Running Hot

[shambug]

This morning, heading on my normal commute I noticed that the temperature needle was a bit higher then normal, I kept my eye on it and it went up to about 3/4 to the top before I got were I was going. I took a look at the fluid levels and they looked good, so I let it cool off. On my way back it got much hotter, right below the red. I pulled over when it got up to red and opened the hood. Sure enough there was antifreeze poring out the overfill and the water hose from the engine felt very hot. I Let it cool off then finished my drive home. I did notice the thermostat connection is bad I will have to replace it. Also the water pump was from a junk yard. What could be causing this?

[dlb]

what do you mean, "the thermostat connection is bad"? are you talking about the temp gauge wire?

usually a bad water pump will either leak itself, or sound like a bad bearing when it spins. to me, coolant pouring out the overflow indicates either the cap is not holding sufficient pressure (it allows coolant to and from the overflow container at certain temps and pressures), or you have a blockage somewhere else in the cooling system causing it to back up. maybe refill the system and put a new cap on it, drive it close to your house so it gets up to temp again, and see if that fixes it. i like trying the cheapest, easiest fixes first.

[shambug]

By Thermostat connection I did mean the temp gage wire, its snapped and twisted back together, barely. I will be soldering it back together today. The cap did have a small crack in the side and I will be replacing it. I just don't see how the cap could cause the coolant to overheat. As for a blockage, do you think running water from a hose though the system in both directions would be a good idea? Or any other way to get rid of the blockage, like some kind of engine safe Drano?
Also as a side note the temp gage sometimes goes wild and bounces up and down rapidly, it will do this for a few minutes then back to normal for another few weeks, never thought much about it. Also when you turn on the fan switch, the temp gage goes up immediately about an 1/8th of the way up. Flip it off and it goes back down. probably not related but I though I would mention it because it was weird.

[dlb]

if a rad cap is faulty, it may not hold pressure and thus always allow coolant to pass to the overflow reservoir. in that case, it's like a lid that is never quite closed.

here's a good link on how rad caps work.

http://auto.howstuffworks.com/how-does- ... p-work.htm

i don't know about running a hose through the system backwards. i imagine that if you have a big enough blockage to prevent coolant flow, it is going to require far more pressure to break down than a garden hose can generate. a few of us here have actually recently purchased such a tool for dealing with such blockages and buildup of scale and rust in coolant systems, there is a thread on that here.

viewtopic.php?f=10&t=9589

but that's an expensive option and most shops do not have those so i would try the cap first.

good luck.

[Petros]

Not very likely you have blockage, sounds like your thermostat went bad, that is usually the only thing that will behave like that. You should not have allowed it get that hot, usually turning the heater on high will bring the temp down (verifying the t-stat is not opening all the way). if you have coolant spurting out likely the temp was actually up, not just a bad connection on the sender.

I recommend replacing the radiator cap if it is questionable, and the thermostat. These should be replaced about every two to three years anyway (Not worth the risk since they are inexpensive parts and the risk of causing major engine damage is high if these parts go bad). Do not buy a cheap thermostat, get the guaranteed one (both NAPA and Autozone, and I am sure others, offer those options). It should cost in the $16 to $19 range, well worth it. the $6 ones are junk, not worth installing.

After you get these replaced, watch your coolant level and temp like a hawk for the next 2 to 3 weeks (check the coolant level when cold daily if possible). If you are loosing coolant with no obvious leak, you will be in for a new head gasket soon. You can keep driving it with a leaky head gasket, but plan on doing it soon, it will get worse and eventually fail altogether.

The head gasket is sensitive to running it hot, just below the red zone on the temp gauge, is enough to damage it. You might get lucky and it will be okay, but it will take several weeks or a month of driving and checking it to know for sure.

You might also carefully inspect your radiator and heater hoses while you are at it, these usually last ten or more years (I have even seen old factory hoses still on 30 year old Toyotas), the upper radiator hose (the high pressure/high temp one) is the most important to replace first if you want to put off replacing the hoses.

Good luck.

[shambug]

Soldered the connections, got a new thermostat, cleaned the radiator and heater core. running good for now. Keeping my eye on the coolant level though. If the head gasket did degrade wouldn't I see oil in the coolant and vies versa?

[marlinh]

Not necessarily. Coolant could be getting into the cylinders and coming out the tailpipe.

[irowiki]

My 87 FWD has what I'm guessing is a bad head gasket. At idle it smells bad and you can see a white stream of smoke. Oil is perfectly clean though, and the coolant slowly vanishes.

[dlb]

bad head gaskets can manifest in many different ways. it depends on where the break(s) are, how many of them they are, how severe, etc. i think the most telltale signs are coolant loss with no visible external leaks and still running hot after all other possible causes have been ruled out. and of course, clouds of white smoke out the exhaust, coolant shooting out the spark plug holes when cranking with the plugs out, oil in the coolant, exhaust bubbling up through the radiator, are all pretty clear indicators too.

[shambug]

Overheated again today Pulled over and let it cool off. Driving at 20 mph It didn't overheat but push it to 25 and I could see the temperature start to rise.

[Petros]

was the coolant level down? If so, you are likely loosing coolant at the head gasket.

[irowiki]

Next time it does that, try turning the heater to max (hot/floor/high fan) and see if it goes down. If it does, radiator is bad.

[shambug]

A year ago I bypassed the heater core cutoff switch in the engine compartment, so the coolant always flows to the heater core now. Both times it overheated the heater fan was already on max and pumping out hot air. There is some kind of strange electrical connection between the heater fan switch and the temperature sensor though, because if I turn the heater fan off the temp will lower slightly like a 1/16 of the way down, turn it on and the temp will go up slightly, and the change happens so fast that no real change in temp is possible. Also every mouth or so the temperature gauge will behave erratically and shot up to MAX temp for a few seconds then down to MIN then back UP. What is happening now this is much different then that though because it slowly goes up and doesn't bounce around. I have ordered a new temperature sensor.

When it overheated today the overfill reservoir was full to the brim and although I didn't see any fluid spilling out the very end of the overfill hose was moist. I removed the engine water bolt and ran water though it, no problem. I took the radiator out again a gave it a good 2 hour vinegar bath, no problem. I did notice that about 1/5 of the radiator fins were bent. When it overheated today I put my hand on the top coolant house and it was very hot, put my hand on the bottom hose and it felt cool. The only other clue I can think of is that running at 30mph in 3rd gear the temperature will stay right in the middle, also 20mph in 2ed gear almost as good. Could this somehow be related to the idle fuel mixture I adjusted recently?

Test driving it today the oil light popped on for a sec. I was driving over a long 2 lane bridge in rush hour but I killed the engine anyway and pushed it off the bridge. With so many horns you think someone could help push but no. When I got her out of traffic I opened the hood and checked the oil, still full. So felling lucky I started it back up, and oil light was gone. I put a new oil pump in 3 months ago but it was the cheapest one on ebay.

[Petros]

sounds like you have eletcial problems, not oil and temp issues. does the car show other symptoms of overheating? it might just be your wire bundle is degrading and starting to short out. My oil light flickers on and off occationally, and it is not even plugged in! I put an oil pressure gage several years ago. A bad connection on either oil or temp sender will make it go off, temp gauge will go to max. If it were me I would add some auxiliary gauges (with their own senders and wiring, auto parts stores have them, not too costly) and watch both temp and oil pressure everyday for a week or more. If they show okay, than replace the senders and fix the wire bundles.

This way you will know for sure if you have engine problems or not, without risking diving it without oil pressure.

[shambug]

I believe you are right that I have electrical issues. I think the oil light was an electrical issue and has not come on again. I do believe that the car is overheating though because of the coolant overflowing the first time and over filling the reservoir the second time. I have ordered a new temp sensor, and I think I will get an oil pressure gauge to make me feel safer. Am I correct that given the radiator is not plugged and the hose at the bottom was cool that its not the radiator?