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Coolant leak

John McIntyre

Member
Joined
January 24, 2008
Messages
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City, State
Pacheco, CA.
Year, Model & Trim Level
2001 Ranger
I have a 2001 Ranger 4.0 SOHC V6 Engine and there is a coolant leak on the top of the motor somewhere. I took out the plastic housing for the termostate and cleaned it and put some gasket goop on it before I put it back, but that does not appear to be where the leak was/is coming from. It is puddling on the top of the motor where I can see it with a flashlight at the first soft plug. I am going to start dismately the top plastic housing thing to see if I can see from where the leak is coming from. No water in Oil; just an exterior leak.... Anyone have this before...?
John
 



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try to clean the sitting antifreeze out with a water and dry it. then run the engine at operating temp and look for the source.

you can also pressure test the system if you have access to a cooling system pressure tester.

just an idea, on my 02 SOHC ranger, there is a coolant line on the passenger side of the engine just below/behind the throttle body. you can trace that line all the way around the back of the engine around the PCV and into a heater hose line.
 






I'm having the same issue with my '02 Ranger...John, did you ever figure out the source of the problem?
 






Yes Red, It was the Plastic thermostat housing (the plastic portion of the thermostat that sits below the actual thermostat) that had started leaking at the little rubber O-ring. What happened on the first time I took it off to replace the O-ring is I broke off one or more of the little plastic tabs that are guides that sit inside the whole of the top of the engine and so it cracked there and continued to leak. This part was not to bad in cost from Rock Auto; extreemly expensive if you go to the dealership. I had it off many times; Also, when I got the new part, the sensors that sit in the wholes in the thing were loose. I thought it could be a factory tollerance error, but the next one I got was the same. I ended up using the same sensors and just gooped them up with a high tack gasket making sealant and it has not leaked. I think the whole thing is a piss-poor design by ford and would not buy a Ranger again. You can't get the sensors out nor change the thermostat without lifting the air intake thing off the top of the motor. Just goofy design. Hope this helps. Any other questions, just let me know.
 






Thanks...I replaced the same part yesterday and still had massive coolant leaks pouring out below the truck. With everything reassembled I could see just a little bit of coolant sitting on the flat top of the bottom T-stat housing and figured it was coming from those 2 sensors, but didn't imagine it could be causing all the volume of fluid I was seeing below the truck. So tonight I pulled the intake manifold and cleaned everything up (lots of coolant pooled on top of the block between the valve covers), then left the intake off while I pumped up some pressure with a Radiator Pressure Test pump. Sure enough...lots of coolant leaking out those sensors. So I pulled the sensors off and stuffed some rubber stoppers into the holes...built up to about 5 psi and crawled down under the truck. No leaks...everything is holding well...until it didn't. My rubber stopper popped with about 5-6 psi pressure built up and I had a 3/4" diameter x 8 ft tall gyser of coolant all over my garage...oops.

The good news is it looked like that was my only leak...I just can't believe that much fluid could leak out from 2 sensor ports. I'm going to try your suggestion of the gasket sealant and let them sit overnight, then retest under pressure in the morning. I'll post the results tomorrow.

Thanks again for the info.
 






yo just change the whole thing upper and lower thermostat housing had same problem lower housing had a hair line crack cant do nothing about it but change the dam thing ford got me on this one cost for part 345 scrips for the complete set up took me 4 hrs of labor. reason the sensors is a factory sealed bolt type i have an 2001 sport some came with a plug and clamp type witch is cheaper just for the lower housing 45 scrips
 






Yep Red, I thought about getting new sensors that might have a newer/larger rubber seal thinking they would fit more snug, but due to the fact that my old ones fit snug in the old T-housing and not the new T-housing I decided not to get new sensors. Go figure. So I did not want to expense new sensors and just used the High tack sealant on the Old sensors (and they sense and read fine)and Thank God it worked and is still working fine. It is a pain taking all that off. I took that thing off so many times, but now I got it down. I am hoping to get 250K out of my Ranger and then go from there... I have 171K now. Let me know if it works for you...
 






Applied the sealant last night and re-installed the sensors. Letting the seals set overnight and I'm going to test when I get home this afternoon. Hopefully I can get everything buttoned back up and on the road tonight; I'll post the results.

So far I've replaced the T-Stat, Water Pump, Upper and Lower T-Stat housings, about half of the hoses, and all the gaskets/seals associated with the tear-downs required to perform the tasks. There is definitely an "unintended consequence" of doing these PITA jobs...you learn a lot about tearing down the engine compartment of your truck!
 






OK, put everything back in play last night. Still have a slow coolant leak from around the coolant temp sensors at startup. As the system heats up the leak lessens; it seems like the plastic body of the thermostat housing/water outlet expands enough that the sensor wells get tighter and the leak isn't as pronounced. Still, an ongoing problem. My bro-in-law works at a Ford dealer in town (body shop), so I'm going to see if he can find out from the Service Dept what Ford's solution to this problem is. I'll post the results when I get something that works.

Bottom line; after 4 days (evenings) of work and replacing pretty much every component in the cooling system (other than block and headers), my truck is finally holding temperature again and is back in running mode. I lost about 2-3 cups of coolant in my 30 min test drive last night, so there is still a leak to fix but at least I'm back on the road.
 






My posting is quite some time past this last one, but I wanted to chime in for some help, as I have TAKEN lots of good info from this site!!
My Exploder is a 99 Sport 4.0 SOHC. At approx. 51k miles in April 2010, I smelled coolant and noticed the same puddle of coolant on top of the intake, as well a slow drip coming off the tranny pan mounting surface!

Read through this entire site for `anything` I could find...seemed from hearing everyone`s thought, that I needed the whole t-stat housing,(upper and lower) to the tune of about $350 Canadian. I took a gamble on the upper housing for $150 because it seemed to appear warped. I set it on my glass coffee table, and you could actually rock it from side to side!

Replaced it myself, and Whalaa!! NO MORE LEAK! Note: NO SEALANT NECESSARY...this is an O-ring only mating surface! My truck spent it`s first nine years in AZ. and just recently moved up to Canada. I can only assume that the extreme desert temps. had an adverse affect on the ****ty plastic housing...no cracks in my lower housing, as many have suggested. I guess I was lucky.

Bikeboy
 






BB - thanks for the post. Happy to hear you were able to fix it.

Reading back through the thread, I realized I never did a "finish" post. You are correct that the thermostat housing itself does not require sealant - it's an O-ring only The sealant we were talking about above was around the temp sensor/sending unit ports. What I found was if these are old, the seal against the thermostat housing is not good and you have a lot of leakage around the sensors. I ended up just replacing the sensors (one of them twice...got a bad part) and that fixed the problem.
 






So the long and short of this is (in order from first to last assuming the leak didn't stop) to first goop up my sensors with a tacky gasket maker / sealant, 2 replace to the hoses if it still exists, 3rs H2O pump, last and most expensive = t.stat housing.
 






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