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4.0 SOHC coolant loss


chiefk

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2011 Ranger, 4.0 engine. I am loosing coolant with no external leaks. No evidence of coolant in the oil. Not smoking. Maybe 50 miles I lose about a quart. There is a lot of condensation coming from the muffler weep hole but it is pure water, no green. I don't have a radiator pressure tester so I can't do that test.
Any Ideas? Anybody else have a similar problem?
 


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gw33gp

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Check your thermostat housing. They are prone to cracking. Usually if it leaks there, the coolant collects in the valley between the cylinder banks. It gets partially dumped out the rear of the engine when driving and you don't notice it. You may be able to find an area to look into that valley to see if there is a pool of green stuff.
 

RonD

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+1 ^^^^

Welcome to TRS :)

Not an uncommon issue on the 4.0l SOHC

How-to here: https://howtoreplacefordthermostathousing.com/

2011 Ranger should have the 1 sensor housing instead of the 1 sender and 1 sensor housing used in earlier models, I think 2006 was when Ford switched to the 1 sensor model
 
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cbxer55

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Yeah, that STUPID plastic thermostat housing. Two piece. It blows the seam between the top and bottom pieces. If it's minor, it can be as stated above. When the one on my 07 Mustang blew, it wasn't minor. Made a f*ckin mess of the entire engine compartment. Fortunately it happened close to home. Replaced it with a one piece metal unit, no more leaks.
 

chiefk

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Check your thermostat housing. They are prone to cracking. Usually if it leaks there, the coolant collects in the valley between the cylinder banks. It gets partially dumped out the rear of the engine when driving and you don't notice it. You may be able to find an area to look into that valley to see if there is a pool of green stuff.
It is dry as a bone in there. Saw a wet spot on the seam where the 2 halves go together but no leak.
 

cbxer55

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How do you explain a wet spot? Have you watched that spot when it's hot, and the system is at 16 psi?
 

chiefk

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How do you explain a wet spot? Have you watched that spot when it's hot, and the system is at 16 psi?
Yep, I sure have for 20 minutes with the engine running and warm. Not a drop.
 

RonD

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Many auto parts stores and tool rental places rent pressure test kits, that will probably be your best bet

Or a UV Dye kit

Also check your overflow tank hose, I had one that was leaking , just a small crack
Cooling system held pressure for hours using tester, yet I WAS losing coolant, WTF???, was the overflow hose
 

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I'm still highly suspect of plastic ThermoStat Housing;
may just leak when engine is at higher RPMs & higher coolant system pressures\temps.
If there's even a small "wet spot" anywhere around the TStatHousing, take that plastic junk out, shoot it with a 12gauge,
then install an Aluminum ThermoStat Housing & get rid of this worry forever.
 

chiefk

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I'm still highly suspect of plastic ThermoStat Housing;
may just leak when engine is at higher RPMs & higher coolant system pressures\temps.
If there's even a small "wet spot" anywhere around the TStatHousing, take that plastic junk out, shoot it with a 12gauge,
then install an Aluminum ThermoStat Housing & get rid of this worry forever.
Thank you, I will study this and make a decision.
 

chiefk

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Well, I never could pin point the leak. Definitely not the thermostat housing. It looked like it was coming from the front corner of the right head. Too much stuff in the way to pinpoint exactly. When it would get hot there would be a steady dripping coming down the right side of the block. And sometimes it would just stop on its own. Intermittent leak. Well I was not about to pull the right head so I put in some K-Seal® - Permanent Coolant Leak Repair | K-Seal®. It looks like it worked, no more leak this morning.
 

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Could be the return heater hose to the pump, or the pump itself
 

G8orFord

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If you've still got the original plastic T-stat housing, it will leak. It may not be the problem now, but it will be eventually.

Stop leak is usually a temporary fix or really more of a bandaid. It also can cause other issues. I've used it before, but I prefer to fix the actual problem. Just my two cents.
 


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