over heating/bad mpg (1 Viewer)

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My son just bought me an 88 fj62 from miami flew down there from va beach and drove it home had no issues for 900 miles got about 17 mpg all the way back. When they got close they realized they did'nt have heat come to find out there was no thermostat.I replaced the thermostat and both gaskets now im getting aweful gas milage and the truck's over heating if I have the heat off if I turn the heat on it runs at normal temp. So since I replaced my thermostat im getting bad mpg, and over heating problem's anybody have an idea? i've burped it twice the second time I tried the redneck burp trick it worked well got all the air out. Thank's
 
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please define "bad gas mileage". Also, what's "normal temp" to you? I'm hard pressed to explain how you go from having no heat to overheating just by adding a thermostat, unless your thermostat is not working or not the correct part for the truck.
 
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Right at or just above the first dial on temp guage is normal on my son's 89' fj and the other two 86's I owned alway's ran cool.This one when he got it home it did'nt have heat so we were going to replace the thermostat come to find out there was'nt one in there.So we installed new thermostat to get the heat to work so now the heat works but now the truck starts to over heat after driving a bit. I say it's getting 11 mpg now.
 
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Sorry the truck was well below the first dail on temp guage almost on c. when he got home that's why we thought the thermostat was bad so now it runs at normal temp and heat works but driving a few miles it goes from normal temp to a steady climb to the red real fast and when I see it I throw the heat on high and it brings the temp right back down to the first dial on temp guage.
 
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Replied to your other post about the same thing... 17 on the highway is good, 11 mpg in town is normal too, not much to worry about. As for the overheating, I would think it is the fan clutch. Can you hear the fan running after you've been driving it around for a while (when it is hot)? You should be able to hear it, it is LOUD.
 

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Replied to your other post about the same thing... 17 on the highway is good, 11 mpg in town is normal too, not much to worry about. As for the overheating, I would think it is the fan clutch. Can you hear the fan running after you've been driving it around for a while (when it is hot)? You should be able to hear it, it is LOUD.
Yeah, the fan clutch sounds like a likely candidate. I can definitely hear mine when I'm driving on the freeway and when it's hot outside. I can hear the fan clutch engaging and disengaging. It will engage for 30sec to 1 minute, then disengage for a minute or two then engage again. It sounds like a loud fan under the hood is turning on then off then on. Although I hear it working when on the freeway, it provides more benefit when you run at slower speeds, and the fan actually helps by pulling more air through the radiator. At highway speeds, the truck is moving fast enough to get flow through the radiator without the fan.
 
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No, fuel gauge works fine I did clean the points on the back of the fuel gauge hoping that would do it but that did'nt solve the issue, im wondering if the radiator has A clog, the only thing is it runs so cool without a thermostat. I filled it up with prestone 50/50 could the mixture be wrong?
 
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Look's like im going to start with the fan, i've checked that it is spinning while im under the hood but I havent heard it engage or change speed. I thought as long as it was spinning I was good.Thank's for the response i'll let ya'll know.
 

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When the silicone oil that is inside heats up the fan locks up and then will spin at the speed of the engine. Otherwise, it doesn't spin as fast as the engine and doesn't pump the air.
 
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Run it for a while,put a piece of paper in front of condensor does it stay up on its own,no clutch fan is not pulling enough,replace fan,yes clean,boil,replace rad. Mike
 
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It sounds like the fan couse it seems to act up when im on a long stretch of road or interstate and the fan not being able to keep up with the motor.I'll try these tips tomorrow and post progress.Thank's to all for your input!
 
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I've replaced the fan clutch and put in an oe t-stat, and burbed the system well. The truck is still overheating only after driving awhile I let let it run for hours in the driveway and will not get over the first notch on temp guage, start driving on the interstate or at 45mph for awhile and the temp guage starts rising quickly to the top the fan cluch seems to catch it now before it gets to the red and brings it back down to first notch on guage without me having to throw the heat on high but I still cant figure out what would couse the truck to run hot only at highway speeds any ideas?
 

brian

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did'nt rear all the replies, but what do teh rad fins look like.
have a celica that acted teh same way, everything looked good, till i touched the fins and they turned to dust...replaced it and it;s been all good.
 
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I replaced the fan along with the fan clutch, Im still confused at what would couse this at hwy speed and not at idol I've never had this happen before , it's like it's overheating in reverse.
 
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If you didn't use OEM Toyota fan clutch, that could be your problem. Never found an aftermarket one that wasn't junk.
 
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Yes, I used an oem fan clutch but the truck's overheating when there should be enough air blowing onto the radiator at highway speed's? The clutch fan should'nt have anything to do with kicking in at that speed but I can hear the fan now I couldnt hear it before it is loud and that's whats keeping the temp from the red.Not to mention it's been twenty degrees the paST WEEK AND IM STILL HAVING THESE SAME PROBLEMS
 
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should I replace the radiator? Ive replaced fan & fan clutch, t/stat,radiator cap,is the radiator the last thing it could be? it's not over heating at idol only hwy speed. could it be the head gasket? the oil looks fine just changed it and im not losing radiator fluid.
 

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