401 overheating problem.

jeepman

well,i've discovered another piece to this riddle.after towing last week and it started running warm again,i got home and pulled it in the shop,never touched it until sat.i raised the hood and the top rad. hose was collapsed.replaced the hose and got to thinking,the overflow tank is s.s. round canister with no vent and the hose just goes onto a fitting on the top,it doesn't go down into the canister.may or may not be a problem,not sure at this point.

Mudrat

Could very well be a part of your over-heating issue! You need to vent the radiator over flow and ensure the pick-up hose is near the bottom - otherwise what good is it doing? Remember the heat/cooling cycle of the whole 'system' : As the coolant heats up it will naturally expand and flow past the *16LB* (some are 17 or 18LB) rad cap and should flow easily into the overflow tank (the need for the tank vent). After you stop and the coolant cools and contracts, it needs easily to suck the coolant back out of the (vented) tank (the reason for the collapsed hose?). The radiator cap is what keeps the cooling system 'pressurized' to raise the boiling point of the fluid. It is not a sealed system, but a closed system. The rate of flow into or out of the tank is not fast so a small hole is all that's needed in the top or the cover. A 1/4" would be plenty, and you can put a nipple on it or a filter if you're headed through the mud or nasty water routinely.

82Waggy

jeepman wrote
well,i've discovered another piece to this riddle.after towing last week and it started running warm again,i got home and pulled it in the shop,never touched it until sat.i raised the hood and the top rad. hose was collapsed.replaced the hose and got to thinking,the overflow tank is s.s. round canister with no vent and the hose just goes onto a fitting on the top,it doesn't go down into the canister.may or may not be a problem,not sure at this point.

System can't purge air if it has no way for the coolant to expand (no vent in the overflow canister). If overflow bottle was vented, it would only pull air back into the system since it cant pick up the expanded coolant from the bottom of the bottle as the system cools.

jeepman

i now have a new top rad. hose on motor,new factory style overflow coolant bottle and new hose running to it.now i'm waiting on a warmer day,with no heater in jeep yet it is a little cool to ride in.i'll keep you updated,thanks again. john

jeepnmatt

what intake manifold are you running?

jeepman

i had a edlbrock.i wanted to try another intake so i had a offenhauser on the shelf that i put on.had the same results.the only change was the edlebrock seemed to idle just a little better.still have not taken jeep for a ride,we have had some snow storms that got in the way. thanks, john

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