gravedancer1969

I have a 1986 F150 a 302 V8 and automatic trans. I bought it new in 1986 and it just turned 63k miles. It ran so hot a couple years ago I just parked it. The original water pump was shot. The bearings were so wore out in the original water pump you could shake the fan back and forth.

Well I replaced the water pump with a new Gates pump, I replaced the thermostat with a new OEM and let it idle approx 15min and everything seemed ok. I drove it tonight and within 3 miles the temp guage was just about to the right,pegged.

I did idle in traffic for awhile and when I started moving the guage started dropping? I don't have any ideas left.

The only things I haven't tried is to have the radiator flushed and replace the fan clutch which is the original one.

Any help or ideas will be greatly appreciated.

Thanks,
Alan

qdeezie

With the engine off, stick your hand into the fan and try to spin it. If it spins freely, the fan clutch is bad. If the fan clutch is good, it will only move an inch or two. Give that a try.

gravedancer1969

I tried that and I can get a good 5-6 spins by using my fingure.

Energized

http://www.haydenauto.com/fan%20clut...1/content.aspx

88xlt

Yes, sounds like the fan clutch. If you can get out on the open road, driving say 50 MPH or more and it stays cool, that would confirm the fan clutch isn't performing. If you are driving fast enough and not in close traffic, the forward motion of the vehicle will push the air through the radiator. ie no fan needed.

gravedancer1969

I ordered a new fan clutch and waiting on it to arrive. Now a friend tells me I could have a blown head gasket? Wouldn't I have milky oil or steam coming out my exhaust or something else?

HwyCycle

Did you "burp" the system.. you may have an air pocket in the cooling system..

gravedancer1969

I drained it dry then refilled it with 2 Gallons of 50/50 pre-mix.

HwyCycle

Let it idle with the reservoir or radiator cap off.. preferably with the front wheels elevated slightly.. you want the open cap to be the highest point of the system.. watch that it doesn't over heat..

qdeezie

The fan clutch has been confirmed as being bad based on the test you did, so I don't see a reason to speculate any further until after the fan clutch has been replaced.