A friend handed me his car (Honda city, 2005, genuine 125k km driven) yesterday to be kept for sometime until he is back from some business abroad.
I picked the car from G-13 Islamabad and drove 2 km and made a stop at some place. Then drove for another 3 km after 15 min and made a stop in G-11 Markaz. Then using Kashmir Highway, Zero point, Expressway made for home, near Bahria Town.
Due to heat of the day (around 2:30 pm), obviously the AC was working and MaShaAllah worked exceptionally well. I had to idle at the airport chowk signal for like 5 minute. During this time the car RPM would drop down after like every 2 min and with shudder then rise back to normal (750-800). Except that there was no issue and everything looked OK.
As the signal turned green and I drop off straight into tight traffic (due to construction of Gulberg interchange), I would have hardly crawled like 100 meters when the car engine suddenly shut down. I immediately turned the AC off and tried to get the engine started but it felt as if the battery was low. I put the hazard lights and kept the car rolling (very slow) thinking that the slope would speed it up and I may need that to dhaka start it. Luckily I was able to do it after 3, 4 tries. I turned on the AC and thank God. I drove another 200-300 m and saw that the RED warning light (for coolant temperature) was flashing. I turned the AC off but to stop at that congested section of road was almost out of question. I kept rolling. The RED warning light kept blinking for like 10-15 seconds and then stopped. I thought may be it was the AC that would be overheating the car. Left it shut down.
But to my horror, the red light showed up again after few minutes. I thought may be it is the go-slow that is heating and the moment I get some speed, it may cool down a bit due to convection in the radiator. Rest of the way to home (some 5-6 km), I did not run the AC, the red-light would flash after few minutes for few seconds and then go away.
Finally I reached home. There was no other issue driving the car. I just prayed no serious issue would result.
Now I was told that the car was recently serviced in detail. The engine cooling system flushed many a time, and then Honda Blue Coolant was used in 50-50 concentration. The car generally was driven in 10 km trips -- that in Islamabad means a drive for 10-20 minute since the place of job and kids school weren't very far away from home.
The car produces a "goonj" sound at higher RPMs and some people said it is the sound of the "crank". This sound had been there for the last 2 years or more. The car was purchased some 3 years ago by my friend.
The engine, allegedly has never been opened. The car has no history of reducing oil as well as coolant. No heating issue as well.
And a good quality T-stat valve was also installed when coolant was put in.
But when I reached home, opened the hood, it felt quite hot. I checked the expansion bottle, it was full to the brink. After an hour or so, opened the radiator cap to see the vents inside the radiator and no coolant/liquid. The expansion bottle at that time had coolant less than half the bottle.
Also found the battery dry so topped it up with some hot water.
Also topped up the radiator with water. Turned on the car, found no leaks with a little inspection above and under the engine bay. Turned ON the AC. Both the fans started rotating. The AC blew chilled air. Turned off the AC, both the fans stopped.
Left the car idling, even accelerated the engine twice or thrice but without the AC, the fan did not run, which, I believe should have, because the car was not cool when we added water and in 4-5 min idling, with AC ON then OFF, the water must have reached the operating temperature.
The FAN did not run without the AC throughout our test, nor did the RED light blink.
The person with me suspects the temperature sensor -- but I do not agree with his diagnostic since the red light blinking meant the temperature sensor did its job. For some odd reason the radiator fan, however, does not rotate. Though both starts rotating immediately as one turns on the AC. They also stop as soon as one turns off the AC.
My understanding is the coolant has to flow in the engine compartment and wherever it has to, and then when sufficiently hot, with the opening of T-stat valve, it passes through the radiator, cools down and keep the merry-go-round flowing!
When the flow through the radiator does not cool it down to a required temperature, the fan aids this cooling.
The fan does not do its intended job. Where can the problem be? Where to look at? I intend to work the system at home if it remains in easily workable domain. I have the assistance of my driver who is also a mechanic.
In the evening, after like 3 hours, I needed to make a short trip to bakery, 1km away. Before starting the car, I opened the radiator cap. Again there was no liquid to be seen in the radiator, whereas previous (3 hours ago) we filled it up, ran the car to see that the fan did not work.
Next day, after reading some Honda City 2004, 2005 heating issues threads, I decided to check for head-gasket test (as proposed). I opened the radiator cap, filled it up to the top. Started the car and checked the water. I saw no bubbles but the water overflowed a little. No bubbles or shot-up of water could be seen.
What does this suggest? Anything related to head-gasket?
Based on a thread on someone's 2004 model heating issue, he seemed to have done everything with the engine and then finally (something which no one had suggested) was done and it fixed it -- water pump was replaced!
So honestly, I feel, I must check the condition of the water pump before checking for anything else. The engine dip stick shows no milking or anything unusual. The car does not give out any smoke.
There is but one thing, which in a run today, for 3 km, I did not observe, and that is, no fan rotating without AC.
Is there any possibility that the T-stat is stuck and not opening? Asking though never heard of it!
I guess I should check T-stat valve first, then water pump and if they are fine, then worry for anything else.
PS: Sorry was too descriptive a description. I hope someone suggests something sane and logical to me.