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Engine problems

MUDmaniac3

MUDmaniac3

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Jul 21, 2008
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Location
LaCenter, Washington
ok so here is the deal i have a mildly built roller motor in my blazer its gear driven and the other day i fired it up to go do some wheelin and while it was idling it just shut off. i went to restart it and would crank over like it had no compression or no spark so i checked it for spark and it had none. so long story short i checked all the electrical parts and replaced with other parts i had laying around and found the rotor to not turn when the motor did. i pulled the distributor it looks fine. So i pulled the valve cover off the driver side and while the motor cranks over the valves don't do anything. i can hear the gear drive so i know its turning over and i can see the fan moving. so my thoughts are i either broke a cam or the gear drive sheered the end of the cam so the gear drive is just not spinning the cam. any help would be greatly appreciated
 
Maybe the bolts walked out of the cam? The dowel pin would have sheared off too then. Or the cam broke. Either way I think you'll be pulling the timing cover. Hope you didn't bend any valves when you were cranking it over.
 
Yep, either a broken cam or a broken gear drive. What brand gear drive is it? Also you now probably have bent valves as chevy's are an interference engine.
 
its the proform gear drive and i have been pullin it apart for the last two hours so i'm almost to the timing cover now already pulled everything else all the lifters and push rods so we'll see. here soon.
 
Keep us posted. I took a look and the Proform gear drive is a 4 gear set and unless the link arm broke and dropped the idler gear you have a broken cam.
 
ok so i got the cover off and started to pull the cam the gear drive looks fine. the cam came out about an inch but will not come out anymore and will not push back in. everything is out so there should be nothing to be caught on. i'm gonna go to the machine shop that did the work on it and see what he says about it but the reason the cam will not turn is because the timing gear on the crank broke the key so it was just spinning on the crank which was making the noise like the gear drive was workin.
 
yeah all the lifters are out and put out of the way i've been toying with it for some time now and talkin it over with a few guys and there is no reason i should have sheered the crank key for the crank gear for the gear drive so the only thing we could come up with is that a cam bearing went bad and its stuck to the cam and won't allow it to come out or go in. sounds like its grinding on something when you spin it.
 
Did you pull the fuel pump pushrod? Cam will not come out unless the pushrod is out.
 
ok so i feel stupid. i pulled the fuel pump and the cam came right out. it looks ok now just gotta figure out why the key sheered so it don't happen again.
 
Was the harmonic balancer bolt tight? If not the balancer could have moved slightly which will then allow the crank key to sheer in half. Usually when a crank key sheers it ruins the crank snout and the crank will need to be repaired by welding the key slot shut and then re-brouching the key slot.
 
the balancer didn't see loose but i'm going to pull the bottom gear off and measure today and maybe try and get the new cam put in it and get all my parts to put it back together
 
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