[Swapnil4585]

Originally Posted by ChoosetoCruze

Oh dear, using the wrong coolant/ratio may well be the source of your intermittent overheating troubles. It may have lead to corrosion inside the radiator/hoses/water pump/head gasket (worst case).
As you said, the correct ratio should be 50:50 or 1:1 using HOAT coolant compatible with Toyotas.

Good luck & hoping it’s a cheap fix for you.

Based on my reading, in warmer climates, one may add up to 90% of water and 10% coolant. I doubt this proportion though.

See, it is not an intermittent issue. I noticed the the gauge rise once, on 14-09-2020. After that I have not used the car. I just start it put on the AC and scan. It does not overheat. Had the hoses cracked, there would've been a leakage. The level of coolant is also fine. So tiny / minor leaks are also eliminated from the investigation. As for the head gasket, the engine oil is not contaminated, neither any white smoke.

But I will follow your advise and change the coolant once again and also inspect if while cleaning the radiator, any fins are blocked.

On a lighter note, due to non use the suspensions and tyres are saved from the horrible roads

[ChoosetoCruze]

Originally Posted by Swapnil4585

Had the hoses cracked, there would've been a leakage. The level of coolant is also fine. So tiny / minor leaks are also eliminated from the investigation. As for the head gasket, the engine oil is not contaminated, neither any white smoke.

Since it’s a Toyota, even I doubt if it’s a head gasket issue as they aren’t renowned for that. It seems to be a simple, yet annoying issue.

[Swapnil4585]

Originally Posted by ChoosetoCruze

Since it’s a Toyota, even I doubt if it’s a head gasket issue as they aren’t renowned for that. It seems to be a simple, yet annoying issue.

After thinking a lot on what may have been wrong, I gave the car to the FNG yesterday night. It is with him and I will get it tomorrow.

My diagnosis -

1. Radiator fins of the front side are bent - too many of them. May be because of the muddy debris of a under construction highway.

2. Fan wiring has to be changed. I had observed presence of rats in the engine bay during lock down.

So fan wasn't kicking in at right times and front fins were bent resulting in the heat being trapped. Since the car was unused since overheating was noticed, it did not deteriorate the fault.

We were granted a few extensions in some tax compliance yesterday, so I can find some time tomorrow to get the thing sorted. Will be replacing all the coolant too.

[Swapnil4585]

Originally Posted by ChoosetoCruze

Since it’s a Toyota, even I doubt if it’s a head gasket issue as they aren’t renowned for that. It seems to be a simple, yet annoying issue.

After all checks, the car is back. All the while I was observing the coolant reservoir level which was fine. But it was the radiator whose cap was worn and was causing the coolant too escape. The radiator itself was clean, fan was working as it should. On my insistence, the engine oil was inspected. It was all oil. Nothing has been replaced. After adding water in the radiator, the temperatures came down and I was told to go home.

But my brains won't let me sit quiet. I will change the cap, hoses, coolant and engine oil soon

[ChoosetoCruze]

Originally Posted by Swapnil4585

But my brains won't let me sit quiet. I will change the cap, hoses, coolant and engine oil soon

Haha, great! If the new cap fixes it, fantastic! Changing the rest may not be required, but since you intend to keep the car for long, it won’t hurt to replace them as preventative maintenance.

[Swapnil4585]

Originally Posted by ChoosetoCruze

Haha, great! If the new cap fixes it, fantastic! Changing the rest may not be required, but since you intend to keep the car for long, it won’t hurt to replace them as preventative maintenance.

So in furtherance to the pursuit, I have done a 1000 kilometer trip after the cap was tightened. I checked today -

1. The radiator is full to the brim.
2. The coolant reservoir is little above the full mark.

So now I hereby declare that the overheating issue has been resolved fully