How to troubleshoot a cooling issue?

[1976pianoman]

Hello,

My 98 Ford Explorer Sport Manual 5 speed V6 is overheating. The temperature gauge is pegged past red after 5 minutes of driving. I initially pulled over to a gas station, let the car cool and added a quart of coolant to the radiator. This did no good. (The coolant reservoir is empty).

I am attempting to diagnose the problem on my own, so I can save money and order the parts and labor on Amazon. I could possibly make the repair myself depending on what the problem is yet typically I pay for labor.

What is the proper protocol for diagnosing this issue? I presume it could be a cracked radiator, the thermostat and/or a bad hose (?). I'm not too well versed in the way of engines. I would appreciate some guidance.

Thank you.

 

[ThreeJs]

First step is to determine where the coolant is going.
With the engine cool. Remove radiator cap, Fill the radiator, Check for immediate leaks.
Install cap, start engine and let warm up and build pressure in the cooling system. Look for coolant loss/leaks.
(If you have/rent a coolant pressure tester. Pressurize cooling system to cap pressure rating. Check for leaks.).

No visible leaks. Check exhaust for steam/moisture/coolant smell.

Pull plugs and run a compression test

 

[Frank1669]

. Do you have a radiator cap on the radiator? If so when engine is stone cold Having set overnight. Here are some basic no tools test you can preform- Remove Radiator cap and make sure radiator is full. Leave the cap off and start vehicle let it Idle. ( best to set parking brake and chalk the tires) Watch inside the radiator threw the fill hole. as it warms up the fluid should start to flow, you should be able to see this. If not its most likely a stuck thermostat or a bad water pump. if water flows and it is still over heating look for air bubbles in the fluid this is a sign of a bad head gasket.

A couple of inexpensive tools you can pick up at harbor freight or at amazon is a coolant system pressure tester to check for leeks. this is useful in determining if its a head gasket failure. and a no contact thermometer can be used to to check for a plugged radiator by looking for areas significantly cooler than surrounding areas (in the part with the fins and tubes).

The reason I asked if the Radiator itself has a cap on it is Adding coolant to a recovery tank on a hot vehicle does nothing, it needs to be in the radiator but it is dangerous to open a radiator cap on a hot vehicle. I am a retired ASE certified mechanic but I don't know off the top of my head if ford ever used the European style of cooling systems.

 

[1976pianoman]

Thanks guys. I'll get going on this tomorrow and report back. Btw Frank, yes the radiator does have a cap. I added the coolant directly into the radiator and not into the reservoir tank. I hosed the engine down with water and waited 20 minutes before removing the radiator cap.

 

[J_C]

Pull plugs and run a compression test

That's what I was thinking, with no leak already noticed. It seems like a rapid loss to not have overheated last time, not have a puddle, yet only takes 5 minutes to overheat. On the other hand I would have expected a rapid rate loss into a cylinder to cause misfires or approach hydrolocking.

If/when you pull the plugs, examine each and if one looks different, focus on that cylinder. If they all look funny then it's more likely an intake manifold gasket rather than head gasket or head itself.

 

[1976pianoman]

It's leaking at the intake manifold. Going to have a local mechanic replace the gasket.

 

[F16pilotjd]

Was just searching for help with cooling system and saw this thread. Started out with deterioration of heat valve. Replace it and hoses. Then thermostat and water pump. Then new top and bottom radiator hoses. Pressure blew them off. I installed 2 new clamps on each and then replaced thermostat housing. Temperature remains in normal level but when driving it sounds like a loud fan or engine reving noise. Lately, I have been manually transferring from cooling resivoir to radiator and it works for a few days and then I have to do it again. Replace radios cap? At a loss. Will try any ideas. I have no leaks