1993 ranger, 3.0 V6 203,000 miles. As engine warms up coolant in blown into over flow and spills out. At that point system is low and truck runs hotter than norman, 3/4 way across gage. What would be causing overflow to overfill from engine. Could it be a bad rad. cap? Just replaced head gaskets at 200,000 miles. Truck runs good. No oil in water, no sign of visible leakes other than overflow tank overfilling and loosing coolant. I'm very puzzled???

 

Stuck closed thermostat, system not holding pressure, like a faulty radiator cap, clogged up coolant passages in the radiator, block, or heads, fan clutch not operating correctly, old water pump vanes erroded so its not pumping enough coolant, old collapsed radiator hose thats restricting coolant circulation, you didn't refill & get a good air burp, to remove all of the air from the cooling system after the head work, warped heads from over heating, faulty new head gaskets or installation, are some of the things that come to mind.

Perform a coolant system pressure check, to determine if its holding pressure. Test the radiator cap to make sure its holding pressure. Most autoparts stores will do this at no cost.

If all those check out ok, check the fan clutch, it should move with some vicious resistance, it shouldn't spin freely.

If all thats ok, perform a coolant system burp proceedure by parking & running the warmed up engine with the heater on max & the front end facing up hill to chase air back to the radiator so the radiator cap can burp the system after cool down, to make sure all the air is out of the cooling system & after it cools down check the radiator hoses to make sure they're not collapsed. if they are, check for a pinched hose between the radiator & coolant recovery tank. My hose was misrouted by the factory & pinched shut under the recovery tank!!!!!

If all thats ok, perform a coolant system flow rate test & let us know what you find.

 

I will add that you can test for CO or CO2 in the radiator to check for cylinder integrity. If you have gas, your may have cracked heads or a leaking gasket.
If you had a head gasket fail, in most cases something made that happen. Corrosion, failed bolts, faulty gasket, improper surface condition, cracks, and gouges can all cause or allow failure. What was your condition 3,000 miles ago? Who did the work? Are you sure you don't have a cracked head. Very small cracks are hard to see, and you may need to use a professional test to be sure. {magnaflux or dye & black light?}
If you did the work, and didn't really find a cause for the head gasket problem, I would not be surprised that you have cracks.
tom

 

thanks for reply...blew head gasket when fan belt came off and engine ran hot. Had the head redone by a machine shop. Inspected and resurfaced.Did the repair myself. What comes to mind after reading your replies is may be clogged passage in the Block. Old coolant was very rusty. New radiator and waterpump installed when head replaced. New radiator cap also. What is best way to flush and clean rust from block.

 

also checked fan and it spins with little resistance with my hand???

 

What to use to try & tidy up the block might be helped by how bad/eroded did the water pump vanes look & how bad was the coolant condition???? How long was it run with the coolant in a degraded condition????

 

was run for a while i think, blades on water pump worn very bad...

 

I agree, if the water pump blades were worn bad, indicates it was likely neglected & run for years without proper care. So the block is likely scaled/rusted up pretty bad inside & the water jacket around the cyl walls are likely heavily scaled over if you got thick, or chunky muck out of it when drained. Those deposits will cause the cyls to run hot, as the rust/scale insulates them, preventing proper heat conduction to the coolant. SO, what to do about that at this point, seeing as how its all buttoned up again???? Maybe look to something like a Prestone product that says its for descaling the block & use it as directed, maybe multiple times, until the flush water runs clear. Then use a good quality long life coolant, mixed 50/50 with distilled water & let us know how it goes.

 

If you only replaced one head gasket, the other one may need the same thing now.

 

I would test a bit before starting to tear things apart.

Find out if there is *** in the coolant with the engine running or right after.
Pull the sparking plugs, and see if any are 'steam cleaned' by vaporized coolant.
Pressure check the cooling system.

After you do some of the above, you will have a better idea of what is happening.
Additionally, to get better sludge access to the water jacket, you can pull the water pump and jet directly into the jacket through the holes, and know if there is sludge in there.
Once you know of ***, you know there's a leak. Is it gasket or crack? Unless you have access to a borescope type device to view through the spark plug hole, you'll have to take it apart.
tom

 

both heads were done when rebult. Will try to use something to clean any scale buildup. Truck was running great before head blew. Where can you test for CO in coolant and how?
thanks for all the replies...