1994 Explorer Craziness - Heatercore Maybe?

[dfb]

Actually, the interesting part is that the gauge is only working intermittently period now. TS-unit has been replaced so I'm either going to have to get an external gauge or replace the cluster. Not something I'm in the mood for this exact second.

Isn't there a "bleeder hole" in the thermostat??? It should be at the 1200 oclock position when installed...

 

[smtcapecod]

cap

Don't forget that the cap pressurizes the system.
I had a little more responsiveness from temp guage after replacing my cap-- which was clearly shot. Didn't resolve the issue, but was part of the picture.
Going in for thermostat and heater core shortly.

 

[elliswife]

The latest...

Thermo was installed properly with bleeder at 12, so was my radiator cap (replaced I mean). I had the system pressure tested and it turns out my intake manifold gasket is shot. Painful... but it'll be fixed by tomorrow evening.

 

[dfb]

Bummer Dude......

 

[elliswife]

No kidding. I had my timing chain cover replaced.. I'm being told that it was probably never leaking (since it didn't fix the leak) and that the above mentioned evil intake gasket isn't far from it... it was probably this the whole time. Nice to know I got a $700 oil change in the end (LOL) not that having the gasket and cover new is bad... just not needed.

 

[firewolfm]

Oh Boy, the thermo could be defective but are you getting heat from the inside vents? are the controls for the heater/defroster working? My '92' Xplorer XLT the gauge goes up to the red zone then it comes back to proper temp I was going to replace the thermostat but the truck doesn't overheat and I believe in letting sleeping dogs lie.
It's like the check engine light... It goes on/ it goes off ,on both of my trucks they both run perfectly and have over 150,000 on them. don't fix what is not broken these trucks have charactoristics/personalities I spend very little money on investigating and keep both trucks serviced and tuned-up, it works for me.
If there is one thing FORD trucks are not it is money pits.... Good Luck and email me if you want straight answers about the do's and don't in these '90s' model Xplorers. These are million mile motors they are built ford tough...

 

[elliswife]

I've replaced the thermo TWICE. Because I was paranoid about it. Still has a wacko gauge. Heater core and heat are fine. My mechanic thinks the actuator (spelling off) or something else electrical is weird in my cluster. We already replaced the sending unit and checked the head gasket and replaced EVERYTHING ELSE in the cooling system. I figure it's just wacked out. What can I say? It doesn't overheat or lose coolant, why fix what isn't hurting the truck? I just make sure to check the fluids frequently because the gauges are funky.

 

[smtcapecod]

har

yeah, these auto hubs are a real gem. As is the body rusting out from under the plastic bits! And door hinges that fail..and the temp guage failures..anyway...
At least the balljoints and parts that fail in under 100K miles are cheap!

..thing about thermostats...if its stuck how do you know you aren't overheating the engine, even if the rest of the coolant jacket is below temp?

Replaced my thermostat, all is well...did the heater core and valve and hoses at the same time, but I'm confident that the thermostat was the problem. EDIT: Notsofast, temp guage was bottoming out on a highway run today..shhesh.

Any chance a p/o used a leak-stopper and clogged your heater core or other passages?

 

[Jason Alexander]

You mentioned your vehicle is a 1994, but the following information might be helpful. If anything, just to know that there are know problems with temperature fluctuations for this engine. This would also seem to support my former theory on how the volume of flow through the heater hoses could affect the operation of the thermostat.

TEMPERATURE GAUGE FLUCTUATION ON 1995-2000 4.0L FORD ENGINES

Temperature Gauge Fluctuation On
1995-2000 Ford 4.0L OHV Engines

AERA members have reported a temperature gauge fluctuation on 1995-2000 Ford 4.0L OHV engines. Along with this fluctuation, the customer may complain of a knocking or thumping noise as well.

This noise is most pronounced with the engine at normal operating temperatures and heard in the passenger compartment of the vehicle. The noise is caused by steam formation in the cooling system. This noise is then transmitted through the heater hoses and heater core.

Ford offers a Coolant By-Pass kit to cure this problem. This kit increases the flow, which reduces steam formation in the cooling system. Refer to the chart listed below to get the correct By-Pass kit as it depends on the type of vehicle the customer has.

Application -
Coolant By Pass Kit

1997-2000 Ranger with auto or manual trans and
1997-2000 Explorer with auto trans -
F8PZ-8522-AA

1995-2000 Explorer with manual trans and
1995-1996 Explorer with auto trans -
F8PZ-8522-BA

1995-1996 Ranger with auto or manual trans -
F8PZ-8522-CA

The AERA Technical Committee

The website:
http://www.rebuiltautoengines.com/ford-explorer-articles.html

In regards to your mechanic informing you that your lower intake gasket is shot; I have replaced my lower intake gasket twice, and I still have the same old temperature gauge fluctuation. I have also replaced my head gaskets, water pump, radiator, radiator hoses, radiator cap, heater core, fan clutch, fan, and my coolant multiple times in the 20k miles I have owned this truck. I have used 4 different thermostats from 4 different manufactures. I have not replaced the heater hoses.

A bad lower intake gasket on this motor will allow oil to leak from under the front and back of the intake, it can allow a vacuum leak which can suck oil into the intake ports from under the intake, and it can allow coolant to leak. But unless your coolant is leaking, the seals around the coolant ports are not leaking. I know what your mechanic did. He put a socket on some of the lower intake bolts, and was able to snug them up a bit. Thus, verifing that your lower intake gasket is "shot".

You will find some useful information pertaining to the lower intake gasket on this website: http://www.explorerforum.com/Singleton/web/pages/ping.html

On this website you may notice that oil accumulation on the spark plug of cylinder #5 is due to a bad intake gasket that is allowing oil to be sucked into this cylinder port. This is not true.

A bad lower intake gasket will allow oil to be sucked into intake ports, (not always necessarily #5) which will cause carbon to build up in the cumbustion chambers. Too much carbon build up can increase the compression enough to degrade the engine's performance, as this engine does not have a knock sensor. Excessive build up will eventually cause pinging.

But, I have replaced my lower intake gasket twice and I still have the same problem with oil accumulation on the spark plug of cylinder #5. The oil is coming from the pcv system. Cylinder #5's port in the upper intake is directly across from the pcv valve port. I have had my intake off enough to know that the oil is coming from the pcv system. I even took the throttle body off and I could see a puddle off oil in the very back of my upper intake. Yes, my pcv valve and air filter is new. I have already ordered two K&N valve cover breathers to do away with the pcv system. Also, if your mechanic has suggested replacing the lower intake gasket based on oil accumulation on the spark plug of cylinder #5, it will not have any effect on our temperature fluctuation.

How does this help. This part is easy. This is not the only mystery problem with the explorer. The ford explorer is the 8th wonder of the world. They don't call it the exploder for nothing. Would you trust a car manufacturer who chooses not warn people or fix such problems in an effort to refrain from making it evident to people that is was a bad design in the first place, thereby dodging liability and in effect, continuing to put people's money, time, and live's in jeopardy. I will be purchasing a GMC 1500 with a 4.3 liter or a 5.7 liter engine, and will be selling my ford!

 

[smtcapecod]

mine

Well said, that last.

After I did thermostat, heater valve, heater core..mine was OK for a little while, then the problem returned. I went back in hunting for an electrical problem. It was (this time) either a loose connection at the sensor, which I'm sure has been checked on other vehicles...or, a scuffed wire where a harness was rubbing against the water neck.

 

[elliswife]

Yipes

No... mine was leaking coolant when pressure tested and pinging. Fixing the gaskets upper and lower fixed that prob... did not fix temp fluctuation... he thinks the temp fluctuation has something to do with the actuator or something like that on the back of the cluster. He thinks it is working fine. Which it is... excluding the sticky governor in my tranny. Gotta love manually shifting to second on cold... all I need is 500 bucks for my tranny shop... it's gonna be a while.

 

[elliswife]

Well said, that last.

After I did thermostat, heater valve, heater core..mine was OK for a little while, then the problem returned. I went back in hunting for an electrical problem. It was (this time) either a loose connection at the sensor, which I'm sure has been checked on other vehicles...or, a scuffed wire where a harness was rubbing against the water neck.

I replaced and then CHECKED the new sending unit... it seems to pass the test. But the mechanic says it will when the actuator thingy is shorting and not gone yet. I have other strangeness with other gauges.

 

[atistang]

I hate to dig this one back up.


My gauge was doing the same thing, it would go all the way over to the "A" on normal then back down to the "N", it was constantly moving


yesterday i had to replace my radiator, do i decided while i had the coolant drained to go ahead and replace the thermostat

now it stays between the "N" and the "R" on the gauge.


I used a 195 stat which is what i took out of it

so as far as my problem, it wasn't in the gauge, or the heater core, I'm 99% sure it was the thermostat

 

[Jack Flash]

probably not helping my emissions, but I replaced the thermostat with a 180 degree one. now my guage fluctuates between the N and the R on the guage. I've been on several 200 mile trips and have had no problems except the fluctuating temp guage.

as for me....not gonna bother with it until something breaks.