Hello,
Sharing my experience on the replacement of the thermostat housing on a 2005 Ford Ikon 1.6 with 76000 km on the odo. Not exactly a DIY but a guide on what to expect if you are facing a coolant leak and find that the source is from somewhere around the thermostat housing.
It started when I noticed coolant leak for a couple of days and wanted to take it to Metro Ford. I tried to search for the exact location one last time early morning and accidentally broke a tube on the thermostat housing leading to the diverter valve and emptied the entire coolant fluid leading to a fluorescent green floor! So there was no other option but to fix it myself, if not opting for getting the car towed! I pulled in my dad for assistance and set off to work.
Removal of the thermostat assembly:
Before removal of thermostat assembly, start by draining the coolant. I did that by disconnecting hose 6 and let it drain to a tub under the car. Removing the battery and battery box might give you some room to move your hands about. Unfortunately I do not have pictures to show the disassembly of battery and battery-box, but I'd say it is pretty straight forward.
Disconnect hoses 2, 3, 4.
You may spill some coolant here and there when you remove these hoses, a bit of cotton waste will come in handy.
Disconnect sensor clip very carefully with a pair of pliers and don't lost it. It's tendency to jump and my inability to catch it meant I had to make one from the spring of a laundry peg to seat the sensor in place, but may that not happen to you! (I sincerely hope it hasn't landed up in the fan shroud or somewhere!). The sensor comes out free once the clip is out of place.
Disassemble the 6 peripheral bolts. (I suggest use a 8mm socket to avoid chances of rounding off the bolt head. Some WD40 might be useful to release the jammed bolts from possible corrosion.)
Once all 6 bolts are out, gently lift the assembly upwards and disconnect hose 1. You will end up spilling more coolant with this hose as its level is much lower than hose 6. You can try and avoid it by resting its mouth at a higher point, something like this:
The issues in my case were the gasket was worn out and cut as shown in blue. I accidentally broke the pipe which was supposed to be in the yellow region. And a weird material warpage shown in red. The warped region broke immediately like a worn rag when I tried to press it back with my finger. I'm not really sure how glass-filled Nylon reacts to OEM coolant, but this is not how it is supposed to be!
Replacing the housing + gasket would solve my problem, at least by the look of it. (The initial leakage should've been from the broken gasket. I purchased a new housing + gasket from Metro Ford (Rs. 3200+720!). The valve assembly and temperature sensor were fine. (The whole assembly would set you back by 8.8K. That is what the service guys do irrespective of the problem)
The valve assembly cover can be removed by unscrewing 3 self-tapping screws:
Carefully remove the tapered rubber gasket (check for wear). The valve assembly with the plunger and spring comes out. (Sorry I do not have photographs of this part. I was concentrating too hard to click!)
The tip of the sensor will have oxide deposits and may look blue in colour. Gently scrub it with scotch-brite and some dilute soap water to remove the oxides and bring back the brass shine.
The area on the engine head, where the thermo-stat assembly mates will have oxide deposits. It would be a good idea to gently scrub off the oxides and other dirt with the tip of a broken hack-saw blade. (CAUTION: The engine head is Aluminium. Any strong movements can score the seating area and get us into worse trouble.)
The new housing with the valve-assembly, cover and gasket assembled. It would be good to not remove the valve cover from the thermostat housing once it is fastened with the self-tapping screws.
Assemble hose 1 first onto the thermostat assembly. Fit the assembly on engine head with 6 screws and torque it sufficient enough to compress the new rubber gasket. Connect hoses 2, 3, 4, 6. Place the temperature sensor in slot 5 and fasten it with the clip. Fit the battery back and all electrical connectors if they were out.
It is a good practice to flush out the entire coolant system before filling in new coolant, if you choose to do it yourself. Else, top-up the coolant tank with water and drive straight to Ford service to get the coolant filled.
While I was at it, I also tried the mod done by dhanushs to fix the A/C diverter valve problem by using a 5/8th Copper pipe about 3 inches long and shorting the two ends after disconnecting from the diverter valve.
Currently I'm running on water + remaining coolant and went on a 20km drive just to check for leaks from the thermostat housing / Copper tube joint and plan to continue for another 20-30 kms. I have also purchased 2 litres of Glysantin G48 coolant from a Shell outlet (because Ford coolant was too expensive at double the price) and plan to fill it in a couple of days. (Please share your experience with this coolant if any of you have tried). The air-con rocks now too. Will post further update in two days time.
Hope this helps!
Regards,
Subramanyam