Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Another cooling fan relay problem

As it has an ali radiator, which tend to have a greater cooling capacity, than the standard rad. is the coolant getting hot enough to have the fan cut in.......I found when I fittted an ali radiator the car ran a lot cooler and rarely did the fan cut in compared to prior to fitting the ali rad.

Do you have an OBD test meter? My Maxiscan has a live running function that displays many readings that you can check. I had a Plus8 . The fan kicked in a lot! Basically the MMC aluminium rad , in my view, was only just capable to maintain coolant temp to an ok level. Hot weather, slow traffic etc led to the fan needed. I had done runs with little mods but it was still kicking in too often. No overheating as the fan did its job. Gauge readings were at expected levels reported for Plus8's. Summer v winter showed clear differences in coolant temp.
I used the Maxiscan to get readings of coolant temp that the system fed to the ECU. These matched the dash gauge so that was assumed ok. A thermometer used on the rad, top hose backed up the readings of gauge and Maxiscan.
On two occasions over 50k miles the fan failed, due to the fuse blowing. I stopped before problems. I hadn't heard the fan when expected and the gauge showed higher than normal.

A common issue with the 4/4 models following fitting of larger more efficient aluminium radiator was overcooling John. This could cause thermostat to partially close with extended hysteresis then ironically causing overheating when motorway speeds encountered. Cure was a lower temperature thermostat.

I thought it was worth a mention........something to eliminate in the ongoing diagnostics, A basic like is it getting hot enough for the fan to activate.....a temp sensor whould eliminate that issue, but hopefully the water temp guage ( although not always reliable reading) would also be an indication if it was getting hot enough to trigger the fan....but an indicated 12o degrees temp would indicate a different problem.
I agree most likely changing the radiator caps would resolve the greater capacity issue,, but has that been done on this car?

As it's had its radiator fitted recently, does it have an air lock in the system?

One thing to check... On the 2007 Duratec you will most probably have the 20p nylon fan connector which is dreadfully unreliable in this application. Mine failed stopping the fan from working so replaced with a ceramic connector block.








The low-speed fan kicks in around 100C and the high-speed around 105C. For what it’s worth, one of the many tricks of the Ford dealer’s OBD diagnostic software (IDS), is that it is able to run a fan test which is quite useful and reassuring.

The Plus8 had Gems management.
It had a coolant temp switch in the top tank of the rad to trigger the fan. A proper screw in one not the older Otter version. There were options to get these with different temperature trigger points. Also aftermarket versions that could be adjusted to cater for winter v summer or track( high speed) v normal road use.
It had an old school mechanical thermostat. Possible to get variants for different temperatures. It also had small bypass holes in the thermostat plate to allow some flow through before it opened fully.
Standard fixed rad cap plus on the expansion tank a pressure release cap. I think a 15 psi one.
As the car didn't overheat my aim was to reduce the frequency of fan kicking in. The system was sentive to smallish variations in airflow through the rad. Slow traffic especially in summer. Hence improving that as the first route. Components had been checked and were ok.

Many thanks all. Good news!! I cleaned up the connections and the fan works. It kicks in about 98/100 and then when it drops below it the then cuts off. Is that normal, when you turn the engine off there is no fan running.

Is the above pattern normal?

Many thanks
Will

Yep, the fan drops out around 94C and doesn't run when the ignition is off.

PS - if it was the connector above that you had to clean up, will you trust it again....

Good result but my 1999 and 1993 model Plus 8's the fan runs on with the ignition key removed but they run very warm in there so they needed to change the protocol to fit.

The fan stops at an indicated 80.

I like the idea of incorporating old school tec to sideline digitec when it may be suspected to provide a possible solution... Though I might be inclined to wonder if there are other aspects of the digital programming might rely on the inputs from the radiator sensor, if any. Were that a possibility I might think to install whatever other sensor and relay used to operate the fan separately, perhaps going even more old school by installing an override switch, to bring on the fan manually, if the temp sensor might have failed , or go the whole hog and install an illuminated means if indicating when the fan is running..... I do remember somee years back when Spanner Juggler was directly behind me in traffic that his fan seemed to be running constantly in his 90`s (?) model + 8 whereas the fan in my old mid 80`s +8 did not come on though my engine was at normal running temps. We chatted about it, and as best I remember Colin may have suggested that the later engines were lean burn (to cut emissions?) and thus ran at higher temps.

My old Mog took us on a few trips around the Med without ever spitting it`s coolant out, and still seems to manage to avoid being incontinent despite it`s age, though never ever liked the look of that otter switch and its grommet in the bottom of the copper/Brass rad... Hmm..

I crawl along my single track for a few hundred yards before arriving home, and on a hot day, my cooling fan often cuts in just as I reverse into the garage, and continues to run when the ign is switched off until the otter switch senses the drop to the required temp..