The Stovebolt Site Forums The Parking Lot Big Bolts Cooling issue

53 chev 5100 COE. I have the truck running and driving for the first time in 30 years and am having some cooling issues. I have replaced the radiator core, thermostat, cap and hoses. The engine runs fine but wants to spit water out the overflow hose. Not a bunch but enough that the fluid level goes down and the. Running temp goes up. Today I noticed that the radiator and top hose were warmer than the bottom hose but don't know for sure what that means. I have not replaced the water pump. Thanks.

the top hose should be hotter than the bottom, it means the radiator is doing what it's meant to do pushing water out probably means you've put too much in, the fill level should be about 2" or more down from the neck to allow for expansion - check the temp around the engine and rad with a good laser thermometer to find out what the gauge is telling you, 5-10* above the thermostat rating is fine

Bill

Did you "burp" the hoses,(purge the system),when you added new fluid? I didn't,and my truck ran fine,for about a month,(after re-building the head). I drove it over 200 miles in that first month,without any problems. The day before it over-heated,i hauled a 4-ton load of railroad ties,and the gauge read the same as the ammeter. Right in the middle of the op. temp. The next day,i gave the guy,(that wanted the r.r ties delivered,a ride into the nearest town,which was only 6-miles. No problems going to town,But,on the way back, after about two miles,the gauge slowly climbed steadily,until,3-miles later,it as almost "pegged". Luckily,I pulled over,in front of a friend's house,who had a garden hose long enough to reach the place where I parked. By the time he purged the system,to rid it of air pockets,I had NO coolant left,(just straight water),but the gauge stayed below the 1/2,(cool side of operating temp.), mark. I bought 2 gallons of premium coolant immediately,and re-filled the system. I made sure to fill the radiator,(engine RUNNING at about 1,200 R.P.M.),and squeeze the upper radiator hose.This helps rid the system of trapped air bubbles,which prevent the coolant from circulating properly). It takes between 15 minutes,to 1/2-hour,but it's definitely worth it. I didn't put the cap on,until I didn't see a bubble,for 5-minutes.you'll need to wear gloves,or wrap a rag around the hose,'cause it'll get HOT. That was two Summers ago. I haven't had any trouble since then. Hope this helps.

Thank you both. Makes perfect sense, now. That's why I posted, I guess. Always good advice. A-Burping I will go.

Some members also drill a small hole in the thermostat top plate for this purpose. You can search the posts it has been discussed fairly often.

Thanks,Brad! i KNEW I was forgetting something! This will allow "trapped" air in the block,to "Escape" out of the overflow tube,via the thermostat "vent",(hole).

Hey Willy...just to be clear, the 3/16" hole drilled in the t-stat plate has nothing to do with the overflow tube, unless your calling the Upper Radiator Hose the Overflow Tube??? The hole just allows trapped air to bubble up from inside the block when the t-stat is closed (engine not running), as you stated. As soon as the t-stat opens the little hole is a mute point...

Mike B

Thanks for clarifying,Mike!