Fan Belt Tensioner Fix for Roadmaster LT1

[Waterdog]

I like my 1994 Roadmaster mechanical fan. It's perfect for hot climates and traffic, needle never moves off the center line, and have no issues with broken manifold bolts and other nasties that happen to our engines with extreme temp changes that come with the electric fans kicking on too late. Yes, you can change it out and program the ECM to kick in sooner, but without Garys electric fan harness upgrade, its now harder to get this done. Tensioners are hard to find in good shape and the pulley is usually worn out if the spring isnt broken on the tensioner. I tried the Dayco pulleys but didnt work in another thread. I ended up using a Napa 6 groove pulley, part # 38082. Shave one lip down. A longer bolt, M8-1.25 13 or 10mm head. 14 gauge and 18 gauge 5/8" ID x 1" washers for backside, and 2 washers for under bolt. Works great now for 30,000 miles. And my car stays super cool without extra electrical draw on the system.

And since the clutch fan robs about 10-12 hp, I used a 1984 Buick LeSabre clutch fan and gained back about 6 hp, since it spins better without any loss of cooling power. Noticed the difference immediately.

 

[BuickGirlFromMars]

I like my fan. Its perfect for hot climates and traffic, needle never moves off the center line, and have no issues with broken manifold bolts and other nasties that happen to our engines with extreme temp changes that come with the electric fans kicking on too late. Yes, you can change it out and program the ECM to kick in sooner, but without Garys electric fan harness upgrade, its now harder to get this done. Tensioners are hard to find in good shape and the pulley is usually worn out if the spring isnt broken on the tensioner. I tried the Dayco pulleys but didnt work in another thread. I ended up using a Napa 6 groove pulley, part # 38082. Shave one lip down. A longer bolt, M8-1.25 13 or 10mm head. 14 gauge and 18 gauge 5/8" ID x 1" washers for backside, and 2 washers for under bolt. Works great now for 30,000 miles. And my car stays super cool without extra electrical draw on the system.

And since the clutch fan robs about 10-12 hp, I used a 1984 Buick LeSabre clutch fan and gained back about 6 hp, since it spins better without any loss of cooling power. Noticed the difference immediately.

what year roadmaster, is this a TBI 350 or a LT1? And explain the fan clutch logic to me, different kind of fan clutches or..?

 

[Waterdog]

1994 Roadmaster LT1. Easier spinning Fan, less drag on system.

 

[Griswold]

what year roadmaster, is this a TBI 350 or a LT1? And explain the fan clutch logic to me, different kind of fan clutches or..?

Yeah, I don't understand either. 94 Roadmaster and 84 LeSabre use the same fan clutch (along with a slew of other GM cars from that era).

 

[Waterdog]

Try it yourself.. ;0)

Mechanical Fan Clutch......??

www.impalassforum.com

 

[ulycyc]

You may see a few HP difference between your two fan clutches only because one is a standard and the other is rated heavy duty. Both are available for both cars mentioned. Outside and engine temps will determine how much HP is loss. When it's hot outside and the engine is 195deg and over both fans will be locking up. If not you will be overheating. Highway driving both will be freewheeling just like electric fan will be off.

 

[Roadmaster 2112]

I also have a 94 Roadmaster, with the heavy duty towing and cooling. I was very tired of the noise and drag of the clutch fan and tried different things over the years. I bought the car with 82k miles in 2005. It is now at 288k miles. I have a PermaCool 14" fan in front of the clutch fan, and it is connected to the stock electric plug for the secondary cooling fan. The stock secondary cooling fan (with HD cooling, it's very powerful, 240w) is running on it's own circuit, activated by a 170 thermostat in the radiator ( I'm using a 160 cooling thermostat). I don't need the clutch fan, but will use it for towing. The two electric fans are fin for even the hottest days in the 90s. But I doubt they move anywhere near as much air as the clutch fan. Whenever I put that belt on, it's crazy how much that fan moves air. If I use it on a hot day, the engine temp drops under acceleration, because that clutch is engaged more tightly, and the fan spins faster.

I have a clutch and a massive, 19 inch fan from a 72 Caprice I had many years ago. I may try that clutch just to see how it works. It seems to be a bit lighter and flatter than this OEM fan. We plan to camp soon so I will use the mechanical set up for towing on that trip.