Thanks for the reverse light info guys, will get to it eventually but been well and truly sidetracked today (in between work of course
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Managed another 100 or so miles today. Has given me a chance to start focusing on the details of performance and tweaking. In fact, that was what I was going to talk about in this post, but on one occasion today, I had the dreaded boil up scenario so that's where the focus is back to for now. Blow off valve adjustment/ throttle response / boost spikes will all have to wait! Glad it wasn't type D in it yet!
Today's testing started with about 50 miles of mixed driving. Some continuous, some stop start and some spirited. The temp gauge generally behaved, moving up a little after prolonged boost but then settling back to 90 mark. On the last journey of the day, I really worked the engine, purposely using a lot of boost, braking, boost, braking etc to try to simulate track conditions (might as well break it before getting there right?) and the temps did rise somewhat but never more than half way between the 90 a left hand edge of the 130 zone. They also settled back down when cruising. So far so good.
At the end of this drive, I got the dreaded coolant smell! Oh no, not the hoses again! But it wasn't. No leaks in sight, good news. I parked the car for around 30 minutes to collect the kids from school. Engine bay fans working, I left feeling sure that the gremlins were gone. But this car always seems to bite as soon as you think something's fixed. When we got back in the car to just dawdle back home around half a mile, no boost, no silly business, the temp gauge began a slow and steady climb up to the 130 zone! I nursed it to the driveway, ushered the kids indoors and waited for the inevitable clouds of steam ...... luckily, they never came, even with the temp needle well into the danger zone. At least the replacement hoses are holding up then. That must be quite some pressure!
So, what's going on?? I could only think that this was an issue caused by latent heat soak whilst the car was parked up or possibly by me checking the level of the water in the coolant reservoir when the coolant was too hot (i.e. lower the pressure in the system and you lower the boiling point of the water back to 100) Any boiling in the system and I assume this could create air locks?
I'm sure I'd initially bled the car correctly as I had it up to temp for a long time with no air coming from the rad or thermostat bleeds. Was also getting reliable heat from the heater matrix. Fingers crossed this is not related to a head gasket issue but I'm pretty sure it would show itself in the 100 miles of spirited driving and Lee got good compression numbers from the engine.
I think I tracked the recent coolant smell to the fact that the cap of the coolant reservoir likes to burp. In fact, this may be happening during the slow down after every spirited drive because that's when I notice the smell.
During the boil up / overheat event, the front rad fans were not operating. The front hoses and the rad were cool to touch so it must follow that coolant was not reaching the front.
I let the whole thing hiss and cool down for a few hours. Refilled the coolant, bled it again for a good while, ensured proper operation of the front fans and then set out to re-create the issue all over again. By now, it was early evening and ambient air temp had dropped quite a bit. I really enjoyed these 30 odd test miles, best performance yet and really enjoyed heaping a lot of work the engines way. Thankfully, during this drive, there was no sign of an overheat but I did get that coolant smell as I rolled onto the driveway and idled for 30 seconds. I cut the engine and this time watched the temp gauge with ignition on for the next 20 minutes. The rear engine fans kicked in immediately but the temp gauge quickly rose to just shy of the start of the 130 zone.
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Then, over the next 20 minutes, temp very gradually fell back to 90. I didn't open the coolant reservoir this time just in case that is the cause of the air locking (pressure drop boil). I'll have to wait until tomorrow to drive it again and see if there's any issue after the last spirited drive.
I think one of the next mods I need is a bypass switch to operate the front rad fans manually. This car is going to need all the cooling help it can get! Any opinions, observations, advice welcome......... apologies for the essay.... and haven't even got to the fun stuff yet!
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