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1990 C1500 5.7L 350 V8 Couple mechanical questions

2419 Views 2 Replies 3 Participants Last post by  kendallt
I have a 1990 Chevy C1500 5.7L 350 V8 and have a few questions I'm hoping to get some advice/suggestions/help with. Thank you so much in advance. :)

1. The fan clutch has quite a bit of play in it. I've had suggestions to either replace the clutch or bypass it with a flex blade fan. Opinions? I've also been told however that the clutch blocks alot of air from getting to the motor and is robbing me of horse power. Is that true or just BS?

2. I have a mysterious antifreeze loss (No puddling or visible leaks) and the temp fluctuates from uber low (not reading) to 210 then back down then back up all in less than 5 minutes of driving @ only 45mph max. I was told I need to replace my intake manifold gaskets and my upper radiator hose. I've already purchased the things to do so and have read the steps in my Haynes manual. However I was hoping to find a simpler (dumbed down) break down to walk me thru changing them. The last time I replaced them (them being the gaskets) was on a 99 Tahoe and I found all the info online and it was a breeze, even with the vortec engine unfortunately I'm not having any luck finding something similar for the C1500.

Thanks again for any help you can give. I do greatly appreciate it.
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Hi StevieLee

If you want to get on the road quicker install OEM parts, the job goes quicker with less headaches of modifying this or that. The other issue of fluctuating temperature is either a problem with gage sensor or a bad ground to the cluster. Take your DVOM and do an ohm test on the sensor ( check your specs), then with ignition on if its a one pin connector have an assistant ground it to any metallic surface. The instrument cluster temperature needle should go all the way up. When you remove it from ground it should go down. This simple test tells you that the cluster's connections are OK so the sensor needs to be more carefully looked at.
Clutch fans and flex fans save power by reducing the amount of air moved at speed.
over 35 mph no fan is needed in most cars, yet a solid fan -tries- to move as much air per revolution which burns up a lot of power. A clutch fan lets the clutch slip so the resistance of the air doesn't pull as much power. The flex fan flattens out at speed, so it doesn't try to move as much air which saves power.

Clutch and flex are both better than a 'solid' fan, a flex is more reliable in the long term.
To save the most power, switch to a thermostat controlled electric fan, the only power drain is when it's running which is normally at times times that power is not an issue (lights, idling, traffic jams etc)

Gaskets are fairly easy, just look for the 350 engine, don't worry about c1500 specific info.
1990, still have the orange antifreeze? Hate that stuff.
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