'91 Exp running hot. Edge of Normal, but not quite overheated.

[papahepcat]

Hi folks, I'm a newly christened owner of a '91 Explorer. I'm running a super tight budget and got this for (amazingly) within budget.

It has a few quirks, and I'm finding a lot of good information on this site. I'd been googling before, but I always ended up here with the answers!

So the first thing I'm going tackle deals with cooling the Exp. It runs pretty hot. It actually didn't when I was driving it the 40 or so miles back home after I bought it, but started doing it pretty quick after that. On the way home, I'd get hot air out of the cab vents; now I don't. Coolant level is ok. No obvious leaks. The needle rides right on the edge of Normal, though it'll drop a little if I'm stopped.

The guy I bought it from dumped a little bit of radiator leak seal when I bought it. He said someone who looked at it earlier didn't buy it because it was leaking coolant. He also thought there might be some other seal stuff in there.

At this point, I'm sure you're all thinking the guy clogged it up when he dumped that stuff in there. That's what I'm thinking. I think it's still flowing, just really slowly. Tomorrow, I'm planning on flushing it and replacing the thermostat. I really liked Doonze's Ultimate Flush writeup, but I don't have that much time. It'll just be a reg flush.

So, any thoughts? Am I on the right track? Tips or tricks I should know about?

 

[Iron Weasel]

A thorough flushing sounds like a good first step.

All those "leak sealers" that you put in the radiator are junk. They normally can seal small leaks, but they also clog up other areas that aren't supposed to have gunk in them. If you have too much of that stuff in there, you could very well have it in the water pump, plugging up the radiator, or anywhere else.

 

[papahepcat]

Hey, I didn't put it in there!

But yeah, I'm not a fan of those things. They're a band aid fix, at best. I'm curious to how much junk will come out when I flush it later. It's supposed to rain today and I don't have a garage, but I'm going to do it anyway!

 

[BWTGUY]

papahepcat, I had a small leak in my 92 and it turned out to be a screwdriver hole courtesy of my not-so-friendly FORD agency. The side areas of your radiator are PLASTIC! (thank you FORD). I looked into getting a radiator from a Pick-Ur-Part but it was $75.00 and a new one delivered to my front door was $94.79 from RockAuto (Spectra Premium), an upper and lower radiator hose, a radiator cap (15 Lbs pressure), and a new coolant temperature sender completed the purchase for an additional $37.91. Total of parts and shipping was $166.81.

It took about 45 minutes to change all of the above (I rented a FAN wrench set from the local Reilly auto store - they return the deposit, $10.00, when you return the wrench so it was essentially free. Read how to do it here on SE and tore into it.

Three gallons of 50/50 antifreeze (O'Reilly had it two for one priced so I now have an extra gallon and a half) add another $25.00. I also bought a new thermostat at O'Reilly for $5.95 and a ECM sender unit, $14.95, to complete the re-do of the cooling system. Total from O'Reilly, $45.90. While you have it apart, take your garden hose and flush the engine by pulling out the thermostat, reinstall the thermostat housing and insert hose in opening to the thermostat and let the water do the work.

Reinstall everything in reverse order. There are several threads here that tell you how to disassemble your cooling system by people smarter than I am and it really works. I also replaced the temperature gauge sender unit and ECM sender units while I was in there.

A gigantic bonus is that the new ECM sender unit started reporting the correct temperature to the Electronic Control Module (the afore mentioned ECM) and gas mileage went from 14.5 MPG to 17.5 MPG in town and from 16 MPG on the road/freeway driving to 21 MPG! It seems my possible defective ECM sender unit was reporting a colder than actual engine so the ECM was sending an excessively rich mixture to the engine no matter the speed.

Total cost (I saved my "mad" money for two months to pay for this) was $212.71. The heat gauge now sets at from between the NO in NORMAL to , when really working hard, like towing, right on the Start of the M in NORMAL. Happy Ex, happy owner.

Oh yeah, ford quoted $940.00+ to do this.

These are excellent vehicles despite the best efforts of some FORD agencies to bad-mouth or replace everything in them. Do it yourself for real satisfaction and I am sure someone in the 87,000 + members of this forum will help you or have an answer. They have always helped me.

 

[huntman58]

papahepcat, I had a small leak in my 92 and it turned out to be a screwdriver hole courtesy of my not-so-friendly FORD agency. The side areas of your radiator are PLASTIC! (thank you FORD). I looked into getting a radiator from a Pick-Ur-Part but it was $75.00 and a new one delivered to my front door was $94.79 from RockAuto (Spectra Premium), an upper and lower radiator hose, a radiator cap (15 Lbs pressure), and a new coolant temperature sender completed the purchase for an additional $37.91. Total of parts and shipping was $166.81.

It took about 45 minutes to change all of the above (I rented a FAN wrench set from the local Reilly auto store - they return the deposit, $10.00, when you return the wrench so it was essentially free. Read how to do it here on SE and tore into it.

Three gallons of 50/50 antifreeze (O'Reilly had it two for one priced so I now have an extra gallon and a half) add another $25.00. I also bought a new thermostat at O'Reilly for $5.95 and a ECM sender unit, $14.95, to complete the re-do of the cooling system. Total from O'Reilly, $45.90. While you have it apart, take your garden hose and flush the engine by pulling out the thermostat, reinstall the thermostat housing and insert hose in opening to the thermostat and let the water do the work.

Reinstall everything in reverse order. There are several threads here that tell you how to disassemble your cooling system by people smarter than I am and it really works. I also replaced the temperature gauge sender unit and ECM sender units while I was in there.

A gigantic bonus is that the new ECM sender unit started reporting the correct temperature to the Electronic Control Module (the afore mentioned ECM) and gas mileage went from 14.5 MPG to 17.5 MPG in town and from 16 MPG on the road/freeway driving to 21 MPG! It seems my possible defective ECM sender unit was reporting a colder than actual engine so the ECM was sending an excessively rich mixture to the engine no matter the speed.

Total cost (I saved my "mad" money for two months to pay for this) was $212.71. The heat gauge now sets at from between the NO in NORMAL to , when really working hard, like towing, right on the Start of the M in NORMAL. Happy Ex, happy owner.

Oh yeah, ford quoted $940.00+ to do this.

These are excellent vehicles despite the best efforts of some FORD agencies to bad-mouth or replace everything in them. Do it yourself for real satisfaction and I am sure someone in the 87,000 + members of this forum will help you or have an answer. They have always helped me.

With all of that may as well just finish the job and do the water pump the heater hoses and bypass hose also. Then you will have just about fully R &R your cooling system minuse the fan and fan clutch.

On a side note if you do change your radiator, ALWAYS CHANGE THE HOSES (all of them) or you will be doing it later one by one at the most inconvenient time! How do I know this? I am a slow learner and had to relearn this lesson a few times (trying to be cheap) before it became a mandatory do with any radiator replacement!

 

[papahepcat]

Yeah, if the flush and stat don't do it, then I'll probably replace the radiator and the water pump. There's a local who has both of them for less than $100 online, but they usually charge less than 1/2 that when you show up and pull the part yourself. I love that place . Part of the reason I bought it was because Ford uses the same parts in so many different vehicles, and their parts are cheap. Easy to find and costs little.

I'm pretty sure it just needs a flush. It was just fine on the way home. The only difference is the guy dropped some of that seal stuff in there right before I bought it. But I need to get it done right away. I'm paranoid about blowing a head gasket. That... would make me VERY grumpy.

 

[BWTGUY]

Huntsman58 the heater stuff including a new core and the water pump were changed three months before I bought it. Since I had the receipts and trusted the shop that did the work, I elected to leave that stuff alone. I replaced the fan (ten blade) and clutch last week as a backup - read just in case. They came from Pick-ur-part cheap ($8.00 for the pair).

 

[huntman58]

Well then you’re on your way to doing a full R and R. My self and this is just for my self there are some parts I just will not go the PYP way with and the cooling system is one of them. I will admit there are few I feel that way with but I just have never had good luck doing that way over my 35 plus years of owning and working on autos.

 

[papahepcat]

Well, I flushed it and replaced the thermostat. It was all so dirty! All water and gunk, no antifreeze. I also put in some of that Prestone Super Engine Cleaner that says in it for like 3 - 6 hours. Took it for a test, and immediately saw it not running hot. Yay.

BUT. I think in flushing it, I may have revealed a larger problem. I think the head gasket is leaking. Bubbles in the reserve bottle. Exhaust seems extra steamy. No yay.

Any suggestions for helping it limp along until... say, next summer?

 

[papahepcat]

The day after my last post, I decided to try some Block Seal out of desperation. Followed the instructions to a T, and what do you know? It worked!

I refilled the radiator and temp is just fine. The radiator leaks pretty bad, though. I have to put water in it every few days. I'll just replace it when I get the chance.

 

[huntman58]

In your case you may want to try a Junk yard pulled radiator as if you’re leaking that bad you really have nothing to lose and a lot to gain. Just make sure that you get one with some kind of warranty so if it to leaks you can bring it back and exchange it tell you get a good one. Just a thought.

When the time comes to redo the head gaskets just have the extra then to do the cooling system then so that you do it all right and have a worry free system from then on at lest for a few years that is. The last thing you want after doing a head gasket or even an R and R head replacement is a cooling system that could go out and over heat your motor warping or cracking the heads as these 4.0 are known to do.