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Hey guys got a misfire on cylinder 6. Was on the highway cruising at 55 then my AC cut out came back on then got a Flashing SES Light on my 99 Blazer 4WD, Top speed was like 20 mph. Took the Valve cover off and found a Bent Push rod on Cylinder 6 first one from the passenger side closest to the firewall. The bend was on the side of the rocker. Is it a stuck valve or something else? Truck has 120k miles on it.
I would worry about that cylinder in general. Piston (or part of a valve) may have come apart and got under the valve preventing it's opening - munching the pushrod..
If it was mine, I would take off both rockers for that cylinder, and pressurize the cylinder with air through the spark plug hole. Air through the exhaust is stuck or bent or broken exhaust valve. Air back through the intake is stuck or bent or broken intake valve. A lot of air coming out of the crankcase is very very bad (but a hiss past the rings is normal).
If cylinder holds some air pressure and engine turns (when you pressurize it) so piston goes to it's lowest position, you might try a new pushrod. They're pretty cheap. But something definitely went wrong that a pushrod probably isn't going to fix.
Also you could look into the cylinder using one of those little endoscopes for your smart phone. I think you can get them for under $10 on Amazon.
Seems you`ll have to take the head off to find out
Actually not. Recently I've been buying an engine into the unknown condition. The seller probably wouldn't answer my claims if I had taken out the heads to check out cylinders Neither I wanted to do the expensive and time consuming job with gaskets, planning surfaces and so on, because You can't just take them off and put back.
A simple $15 usb camera fed through the spark plug mount let me do these photos:
It may sound stupid, but did You install a new pushrod prior testing? Otherwise, the valve won't close tight (or at all) and all the air You are trying to compress will escape easily.
As to the question "is it worth", I would suggest a following routine:
First of all, find out what made the pushrod bend. If You don't find anything visible with a camera inspection, You may take off the heads and deliver them to a workshop that makes the cylinder honing, etc and ask them for measuring the valve guide liners play. Once You have the measurements done, You may heck out the prices and reconsider is it worth. Without finding a reason and not knowing the possible options, it's really hard to tell.
It may sound stupid, but did You install a new pushrod prior testing? Otherwise, the valve won't close tight (or at all) and all the air You are trying to compress will escape easily.
As to the question "is it worth", I would suggest a following routine:
First of all, find out what made the pushrod bend. If You don't find anything visible with a camera inspection, You may take off the heads and deliver them to a workshop that makes the cylinder honing, etc and ask them for measuring the valve guide liners play. Once You have the measurements done, You may heck out the prices and reconsider is it worth. Without finding a reason and not knowing the possible options, it's really hard to tell.
To have the cylinders honed you would have to send them the block The heads are separate
08-27-2018, 09:52 PM
Misfire Cylinder 6 P0306
Neither I wanted to do the expensive and time consuming job with gaskets, planning surfaces and so on, because You can't just take them off and put back.
