My coolant was previously brown and a bit rusty as well as containing silicates so I drained the old coolant and did a coolant flush with Holts Speedflush and deionised water. I then drained all that and filled the engine with around 50/50 of Comma Super Coldmaster and deionised water.
I have tried burping the engine three times now. Twice I had the front up on jack stands, let it run and the thermostat open and squeezed the pipes, and the other time I did just now on my driveway which is much steeper, just to truly let the radiator cap be the highest point. This is also with a funnel with coolant in to let air get replaced by coolant.
Now, when I idle my engine it seems fine, ran it for about 24 minutes yesterday and the temperate gauge stayed right before 12 o clock where it should be. I can also drive my car and rag it all I want, the temperature will be fine. The only time I get an issue is when I am in stop start traffic. The temperature gauge starts slowly overheating then before you know it you’re approaching H but not quite there. If I were to then exit traffic and drive normally, allowing the radiator to get air through it, the temperature will go down though not necessarily to the right spot before 12 o clock. Even when I just went to a carpark and left the engine running, but then exited out of the car part I found it started overheating again, and that’s with the clutch only being used a few times.
I thought that perhaps the coolant fan wasn’t working, but I ran the engine and found that it would periodically start and stop as it should when operating temperatures are reached. This was both last night just running it for 20 minutes and when trying to burp the coolant this morning. Yet, when my engine is overheating and I take it home and leave it, the fan is not turning on once when you would expect it to be going full blast. Even though I was stationary, the temperature gauge would still fluctuate as well, and did get quite hot again until I turned it off. I also don’t see why a coolant change would effect the fan, as I had absolutely no overheating issues before even if I did a bit of drifting, so whether the fan was working before or not I shouldn’t be getting these overheating issues right?
So this leads me to believe that it’s due to the coolant change, maybe an airlock, but as mentioned I have tried to really burp the engine. Squeezing the s*** out of the three big hoses, leaving the engine running for at least 20 minutes all at operating temperature so the thermostat should be open. Worth mentioning, the thermostat and waterpump were changed last April, though an aftermarket thermostat from mx5parts was used. Any help would be greatly appreciated as I currently can’t rely on my car to take me to uni as running into traffic could cause major overheating problems.