I recently acquired a 250 motor and tranny. I pulled the oil pan to replace the gasket as it had a leak, and then I opened up the valve cover and found plastic pieces inside. Are these necessary? I believe they are called Valve seat gaskets? Is the plastic going to ruin the motor, if it falls down into the block? I found no plastic pieces in the oil pan, just in the valve area. Any help is appreciated!
They are called 'valve stem seals'. They get hardened over time from the heat and fall apart. Hopefully they don't get down into the oil pan. Just being there won't hurt anything as long as there is no way for them to get into the oil pump. Hopefully the screen is intact so that can't happen. Sounds like you are due to replace them. You don't need to remove the head. You have to remove the valve spring retainers and springs. You need either an air compressor and a fitting to pressurize each cylinder one at a time. The air pressure keeps the valves from falling into the cylinder. If you don't have access to an air source, a length of rope works just as well. How is that you say? With the piston moved down, stuff some rope into the cylinder. Leave the end hanging out. Then turn the crank to raise the piston up till it compresses the rope against the valves. The rope won't hurt anything. That will hold the valves closed while you remove the springs. Now you can replace the seals on that cyl. Once the springs are reinstalled, turn the crank backwards to uncompress the rope. Move on to the next cyl and repeat the procedure. Should cut down any oil consumption and oild fouled plugs you may have had. Good luck RS
I suspect that the oil pump on a six is a lot like on a V8. If so, while it is apart, I would get a Mellings replacement oil pump and pickup. I had pieces of valve stem seals kill two pumps until I replaced the pickup. The stock V8 screen can move up out of the way and suck junk into the pump. I think it was designed for the people who never change their oil and get sludge in their pans. If it picks up a piece of valve seal, that will jam the pump, and the driveshaft coming off of the distributor twists and breaks. The Melling pickup is fully sealed and can't do that. Cheap insurance ... I think I paid less than $40 at NAPA, but that was a long time ago.
The stock ford pump pickup screen (V8) has a grommeted hole in the center. If the screen gets spread away from the center cross piece it opens up the hole so that any large pieces in the oil pan can get sucked up into the pump. Either reform the screen so the hole stays closed by the cross piece or fab another piece of screen to attach over the hole. then no matter how much the screen moves nothing can get through. Have had it happen one time and the piece ( I think it was cork from an old valve cover gasket) got into the pump and twisted the shaft in two. I would never install one of the heavy duty driveshafts as I would rather have the shaft twist in two. That's better than breaking the pump or having stuff get by the pump to cause a plug up somewhere else. Other than a piece of debris getting in the pump something floating around in the oil pan most likely won't hurt anything else. Though it's a good idea to flush the pan to get the debris out of there. RS
"With the piston moved down, stuff some rope into the cylinder. Leave the end hanging out. Then turn the crank to raise the piston up till it compresses the rope against the valves. The rope won't hurt anything. That will hold the valves closed while you remove the springs. Now you can replace the seals on that cyl. Once the springs are reinstalled, turn the crank backwards to uncompress the rope. Move on to the next cyl and repeat the procedure." ...Frank...
that is a very short time for seals to harden. has the motor been ran hot after the rebuild? ...Frank...
If rope in cylinder scares you, You can hook up an air compressor to a compression tester fitting, that plugs into the spark plug hole. Open the air, and the compressor will keep the valves pushed up, then use a vavle spring tool to push the springs down, remove the locks and retainers, swap the seals. Replace. Repeat 2X for every cylinder.
Honestly I think the rings, freeze plugs and major gaskets where replaced only. The pistons look great where the valve stem seals are intact, but where they are cracked (not missing, but with some minor plastic pieces off) the sparkplugs where fouled.
Sounds like the seals were never replaced when the other work was done. Explains why the plugs are fouled where the seals that were cracked or missing. Amazing how many people bypass doing the simple stuff while they have the engine apart. Why not do it as a precaution while it is apart. Sure saves going back in later. RS
