91 safari rwd does fine in town but not on long drives

FROM RADIATORS TO THERMOSTATS TO HEATER CORES, IT GOES HERE.

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Derek939
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91 safari rwd does fine in town but not on long drives

Post by Derek939 » Wed Aug 08, 2012 5:24 pm

So I got a 91 safari from the original owner. Has 151k on it. I've put a new thermostat and fan clutch on it. When driving around town it does ok the temp stays below or right in between the 2nd and 3rd bar. But if I turn my air conditioning on the climbs into the middle of the 3rd bar. Also on long drives without the Ac on it does the same thing. I haven't let it go higher because I usually crank the heat on just to play it safe. Is this normal? Where does everyone else's temp gauge sit at? I have a 91 Astro that never climbs over the 2nd bar. Does anyone have any tips or ideas on what I should do next?

Thanks!
1991 Astro RWD EXT w/187000 miles
1991 GMC safari RWD shorty w/151000 miles
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Re: 91 safari rwd does fine in town but not on long drives

Post by 6spd_monte » Wed Aug 08, 2012 6:08 pm

It could be that the radiator is a bit dirty inside, maybe not transferring heat as efficiently as it used to. The factory thermostat should be 195 degrees I believe. My '87 would always run hotter than I was comfortable with so I replaced it with a 180 degree thermostat, now it stays nice and cool, usually just reaching the middle of the gauge.

Another thing to check is to be sure the air is actually going through the radiator like it's supposed to. Make sure the fan shroud is installed correctly, sung against the radiator. Also there should be a heavy duty black plastic piece under the core support that covers the gap between the core support and the front steel panel (the steel panel that you can see just below the grille and extends down behind the bumper). If this piece is missing then air passing through the grille could just flow down and under the vehicle instead of going through the radiator. Also, when you're stopped the fan clutch can pull hot air from under the vehicle back up through the radiator if this piece is missing.

For 1987 it's #20 in this diagram:
http://www.genmotorinfo.com/Picture.asp ... 28TM01-001

In the 1991 diagram I think it's #17:
http://www.genmotorinfo.com/Picture.asp ... 22TM01-403

The '90-'94 radiator mounting is a bit different than mine, but #17 looks like the part I'm talking about.
-James

1987 LT
249,000 miles

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Re: 91 safari rwd does fine in town but not on long drives

Post by Kidhauler » Wed Aug 08, 2012 8:06 pm

You might have gotten the wrong fan. This happpend to Canadavan a few years ago and the fan was pushing air out the front instead of pulling in.

At speed it would balance the pressure and the van would over heat but in town it was fine.
1999 Safari Touring edition.
trailer tow pack with a 3:73 posi
Bucket bench seats, Rear heat, Rear Airconditioning.
teal green
300 000 kms
AirRide air bags in the rear to fix soft stock suspension.
Onboard aircompressor to make it all work nice.

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Re: 91 safari rwd does fine in town but not on long drives

Post by LiftedAWDAstro » Fri Aug 10, 2012 12:23 pm

If the fan is mounted to the new clutch correctly, I would look at the radiator being plugged internally. Getting a new one locally or off E-bay is pretty cheap so it would be worthwhile to replace the 21 year old one anyway.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy

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