I have a 743 that the engine and radiator, have been rebuilt. Overflow tank and radiator cap are new. My question: After filling the radiator and expansion tank at "cold" level and running the engine to temp fluid goes into the expansion tank just as it should. But when the engine cools the fluid does NOT go back into the radiator. Just stays at the "warm" level in the expansion tank. I used a generic 12 LB cap. Thanks
Bobcat 743 Cooling system radiator cap question
- Thread starter ozark18
- Start date
flyerdan
Well-known member
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- Mar 7, 2009
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The cap needs to have a seal where it goes into the pocket on the filler neck as well as one at the top so the vacuum in the cooling radiator doesn't pull in air from around the top of the cap.
My guess would be that you don't have (or have a defective due to a tear or obstruction) the rubber seal inside the cap. Or there could be a bend or gouge in the top flange of the filler neck that doesn't allow a full seal; the radiator will draw in air a lot easier than pulling the coolant back, least resistance and all that.
My guess would be that you don't have (or have a defective due to a tear or obstruction) the rubber seal inside the cap. Or there could be a bend or gouge in the top flange of the filler neck that doesn't allow a full seal; the radiator will draw in air a lot easier than pulling the coolant back, least resistance and all that.
My thoughts exactly. You get caps that are not for overflow tanks, and others taht are for “revocery” systems. They need a rubber outer seal so when the fluid cools and shrinks, it draws fluid from the overflow tank.
I had this issue till my dad pointed out what i did wrong
