1996 Ranger XLT 4.0 Coolant Leak with Pics, Help diagnose...

[toyopnoy]

Hello everyone my name is Pat and this is my first post here. Been a long time home garage mechanic but this is my first Ford. It's a 96 Ranger 4.0 with 200,000 miles. Do not know much history on the vehicle but it runs well and just passed smog without problems. Have daily driven it for the past week on fairly long trips in traffic with the AC on and have no signs of overheating or coolant overflow. I am not losing coolant but do have a small leaks that run down both the driver and passenger side of the block. I changed the spark plugs and wires a few days ago and noticed the leaks running down the side of the block. Did an oil change recently and there is no sign of coolant mixing with the oil. Did a coolant flush and there is no sign of milk shake (oil mixing with coolant) in the radiator. I have searched the forums and found some possible culprits lower intake gasket leak, headgasket leak, or cracked/warped heads. Any insight is greatly appreciated, thanks in advance. Here are some photos to help illustrate:

-Passenger Side view through wheel well. Leak stains running under header.



-Driver side view from the top. Bad photo but there is also some coolant leaking down the side of the block that drips onto the front crossmember.



-Underneath the truck on the passenger side. Coolant dripping down the side of the block onto the cooler lines and oil filter area.

 

[RonD]

Welcome to TRS Pat

If you are not losing coolant then why do you think you have a coolant leak.
I see the residue but can't say it is old or new.
Under side looks fresh but can't say if it was older and just wet now because of road moisture, or a current leak.

Very rare to have a head leaking coolant on a cast iron engine, aluminum heads will, in cold weather.

Core plugs(freeze plugs) can rust out and start leaking.

Yes, the aluminum lower intake where it meets the case iron head can leak because of electrolysis eating away at the gasket, that happens passenger side front or drivers side rear, no where else, that's where the coolant flows thru the intake from one side to the other.

You can get ultra violet(UV) dye kits, the dye is added to the coolant and you run the engine normally for a few days, dye is safe to use and you don't have to flush it out when done.
Then you use the UV flash light that comes in the kit and shine it on areas you think are leaking, the dye will leave a trail right to the leak point.
UV dye is used so there are no visible stains on the engine or on the driveway, lol.

The UV dye can be used in oil, ATF, manual trans, differentials, and even in AC system.
So not a one hit wonder

You could also rent a cooling system pressure tester.
This is a hand pump with a gauge that is put on in place of the rad cap.
This allows you to pump up the pressure in the cooling system while engine is cold, making it much easier to get your hand and fingers into areas that are too hot to get to otherwise.
Normal system pressure is 14-16psi, look at Rad cap rating, you can safely pump it up to 20psi, this will often show the leak point(s) better.

I did have a leak one time that was a real PITA, turn out to be a pin hole in a hose, only leaked under pressure and it sprayed a fine stream, invisible, lol, the stream ended up on a part of the engine that couldn't have a coolant leak, but I tore it apart anyway.
New gaskets, double checked every thing, knew it was fixed..................nope.
Was reaching in to check something when engine was all warmed up and cooling system had some pressure and felt the stream on the back of my hand, still couldn't see it very well.

Warped head would also be a rarity for the 4.0l OHV, crack heads are more common but only after overheating, and the crack is between the valve seats so no external leak, would show same symptoms as blown head gasket, but no coolant in the oil, just full overflow tank

 

[enjr44]

Not losing coolant! Put a mark on the overflow tank and watch it to make sure.

Wash all that stuff off and see if it comes back. If it does get the dye.

And I don't think a leaking lower would run down the sides of the block (sort of hard to jump over the valve covers).

 

[toyopnoy]

Thank you for the detailed responses. I will degrease the engine and underside and see if the leaks return. I'm not losing coolant the radiator stays full and the overflow tank is staying pretty constant, no noticeable loss. My truck doesn't leave puddles on the ground I just notice some drops here and there.

 

[aspevacek]

Not losing coolant! Put a mark on the overflow tank and watch it to make sure.

Wash all that stuff off and see if it comes back. If it does get the dye.

And I don't think a leaking lower would run down the sides of the block (sort of hard to jump over the valve covers).

The leaking lower does not have to jump Valve covers the coolant can actually flow down the front corner of the mating surface over the front time cover right at the edge of the head to block mating surface, the air flow from driving a vehicle can make leaks seem like that are coming from different places, hence why dye is such a useful diagnostic tool.

 

[enjr44]

Once you find the leak come back and let us know. A few drops here and there is a leak that can become a big dump.

And a 4.0 cannot stand to be over heated. The heads crack between the valves.