Overheating

[fire57dan]

I have a constant overheating problem. About 6 months ago it was running hot and I replaced the coolant sensor, thermostat. I have also recently replaced the water pump and radiator. I also have an electric pusher fan. Yesterday I was sitting in traffic and it started to overheat and shut off. When I'm at freeway speeds it runs fine at normal temps but when I slow down and am in stop and go it dies. It has happened about 6 times the last 6 months. I dont really know what to do considering it has basically a new cooling system. The coolant and oil were also right where they are suppose to be and the coolant is less than 6 months old.

 

[MAKG]

Sounds like your fan clutch is inoperative.

If you removed it, believing the bullcrap about electric fans being "better," put it back on. You can have the stock fan and a pusher at the same time.

 

[Bob Ayers]

YUP, go back to the mechanical fan/clutch and that will solve your problems!!!

 

[fastford04]

i didnt think u had to have a fan clutch if you put a electric fan on...???

 

[Psychopete]

i didnt think u had to have a fan clutch if you put a electric fan on...???

Not technically... I run a 16" electric without any problems, and it's been installed for at least 4 years. It works, my old stuff was shot, so I just never replaced with good working mechanical. It doesn't get too hot where I am, this will make a difference. Plus I have aftermarket heads, they're not as prone to crack. I am not as worried about it.

I don't have an aftermarket gauge either, but it's never gone up past half way since I've rebuilt it. It did overheat before the rebuild w/ cracked heads (ran out of coolant ) and topped the gauge.

My Ranger came w/o A/C from the factory, and stated right on the cooling fan, "Not equipped for A/C", so I don't have that creating more heat.

It's more of a tolerance thing, I can get by with it, but it's not going to work as well as the mechanical fan.

However, I do plan to go to a mechanical fan on my 5.0L swap (and maybe use the electric as a pusher, but probably not).

Pete

 

[Big Jim M]

Dan If it don't puke out it's coolant it AIN'T hot! The temp rising some in stop and go traffic is normal for all vehicles..
In any event the temperature isn't causing the engine to cut off. I'd suspect a coil or other lectric feature to be causing the stoppage.
Big JIm

 

[philS]

Sensor

About 6 months ago it was running hot and I replaced the coolant sensor

Which coolant sensor did you replace -- the ECT (for the computer) or the gauge sensor?

 

[MAKG]

In any event the temperature isn't causing the engine to cut off. I'd suspect a coil or other lectric feature to be causing the stoppage.

It can, but it's not too likely (and it's VERY serious if it happens).

An overheated piston fits more tightly in the bore. Get the ring gap to zero, and it will stop.

 

[Big Jim M]

It can, but it's not too likely (and it's VERY serious if it happens).

An overheated piston fits more tightly in the bore. Get the ring gap to zero, and it will stop.

Yep! But usually before that happens a hole is burnt into the piston or the top of the piston collapses amd the driver begins to understand he has a problem..
Big JIm

 

[fire57dan]

I have an electric fan and I chose to leave the mechanical one on knowing that these overheat easy. The coolant was boiling well when I remove the cap yesterday. Since everything is new, I heated up the old t-stat on my stove and it didnt start to open till about 205* I thought that was too high.... I replaced the sensor thats right behind the t-stat, I did not know about another one. Im thinking I should put in a lower temp t-stat they list both a 195 and 165 in the computers at napa and kragens.

Thanks for the quick responses guys!

 

[AllanD]

It can, but it's not too likely (and it's VERY serious if it happens).

An overheated piston fits more tightly in the bore. Get the ring gap to zero, and it will stop.

An overheated piston has nothing to do with Ring end-gap.

the piston skirts which are the woidest part of the piston "swell" and
try to spot weld themselves to the cylinder walls.
Sometimes they succede and this is the engine Seizing.

The only thing the rings have to do with it is collecting
all the little blobs of aluminum by scraping them off the
cylinder walls this jams the rings in the piston and they
stop sealing, this is a loss of compression.

An "overheat" usually won't "burn holes" in the pistons
that is usually a mixture problem OR a result of cylinder heads warping form the heat and allowing coolant into the combustion chamber.

Coolant is flammable.

AD

 

[Big Jim M]

OH Dan!

I have an electric fan and I chose to leave the mechanical one on knowing that these overheat easy. The coolant was boiling well when I remove the cap yesterday. Since everything is new, I heated up the old t-stat on my stove and it didnt start to open till about 205* I thought that was too high.... I replaced the sensor thats right behind the t-stat, I did not know about another one. Im thinking I should put in a lower temp t-stat they list both a 195 and 165 in the computers at napa and kragens.

Thanks for the quick responses guys!

When the cap is removed after running, the coolant is SUPPOSED TO BOIL OVER!! Put the 205* BACK IN THERE! NEVER use a lower temp than stock thermostat.
Overheating is when the coolant boils over all by itself. It is summer time for crists sake.. quite looking at the gauge and drive her till she pukes...I'm betting she NEVER WILL!
Don't be afraid of a little temperature rise, it is normal.
Big JIm

 

[MAKG]

I had this argument the other day with a rather clueless parts guy.

205 deg is a bit high to START opening, but it's more or less normal for it to be completely open. I'd replace it, but it's not causing overheating (yet). Stock for most (all?) RBVs is 195 deg.

People think cooler coolant makes more power. No, it doesn't. Cooler AIR CHARGE makes a little more power, but unless you have nitrous on your intake (which is illegal on the road and will give you cryogenic intake temperatures), the difference is VERY SMALL. Why? At high airflow (WOT, high RPM), the intake charge is within a few degrees of ambient regardless of any manifold heating or whatever. At low RPM, it matters much more, but you aren't really measuring power off idle, are you? The air just doesn't spend enough time at high flow -- in a properly sized intake on a tuned engine, it's transonic -- in the manifolds to change temperature much.

People also seem to think a lower thermostat does something about overheating. EVERY working thermostat will be wide open well before overheating takes place.

I replaced the thermostat on the Chevy on Sunday. The parts guy INSISTED on giving me a 160 deg thermostat. It's carbureted, so the computer won't be confused into continously warming up. BUT it has enough of a fuel atomization/evaporation problem with wildly different intake runner lengths (3/4 is extremely short; the rest are substantially longer) even with a properly working heat riser, at idle and low RPM, that it makes no sense at all to try to cool it down.

I insisted on a 195 deg. It works. No way this thing is overheating; it has a massive 4row radiator (intended for V8s with air conditioning and the tow package).

 

[fire57dan]

Sounds good. I got a new 195* t-stat and will investigate the fan clutch next.

 

[cocoasranger]

After I swapped my A4LD for a Mazda manual trans I noticed that my overheating problem when stopped in traffic in summer had vanished. I did not change anything else. Maybe the drag of the torque converter when stopped combined with the heat of the trans fluid in the trans cooler mounted on the radiator was enough to show a high guage reading.