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Overheating. HELP!

dr fildo

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Year, Model & Trim Level
1999 Mercury Mounaineer
'99 V8 AWD Mounty. Temp went way up. I turned the car off before it overheated. Steam from the passenger side of the radiator by the air filter box. No heat in the car. Overflow reservoir is full. The drivers side cap is barely hot. Engine temp cools down in about 10 mins. I can go 3 or so miles before temp gets too hot. The water/antifreeze doesn't seem to be flowing at all. Limped home and there she sits.

Thermostat was replaced less than 2K miles ago.

How can I tell if this is a water pump issue, or a blocked radiator issue? Could it be a bad thermostat? Bad heater core?? Where do I start?
 



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When it's cool, remove the radiator cap. The radiator should be FULL. If it's not my guess is you have a leak in your radiator on the passenger side. Most likely the end-tank gasket has failed. When this happens (which is a common failure with plastic tanked radiators) the system is no longer sealed, so even though the overflow tank is full the cooling system will not draw the coolant from it. My suspicion that your radiator is low/empty is bolstered by the fact that you're not getting any heat from the heater core.

BTW: Changing the radiator on a V8 is a PITA. It's doable (I've done it 3 times now) but it's a wrestling match because of the way the A/C condenser is attached to the radiator. Changing the radiator on the V6 is a piece of cake.
 






Thanks, Koda. I did the steering rack last year which was a beast. I hope I can handle this.

Any recommendations on where to pick up a radiator?
 






Thanks, Koda. I did the steering rack last year which was a beast. I hope I can handle this.

Any recommendations on where to pick up a radiator?
I've purchased 3 CSF brand radiators through places like the Frugal Mechanic and PartsTrain (whoever had the best price + shipping at the time). They are single row (that's what my trucks came with from Ford, so I figure that's good enough). As I recall I paid around $100-$120 w/free shipping. I find these radiators are identical to OE in appearance and fit. I think the first one I purchased is 4+ years old now and I haven't had a problem with any of them. If you need a replacement quicker check Advance on-line with promo codes. Even if your local store has the rad in stock, if you buy it on-line using a promo code you can save money and pick it up immediately at your local store.

If you look in the HELPFUL THREADS sticky's, Joe Dirt had done a thread on changing the 5.0 radiator w/pics. It's helpful, but it's still not an easy job. I did the first one by myself and needed extra hands on the next two. Good luck.
 






Koda, you are ALWAYS right on target. Thanks for the help. picked up the new rad with a 20% online discount for $129 +tax at Advanced online. It wasn't even that difficult to change, thanks to you and the helpful thread section, but I do have another problem now. 2 actually.

1. I started the car with the MAF sensor relay unplugged (I took the whole air assembly off to get it out of the way) and now I have a Check Engine light on. Can I just unplug the battery for a few minutes to reset it?

2. The fan for the HVAC unit in the car isn't doing anything at all. Was working fine after the repair. Just went to start the truck maybe an hour after I finished the repair and now - nothing. Could this be related, or coincidental? Where is the fuse for this?
 






1. Unplug the battery for 5-10 mins and turn the headlights on to drain any residual power from the electrical system. This will reset the CEL. You didn't hurt anything by not having the MAF sensor plugged in.

2. The HVAC blower fan not working seems totally coincidental to me, unless maybe you left the battery connected (always disconnect the battery when working under the hood) while replacing the radiator and shorted something out blowing a fuse, but then you say it was working afterward... Check fuses first. Refer to your owner's manual for fuse & relay locations

Do you have the automatic or manual HVAC controls?

Try tapping on the blower motor with a hammer (from the engine compartment). If it starts working the motor is worn out.
 






Ok. Thanks. I went out to get the owners manual out of the truck to check the fuse location, and just for ***** and giggles I figured I'd start it up and try it, and it seems to be functioning normally again. Which is good, but a little concerning. They're the manual controls with the dial.

I'm going to reset the CEL later. Thanks again for all the help. You're the man.
 






Ok. Thanks. I went out to get the owners manual out of the truck to check the fuse location, and just for ***** and giggles I figured I'd start it up and try it, and it seems to be functioning normally again. Which is good, but a little concerning. They're the manual controls with the dial.

I'm going to reset the CEL later. Thanks again for all the help. You're the man.

Well if it's working intermittently it's not a fuse and I don't know if it uses a relay. With the manual controls the problem doesn't sound like the ballast resistor, so that leaves the blower motor, the wiring or the fan switch. My guess would be that the motor's worn out.
 






Looks like it's the blower motor. CEL is off. Tapping on the motor turns it on.
 






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