Pulley size?

[matt69]

I am having problems keeping the bronco cool at idle. I had heard somewhere to change the waterpump pulley to make the fan turn faster at idle. Does this really work and would I want a smaller or larger pulley? Are there any other things I should look at. It runs at about 180-190 when moving down the road, but if at a stop it will start to get hot real quick.

thanks
matt

 

[Cactus killer]

Yes a smaller pulley will help do you have a fan shroud? what type of fan do you have?

 

[matt69]

I have a fan shroud with a mechanical fan. I am not sure what kind, but it has aluminum blades. I will have to go out and check how many blades. It does not seem to pull much air at idle.

matt

 

[Pa PITT]

we change from about 5 3/4 down to 5 1/4 but it only took less than 5 degree off the temp but when my buddy finally got his fan shroud built it stopped the temp from riseing any more It'll go to about 195 but diesnt get hotter ...

 

[72Sport]

If you have a v-belt system a stock 7 blade fan would help. The stock one has about an 1 1/2" pitch. There are some 7 blade fans on vans that have 2 1/2" pitch but there might not be enough radiator to fan clearance. Changing fan spacer maybe necessary or it just may not work. I have never tried the van pulley just taken measurements.

Take the radiator out and have it checked to make sure it is clean.

Stock water pump v belt pulleys are about 6 1/8" W/PS or without. The smallest double groove pulley I have found that is made by Ford is 5 7/8".

 

[matt69]

The radiator is brand new. How far away should the fan be from the radiator? Will I get more air flow with a greater fan pitch?

matt

 

[Cactus killer]

You have a flex fan(around 3500-3800 cfm for a good one)BC sells the 17" derale and it pulls 4500 cfm at idle it kicks ass the good thing is you can use a 1/2 fan spacer, makes the fan about 1-1 1/2" from the rad & it is only $42. The bad thing it is noisy, cheaper than the price of a new engine.
Good luck,

 

[72Sport]

The radiator is brand new. How far away should the fan be from the radiator? Will I get more air flow with a greater fan pitch?

matt

I would shoot for about 1 1/2" fan to radiator clearance. The greater the pitch the more air flow. The van fan mentioned earlier has 2 3/4" pitch rather than 2 1/2". The greater the pitch the greater the noise. The faster it turns the greater the noise. Do you have ac or anything added in front of the radiator? I have a heavy duty 3 core brass. I didn't have a problem until I added ac.

 

[matt69]

Nope no AC or anything else in front of the radiator. Should the wings on the fan be towards the radiator or the engine? My fan blades are aluminum and have a pretty aggressive pitch to them.

thanks for all the help so far.

matt

 

[72Sport]

The blades should curve back toward the engine. The heads of the 4 mounting bolts for the fan should be just about flush with the front of the fan. When standing in front of the grille the fan should turn clockwise.

What are you calling hot? 195 thermostat will not fully open until it reaches 215f. A 180 thermostat will not fully open until 200F. The thermostat controls the minimum operating temperature of the engine.

 

[matt69]

72Sport, According to your description my fan is installed correctly. I have not let it get as hot as it wants because I have not had to sit at a light for that long. It will climb from 180-190 when traveling down the road or trail and immediatley start climbing the hottest I have seen it get is about 210.

matt

 

[matt69]

Okay, I started it tonight and let idle for about 5 minutes and it went up to about 220 it would have kept climbing, but I drove it around the block to cool it down and shut it off. I am not a mechanic, but I would think that I am not getting enough air through the radiator at idle.

matt

 

[72Sport]

Have you changed the thermostat? It may be stuck partially open or it may not be opening all the way. I would take it out and put it in a pan of water and bring it to a boil. Hang the thermostat by a piece of wire so it doesn't touch the bottom of the pan. It may have the temperature it starts to open stamped on it somewhere so you can get an idea when it should start to open and at what temp it should be fully open. Twenty degrees is usually the range. Meaning the thermostat should be fully open 20 degrees above the number stamped on it. The thermostat will move rather slowly so be patient. You can check it with someone's candy thermometer. A slow boil is all you need.

Note how the thremostat is installed when you pull it out.

 

[matt69]

Okay, I am not at home the rest of the evening, but I will pull the thermostat tomorow night and check it.

Thanks for all the help so far 72
matt