Overheating


82Stang
05-13-2011, 11:24 AM
1998 Dodge Ram 1500 318/5.2L 213K

Truck ran normal before, just using coolant, slight white out tail pipe. Noticed pinhole leak at back of timing cover gasket and radiator was shot. Parts replaced.... Radiator, thermostat, radiator cap, water pump gasket and timing cover gasket. Water pump looked good and tight, fins excellent.

Propped up right front to bleed, just kept getting big bangs of air coming out of radiator open cap every 2-3 secs. So much so, it blew a cup or more of coolant out with it. Got hot. Let it cool down, then topped off radiator and ran. Could hear noises from heater core, possible leakage. I bypassed the heater core under the hood by hooking the hoses together. Topped system off once again and ran. With radiator cap off, let it run for half hour and I don't get that big burp or even opening of the thermostat. I am positive the thermostat is not opening because the radiator is stone cold and the closer I get down the top/bottom radiator hoses to the water pump/intake, they get hot. I've bled the heck out of it and when I install the radiator cap, the temp rises steadily to overheat. Oil looks good, no milkshake, trucks sound like it runs fine.

Why wouldn't the thermostat be opening? I could purge air forever it seems and it still get's temp gauge pegged. Thanks for your ideas.

Chris Stewart
05-13-2011, 07:45 PM
I drill a 1/16" hole in my thermostats to relieve air and let the hot water get the the thermostat.
The thermostat in my Cummins comes with 2 small holes for that reason.

82Stang
05-14-2011, 07:22 PM
These Dodges aren't a pleasure to burp. Air in the system is a common problem. One of which I have been working on for some time. If that is the only problem, I will be happy.

aleekat
05-15-2011, 11:28 AM
Run it without the thermostadt. If it doesn't overheat. New thermostadt bad

82Stang
05-15-2011, 06:49 PM
Run it without the thermostadt. If it doesn't overheat. New thermostadt bad

I'm going to be safe and sure, by boiling the old one and see if it opens, same with new one. I'm pretty sure it's an air pocket issue though. Everything I've read says to lift the right front of the truck, which I did and tried bleeding it many times, but thermo wouldn't open. One told me to have truck level, otherwise air will get trapped. I would not be surprised at all to find out the new thermo was bad though. The quality of new parts today isn't what it used to be. Was also tipped about filling the engine through the thermo hole when open, thus making bleeding easier. Thanks for the response.

82Stang
05-16-2011, 02:02 PM
Problem solved. An obstruction in the lower radiator hose. Never would've found it unless I replaced the thermostat. Thanks for your responses and ideas.

Chris Stewart
05-16-2011, 06:15 PM
Thanks for the update.
What sort of obstruction...bird nest?

82Stang
05-16-2011, 06:21 PM
Thanks for the update.
What sort of obstruction...bird nest?

Piece of rubber/plastic wedged in.

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