Radiator fluid keeps leaking and boiling over.

[cherylea]

HELP... Whenever it's hot out, my antifreeze pours out and it starts boiling over and out of the cap. It is so hot, it seems like it's not cooling itself down. I fill it with anti freeze daily and it's getting expensive and it seems like I can only drive it at night when it's cool out. PLEASE HELP!!!

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section. It sounds like your thermostat is stuck in the closed position.

 

[safn1949]

Stop putting coolant in,fill it with water.Now does it leak right back out or does it overheat and then spew out.2 different things.

Ever been flushed? Did it start suddenly or has it been leaking for months,these are the things we need to know.

 

[cherylea]

thanks.. and i have been occasionally putting water in instead because it's cheaper, although it hasnt always done it. I bought my 99 explorer last september so i'm not sure if it did it last summer as well. But it only does it when it is driven on hot days and then it gets really hot and boils over and everything in it will leak out.

 

[cherylea]

It was fine all fall and winter though.

 

[cherylea]

another thing that might help is the heat barely blew out in the winter. The blower works, although not really any heat!

 

[BrooklynBay]

A stuck thermostat will prevent coolant from circulating through the radiator & heater core.

 

[my98nnj]

A stuck thermostat will prevent coolant from circulating through the radiator & heater core.

Incorrect!

The T-Stat is designed to fail in the open position. Spring gets weak and it opens early, result is you don't get up to operating temp.

When the T-Stat is closed coolant circulates thorugh the pump, block and heater core only. This is so the engine heats up quickly. Once it's up to operating temp, the T-Stat opens and lets coolant flow through the radiator.

To the OP. Have and exhaust gas analizer sniff your radiator. It's possible you have a small head gasket leak which shows up when things heat up.
It's also possible that your cooling system is plugged up. Have it completely flushed and check for proper circulation and heat dissipation from your radiator. Being you state your not getting any heat, my guess is a circulation issue. Two things cause that 1) system plugged up, 2) air gets into the system ie. exhaust gases.

The water pump generally doesn't fail to pump as it's a vane type. When it fails, it simply leaks.

Another thing to check is the fan clutch operation. It should have a fair amount of resistance, yet allow the fan to free spin. When the air running across the radiator heats it up it should bind up and spin the cooling fan at near engine speeds to aid in cooling.

Do make sure you use at least a 50/50 mix of antifreeze and water. Premix would be best to top the system off with. The reason is that antifreeze itself is a horrable heat dissipator and needs the water to help it disperse the heat from your engine out through the radiator.

 

[cherylea]

Thanks so much for the quick responses... hopefully this just saved my truck and alot of time!!! we'll see!!

so again... thank you all so very much!!!

 

[BrooklynBay]

I've experienced overheating due to a stuck thermostat which failed in a closed position. There are fail safe thermostats designed to fail in an open position, but not every thermostat is designed to fail in this manner. I understand that the thermostat acts like a valve to allow coolant to circulate through the radiator. Here's a link with more information: http://www.mgf.ultimatemg.com/group2/coolant/index.htm

 

[Tom G]

Incorrect!

The T-Stat is designed to fail in the open position.

I've had a thermostat fail closed and know of another guy who had it happen 2 weeks ago...

 

[safn1949]

I have had a lot of them fail in the closed position during the time I was tech,including some of my own..

 

[cherylea]

Thanks everyone!!! It makes sense now that it would be the thermostat stuck closed. I have it being looked at now to fix that...

Thanks for all your help!!!

 

[joe doe]

change the stat and the cap .the rad cap has been weakened now .

 

[ukdal1]

I've experienced overheating due to a stuck thermostat which failed in a closed position. There are fail safe thermostats designed to fail in an open position, but not every thermostat is designed to fail in this manner.

Fo sho! I had a 97 Ranger that did the same thing. I was on vacation with the wife and mine thermostat stuck closed. Had to get someone to change it for me. :thumbdwn:

 

[Oasiswoman]

I recently had my 1995 explorer sport overheat on me. The PCV valve was broken so we replaced it. Now the engine overheated again, and when you start it (after it's cooled down) the radiator fluid shoots 5 feet in the air, and the reservoir starts bubbling immediately. Help!

 

[my98nnj]

Oasiswoman - Sounds like a blown head gasket.

 

[Oasiswoman]

Nooo! How can you tell if the head gasket is blown? Also if you open the radiator cap, and put your palm on it it feels like it's sucking, then when you take your hand off it shoots into the air.

 

[bobflood]

Oasiswoman - Sounds like a blown head gasket.

+1 on this. Several ways to diagnose; best way is to have cylinder compression test done. Look for coolant in oil or oil in coolant; do a cooling system pressure test; look for white smoke (really steam) out your tailpipe; inspect spark plugs and look for wet ones; have radiator shop test for exhaust gases in coolant.