Continued...............
5) Once certain I had done enough with the garden hose flush, I repacked every hose and plug and removed the thermostat housing (Held by 2 10mm bolts. One is on the top, the other on the bottom) so I could remove it and go ahead with the citric acid flush. I had to remove the lower radiator hose ( No4 ) because the t.stat housing was stuck with something broken inside.
Sure enough, here is what I took out. A split thermostat.
It took me an hour alone just to remove the seal and t.stat. I cleaned up the housing using a scotch brite pad.
Lol..... Made in W.Germany. I wonder how old that t.stat was. What surprises me is that up until a month or so, this thermostat was working fine. The car never had any heating issues, the temp gauge would stick around 85 and would go upto 90 or in the summers with the air-con on and stuck in traffic. Well, its obviously dead now.
6) I went ahead and put in a cork into the bypass hole. I did a few changes and shoved it up the bypass hole.
Once the cork was in place, I put back the t.stat housing and tightened it. I will only install the t.stat at the last stage. So all of these steps were done without a t.stat.
7) I mixed 400g of Citric acid in hot water ( 1 gallon = 3.8 Liters ) and poured it in through the reservoir. I then topped it off with the garden hose. I started the car and let it idle for 4-5 minutes. Then, backed it up and drove around my house ( Yup, we have a driveway that goes around the house and gardens so its pretty long ). Kept doing this for the next 25 minutes before finally stopping onto the ramp again. I kept the heater on full during this time to make sure the heater core got some of the action too.
I let the car cool down for 2 hours before I re-flushed the whole system again by removing the radiator plug, reservoir cap and engine plug. I then went ahead and removed hose No1 and No6 and flushed/back flushed using the garden hose. Put back everything. This became my Sample No 1.
8) I went ahead and removed the cork this time from the t.stat housing. I then mixed the remaining 100g of citric acid in hot water ( 1 gallon ) and poured it into the reservoir, topping it off with the garden hose. Heater of full, I started the car and let it idle for the next 20 minutes.
Again, let the car cool down for a little over 1.5 hours and got around to flushing the acid out. Again, remove both the drain plugs and reservoir cap and out comes the waste. I removed the same hoses, flushed/back flushed until I had clear water coming out of the drains and put everything back into place. Sample No 2.
At this point it was getting dark and started to rain lightly. So I packed up everything and rolled the car into the garage to do the final flush for the day.
9) In order to neutralize the citric acid, I went ahead and mixed 250g of Baking Soda ( Baking Soda, not Baking Powder ) in a gallon of water and poured it into the reservoir. I did this step with the cork re-installed. I topped it off with the garden hose and started up the car. I ran the car for a little under 10 minutes with the heater on. Shut the car off, drained the soda water, flushed/back flushed the same hoses and components and put back everything. This would be Sample No 3.
10) Next, a 250g Soda flush with the cork removed from the t.stat. Ran the car for 10 mins and flushed out all the system. At this point, there is no acid left in the system. All the gunk is out. I still had to do a couple of distilled water flushes to be absolutely sure there were no tap water minerals inside. The sample collected here will be Sample No 4.
Here's the soda water, degreaser and scotch brite pad I used for cleaning the thermostat and water pump housings.
11) The final two flushes were pretty simple. The first one was done with the cork in place. Ran the car for 6-7 mins, let it cool for an hour and drained out the water ( Sample No 5 ). No flushing here since this is a distilled water flush by itself. I then removed the cork and did one last final flush with the D.water. The heater was in use in all of these steps. The final sample was collected and marked as Sample No 6.
So basically, the coolant system has come a long way from where I started. It took me 2 days to do all of this but I took my time and made sure I did everything properly. All i'm now left with is putting back the t.stat and filling up the system with the coolant + distilled water mixture.