Dang.

[KZ750]

About a month ago on my way to work, my car blew out the top radiator hose.
It was pretty interesting. When the hose bursted, it started to squirt coolant at the exposed filter on my carb.
At first I thought that I had blown a head gasket after seeing all this white smoke coming from the back of the car.
Needless to say I'm glad that the motor is fine.

So for a while I've been concerned with this top radiator hose. It always heats up and bulges really bad. I guess it finally tore open that day. So there's obviously something going wrong some where. I've noticed that the lower hose does not get hot like it should. There's got to be a blockage somewhere or the thermostat is not opening.
I've since put it all back together and I'm still concerned that it is going to happen again. The PO hard wired the electric fan to always be on and I'm wondering if maybe they knew something that I didn't. New motor, new water pump, new thermostat. Is there some kinda sensor or something that I should look at? Maybe the fan always being on keeps the motor just under 180*F so the thermostat never opens????

[Gottolovem]

There is a sensor at the bottom of the rad "thermal switch" is it plugged in? If not plug it in and see if it cycles your fan at temp
Crappy old hoses will bulge even collapse on the bottom hose.
I would replace both hoses and go from there keep an eye on the gauge and don't red line it ever.
Did you get a cheep t-stat? that could be your problem.

good luck

[irowiki]

Was the hose an old hose, or a replacement?

[Petros]

Always replace any suspect hose, much better do that than have to rebuild the engine when one of them blows.

the upper hose is both hot and under pressure, it where the heated coolant returned back to the radiator. the lower hose should always be at a lower temperature, ALWAYS. if it was cooler than that means the radiator is not working, coolant coming out the bottom is supposed to be cooler than the coolant going in the top (it seems that should be obvious, I guess it is not).

The fan accomplishes no additional cooling above about 25 or 30 mph, the moving air provided more cooling than the fan, so it should only come on when not moving, or in hot slow moving traffic. the thermal switch as noted above should be checked and replaced if faulty. this fan, and this radiator can not over cool the engine, because the thermostat is supposed to maintain engine temperatures within a narrow range after it warms up, no matter the outside air temp.

Lower hose failures are very rare because they do not run as hot and have the suction from the pump on it, so it generally not under pressrue. sometimes they get soft and will collapse from the pump suction, and can cause it to over heat since the coolant flow is restricted, but this is pretty rare in our cars. If any of your hoses are in question, upper and lower rad, and any of the heater hoses, best replace them before you damage your engine.

[Tercel__jon]

Just to add to this, if the thermostat is stuck OPEN, the car will never get to operating temp while moving.

[KZ750]

Thanks Guys
Gottolovem- I think I might of spent $10 on the T-stat. There's probably a better one I can pick up. Definitely, I always keep my eye on that gauge. As soon as I noticed the temp rising I was at an intersection in the middle lane. I mobbed a curbed and pulled into the gas station right next to me. I'll check that sensor and see if I can get the fan back to normal.

Unfortunately, I have not replaced the hoses, but I will along with the T-stat. I just snipped the rupture off of the hose and put it back on with some fresh coolant to get home.

Petros- The way a radiator works is obvious. After feeling both upper and lower hoses after warming up on two different vehicles, I think my Tercel has a problem. The lower hose isn't even the least bit warm. It should be on the hot side of warm.