Coolant leak after engine cool down

[stusainte]

Hey Guys Been a long time !! Have a question for you  Ok for about a few weeks now everytime I shut down my truck and the engine cools i find a coolant puddle under the radiator It doesnt leak or overheat while driving  and can't find out where its leaking from THis past summer I flushed the system and replaced the Radiator ,therm, water pump,and hoses and was fine until just a couple of weeks ago  could this be just Preasure building up after cool down or somthing else  any addvice would be greatly appreciated Thanks Stu     PS its a 302 5.o auto   

 

[miesk5]

yo STU,

As a guess, it is same radiator "plastic end cap leak that I have had twice since we bought our 96 new.

Plastic End Cap Leak Repair; "...Plastic radiator tank and gasket replacements. In this procedure the radiator is removed from the vehicle and placed in a special fixture to detach the damaged tank and/or gasket. The tank and/or gasket is replaced with a readily available new or restored part. Afterward, the radiator is reassembled and tested..."
Source: by NARSA narsa.org Plastic End Cap Leak Repair; "Leaks in plastic end tanks can be filled with epoxy, covered with fiberglass and epoxy, or hot-air welded using nylon plastic filler rod. Welding plastic takes some skill and requires careful surface preparation to get good adhesion. The leak must first be "V" ground and sanded, then cleaned with wax and grease remover to assure a strong bond. The other alternative is to simply replace the damaged end tank. But the job is harder than it looks because the end tank must be pressed down on the core with about 150 lbs. of pressure while the header tabs are clamped in place. Radiator shops have the proper fixtures for doing this, but many underhood repair shops probably don't. Radiators with plastic end tanks are very vulnerable to steam erosion. If the coolant level is low and the engine starts to run hot, steam can erode and melt a hole right through an end tank. White deposits on the inside of the plastic is evidence that hot steam rather than coolant was flowing into the tank. If you find this kind of damage, check the thermostat and pressure test the system for leaks after the radiator has been repaired or replaced..."
Source: by Larry C at arrowheadradiator.com

95 Bronco-F-Series Workshop Manual by Ford https://www.motorcraftservice.com/pubs/content/~WSSJ/~MUS~LEN/20/SSJMAIN.HTM

see Section 03-03:
Engine Cooling

https://www.motorcraftservice.com/pubs/content/~WSSJ/~MUS~LEN/23/SSJS330L.HTM

Try a cooling system Pressure Test  including rad cap; borrow, w/refundable deposit the Pressurization Kit

Pressure Test

1. 
    WARNING: NEVER REMOVE THE RADIATOR CAP (8100) OR DEGAS BOTTLE CAP UNDER ANY CONDITIONS WHILE THE ENGINE (6007) IS OPERATING. FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE OR PERSONAL INJURY. TO AVOID HAVING SCALDING HOT COOLANT OR STEAM BLOW OUT OF THE RADIATOR (8005), USE EXTREME CARE WHEN REMOVING THE RADIATOR CAP OR DEGAS BOTTLE CAP FROM A HOT RADIATOR. WAIT UNTIL THE ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE RADIATOR CAP OR DEGAS BOTTLE CAP AND TURN IT SLOWLY TO THE FIRST STOP. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN YOU ARE SURE ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE RADIATOR CAP OR DEGAS BOTTLE CAP (STILL WITH A CLOTH), TURN AND REMOVE IT.
   
   Shut the engine off.

1. Open hood and install protective fender covers.

1. When engine is cool, cautiously remove radiator cap or degas bottle cap.

1. Disconnect battery.

1. Adjust the radiator coolant level (fill or drain) to 25mm (one inch) below the filler neck opening before testing. Wipe clean, and then wet the rubber sealing surfaces in the cap and filler neck before installing the radiator cap tightly on the radiator.

1. Disconnect the electrical connector from the coolant temperature sending unit and remove the temperature sending unit from the engine. With the radiator cap installed and the cooling system pressure relieved, only a small amount of coolant will be lost when the sending unit is removed.
   

1. Install the adapter fitting from Rotunda Cooling System Pressurization Kit 021-00012 or equivalent (male thread on one end, and a hose connector on the other end to accommodate the tester hose) tightly into the intake manifold (9424) or cylinder head (6049) in place of the sending unit.

1. On Bronco, F-150-250-350 and F-Super Duty series vehicles, remove the radiator overflow hose (8075) from the overflow ******. Install a separate radiator overflow hose firmly on the overflow ******. Insert the free end of separate radiator overflow hose into container of water.

1. Attach the pressure pump and gauge to the adapter-fitting and pressurize the cooling system to 69 kPa (10 psi). No bubbles should appear in the water container when the system is pressurized to the LOWER LIMIT (69 kPa [10 psi]). If the system is satisfactory at the lower limit, gradually increase the system pressure until a slight stream of bubbles appears in the water container. This is the release pressure of the pressure cap.
   
   Replace any radiator cap or degas bottle cap which has a release pressure that is greater than the specified UPPER LIMIT pressure (90 kPa [13 psi]) without discharging bubbles.
   

1. If the radiator cap or degas bottle cap does not hold pressure, remove and wash the radiator cap or degas bottle cap in clean water to dislodge all foreign particles from the gaskets. Check the sealing surface in the radiator filler neck. Inspect the cam lock flanges on both sides of the filler neck for maximum cap engagement.
   

1. Pressurize the cooling system as described in Step 6 (using a radiator cap and degas bottle cap that operate within the specified upper and lower pressure limits) and observe the gauge reading for approximately two minutes. Pressure should be held between 69 and 90 kPa (10 and 13 psi) and should not drop during this time.

1. If the pressure drops, check for leaks at the engine-to-heater core hoses, engine-to-radiator hoses, bypass hose, water valve hose (if applicable), thermostat housing gasket, radiator and heater core (18476). Also refer to engine system checks if a leak cannot be located in the cooling system. Any leaks which are found must be corrected and the system checked again. If the system holds pressure proceed to next step.
   

1. Release the system pressure by loosening the radiator cap and removing the adapter. Install the water temperature indicator sender unit (10884), check coolant level and replenish, if necessary, with the correct coolant solution.

1. NOTE: When the battery has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module (PCM) (12A650) relearns its adaptive strategy. The vehicle may need to be driven 10 miles or more to relearn the strategy.
   
   Connect battery ground cable.
   
   
   
   
   
   
   Item Part Number Description 1 8100 Radiator Cap 2 — Filler Neck Seal
   (Part of 107-01301) 3 — Filler Neck Adapter
   (Part of 107-01301) 4 — Quick Disconnect Fittings
   (Part of 107-01301) 5 — Temperature Sender Pressure Hose Adapter
   (Part of 107-01301) 6 — Pressure Test Pump 021-00012 or Equivalent (Part of 107-01301) 7 — Pressure Relief *****
   (Part of 107-01301) 8 — Radiator Cap Pressure Test Adapter (Part of 107-01301)

 
Radiator Cap Pressure Test

1. Remove the radiator cap from the radiator filler neck.

1. Use water to clean the radiator cap in the area of the rubber seal and the vacuum relief valve as described in this section. Immerse the radiator cap in water to wet the seals and install on the shallow filler neck of Rotunda Radiator Cap Pressure Test Adapter 021-00012 or equivalent. (The adapter is designed to accept both deep and shallow neck radiator caps.)

1. Before installing the radiator cap on the adapter, immerse the filler neck seal in water and install it in the filler neck adapter. If the adapter is made of plastic, check its sealing surfaces to be certain that they are free of rough spots and contain no parting lines or core marks. The filler neck seal is reversible so that it may be used on either a deep or shallow radiator filler neck. It will also fit either end of the radiator cap pressure test adapter.
   

1. Install the filler neck adapter with filler neck seal on the deep filler neck end to the radiator cap pressure test adapter.

1. Connect the female quick disconnect fitting of the pressure test pump to the male quick disconnect fitting of the filler neck adapter.

1. SLOWLY depress the plunger of the pressure test pump until the pressure gauge reading stops increasing and note the highest pressure reading obtained. If the plunger of the pump is depressed too fast, an erroneous pressure reading will result.

1. Release the pressure by depressing the pressure relief valve stem. Then, tighten the pressure relief ***** and repeat Step 6 (at least twice) to make sure the pressure test reading is repeatable within the acceptable gauge reading limits of the radiator cap and is not erratic. Refer to Specifications at end of this section.

1. If the pressure test gauge readings are not within the acceptable gauge reading limits, replace the radiator cap, and perform a Cooling System Pressure Test. If the pressure test gauge readings are within the acceptable gauge reading limits, perform the Cooling System Pressure Test.

 
Thermostat, Water

NOTE: The following test can be preformed at 54°C (129° F) for regulator thermostats and at 167°C (333°F) for high temperature thermostats.

If the problem being investigated is insufficient heat, inspect the water thermostat (8575) for leakage. Hold the water thermostat up to a lighted background. Light leakage around the water thermostat valve (water thermostat at room temperature) is unacceptable and the water thermostat should be replaced. A slight leakage of light at one or two locations on the perimeter of the valve of some water thermostats may be detected. This is considered normal.

 
Radiator Leak Test, Removed from Vehicle

 CAUTION: Do not leak test an aluminum radiator in the same water that is used to leak test copper/brass radiators. Flux and caustic cleaners may be present in the tank and they will attack aluminum.

Clean the radiator before leak testing to prevent contaminating the test tank. Leak test the radiator in clean water at 145 kPa (21 psi) air pressure.

A separate, clean test tank is recommended for aluminum radiators. If a separate tank is not available for aluminum radiator testing, thoroughly clean the test tank each time before testing an aluminum radiator.

When a plastic tank is removed to service a tube-to-header leak, the core can be tested by clamping the tank to the core.

===

Coolant Leak May Occur at the Radiator Hose Joints, Hose Clamp TSB 95-6-16 for 95-96 BRONCO, ECONOLINE, F-150-350 SERIES; A coolant leak may occur at the radiator hose joints. This can be caused by: Debris on the sealing surface; Misassembly of the hose and/or clamp; Defective or damaged hose clamp; "Mega" hose clamps are to be used, if needed, because they have 30% more clamping force than clamps used in the past. They expand and contract with the thermal cycling of the joint, thus retaining their clamp load and efficiently sealing the joint over long periods of time. The *****-type dual-wire and worm gear style band clamps are less robust under climatic and system thermal cycling. THE "MEGA" CLAMPS WERE SPECIFICALLY SIZED FOR 1995 AND LATER VEHICLES. THEY ARE NOT APPROPRIATE FOR VEHICLES BEFORE THE 1995 MODEL YEAR BECAUSE THE JOINT SEAL CONFIGURATION AND DIMENSIONS ARE DIFFERENT. IF A 1995 VEHICLE IS RECEIVED WITH A DUAL-WIRE CLAMP, REPLACE IT WITH A COMPARABLE BAND CLAMP..."

 

[stusainte]

Thank You once again Miesk5 allways have a ton of info  I didnt even think of the end caps leaking but I will check it out Tommoro I also picked up a pressure tester at Auto Zone the radiator is only 6 monthes old and have a 3 yr warranty so if its the end cap im just going to get a new one all the other parts seem to be ok so wish me luck  and Thanks Again Stu 

 

[Bully Bob]

Yep.., as stated, the most likey culpret is hose clamps.  Almost always need to be re-torqued

after new installations & cool down.