Hi all.
As you all may remember I switched my car to Evans waterless coolant last year. All is going well with no signs of any problems. I did have a weep through the winter but a nip up on the hose clip sorted that. Anyway my question is about heat soak after a run. I have a temperature monitor on my car so I can keep an eye on both banks with the probe fitted to the rear of each cylinder head. I have noticed that after a run and switched off I get temperatures of around 105c or 221F which drops away fairly quickly. I’m not worried about this just interested. Your thoughts please.

Rob.

 

As long as you open the bonnet after a run, all will be well. Are these water, cylinder head or under bonnet temps?

 

Hi Greg.
Cylinder head temps. My infer red temp gun agrees with the gauge temp. Drops to low 80s after around 15mins with the bonnet open.
Rob.

 

Sounds Ok to me Robbo. I measured air temps bonnet closed and they were 85° if the bonnet left closed and did not significantly drop in a hour! I put temp strips on the front of the head on the rocker cover, to get a decent approcimation of max oil temps and they were never hotter than 83°. If your probe is on the head outside (rather than sticking into the water jacket somehow) that might be a bit hotter than mine, but after shut down the water temp in the heads must be around 95° I would have thought.
It will not do the engine any harm, the point of opening the bonnet it so as not to cook the ignition amplifiers, wiring, fuel pipes etc etc. This is by far the most essential thing to do after a hot run.

 

Hi Greg. The sensors are sort of a ring terminal and are bolted to the rear water rail housing on each bank. I didn’t think there was anything to worry about just interested. I have searched on google but there isn’t that much info I could find.
Rob.

 

https://engineguard.eu.com/product/e...re-sensor-kit/

This is what I have fitted to my car.

Rob.

 

My V12 came with Evans in it. It did suffer bad heat sink and vapour lock last fall which put the fear of God in me. I just switched back to regular coolant after learning that Evans has less heat adsorption capacity. There was also a living with a classic episode where the guy did the switch and concluded his V12 was running a bit hotter, so switched back.

I am not answering your questions, but for me Evans is a firm no. So far this year zero heat sink issues.

Quentin

 

Greg,
To clarify, is bonnet raising a standard precaution for most V12 owners even if cooling system up to snuff?

Quentin

 

Many do, not sure if I'd consider it a rule, so many reasons - ambient temperatures, how was it driven before you came to turn it off. It can't hurt anything to do so.

If you've been ragging it then you should drive around a while to give things time to fall to more sedate levels, sometimes you can panic yourself by knowing too much, the temperatures seen here are no big deal, it happens in all car engines, many modern cars have electric pumps that run on for a while after shut down.

Biggest challeng with the V12 is the air movement - or lack of - so really driving in heavy traffic is worse than a little overshoot as it is cooking way more than the engine.

 

Morning guys.
Thanks for all your replies. Like I said no problem with my car just interested in what you guys thought. As for the Evans I’m very happy with it can’t say I have noticed anything different from when I had std coolant in the car apart from the system is running at a lot lower pressure. Bonnet opening is something I normally do as most trips are to car shows and I do like to show the engine off as it’s such a talking point.

Rob.

 

Absolutely. Heat under the bonnet (hood) post a hot shut down, cooks the wiring, the electronics and the fuel injection flexibles. On the move the airflow keeps things fine, but when stopped, bonnet closed, it is a fantastically hostile environment in the XJS engine bay, as it is so crowded. On the move the danger of a poor/failing cooling system is a danger for the engine itself; once stopped it is the under bonnet stuff, rather than the actual engine hardware that is at risk.

 

Absolutely raising the bonnet/hood is standard operating procedure if you live anywhere south of the arctic circle. I'll even release the hood lever at Stop lights in the summer and then pull it down again as the light turns green. Central Virginia is very hot and humid. I personally also pull the oil dip stick up and inch or so and take off the oil filler cap after driving the car in hot conditions to help cool the beast off easier. It provides a faster exit for all that internal engine heat.