I am having a problem with the engine overheating, on my Eunos Mk1 1.6 Roadster.
About two weeks ago I was driving on a motorway on the hottest day of the year, at the time, and I was caught up in slow moving traffic and I suddenly noticed that the temperature gauge was pointing all the way over to the right of the gauge.
I pulled off the motorway onto the hard shoulder to try to see what the problem was. Upon lifting the bonnet I found that a coolant pipe, that passes under the thermostat, had a hole in it and was loosing very hot coolant.
After letting it cool down I managed to get some tap water to refill the engine radiator so that I could nurse the car home by continually topping the coolant up every few miles.
When I got home I started to check all the coolant hoses and only found the one, that was holed. This I replaced, and I also decided to replace the plugs and the plug ignition cables too as they were over due for replacement.
The problem I am still having is that the cooling fan kicks in after only about two or three miles of driving. I realise it is very warm weather at the moment but is this normal for the coolant to get so hot so quickly?.
What I have done though, is to only use tap water without any antifreeze added to the coolant, as yet.
Would this cause it to over heat so easily?
Another point, that I have read in the Rod Grainger MX5 Manual, is that you should only use distilled or demineralised water and ethylene glycol antifreeze as coolant.
Could this be the cause of the coolant over heating, it being just tap water?
Any helpful suggestions would grateful, as at the moment I don’t feel confident that the car will not let me down again when out for a drive in this beautiful weather we are having at the moment.
I intend to get some some of the above coolant and antifreeze as suggested in the manual but, I am still concerned that this may not be the answer to my problem.
Ok first off, get the water out, flush the system and ad the correct amount of water/ coolant/Antifreeze.
Just having water in there is doing the engine no favours what so ever, the rust will be building up and turning to sludge which will end up blocking so many items on the system that will then need replacing, the " antifreeze" is also a coolant for summer and has rust inhibitor proprieties in it also ( well the correct ones will).
The fan should be kicking in at 98 degrees and dropping her down 10 degrees or so, so you know the switch is working and the fan( check what temp it is kicking in) , if it is kicking in at a lesser temp ,then change the switch, but it sounds like it is the fact that you are running her with just water in which is or will end up being a major issue.
M-m
What is the best way to flush the system?
I’ll put something together for you and fire a PM through buddy on how to do it correct, just give me some time as i get through friday madness.
M-m
Tap water won’t cause overheating (it actually absorbs more heat than glycol does), it’s just a bad idea to have diluted coolant in there for any length of time.
If the car is still on its original hoses, thermostat and radiator, these are long overdue a change. It’s all DIYable and not too expensive, but two of the small hoses are tricky to reach.
Flushing with a hosepipe is fairly easy once the stat is out.
Is the fan working? On cars not driven in stop-start traffic, it almost never comes on and can seize solid.
Its not over heating now, it was because of a leak, which as been repaired, read what alan as put.
His concerns are that it gets up to temp very quickly hearing the “fan kicking in” to cool, just water will do that , not taking into account that it is not here in the flesh to get down and dirty, it could also be a dodgy switch, water pump not working correct, thinned passage ways in the rad from lime scale build up from tap water neat or mixed and not deionised water being used, we deal with it a lot.
M-m