This information may be applicable to various models and engines from 1965 through 1990.

I recently replaced my fan clutch with a Hayden 2747. It is the HD model. Same as Imperial 215046, 4-Seasons, etc (these are all made by the same company). The HD model spins the fan at 25-35% of the water pump shaft speed when the thermostat is disengaged, 70-90% when it engages at 170F. It is not listed by Hayden for my car, but it fit and my temp runs around 190F (with a 180F thermostat).

Hayden lists the Std Duty 2705 for my car (Imperial 215049) - and for many other models/years/engines. I installed the 2705. My temp ran over 210F, and the fan did not seem to move enough air. The Std Duty model spins the fan at 20-30% of the water pump shaft speed when the thermostat is disengaged, 60-70% when it engages at 170F. Although the specs imply a 5% difference in fan speed from Std Duty to HD when disengaged, the HD fan clutch seemed to move a good bit more air all the time.

My engine is a stock 1968 400 with AC and AT. It has a 4 row Harrison radiator, 19 inch 6 blade fan with 2 inch pitch. I just overhauled the cooling system - new radiator core, water pump, 180F thermostat, heater valve, hoses, belts. The car lives in Mississippi where it gets hot. The AC works and I use it.

The CSM calls for a code OU for my car. I called Hayden and Flexalite tech support and they both said no one makes a fan clutch that meets the old code OU specs. The code OU thermostats engaged at 155F. Flexalite said that their thermostats don't engage until 180F - so I did not try their part.

The Hayden website has pretty good technical info on their fan clutches. They are marketed under a number of different brand names - not sure why. Many of the fan clutches I found online and at my local auto parts stores appear to made by Hayden.

Based on my experience, I recommend a heavy duty fan clutch - particularly if your car has a HD cooling system. A temperature gauge is also very useful.

 

Nice tech writeup. I think I have the STD duty one, as it does not seem to engage untill the temp rises above 200. It was sold by the parts place but was probably made by one of those companies. I will get an HD one next time.

 

I purchased mine from Summit. Advertised @ 180 kick in. Works Great. Running a 180 stat and it cools it down to 175 before kicking out so to speak. 90 degree temps.

 

Very nice. This is the kind of information all of us need.

Thank you.

- Eric

 

This great info. It's the type of post we all can learn from.
Will have to note the part number and file away.

Gene

 

Great write up. I am lucky my car still has the original "OU" clutch.

Just a note: I recently went thru three thermastats as two of them were defective. The first one never opened, and the second one opened only 60 to 70 percent. And finally, on the one it opened all the way. These were Milodon 16400 units. Ofcourse, these thermastats are nolonger made in the U.S.

 

Thanks for the kind words.

I suppose I should include some application and where to buy info.

Here is a link to the Hayden catalog and application guide.

http://www.haydenauto.com/upload/Hay...fan-clutch.pdf

You can see that the Hayden 2705 is listed for a lot of Oldsmobiles. The Hayden 2747 HD fan clutch is listed for some Oldsmobiles - but for some reason it is not listed for any Cutlass/442 455s or 400s. My guess is that the 2747 will fit in any car that the 2705 is listed for.

I think these application guides form the basis of what the various parts companies show for your car when you look for a replacement part by car/year/engine/etc.

I bought my Hayden 2747 at O'Reilly - it was in stock. I think it is also available from Napa, Summit, and Amazon. Cost $50.

 

+ another on the good info.

I started snooping around some more after reading this yesterday.

A few GMC Motor Home links had some pretty good info on 403/455 fan clutches as well.

I saved some of the stuff I found on my other PC .....

But it's not too hard to find if you get creative with a Google search.

 

i got a bunch of NOS delco fan clutches laying around, i used one on ernie with no problems. application is B O P rwd station wagons through '90 with the olds 307.


bill