227 Degrees, 7 Minutes From Start w /Heater Blasting

jaymar

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Ambient was 73F. Mild grade I drive all the time with no issue, 800-1100 feet over about 4 miles. Turned the heater (including rear) on full-blast, high vents when I hit 204. Air coming out of vents was NOT HOT. I'm baffled by this. After a few minutes, the vent air became hot--too hot to keep my fingers in front of--and the temp dropped 37 degrees in two minutes of more or less level travel.

Parked it, came back 20 minutes later and it was 186 (right where I like it.) Start home and it's back up to 216 in two minutes. Took a steeper downgrade home, foot off the gas for much of it, wound up back at 186 when I reached the driveway.

W.T.F.?

Coolant, oil, tranny fluid levels fine. Radiator does have a slowish leak, but that's been true for a year. Hoses replaced a few years back. Checked coolant prior to trip. Will check fan clutch tomorrow.* Only recent work front brake pad swap.

Could be unrelated, but the day before I noticed a shaky idle on startup, with rpms down around 400. Dunno what that was, but didn't feel right. I'm thinking to check out Joey's famous overheating thread.

In the meantime--any ideas?


* I'm told the process is, have someone kill the engine--and grab the fan a half-second later. If you can stop it, the clutch is gone. Sounds like a finger-breaker to me, but I'm told it's not. Is this the correct procedure?

227.jpg
 
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jaymar

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CEL 170, 130, 133; all O2 sensors I believe.

Is there an overheating-specific code that should have been thrown? I mean, that would use the same sensor (as the one I'm tapped into) for the reading, right?
 
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Mine did this to me two weeks ago, it was the fan clutch on mine. I could grab the fan and spin it and it would go around a bout a 1/2 to 3/4 of a turn.
On the flat with no trailer it would register fine, start pulling a grade and low speed with the trailer and the temps would climb into the mid 220's.
In stop and go traffic it would kill the AC.
I'm changing the fan clutch this AM, then I'll take it and the trailer for a slow cruise up a local grade.
 

WarDamnEagle

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This "procedure" doesn't sound even remotely safe.

* I'm told the process is, have someone kill the engine--and grab the fan a half-second later. If you can stop it, the clutch is gone. Sounds like a finger-breaker to me, but I'm told it's not. Is this the correct procedure?
 

NLXTACY

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This "procedure" doesn't sound even remotely safe.

* I'm told the process is, have someone kill the engine--and grab the fan a half-second later. If you can stop it, the clutch is gone. Sounds like a finger-breaker to me, but I'm told it's not. Is this the correct procedure?
It’s fine. Done it more times than I can count and it’s the quickest way to find out if the clutch is even worth a damn.
 

fj80pb

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Besides dealing with the mentioned codes and assuring the clutch is OK, I suggest making sure the gap between the rad and shroud is sealed. Significant volume of air can scape through it before hitting the rad
Good luck!
Cheers!
 
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FJ80pb, you realize the fan pulls air through the radiator and not pushes air through it, right? The fan doesn't fight the direction of air flow in relation to vehicle movement.
Having the shroud tight is important but it's because the air will get sucked into the fan between the shroud and the radiator rather than pass through the radiator first.
 

LandLocked93

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It’s fine. Done it more times than I can count and it’s the quickest way to find out if the clutch is even worth a damn.
If you can hear the fan cycle between locked and free while idling (ya know, air whooshing and not whooshing) at nearly regular intervals, would it indicate proper operation of the clutch, or not really?
 

flintknapper

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If you can hear the fan cycle between locked and free while idling (ya know, air whooshing and not whooshing) at nearly regular intervals, would it indicate proper operation of the clutch, or not really?

Depends on the length of the interval. If it happening over a period of say 5 minutes or more....then its possible that is the fan clutch engaging and disengaging due to the bimetal spring regulating the clutch. But I wouldn't use that as a diagnostic tool to evaluate the health of the fan clutch since the silicone fluid inside could be degraded.

BlueFanClutch2.jpg
 

jaymar

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It’s fine. Done it more times than I can count and it’s the quickest way to find out if the clutch is even worth a damn.
I'd be astonished if it's a bad fan clutch, as I replaced it, what--2 years ago? But it's easy to test, so. Should the engine run awhile, or can I cold-start-switch-off-grab-fan?
 

jaymar

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Depends on the length of the interval. If it happening over a period of say 5 minutes or more....then its possible that is the fan clutch engaging and disengaging due to the bimetal spring regulating the clutch. But I wouldn't use that as a diagnostic tool to evaluate the health of the fan clutch since the silicone fluid inside could be degraded.

View attachment 2739923
Clutch maybe 2yo.
 

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