are on it?
 
rattlecanpaint said:
Sell that POS and use the money to getcha a Schwinn. At least that will be reliable. You're learning exactly why I don't like GM products. Just out of curiosity, how many miles are on it?
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Oh this has in no way got me mad at Chevy stuff :flipoff2:

lol, the engine probably blew due to simply what I put it through and its 190,000 miles :shaking:
 
this must be an example of Z71 badassness:poop::lol:
Good luck--check your local Iwanna there is always good deals on engines in there
 
jrraw23 said:
lol, the engine probably blew due to simply what I put it through and its 190,000 miles :shaking:
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Damn, If that was a Toyota engine you could put it through everything you threw at it and it would STILL last 250k before the blow by would require a rebuild. Drive it reasonably and you could get twice that.:flipoff2:
 
rattlecanpaint said:
Damn, If that was a Toyota engine you could put it through everything you threw at it and it would STILL last 250k before the blow by would require a rebuild. Drive it reasonably and you could get twice that.:flipoff2:
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Yea cept the yota would only have a top speed of 5 mph and cry everytime I tryed to tow with it :shaking:
 
awspence said:
^ this whole thread is your truck crying because of what you do with it, you DO realize that, right?
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Tru, but at least its not a wimp outta the box like all the yotas and jeeps :flipoff2:

Thanks Goodness I own 4 chevy's (Z71, 81 Chevy on 44's, 98 4x4 1500, Z71 Jeep) yes the Jeep is a chevy thats why its called a Z71, there is nothing jeep on it except the body which has official Chevrolet symbols and lettering so i guess I win as usual :driver:
 
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