94 4.0 Heater Core
#1
10-05-2018
94 4.0 Heater Core
I have a 1994 Ranger 4.0 with approximately 310,000 miles. I suspect my heater core needs replacement. Symptoms I’m seeing are constant low antifreeze levels despite no evidence of dripping under the truck or on the engine causing the truck to run hot if I don’t really stay on top of the fluid level. BOTH of my floorboards are wet under my dash. I have often read that a heater core will cause the passenger side floorboard to be wet with no mention of the driver side.
Is it strange I’m seeing my driver side floorboard wet as well?
Is it strange I’m seeing my driver side floorboard wet as well?
#2
10-05-2018
Yes, that would be odd for drivers side to be wet from heater core leak, but core could leak on to the "hump" and maybe a bit could run over to drivers side
On the plus side it only takes about 30 min to change heater core on the 1994 Rangers, 2 hose clamps and 4 screws, only takes 20min if you have done it before
Remove the 2 hose clamps at firewall for the heater core and remove hoses
There are 4 screws holding bottom cover of cores box in passenger side under dash, 3 are low and one is higher up, you can fold down glove box all the way to see this one
Once cover is pulled off, you can pull heater core back and tilt it to drop it out.
Have a towel under it as fluid will come out as you tilt it
New core is not expensive, under $30, usually
Old core will have foam strips, you can install new strips on new core, it is just peel and stick weather strip, maybe 3/8 to 1/2 inch wide will work, but not "required"
Just as a heads up
When you change coolant, every 2 years right, lol, swap heater hoses at the firewall, to reverse the flow thru the core, this will make heater core last twice as long
Heater core has smaller passages and debris can clog some passages, this prevents coolant circulation thru those passages and you lose the Corrosion Protection the flowing coolant provides, so core can corrode and then leak.
When you reverse the flow it can push the larger debris OUT the way it came in, this is called Back Flushing, but you can do it full time just by reversing the hoses
This applies to ANY VEHICLE with a heater core
On the plus side it only takes about 30 min to change heater core on the 1994 Rangers, 2 hose clamps and 4 screws, only takes 20min if you have done it before
Remove the 2 hose clamps at firewall for the heater core and remove hoses
There are 4 screws holding bottom cover of cores box in passenger side under dash, 3 are low and one is higher up, you can fold down glove box all the way to see this one
Once cover is pulled off, you can pull heater core back and tilt it to drop it out.
Have a towel under it as fluid will come out as you tilt it
New core is not expensive, under $30, usually
Old core will have foam strips, you can install new strips on new core, it is just peel and stick weather strip, maybe 3/8 to 1/2 inch wide will work, but not "required"
Just as a heads up
When you change coolant, every 2 years right, lol, swap heater hoses at the firewall, to reverse the flow thru the core, this will make heater core last twice as long
Heater core has smaller passages and debris can clog some passages, this prevents coolant circulation thru those passages and you lose the Corrosion Protection the flowing coolant provides, so core can corrode and then leak.
When you reverse the flow it can push the larger debris OUT the way it came in, this is called Back Flushing, but you can do it full time just by reversing the hoses
This applies to ANY VEHICLE with a heater core
Last edited by RonD; 10-05-2018 at 08:56 AM.
#3
10-07-2018
Thank you for the tips! I replaced it with no problems, I’m thankful it was as simple as it was. Hopefully that takes care of my issue in that regard.
I do have another issue that has popped up in the last 2-3 days and I hate to start another thread. The motor has now begun making a tapping/clicking noise from what appears to be the top of the motor in the valve cover area. The noise seems to go away as the truck gets warm but just this morning the noise began again as I drove after it had originally stopped earlier in my drive. I took a video of it I will try to post below. I noticed the noise within a day or so of changing my oil this past week. I’m guessing it’s just a coincidence in that front but it does make me wonder.
I do have another issue that has popped up in the last 2-3 days and I hate to start another thread. The motor has now begun making a tapping/clicking noise from what appears to be the top of the motor in the valve cover area. The noise seems to go away as the truck gets warm but just this morning the noise began again as I drove after it had originally stopped earlier in my drive. I took a video of it I will try to post below. I noticed the noise within a day or so of changing my oil this past week. I’m guessing it’s just a coincidence in that front but it does make me wonder.
Last edited by rifleman85; 10-07-2018 at 06:35 AM.
#4
10-07-2018
#6
10-07-2018
#7
10-07-2018
4.0l hydraulic lifters would sometimes stick making that tapping sound and it would come and go.
To replace the lifters you have to pull the heads, so not an easy project.
The changing of the oil was related because you may have air or debris in a lifter or passage for that lifter, it should clear itself out over time.
There are additives for older high mile engines that can help keep lifters "loose"
Google: How do hydraulic lifters work
Diagram here of lifters internal parts: http://performancetrends.com/Definit...Lifter-Lrg.jpg
Basically a lifter is a steel cylinder with a piston inside
There is a spring at the base of the piston that keeps it pushed up
When you install the rocker and push rod you tighten it so piston is pushed down about 1/4", this is called the Pre-load, so rocker and push rod are always tight, no tapping noise on startup
After engine starts oil pressure is forced into the hole on the side of the lifter, this pressure takes over from the spring
When cam pushes lifter up the oil pressure absorbs some of the lifting but lifter pushes up on push rod and rocker to open the Valve in the head, valve opens fully when piston is at the bottom of the lifter
(some prefer solid lifters so there is no "delay" when cam lode pushes up on lifter, but these need constant adjustment or the will tap, tap, tap)
Some engines use hollow push rods and have a hole in the rocker where pushrod sits
The lifter has a hole where push rod sits as well, as piston in lifer is compressed it forces oil inside up the push rod and it sprays out inside valve cover, keep "top end" oiled
4.0l OHV has solid pushrods, "top end" is oiled by Rocker asssembly
But because the oil is not easily pushed out, up hollow pushrod, the oil exchange inside these lifters is not fast, so they can take a while to clear once they start tapping.
Tapping can be broken spring, usually always heard at startup, or worn piston, doesn't always return to top, this is a 'stuck lifter'
Broken spring doesn't effect much, just the tapping at startup which isn't alot of wear and tear, oil pressure takes over, but if oil pressure at that lifter should get low, debris or air, then it would tap because spring is not working
Next oil change, put on the filter and drain plug, but do not put oil in yet
Disable spark or fuel, so no start
Crank engine, without oil pressure, and listen for tapping noise, those would be broken springs
Other tapping noise
Ford fuel injectors are quite noisy, tick, tick, tick, lol
It is a different sound but similar and the same rhythm.
You can use a small hose, like vacuum hose, as a stethoscope to listen to each injector, could be the noise you are hearing
To replace the lifters you have to pull the heads, so not an easy project.
The changing of the oil was related because you may have air or debris in a lifter or passage for that lifter, it should clear itself out over time.
There are additives for older high mile engines that can help keep lifters "loose"
Google: How do hydraulic lifters work
Diagram here of lifters internal parts: http://performancetrends.com/Definit...Lifter-Lrg.jpg
Basically a lifter is a steel cylinder with a piston inside
There is a spring at the base of the piston that keeps it pushed up
When you install the rocker and push rod you tighten it so piston is pushed down about 1/4", this is called the Pre-load, so rocker and push rod are always tight, no tapping noise on startup
After engine starts oil pressure is forced into the hole on the side of the lifter, this pressure takes over from the spring
When cam pushes lifter up the oil pressure absorbs some of the lifting but lifter pushes up on push rod and rocker to open the Valve in the head, valve opens fully when piston is at the bottom of the lifter
(some prefer solid lifters so there is no "delay" when cam lode pushes up on lifter, but these need constant adjustment or the will tap, tap, tap)
Some engines use hollow push rods and have a hole in the rocker where pushrod sits
The lifter has a hole where push rod sits as well, as piston in lifer is compressed it forces oil inside up the push rod and it sprays out inside valve cover, keep "top end" oiled
4.0l OHV has solid pushrods, "top end" is oiled by Rocker asssembly
But because the oil is not easily pushed out, up hollow pushrod, the oil exchange inside these lifters is not fast, so they can take a while to clear once they start tapping.
Tapping can be broken spring, usually always heard at startup, or worn piston, doesn't always return to top, this is a 'stuck lifter'
Broken spring doesn't effect much, just the tapping at startup which isn't alot of wear and tear, oil pressure takes over, but if oil pressure at that lifter should get low, debris or air, then it would tap because spring is not working
Next oil change, put on the filter and drain plug, but do not put oil in yet
Disable spark or fuel, so no start
Crank engine, without oil pressure, and listen for tapping noise, those would be broken springs
Other tapping noise
Ford fuel injectors are quite noisy, tick, tick, tick, lol
It is a different sound but similar and the same rhythm.
You can use a small hose, like vacuum hose, as a stethoscope to listen to each injector, could be the noise you are hearing
#8
10-07-2018
Wow, thank you for the information RonD. I will be looking into all of that and attempting to dissect things a bit more.
I forgot to add that the ticking does increase or decrease in rate with the revving of the engine. I add that now because I’m not sure if that would be more indicative of a lifter or fuel injector. I admittedly am not an expert on any of this but I would imagine a fuel injector would NOT react in its rate by how the engine is revving? Or am I incorrect?
I forgot to add that the ticking does increase or decrease in rate with the revving of the engine. I add that now because I’m not sure if that would be more indicative of a lifter or fuel injector. I admittedly am not an expert on any of this but I would imagine a fuel injector would NOT react in its rate by how the engine is revving? Or am I incorrect?
#9
10-07-2018
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