Hi guys, please excuse if I'm doing this incorrectly, this is my first post here and I've made an account because I can't seem to find the culprit of my issue. To start off, I have a 95 Ranger XLT 4.0. So far I have replaced the Radiator, Radiator Cap, Upper and Lower Hoses, Overflow Hose, Thermostat (Failsafe 198), and have also flushed/drained the system several times. Mechanically, it doesn't seem like anything is wrong (Truck never overheats, I'm not losing coolant ANYWHERE. There are no coolant leaks, nor is there coolant in the oil). The thing that got me concerned is when I saw my temp gauge spike up, initiate my overheating light and immediately disappear. That is how I found out about the vacuums collapsing, otherwise I would not have known to even look there. Since then, I've observed the following issues:

• First issue I'm running into is the engine takes a while to reach operating temp in idle. It usually takes anywhere from 20+ minutes to reach closer to the 'mid' if I just let it idle. All my other cars/trucks in the past heated up way quicker. (However, I do get heat from the cabin not long after I start the car, so I don't believe the tstat is stuck open). If I rev the engine it will warm up a bit quicker, but still takes some time.
• Second issue is; as I'm driving and once the engine is (hot), as I accelerate, the hoses will start to collapse. Almost as if it's breathing in and out as I accelerate, assuming due to air trapped in the system. Subsequently, I'm noticing I am getting fluctuations in my temp gauge readings as well ONLY WHILE I DRIVE. In idle, the gauge almost never fluctuates, if ever. However, once I start driving, is when the needle starts to move, I'm assuming due to the air trapped in the system. If I get on an on-ramp or give it heavy acceleration, the needle will go from near-mid, and go towards "C" and then make it's way back up to the middle fairly quickly and will stay there. This usually is only after a big acceleration spike. After this first initial and sudden drop of temperature, is when my needle starts to move closer to the "H". I went for a drive today to measure my temp digitally with my OBD2 reader and out of a 20minute highway drive, my truck maintained an average of 180-195F, and had rare peaks from 200-210F. If I am on the highway for a much longer time, (sometimes, but not always), the needle will spike all the way to the "H", initiate the overheating light, and then IMMEDIATELY drop down back to middle. It didn't this time though. I've never experienced this before and I've had 3 other rangers lol.
• Third issue (if it's even an issue?), is that my truck is technically never overheating. You would think with my hose collapsing, it would cause pressure in the system and cause it to overheat, however my truck has never maintained a temp over 210 consistently for more than even 2seconds. It will literally spike then immediately drop. It has NEVER stayed above 3/4 consistently.
• Fourth issue I noticed today is that after my 20minute highway drive, I popped the hood and everything seemed normal other than a few drastic things that weren't visual. Coolant in overflow was over cold fill line(that seemed to be fine), upper and lower hoses were in good visual condition, however the one thing that caught me off guard was that my upper radiator hose was EXTREMELY hot and my bottom hose somewhat warm, (I was able to place my hand on the bottom hose no problem, whereas I wasn't able to on the upper radiator hose for more than a second). Lastly, my radiator cap wasn't even that hot, nor did it seem pressurized. I was able to take the cap off extremely easy and there was no air (or pressure) escaping the cap. I used a towel to open the radiator cap to check and instead of coolant starting to seep out from the pressure, I was able to take off the cap no problem. I thought that was a bit odd because I had the truck idling at least 20minutes before I drove it on the highway for 20minutes straight
• Last issue is I'm hearing a weird puff of air sound as I accelerate. I posted a video for reference below, but I'm unsure if this is what is causing my vacuum leak or not.

I have been advised to change my newly installed thermostat with another one, as well as to change the coolant temp sensor and send sensor. Someone else also mentioned the fan clutch and also my water pump. My question is, if my fan clutch was bad, does that have any affect on the hoses collapsing? Also, if my water pump went out, wouldn't my truck overheat? That is why I mentioned this as "an issue" listed above, because it isn't consistent with symptoms of a bad water pump (I think).

Any and all suggestions or tips and advice are more than greatly appreciated. Thanks so much in advanced guys!!

 

Odometer readings help, especially with older vehicles.
Have you owned this Ranger since new?
Could the radiator be internally clogged with leak-stop products? A relative's system (old, used car with 7 colors of lunar rock formations covering the radiator's backside) was filled with grey clay only gasoline could dissolve.
The collapsing hoses make me think the water pump is OK.

 

All Rangers except for the 2.3L DOHC Duratec(2001-2011) used an Overflow cooling system

This has the Overflow tank and a TWO valve radiator cap
Anytime you heat a fluid it will expand in volume
Anytime you increase the pressure on a fluid it raises its boiling point
physics 101
A Pressure cooker uses these principles, it can cook food faster because fluid inside expands in the sealed container when its heated, this increases the pressure inside the container so the "water" inside isn't limited to 212degF(boiling point of water with outside pressure)
So the temp inside the Pressure cooker can get hotter and cook the food faster

Vehicle system works on the same principles
It will have a radiator cap with a larger valve rated at 14psi(or 16psi)
As coolant is heated by the engine it expands and pressure inside the system goes up, this raise the boiling point of the coolant
If cap is rated at 14psi then at 15psi the big valve is pushed open and sends extra coolant over to the overflow tank via the Overflow Hose
Overflow Hose is connected to the BOTTOM of the overflow tank<<<<<this is important

When you shut off the engine, the coolant will start to cool down and SHRINK in volume, so 14psi pressure slowly goes down
If ANY coolant was sent over to the overflow tank then when the coolant cools down enough, pressure in the system will drop to -1psi, negative pressure, because there is less coolant than there was to start with
The smaller valve in the center of rad cap will be SUCKED open by the -1psi, and it will pull in coolant from BOTTOM of overflow tank until 0psi is achieved

Overflow system is SELF PURGING of air in the radiator
If there was air in the system it would work its way to top of radiator
When pressure got to 15psi the AIR would be pushed out to BOTTOM of overflow tank, where it would bubble up to the top of the tank and be gone
On cool down coolant would be sucked back in from the BOTTOM of the overflow tank
Self purging of air
When you remove rad cap on cold engine rad should be filled to the top, 0 air inside, if not then there is a problem with the system


Collapsed upper rad hose after cool down
Could be a few things
Cold engine
Pull off overflow hose from radiator and blow thru it, should be easy to make overflow tank bubble up, if it hard then could be hose is clogged or VENTED CAP on overflow tank is clogged, overflow tank is NOT a sealed container, it must be VENTED
Overflow tank can get debris at the bottom, prevents coolant from being SUCKED out, but can be pushed in, flush the tank out

Rad caps smaller valve, the larger spring is for the 14psi pressure, and you can see the smaller valve in the center easily, it will be pulled open by negative pressure in cooling system
If valve can't open then negative pressure in radiator causes collapsed hose on cool down
If no center valve then you have the wrong cap

Collapsed hose when running
Water pump is spinning backwards
Serpentine Fan belts have a ribbed side and a smooth side
Water pump pulleys are either ribbed or smooth
These MUST match
4.0l has a smooth water pump pulley so smooth side of fan belt should be on it, turning it in the correct direction
Engine usually won't overheat with water pump spinning in reverse, its still circulating coolant, just in the wrong direction, and that can cause a suction on upper rad hose, collapsing it


Engine should get to operating temp in 5 to 10 minutes(just below 1/2 on temp gauge), depends on outside temp of course

 

​​​​​​​Apologies. I bought the ranger at around 170K and it is now around 195K. I replaced the radiator and ensured there are no clogs.

 

Hi Ron,

Thank you so much for the extremely detailed write-up. My reservoir flows just fine, the hose is new and doesn't have any holes and it is easy for the coolant to flow into the reservoir and also back to the radiator. I also checked the serpentine belt and the water pump pulley has the smooth side on it, although it doesn't seem to be 100% aligned with the pulley, not sure if that's an issue or not. My rad cap has a lever on it. I think it's a safety valve? But it is rated at 16psi. After further investigation I have a theory and would like to present it to see if it has any logic to it, prior to applying it.

First thing's first. I purchased this truck last year at 170K and never had any overheating or spiking issues when I bought it. The reason I touched the cooling system on this truck was because when I purchased it the coolant was pretty ugly, so I wanted to do several flushes and get it nice and green again. After I flushed it several times and refilled it, I think I mistakenly locked air into the system by incorrectly burping, or not burping the system at all. My process was: I added coolant to the overflow cold fill line, topped off the radiator with a funnel and had coolant in the funnel, then I turned the car on, set the heater on to the MAX heat with the Highest setting. As coolant went down, I added more into the funnel until it was full. What I'm pretty sure I failed to do, is let the thermostat open up, which kept the air in the upper radiator hose. After my first time messing with the system and incorrectly burping, is when I started to get the collapsed hose(s) and spiking on my gauge. One other thing I've read was that a faulty fan clutch can keep the engine temp low/cool and make it harder for the thermostat to open up while idling. I saw you comment on a separate forum and stated that after my truck has sat overnight, to open the hood and move the fan as it should be locked while the engine is dead cold. In my case it was completely free (while cold), and it actually looked as if someone had previously done work on the fan clutch or at least the bolt. The bolt itself has scratches. I'm thinking due to my lack of knowledge on how thermostats worked I incorrectly burped the system and trapped air.

Now, here's my theory:
Since my fan clutch has failed, the fan is constantly spinning (keeping the engine at roughly 180-185F MAX when idling), which makes it almost impossible for the thermostat to open, which in turn, leaves the air in the system. I have a thermal fan. After I fix my fan clutch (if I'm correct, as it should work this way), my fan should ONLY engage once the clutch has reached the temperature to do so, correct? With that being said; with a properly working fan clutch that isn't always spinning, my engine should reach up to 198 degrees (to open the thermostat) within 5-10minutes right? Once the thermostat opens (without heavy acceleration or having to drive it), is when I can PROPERLY bleed the system. Can you please confirm if this 'could' or 'should' work?




This is the only 'logical' thing I can think of as I am absolutely not a mechanic in any shape or form. I am just trying to understand how these mechanics work and apply logic to them. I have also added pictures for references.

Thanks again!!!

 

Image of 2 valve radiator cap here: https://ricksfreeautorepairadvice.co...s-1024x567.jpg

Don't think I have ever seen a 2 valve cap with a lever, certainly could make them, just never seen one myself
Just look at the under side of cap for that small valve in the center and pull it down a bit with finger nail
If center valve is not there then get a different cap

Lever type was popular on the older Degas systems, older cars/trucks that would have a FILL TO line on the outside of upper radiator tank, so there would be air left at the top of radiator, this allowed the coolant to expand when heated compressing the air inside the radiator to 14psi to 18psi, cap rating
If it was overfilled it would blow extra coolant from a hose on rad cap opening, but blow it out on the ground

Problem with that type of system was if there was a small coolant leak you wouldn't know it until engine was overheating, which is why there was a lever, if engine WAS overheating that would mean coolant was low in radiator(system), so you could release the pressure using the lever, mostly air from top of radiator, without getting scalded
Once pressure was gone you could remove cap, add water/coolant to radiator and put the cap back on

Overflow system uses a semi-transparent tank so you can see the coolant level inside, if you notice its been dropping then you know there is a small leak but coolant IN the radiator stays full

New Degas systems use a semi-transparent Degas Bottle, so you can see coolant level without removing the cap, so can see if it has dropped from a small leak
And the radiators on these systems have a solid cap, no spring, no valve, the Degas Bottles cap has the valve, single valve

Larger leaks usually show up UNDER the vehicle, lol, so are caught pretty quickly


Fan belt is on the right way, alignment looks fine, but time to replace the belt, you can see it starting to crack on the ribs