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Bent pushrod
https://slantsix.org/forum/viewtopic.php?t=31656		 Page 1 of 2
Author:  Chuck [ Sun Oct 12, 2008 12:36 pm ]
Post subject:  Bent pushrod
OK Guys, the Webmeister needs your help. The Dart just started running poorly so I removed the valve cover and discovered a bent pushrod on #6 intake. I have seen this once before over 20 years ago but I don't remember if I figured out the cause.

What can cause the pushrod to bend? It bent about 30 degrees. I'm going to replace it in a few minutes then turn the engine over by hand to make sure that nothing is hitting.
Author:  SlantSixDan [ Sun Oct 12, 2008 2:28 pm ]
Post subject: 
Lack of lubrication (how's your top-end oiling?) and/or plain ol' metal fatigue...
Author:  Joshie225 [ Sun Oct 12, 2008 3:04 pm ]
Post subject: 
Old gas can gum up the guide and stick the valve bad enough to bend a pushrod. How old is the gas in the car? If the fuel smells bad, regardless of age, drain it.
Author:  Chuck [ Sun Oct 12, 2008 5:18 pm ]
Post subject: 
Old gas may be it. The car has been sitting for a while and the gas smells funky. I added some fresh gas a few days ago but maybe it didn't help.

The lubrication is good and the head is really clean (only about 70k on this motor).

You probably can't see it in this picture but this whole area of the block is wet, probably oil. I've never seen that before. There are also black marks around the exhaust manifold like it has a leak there. I guess I'll be doing that valve job sooner rather than later.

Image
Author:  66aCUDA [ Mon Oct 13, 2008 6:08 am ]
Post subject: 
Chuck
My symtom was bending push rods (valves were loosening up on #5) ended up being a cracked adjuster.
Frank
Author:  Chuck [ Mon Oct 13, 2008 9:02 am ]
Post subject: 
Quote:
Chuck
My symtom was bending push rods (valves were loosening up on #5) ended up being a cracked adjuster.
Frank
Well, this baby is down for the count until I do a valve job, so I'll check the adjusters when I do that. Thanks.

With the oil all over the back of the motor, it looks like a blown head gasket as well.
Author:  Doc [ Mon Oct 13, 2008 9:55 am ]
Post subject: 
I would re-torque the head, replace the bent pushrod, recheck the valve lash (cold - pelim. settings) then disconnect the fuel feed line from the fuel pump and run 2 feet of hose into a can of fresh gas.

Start it up and see how it runs... and go from there.
Slants are tougher then most people realize.
DD
Author:  SlantSixDan [ Tue Oct 14, 2008 8:19 am ]
Post subject: 
It is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions.
Author:  Chuck [ Sat Oct 18, 2008 10:06 pm ]
Post subject: 
Well, I did a compression check on #6 with the intake pushrod out and got 3 lbs of compression. I think there is a hole in the piston. I can't see enough through the spark plug hole to be sure, so I figure I will have to pull the head when I can be sure that I can also replace a piston if necessary. (I wasn't able to get the lifter back in the hole after it popped out.

I might be able to put a wire through the spark plug hole and feel around a bit.
Author:  norcalmoparnut [ Sat Oct 18, 2008 10:41 pm ]
Post subject: 
If your intake valve doesn't open, you wont get any cylinder pressure.
Author:  rock [ Sun Oct 19, 2008 7:08 am ]
Post subject:  Chuck, here is sumpin else cool to try
Chuck,

I have a lot of friends in the bug extermination business. Almost all companies doing the work have a camera on a 5/16 flex coax that goes in holes in the wall to look for tremites and roaches.These are called boroscopes (from bore scope) and if you know a bug killer that person might find it intriguing to look inside your cylinder for a very low price if in your neighborhood. (remember the recent post from the guy that had roaches in the carburetor?

rock
'64d100
Author:  SlantSixDan [ Sun Oct 19, 2008 7:18 am ]
Post subject: 
If you had a holed piston, there would've been a more dramatic "show" than just noticeably poor running. You'd've had high-volume blowby and smoke out of the crankcase (visible coming out of the oil cap, etc.). As norcalmoparnut says, if the intake valve doesn't open, there's nothin' for the piston to compress, so you won't see any compression pressure! :shock:

I'd toss a good pushrod in just to see what happens...
Author:  Chuck [ Sat Oct 25, 2008 2:16 pm ]
Post subject: 
Quote:
If you had a holed piston, there would've been a more dramatic "show" than just noticeably poor running. You'd've had high-volume blowby and smoke out of the crankcase (visible coming out of the oil cap, etc.). As norcalmoparnut says, if the intake valve doesn't open, there's nothin' for the piston to compress, so you won't see any compression pressure! :shock:

I'd toss a good pushrod in just to see what happens...
Thanks Dan. I was going to try that but I can't get the lifter back in the hole. I figure maybe the hole got buggered up from the loose pushrod. I also didn't figure on no compression if the intake valve isn't opening. Makes sense now that I think about it. I need to work on that lifter some more.
Author:  steponmebbbboom [ Sat Oct 25, 2008 7:09 pm ]
Post subject: 
why don't you do what the professionals do and just install a leakdown tester? it will not only tell you if you are losing pressure, which you are, but from where. harbour freight, $20.

you hook it up to shop air and listen for a hiss from intake, exhaust, or crankcase. BDC, power stroke.
Author:  Chuck [ Sun Oct 26, 2008 9:54 pm ]
Post subject: 
Quote:
why don't you do what the professionals do and just install a leakdown tester? it will not only tell you if you are losing pressure, which you are, but from where. harbour freight, $20.

you hook it up to shop air and listen for a hiss from intake, exhaust, or crankcase. BDC, power stroke.
Sounds good. I never bought one because I haven't needed it yet! Thanks.
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