OMG I must be mad grafting on a Bank Holiday and now passing on to you guys some useful advice.
Three customers have said the same thing, their cars aren’t consistent. Michael took one out on the road with a data logger on it. The water temperature was fine when he left the workshop at 85 degrees, but the temperature dropped and dropped – the guage stayed at ‘normal’ – but the water temperature dropped to the point where the temperature corrections kicked in and would reduce the power. One good pull and the temp was back at 80+, next pull and full power. Drive a bit and the water temperature dropped to 60 degrees, the mixture richened up, the ignition retarded, boost reduced etc etc. The engine thought that is was warming up. The inconsistency that we had heard about. It would not have shown on a chassis dyno.
We have also lost an engine with a cracked block just by the water pump having been running at serious power - time for the thermostat to be investigated. What I found was not what I expected. The thermostat on the 500 is very Italian and different, it is held in place and on it’s seat with a spring. When the thermostat material reaches 80 degrees the spindle extends and compresses the spring pushing the plate off the seat and allowing the water to flow. There was a lot of deposits and scale so I used some Tesco scale remover to clean the housing. What I then found was that the housing has been eaten by something and the thermostat plate doesn’t fill the void. Has the car had acidic coolant?
The spindle sits in the hole in the middle and the thermostat plate sits on the dark ring.
This is the housing as I removed it from a 2010 car:-
Here is me cleaning the housing:-
So now a photo of the cleaned thermostat being pushed into the housing, it should seal the water flow, but not with that gap!
The point here is that the temperature gauge in the dash shows a body computer modified output. It looks as though is sits at ‘normal’ from below 60 degrees through to 90 degrees plus. No problem with a standard car, but for anybody with a nicely mapped modified car it will give inconsistency – with our mapping it can mean just 3 or 4 degrees of ignition advance instead of 10 plus, probably 50bhp.
As at today I don’t have an answer other than a new thermostat and housing – but watch this space, we are working on it.
