Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Plus 8 Cooling fan cycling

Thanks for the additional information. My car has the Otter switch in the bottom tank of the radiator. My (sometimes flawed) thinking says that the water (coolant) in the radiator warms up to the cut in point on the fan switch due to inadequate airflow through the radiator. The fan comes on, increasing the airflow and cooling the water in and flowing through the radiator. Once the water cools to the cut off point of the fan switch the fan shuts off. The hot water from the engine starts flowing into the radiator again re-activating the fan switch and so on, causing the cycling I am getting. My plan is to do everything I can to increase airflow through the radiator. This includes an air dam under the radiator to help keep air from flowing under the radiator and into the engine area causing high pressure behind the radiator. I also am going to put a manual fan switch in so that when the coolant does get warm I can leave the fan on long enough to cool all of the coolant in the system. I may also add one of the air scoops that are available aftermarket, or I am told, from the factory. At least having the manual fan switch will tell me that when there is more airflow, the rest of the cooling system is up to the job.

I looked at the Tornado chip, and it looks a bit on the pricey side, especially as I am very happy with the way my car runs. Most of the Morgan related websites seem to say that the longer aluminum radiator is the final solution. Also pretty pricey.

I am going to try the easier (cheaper) things first and if unsuccessful move on to the more costly ones.

Thanks again for all of the ideas.

Dave

Dave - I'm based near L.A. and certainly the fan will cycle quite a lot at >70F in traffic, but even at 100F my 2003 plus 8 "self cools" above 30mph continuous on a level road.

I think one factor is you say "Before I purchased it the owner had all fluids changed, including flushing the cooling system and new coolant." This was probably well intended, but I recently changed mine and it has taken several weeks and a few hundred miles to purge all the air - even parking on a slope after a long run to encourage the air out.

The Tornado chip is pricey but in my experience completely transforms the car for the better

On my car the fan cycles continuously up to at least 40mph with an air temp of 60F. Here on the north coast of Calif. I won't ever see more than that, but as soon as I head east in the summer I'll be at 100F plus. So I am a little concerned. I haven't had it long enough to put more than a few hundred miles on it, but during this time the coolant level has stayed the same. The fluid changes were because the car sat for 6 or 7 years. The work was done at the Rover dealer in San Diego. I am still trying to get a feel for what is "normal". All of the input from other owners helps.

Dave

Perhaps if you take an extended run with the heater on full you could ensure there is at least no air trapped in the heater core? Does the heater put out plenty of hot air in the cabin by 'ram effect' at speed without the (interior) fan being switched on?

Do you observe the colored coolant liquid in the expansion tank when the engine is cold? Mine has a metal tab indicating the 'fill level', when I did the flush and refill I couldn't see the liquid level a few times without topping up.

We're supposed to have nice weather this week, so I'll take it on a long ride with the heat control on high and then check the coolant level. The heater seems to work OK. Coolant level cold has been right at the tab.

Dave

Yes, but it's obvious when you think it through, the better the oil the better the engine will be, less wear as friction reduced, a small increase in power, and lower heat due to less friction. If you do try this type of oil out be prepared for it to get dirty quickly the first time as it will tend to clean things out. So I would change again after about 5k miles.

The other action you can take is to fit an oil cooler. It wont do a lot in stationary traffic but as soon as you are on the move, it will help. Both my plus 8s had one fitted.

The oil that is currently in the car is Total Quartz 9000 Energy 5W-40 full synthetic. At the next change I may give the Fuchs a try, at least if I can find it in the US. An oil cooler does sound like a good idea.
At this time, in cool weather, no overheating, just a lot of fan cycling. I am worried about the 90 - 110 F weather this summer, at least if I leave the cool coast. Perhaps when it is warmer the fan will run longer and not cycle as much.

Dave