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Joined: Jan 2002
Posts: 89
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jan 2002
Posts: 89 |
I have a 1953 235 pg block that was rebuilt by a engine shop.The motor was line bored ,balance the works and has been a very strong motor until yesterday.After a 2 hour run down the freeway I stopped and when I took off again the motor backfired and stop running.Aftr the usual checks I pulled the value cover off and the #2 intake push rod top had broken in half.Does any one know what my have caused this? I guest the first thing now is to remove the side cover and try to find the top half of the rod. MARK47
mark47
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Joined: Dec 2001
Posts: 11,162
ChatMaster - 10,000
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ChatMaster - 10,000
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You may or may not have lost the cam timing gear, after you check the valves and pushrods for stuck valves, pull the distributor cap and see if the rotor turns as the engine is cranked by the starter.
Life's a long winding trail, love Jesus and ride a good horse!
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Joined: Jan 2002
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ChatMaster - 25,000
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ChatMaster - 25,000
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If your lucky it was just a push rod metal failure.
My thoughts it was a stuck valve. They may have made the guides too tight when they rebuilt the engine causing the valve to stick when things got heated up. If the piston did strike the intake valve it may have bent the valve. If so engine will miss when running and pop back through the carburetor.
I would install a new push rod and turn the engine over by hand and see if the valve is moving OK. Before doing that I wold squirt some Marvel Mystery Oil on the valve stem (or WD 40)-lubricate stem by shooting oil through the coils of the valve spring. Then if its running OK I would dump some MMO through the carb. throat with engine runing.
Other possibility - If engine will not start - timing gear went out. Does the rotor turn when you crank over the engine?
Gene Schneider
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Joined: Jan 2002
Posts: 89
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jan 2002
Posts: 89 |
Thanks for the reply. Yes it does turn over. Before I removed the valve cover I did get the motor started again because I was sitting in the middle of the street. I had to drive it about 1/8 mile before I could pull over safely. It was running rough and backfiring. I know that wasn't the right thing to do now. The engine builder used - I dont know if I'm spelling this right - Melling push rods. Thanks - Mark 47.
mark47
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
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Are they hollow push rods?
Gene Schneider
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Joined: Jan 2002
Posts: 89
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Jan 2002
Posts: 89 |
They appear to be solid.I haven't removed them yet.The top of the rod is shaped like a Y .
mark47
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Joined: Aug 2002
Posts: 410
Backyard Mechanic
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Backyard Mechanic
Joined: Aug 2002
Posts: 410 |
It is odd that it broke, I have had them bend from stuck valves but never broke.
Cleon
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Joined: Dec 2001
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ChatMaster - 10,000
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I am like Cleon, but i haven't used any of these repop push rods, may just be sorry metal from Asia.
Life's a long winding trail, love Jesus and ride a good horse!
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Joined: Jan 2002
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ChatMaster - 25,000
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ChatMaster - 25,000
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For mechanical parts I prefer to use new old stock genuine Chevrolets parts or if its a non-wearing part like a push rod just reuse the old originals.
I do have hollow tubular push rods in my '39 but they are not of recent manufactoring.
A good hollow is lighter and stronger and help to reduce valve train noise.
Gene Schneider
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