astrotek

I have been working on an 87 GXL which has been sitting for several months as I'm getting it back into working condition, I have this problem -

The car would run at about 1/4 - 1/3 temperature solidly for roughly 20 minutes (freeway or highway driving) and then suddenly skyrocked to above 'H' and overheated. This happened consistently. I would let it cool down, refill with water, start driving again, and this entire process would repeat 20 minutes later.

I replaced the upper and lower radiator hoses, the thermostat, the cooland overflow hose, the radiator cap, removed the radiator and pressure-hosed it out to ensure smooth flowing (fine), checked the water pump (fine), and put it all back together.

So today I take it out for the first test run (to work) and the temp is running around 1/4 for a good 20 minutes (freeway driving). I stop, get gas, leave the station, get back on the freeway, and about 5 minutes later the temp had skyrocketed to 'H' again, but not past (unlike before where it would be pinned past 'H' unless I shut her down quick).

The fan clutch was slipping pretty badly a while back, but I epoxied the fan to the fan clutch as a temporary solution (I was in the middle of the desert and didn't have any tools) until I can replace it with an electric.

The big question - do these symptoms sound like something that could possibly happen from the fan clutch? Or would the fan clutch not give these type of symptoms?

I cannot figure this out. Any help is greatly appreciated.

HAILERS

Not much help here except to say I've driven cars with absolutly no fan whatsoever on long trips i.e. highway only with no problem. Is it possible that the belt is slipping? Probably not seeing what you have done. How about removing the thermostat completly and driving it. The gauge will remain in the lower eighth of the gauge. Is the car really overheating? Besides the gauge does it boil over into the overflow tank? Just thought I'd ask. EDIT....the removal of the thermostat was not meant as a *fix* just to get a clue what is happening. Could be just some electrical short on the wire to the temp sensor if its not really overheating. Is there any chance that the wire to the sensor has a bare spot that is touching ground? Probably no. You seem to be sure its really overheating. Might even try to run without the fan on open hwy. That is suspicious what you said about the epoxy. Only four nuts to remove it. Could do it at a rest stop and avoid stop and go driving.

psycheus

What's up Ryan,

Still having a overheating problem? I remember that you saying that it was the lower hose that was pinching the coolant out of the engine? That didn't fix it? The post before me mad a good point, it could just be a short in the wire.

Sorry I can't help more.

Rick
rtm@frys.com

jizzajuice

There are some things that I didn't see in earlier posts. I've had a bit of these problems and a solution that seems to be working is replacing either cracked hoses *if you have any, and/or replacing the clamps themselves. The stock mazda clamps kinda suck. I'd recommend the ones with the screw in them. Also, another place to check is the thermostat housing. Is there a greenish tinge on the seal? If you see some, that means coolant is leaking from there. Basically check the cooling system for coolant leaks. One final thing, the radiator is a good spot to check. If you have the tools available, jack up the car and take a peak underneath. Take off the front bedpan protection plastic thingy.... pardon my bad description ^_^. You should be able to see the radiator from there. Mine had mucho debris on the side of the radiator closer to the engine. After clearing a lot of that stuff off, the temp decreased somewhat. Anyways, if you STILL have cooling problems, the final solution is to get an aluminium radiator. To flush out the radiator is really costly cuz there are a few parts on the OEM radiator that are plastic and have to be 'broken' off in order to remove the radiator to be flushed. I hope this helps, and sorry for the extremely long post!

Peace,
AJ ^_^

astrotek

Hey Guys,

Thanks for the informative responses. Here's a bit more information to help narrow it down:

(1) When I replaced the thermostat, I cleaned all any crap/residue off the face of the pipe housing before I reapplied new Silicone Based sealant crap. I believe the seal there is not the problem because the overheating issue was exactly the same before I did this work as well as after (now).

(2) Replacing the clamps - Good idea...I did notice that the hose to the overflow is dripping little drops of water/coolant right where it clamps onto the plastic cap. I'm going to tighten that when I get home.

(3) As I mentioned, the radiator was taken out and flushed/checked (by a knowledgable mechanic friend (who has an SE himself)) as well as the fact that the radiator was brand new before the car sat for several months.

This problem has not only myself but two knowledgable friends stumped!

---Here's an update---

I drove it back from work after this original post yesterday and although it didn't overheat, the temp was at 1/3 (and was slooooowly rising). The drive to/from work is 20 miles one way-almost all freeway. Driving it back to work today was successful, but just like yesterday, as I arrived at work, the temp creeps past 1/3. I feel confident that in another 5 miles on the highway, it would have skyrocketed just like yesterday. The pressure in the hoses was significant (simply tested by feeling the pressure) although not boiling over [yet]. Another important thing is that after I gave the car 5 minutes to cool down, it took almost 1/4 gallon of water (It was full right before I took it). The overflow was full when I left and even fuller as soon as I arrived. After waiting 5 minutes for the car to cool down, the overflow went back to just 'full'. I've checked for major coolant leaks and I simply can't find anything other than the above mentioned tiny dripping from where the overflow tube goes to the plastic cap.

Does this shed any new light for anyone else?

punkncat

Ok , the problem is that you are losing water.Find out where the water is coming from and stop all the leaks.Hopefully it is just a hose or line somewhere.You may have to check to see if the engine is leaking water internally.I doubt this as you evidence the water leaks above. Likely spots that are easy to miss are the water hoses running under your intake, and the heater core. My car had this same exact problem.It turned out to be the heater core hose was leaking . The water system will not pull water from the overflow correctly with a leak , so the heat up progresses quickly .If you haven't ,replace both radiator caps too.Good luck .

Evil Aviator

My SE had a problem similar to this. It turned out to be a pinhole leak in the heater hose that only leaked once the pressure and temperature rose (and of course it never leaked when I checked under the hood because the engine was at idle and under no load). The pinhole leak in the hose was caused by oil leaking on it from the o-rings under the oil filter baseplate. The hose is kind of a pain to replace because of its location, but the o-rings are inexpensive and really easy to replace.

bflette

I had the same porblem a few months ago and I had to replace the engine due a broken seal inside the engine that caused exhaust gasses to blow into the coolant. This would cause the coolant to increase in temp. like you described and be ejected through the overflow tube along with the exhaust gasses. I am alomost certain that you have the same problem. With the number of times you have overheated the engine it must be toast by now. IF you would like any more info feel free to email me.