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

I recently purchased a 2003 Plus 8 35th Anniv. Special. I greatly enjoy driving the car, but have one concern. In normal driving, in cool weather (15 C)the cooling fan continuously cycles. About 10-20 seconds on, 30-60 sec off. The dash temp gauge stays between 100 and 110. Is this cycling normal for this car? How about the temp range? I haven't yet driven the car in one of our warm California summers to see what happens when it is warmer out. I have already had the cooling fan relay fail.

Thanks,
Dave

Plus 8s do run hot and 90/95 was normal on my cars but during the summer as high as 115 and even higher in standing traffic. I had a manual override switch fitted to the fan which helped. At times I have even had to have the heater on full blast.

Hi Dave

Not sure that your fan should be cycling like that, though I agree classic Plus 8 is rather marginal on the cooling front. Last Saturday I took my 2002 Plus 8 out for a run over Exmoor. Ambient temperature 12 C(?) and car ran at indicated 85-90 C, no fan, except when crawling through traffic in Dulverton.

Might be worth a check-over ?

Andrew Green
Glorious Devon

Thanks for the information. It sounds like I may be running a little warm, but not unusually so. Based on information from various Morgan websites, my plan is to check the thermostat operation and then add a manual fan switch and an under radiator rubber air dam. Thanks again,

Dave
Arcata, California

Unfortunately, they do have a tendency to do that as the cooling is marginal at least. Worth checking that the radiator cores is not becoming blocked. A good blow through with a hose is an excellent idea. Definitely fit a manual override, which acts as a backup if the temperature sensor fails. If it is a really hot climate, then a second fan pushing the air through the radiator does help. Also it might be worth looking at the ecu chipping and upgrading to something like a tornado chip. Not only does it improve the running of the engine but helps the cooling as well.

Neil

The MGBV8 can get that cooling fan cycle - mine often did it. I think that part of the problem is the otter switch being in a position where it may not stay constantly submerged in coolant. Check the coolant level, because the system is hard to purge of air. And definitely fit a manual over-ride - easy to do off the single feed to the otter. (Assuming you have one - the sensor may be in the radiator?).

Neil,
I had not heard about changing the chip. I'll look into it. There are no blockages in the fins on the core. The car is a 2003, but only had 750 miles on it when purchased in January, so other than lack of use issues there aren't likely to be any "wear" issues. Before I purchased it the owner had all fluids changed, including flushing the cooling system and new coolant. The car has not overheated, other than when the fan relay failed, but runs uncomfortably close to doing so.

Dave

Dave,

MMC were not renowned for refining the ecu chips on the later plus 8s. The 4.6L was a prime example and it needed an updated chip to get it to run properly. Certainly cooling was a major issue with that model and after I changed the chip it was a totally different car. I had to change the radiator to a larger version, install an air dam under the grill and add the second fan. Even after all the mods, it still tended to run hotter than normal.

Neil

Hi Dave

I have a 96 Plus 8, and when I first got her ran at around 95c and higher on hot days, how accurate the temp gauge is questionable but used it as a constant indicator. Two years ago I read up on motor oils, I have always been a firm believer that the oil in the engine can make a big difference on engine wear, performance and heat. I invested in Fuchs Titan Race Pro S 5W-40 Ester Synthetic Engine Oil and a hi-flo K&N oil filter, the difference was instant and normal running temperature dropped by 5 degrees and stayed much more constant. I was persuaded to change back to Valvoline when having some work done on the car as was told this would result in quieter cam followers, the higher temperatures returned and change in cam noise was minimal.

So this summer I will be changing back to the Fuchs. There is lots of stuff out there on it, but basically any fully ester synthetic will maintain its viscosity rating over greeter temperature ranges and the result is better friction management and less heat created and as a result less engine wear. Fuchs produce Titan Race Pro in various viscosity ranges. www.opieoils.co.uk is a good source. By the way it will be going in the MR2 MK1 race car.

Interesting stuff Adrian.