have been chasing the sos intermittent cooling issue that gets my ultragauge up to 215/216 at times for no reason.
new fan clutch (had to go through 2 of the autozone 977220 variety to get one that worked right) new auxiliary fan and confirmed they are all facing the right way..
the one piece confirmed that is wrong is that the auxiliary fans that come on with a/c do NOT come on as the temps hit that high w/o a/c on..
SO to the RAVE.. but the rave only addresses the NAS version of the v8 stating that the ECU says when to turn on the aux fans..

My Question is at what temps do you all hear your aux fans kick in with no a/c turned on.

Please note that the RAVE specifically gives the temp for MFI and TDI's at 212f.
And it also states that it is the switch x113 that triggers the fans on those versions but that is not the case with the NAS SFI.

Last note for ALL d1 drivers.. the RAVE states that the only time the aux fans kick in on the v8 after engine shutdown is when temps hit 230f !!!! that seems way to high to me..

tanks 2 all

 

First thought is that if your trouble is intermittent, you may simply need to bleed air out of the system. Many suggest raising the front passenger corner while bleeding can help.

Outside of that the only other details which come to mind are...
- is your fan cowl in proper order
- is your fan installed correctly (cupped side toward engine)

 

Thanks
yea.. the only reason I have not tried bleeding is that no gurgling sound is present and that was a strong indicator on my last d1 that always had air for some reason. Also the heater is strong and hot. yep all fans are blowing the same way.

Have you ever heard your aux fans kick in on a day that you were not running the a/c? If so do you recall the temp?

My next step is to rod the radiator, but not knowing if the aux fans are doing what they are suppose to is bugging me.

 

Have you checked the temp sensor?

 

Would be a good idea to ohm out your sensor in the morning and compare it to ambient temps, and also ohm it out when it reaches operating temp. You can leave it in place and either ohm it out at the ECM or at the sensor. Or, just replace the sensor with a good known one.

You didn't say anything about the thermostat, but I assume you looked into it? Tstats can become sticky ...the shaft or pintle can 'catch'. It's not super common, but as they wear, it's possible it can happen.

What about air flowing 'around' the radiator and fan? Is all the rubber gasketing and shrouding that should be around the radiator and shroud, in place like it should be, or did another owner throw it away and therefore not all the air is flowing through the radiator that should be. Pretend you are an air molecule ....how many different holes, gaps and routes could you flow around and NOT go through the radiator. The more there are, the less effective cooling you're going to have. On older Corvettes, owners used to complain about 'chronic' overheating problems and so many owners would go to great lengths and expense to buy a larger aluminum radiator, special high-flow fan, aux fans and so on but didn't address the root problem which was ensuring that all the places that air could be pulled 'AROUND' the radiator were closed ....like ensuring the foam (like installed at the factory) was in place (which most never do), and the fan blade-to-shroud-distance is correct. Usually you address those first, problem solved even with a stock radiator.

Is the fan the right distance into the shroud? If someone installed an incorrect waterpump, spacer or fan clutch, then the fan might be sticking too far in or out. If its too far out, it's pulling in some air from the engine compartment and not 'through' the radiator like it should. On mine, the rear of the fan is flush with the shroud as I look down at the fan. Check for any paths which air could be pulled from areas NOT through the radiator.

Is the fan belt routed properly. This is a VERY common error guys (and even mechanics) make on these Discos. If you route the belt like you would 'think' it should be routed, it's probably incorrect and has less tension that it should which can cause lack of airflow. I know because that's how mine was when I bought it. I had the same thing ...spend a bunch of time tracking down exotic problems when all it was was the stupid belt put in wrong! When this happens, the belt tends to slip at high speeds and eventually causes sharp grooves on the alt and maybe even the fan pulley, glazing of the pulleys (meaning they're worn and should be replaced) and at that point, you really need to even replace the pulleys because a new belt won't ride in them and get traction like they should. Seriously, check the belt routing and make sure it's correct, then inspect the pulleys correctly.

Do you have a winch or bull-guard on your truck? These can cause overheating problems by blocking airflow. My brother's truck overheats with his plow pump installed (even with the blade off). Anything that can disrupt airflow can be a problem.

Is there a bunch of debris between the air conditioning condenser coil and the radiator? This could include mud, bugs, plant material and so on. Make sure the air path is super clean.

What's your lower radiator hose look like? Check it for firmness. Is there a coil spring inside it? At high speeds I've seen (and experienced on other vehicles), the lower radiator hose collapsing on itself due to suction. If the hose is flabby, you're at risk anyway (leaking lower hoses destroy a lot of L/R engines) ...queeze it in different places to make sure it's strong enough.

Pressure - Is your system holding sufficient pressure? If not, that can cause overheating as pressure is used to raise the boiling point. If it's too much pressure, then consider the next problem:

Head gasket - Maybe you have the early stages of a failing headgasket? This can cause overheating too. Do you hear gurgling of water when you start your truck in the morning (from the heater core)? Bubbles in your overflow tank (may or may not be present). Well, chances are ...if you've bled out the air previously, and you hear this, you may have the beginning stages of head gasket failure. Sometimes H/Gs can leak air and drip a little fluid for years until they completely fail, because the head gasket is kind of made in layers and a minimal amt of leakage can occur where a couple layers swell and develop a 'split' between the layers kind of like water leaching between bricks. Check under the oil cap for milky substance.

Double-check the belt routing... so, so common.

On mine, my aux fan tends to go on often when I park the vehicle and shut it off ...so yeah, it's probably in the 230 stage though I never checked.

 

Thanks all, checking the sensor for sure, did not think of that.
Mark, your rich knowledge and details of your post .. wow! perfection. I can't even pay for info like that in this town!

 

You're welcome. All that 'knowledge' was from living all those mistakes

BTW, you probably know this, but you can take your thermostat and place it in a pan and raise the temp of the water. Have a thermostat in the water. Watch closely as it approaches 192 or whatever t-stat yours is ....watch for it to open up. If it's good it should open up ...but even so, use your fingers and double-check for smooth actuation and no hang-ups. A new one isn't very much money. If you haven't changed it, probably worth buying a new one if you have the old one out of the vehicle. But don't replace it until you have double-check your belt routing to this diagram:

 

Bleed that sucker. Chased temp spikes for days and couldn't figure out where the air was trapped. Turned out the replacement top radiator hose I had installed earlier was just too long where it goes into the pump. Trimmed several inches off that sucker and this lowered the hose and took away the air pocket. Then I took a 8 foot six by six cut in half, nailed together, cut an angle and made a ramp to put that r/f tire on. Purged the system FINALLY. The curb thing just didn't get the height.

Some have also reported a tiny air pocket developing around the actual sensor that'll steam and play havoc with the temp gauge.

BTW mine never gurgled but I just knew it was air in there somewhere.

 

Thanks for that input Rob - talked me into it. I have a ramp that should work . 1st troubleshooting rule.. start with the simple stuff