cooling system issues

[87351ranger]

have this cooling problem, never heard anything like it before. This is my 94 ranger 3.0 splash. Basic rundown on the truck, 125k, motor was out and resealed due to oil leaks, headgaskets were also done. I have put about 3k miles on it since. cooling system was replaces when motor was out, radiator, waterpump, clutch fan, heater core and all hoses. truck runs 185*-190*. Recently had heat issues out of vents due to crap in the cooling system, 100*, now 150*. Here is where the problem lies. Getting a thumping nose out of the cooling system, its not all the time. You can hear it from inside the truck, noise is from under the hood. You can feel the feed hose to the heater core pulse, like it has a heartbeat. Does not do this all the time, engine speed does not seem to effect it, ran it up to 1700rpms and seems to maintain a steady rythem, noise does not increase with engine speed. It the noise accurs and you shut the truck off it continues and slowly fades away. Should be no air in the system, used a no spill kit and had it idle for at least 45mins when refilling it with new antifreeze and distilled water. Had flushed the entire system and ran red devil cooling system cleaner through following their directions. The problem was not there prior to flushing the system. I know its going to be something stupid, just not sure what. Hopefully somebody knows of this problem and knows what it is. truck runs fine, no other issues.

 

[Frozen_Ice]

I never had thumping, but have you changed thermostat, radiator cap and do a heater core flush? Not just the radiator but a specific heater core flush. the thumping is caused by pressure build up.
1) you may be low on coolant (run truck and check coolant level after you have changed the Tstat and cap.
2) Thermostat installed wrong or bad thermostat
3) Old radiator cap not allowing coolant to flow
4) the worst case may be a blown head gasket, but I bet the 1st 3 fix your problem


Bulletin
ARTICLE NO. 99-23-8

• GAUGE—TEMPERATURE GAUGE FLUCTUATION AND/OR “KNOCKING/THUMPING” NOISE FROM COOLING SYSTEM—4.0L OHV ENGINE

• COOLING SYSTEM—PULSATING COOLANT FLOW —NOISE—“ KNOCKING/THUMPING”— AUDIBLE IN PASSENGER COMPARTMENT—4.0LOHV ENGINE

FORD: 1995-2000 EXPLORER, RANGER

This TSB article is being republished in its entirety to include 2000 model year vehicles and to provide Service Part(s) and Labor Time information.

ISSUE
A temperature gauge fluctuation and/or a“knocking/thumping” noise may be audible in the passenger compartment on some vehicles. This noise is most pronounced with the engine at normal operating temperature. The noise is caused by steam formation in the cooling system. The noise is then transmitted through the heater hoses and heater core.

ACTION
Install a Coolant By-Pass Kit. This increases coolant flow which reduces steam formation. Refer to the following Diagnostic and Service Procedure for details.

DIAGNOSTIC AND SERVICE PROCEDURE
1. Check for excessive exhaust system restrictions. A restricted exhaust could elevate cooling system temperatures.

2. If dash-mounted cooling temperature gauge fluctuates, check that gauge and sending unit are functioning properly.

3. Check for restrictions or kinks in the radiator or heater hoses.

4. Pressure check cooling system for leaks.

5. Confirm proper Engine Coolant Temperature (ECT) sensor signal to EEC-V processor.

6. Check for correct 50/50 coolant mix. Verify that freezing point is -37*C (±-15*C) or -35*F (±5*F).

7. If concern still exists, install service Coolant by-Pass Kit and verify that concern has been resolved. Refer to the Application Chart in this article.

PART NUMBER / PART NAME
F8PZ-8522-AA / Coolant By-Pass Kit (‘95-‘96 Ranger)
F8PZ-8522-CA / Coolant By-Pass Kit (‘97+ Ranger)
Good Luck

 

[RonD]

have this cooling problem, never heard anything like it before. This is my 94 ranger 3.0 splash. Basic rundown on the truck, 125k, motor was out and resealed due to oil leaks, headgaskets were also done. I have put about 3k miles on it since. cooling system was replaces when motor was out, radiator, waterpump, clutch fan, heater core and all hoses. truck runs 185*-190*. Recently had heat issues out of vents due to crap in the cooling system, 100*, now 150*. Here is where the problem lies. Getting a thumping nose out of the cooling system, its not all the time. You can hear it from inside the truck, noise is from under the hood. You can feel the feed hose to the heater core pulse, like it has a heartbeat. Does not do this all the time, engine speed does not seem to effect it, ran it up to 1700rpms and seems to maintain a steady rythem, noise does not increase with engine speed. It the noise accurs and you shut the truck off it continues and slowly fades away. Should be no air in the system, used a no spill kit and had it idle for at least 45mins when refilling it with new antifreeze and distilled water. Had flushed the entire system and ran red devil cooling system cleaner through following their directions. The problem was not there prior to flushing the system. I know its going to be something stupid, just not sure what. Hopefully somebody knows of this problem and knows what it is. truck runs fine, no other issues.

New heater core?

I would get a connector and a couple of hose clamps and by-pass the heater core, or run the longer heater hose(from water pump) to the intake manifold heater hose connection, so by-pass the heater core that way

Just seeing if the thumping is related to low flow thru the new core


Thumping can be a hot spot in one of the heads, I assume you used Ranger 3.0l head gaskets, because there are 3.0l Taurus head gaskets which would cause hot spots in Ranger application
Hot spot causes coolant to overheat and expand quickly at that one spot, making the thump noise
Can be more noticeable after shut down of warm engine because coolant circulation stops but heads are still HOT

 

[87351ranger]

I would say they are not the wrong head gaskets. This problem just started last week and I resealed the motor last year along with the head gaskets (3000 miles). All new cooling system parts at the same time. The problem is not there all the time. Motor runs 185*-190* all the time, no surgeing of temp. Going to bypass the core first to see if the noise goes away. #2 will be refilling the system with the nose of the truck up higher. I have mechanical gauge on it so I know what temp its running.

 

[RonD]

You just need to have one heater hose disconnected at the firewall when refilling, that will let the air out of the engine side

 

[Ohmsguy]

have this cooling problem, never heard anything like it before. This is my 94 ranger 3.0 splash. Basic rundown on the truck, 125k, motor was out and resealed due to oil leaks, headgaskets were also done. I have put about 3k miles on it since. cooling system was replaces when motor was out, radiator, waterpump, clutch fan, heater core and all hoses. truck runs 185*-190*. Recently had heat issues out of vents due to crap in the cooling system, 100*, now 150*. Here is where the problem lies. Getting a thumping nose out of the cooling system, its not all the time. You can hear it from inside the truck, noise is from under the hood. You can feel the feed hose to the heater core pulse, like it has a heartbeat. Does not do this all the time, engine speed does not seem to effect it, ran it up to 1700rpms and seems to maintain a steady rythem, noise does not increase with engine speed. It the noise accurs and you shut the truck off it continues and slowly fades away. Should be no air in the system, used a no spill kit and had it idle for at least 45mins when refilling it with new antifreeze and distilled water. Had flushed the entire system and ran red devil cooling system cleaner through following their directions. The problem was not there prior to flushing the system. I know its going to be something stupid, just not sure what. Hopefully somebody knows of this problem and knows what it is. truck runs fine, no other issues.

It may be your water pump . Some aftermarket water pumps don't have the anti-cavitation plate on the impeller. And it will make a knocking sound from under the hood just like you describe. You stated that you had replaced the water pump. I have a 2001 3 L and had the same problem until I went to the dealership and bought a factory replacement pump ,if you have the old pump,you can compare the impellers with an aftermarket and see the difference. Mind you the dealership pump is expensive .