Cooling system - monitoring and management

[GeoffSmith]

This thread has been started to collect together thoughts on the coolant system which MAY be contributing to head gasket failure, of which there have been too many of late.

I think the main issues are:

1. Temperature Sender and gauge are not matched - normal running is at ¼ scale and fans kick in at ¾ scale which can be quite scary even to old lags.

2. The fan switch is on the rad side of the thermostat so a stuck thermostat can seriously affect when the fans kick in.

3. The head of water is not much higher than the head of the engine so any loss of coolant can be serious.

Some have gone for a Dickman lower temperature fan switch, I outlined some ideas about switching the fans earlier / coolant level indicator and Mikeydude has raised some additional salient points on the Bling-bottle thread and obviously has similar concerns to me.

My current thinking is that a coolant level sensor is highly desirable and that using the CTS to switch the fans earlier gives the opportunity of turning the fans on singly, the additional benefit of dual redundancy in the sensor and the possibility of linearising the gauge so normal operating temperature gives a vertical needle at ½ scale (as most of us are used to in other cars) and the fans kick in at ¾ scale.

This lot will require a box of electronics which could include provision for a temperature probe on the engine. I've got too much on at the moment to fully research and develop it, but if anyone has any thoughts or suggestions, fire away.

Geoff

[Readit]

I cannot assist with the complicated electronics required for your solution but I can offer a simple solution which allows more control over the cooling system. After owning a 1979 Elite which boiled up in traffic because the fans did not cut in, I am now wary about coming to a slow crawl in traffic queues after a fast burst on a motorway.

The solution on my Elan is quite simple A MANUAL OVERRIDE SWITCH TO THE SENSOR IN THE RADIATOR. It is simple to wire and I can post a wiring diagram if anyone is interested.
I had a spare rear fog light switch from a salvaged car and installed it in place of one of the dummy switches, some touches of black paint can change the rear fog light to look like a fan blowing ( but not absolutely necessary) I just turn the fans on manually in traffic jams when the temp gauge rises.

A spin off from this solution is that when the ignition is switched off with the new switch ON the small circulation pump runs allowing manual turbo cooling when stopping the car after a hard run. The switch has no affect on the automatic operation of the fans or pump. The only thing to remember is to make sure the switch is always in the OFF position when leaving the car

Unrelated to the above I discovered another cooling problem on my Elan. When I first owned it ,it was prone to over-heating the temp gauge hitting the roof at the slightest provocation. I had occasion to remove the front bumper and found the rad and oil cooler were clogged with years of muck. I carefully cleaned it with a soft brush and washing up liquid solution taking care not to damage the cores, over-heating is now a thing of the past. HOPE THIS HELPS!!!

[Monty]

There`s already a few off us who have the fans on a manual switch
There was a couple of thread on how to do it
It`s just the case of coming from one of the legs on the relay and the other is just earthed


Oh here you go

viewtopic.php?p=150829&highlight=

viewtopic.php?f=29&t=11692&st=0&sk=t&sd=a&hilit=cooling+fan+manual+switch

[Readit]

Thanks for the links I hadnt seen these.
I didnt wire to the relay I just put the manual switch in parallel with the sensor. seems to work fine.
I understand from the other threads that there is a worry of leaving the switch on with the ignition off and flattening the battery but I think it is outweighed by the possibility of cooling the turbo manually with the ignition off. Most authorities on cars with turbos suggest at least 30 secs at idle before switching off. A manual cooling control is more effective.

Love the sound of the twin fans switched on in a traffic jam, sounds like a jumbo jet landing in the fast lane.