Thread: Why is my "Y" block bending pushrods?

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Hey I was wondering if one of you guys could explain why my 312 ford thunderbird "Y" block is bending push rods? I know it is because the valve are sticking for some reason on that head but what is making them stick. I have driven the car about 7500 miles in the last 3 years with not as much use in the last year. It is stored in a dry heated garage year round. I had one bend this spring and I removed it and replaced it and then pulled the other valve cover and adjusted all the valves on both heads and then visually inspected the rocker arms which are very clean, no deposits. Then I treated all the valves to a double dose of mystery oil on two seperate days, put the whole thing together and gave it a tune up and reset the carb and timing. Just today I took it for a 10 mile drive to my shop, gave it some fresh 93 octane gas, and added another half quart of mystery oil to the crankcase oil. When I went to come home I started the bird and it bent another push rod. I limped it the 1 mile home and tore off the valve cover to discover a different one bent. How can I fix this problem. Besides carry extra push rods? Thanks for any help you can give. Randy

I know I have posted this before; but, it is possible (especially since you haven't driven it much this year) for the fuel to schalaque (sp? anyway go bad) and cause things (like a valve or a carb) to gum up. Usually there are other signs of this or a sticking valve too though. Like backfiring through carb/exhaust, very low power etc.

Anyway, if the valve is sticking in the guide and causing this, one thing you can try is this:

Start the vehicle, and get it idleing. Remove the air cleaner and raise the throttle a bit off of idle. Next SLOWLY pour a small amount (about a tablespoon) of automatic tranny fluid into the carb. DONT let the motor die while you are doing this or it will fowl the plugs. As the tranny fluid burns in the cylinder along with the A/F mixture it will lubricate the valves and should free up any that are sticking on you.

Good Luck,
Firechicken

I had a similar problem with a 472 Cadillac that I drove infrequently. Turned out the valve guides or the valves in them were corroding and binding up. Had a valve job done, no more bending pushrods.


Don

Y-blocks are noted for poor oiling to the rockers and valves. There used to be kits to fix the problem, but you can just Tee into the oil system at the pressure sender and run 1/8" lines under the valve covers to the U-bent pipe on each rocker shaft. It's caused by misaligned or wrong cam bearings not allowing oil to flow past them to passages in the block, up past a head bolt on each side, and to the rockers. A full teardown is required to fix it "right".

Thanks for the help. I'll try that tommorrow when I put the new push rod in. Hopefully that will solve the problem atleast for this summer cruising season.

I would first check to see if oil is exiting overflow tube, on the affected head, with motor running. If it is not then like R Pope said, there is a fault in the area of the cam bearing, or there is a plug in the oil passage, most likely on the top of the block where it makes a dogleg before going into the head.
If it is a problem with lack of oil getting to the rocker shaft, then there is probably a galled shaft and grooved, worn rockers as well. Check the bores of the rockers.

hi guys. if i'm reading this right then i'll bet it's the gas gone bad as stated above. had this happen to me on a 5.7, had 3\4 tankof fuel in the truck and had some old gas (that i dn't think was that old) so i through it in the tank and drove to work the next day.drove to work the following day and on the third day went to start the engine and all i got was a very bad noise. (stuck valves. very costly 2 gal's of gas. if you don't drive that mush maybe you could try to add something like (sta-bil) to the tank and that should help in the long run.ithink that you are going to have to pull the heads to fix it right good luck