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Carrera 3.0 5 fan upgrade


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My 1976 Carrera 3.0 has the original 5 blade engine cooling fan. On warm days and under more testing driving conditions the engine gets hotter than my liking and can run between 210 and 250 degrees. Sometimes the rear bumper is too hot to touch! Having checked the owners manual it only states 'if the temperature reaches 300 degrees stop the engine' which is basically the top of the gauge.

I have looked into an oil cooler to replace the simple 'trombone' cooling pipes in my front wing but it is a £1500 + upgrade. I am considering upgrading my 5 blade fan to an 11 blade as fitted to the SC. A couple of questions if anyone can help...

1. Will the 11 blade fan giving much better cooling?

2. Is there anything else to change (other than the fan) to make this upgrade?


Thomas (in anticipation of a warm sunny summer!)

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May be worth looking a Jonny's alternator thread as the depths of alternators are different  between years - not sure if the fans themselves change or whether you'll need a fan, shroud, and alternator set to make the change?

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11-blade fan is a popular change on anything that had a 5-blade originally. The 5-blade was said to be the cause of a lot of 2.7 cylinder temp issues.

The 5-blade has a specific housing, as does the 11-blade up to SC. 11-blade pre-SC is a different housing. So if you buy a fan then buy the matching housing. The front must match the back as the back controls the swirl off the front. You can probably get them to fit between models but better if they match. Pelican has a bunch of threads on fans and how much flow they generate.

There is a small difference year to year but the big advantage of 11-blade at speed is lower cylinder head temp. The 5-blade draws less crank hp but the 11-blade keeps the heads cooler so it is a balancing act. You can up the speed of the fan to push a bit more air by changing the pulley size but the 5-blade gets much noiser with a larger pulley. The 11-blade is pushing a bit more at idle.

Remember that the engine temp is not the bumper temp. The bumper temp is heat from the silencer. You could get probably some heat insulating material in there to keep that cooler. My C3 runs an 11-blade fan and has been known to warp/melt number plates. Cloudy rear number plates are a definite 3-litre thing.


See this thread on Pelican - 11-blade fan upgrade - for some more details. Make sure you get a 245mm fan. If by some miracle you find a 226mm fan (they are quite sought after), you need to change a ton of stuff. Personally given the availability of this stuff I would just find the fan first and see how that works out.

But again don't confuse bumper temp with engine temp: these cars can handle heat. I have had mine sitting for ages in ambients of over 40 degrees. I wouldn't turn it off in that if I could help it though - a cool down drive is a good idea. This is one reason we always stayed out of town at Classic Le Mans: circuit traffic was a nightmare so a 20km run home was a good thing all around.

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Many thanks for the comments, some useful information to go on. 

I think the hottest I have seen my car was in heavy stop/start traffic on the M1 on route to Shelsley Walsh when the outside temperature was around 32-34 degrees. My temp gauge was just heading over the 250 mark and I spotted a fuel station and decided a 20 minute cool off was needed. The joys of driving UK motorways on Fridays! As long as the car is moving at reasonable speed it never seems to top 230 even in circa 40 degree weather on the Continent. 

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My C3 used to always run very hot.

Initially changed to an 11 blade fan and kept the small pulley to keep the fan speed up.

This did improve things a bit, as did running the car a bit rich.

Now have a late 3.2 cooler(ebay) with an electric fan from Merlin motorsport and all temperature worries are gone.

There is a great post in the oil section from David (flat666) which I followed.

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Before and after pics. Even without the fan, this is a great improvement. I also cut out the front bumper, like a 3.2 and changed my oil thermostat, but only because I broke the original try to remove a pipe. Had to drill and bolt the support bracket at the bottom and one to the rear of the headlamp bowl.



Edited by hagarep
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