2000 JGC V-8 overheating/ occasionally only !!

Holy Jeezus.

Do me a favor and either explain to me how a fan clutch will work properly with a plugged radiator (intermittently or not) and sort this out:

"The weakness of the bimetal coiled clutch fan concept is that it reacts to the tempature of the air coming through radiator core not coolant so on a cool day it is possible to have it run hot and not have fan engage because the air is still not that hot because it started out cooler."

...or please stick to the Chevy Plow Forum.

Jon

If your cooling fins are all smashed in or full of dirt, so that air can't get through your radiator, then your fan clutch won't get hot and won't engage. On the other hand, if the radiator is plugged internally so that coolant can't get through it, then there won't be enough heat passing through the radiator to warm up the fan clutch. Simple, elementary physics. What comes out, is equal to or less than what goes in. If you pour water in there, you can overheat your engine with a radiator full of ice.

Earle

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Please explain how a good fan clutch will operate properly with a clogged (intermittently or not) radiator.

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Please explain how a good fan clutch will operate properly with a clogged (intermittently or not) radiator.

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Oops, server problems, big dummy.

Suffice it to say, that's the point, and thank you. I thought it was being overlooked...

"I do not think so here because at times is runs cool under same conditon as it sometimes runs hot. If raditor was plugged it would be hot all the time. Also, anoth thing, if you do not here the clutch fan humping when gauge is climbing you know it is not doing its job.

----------------- TheSnoMan.com "

Jon

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Please explain how a good fan clutch will operate properly with a clogged (intermittently or not) radiator.

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It 'doesn't' operate properly, hence the overheating....

Mike

In article , L.W.(Bill) Hughes III wrote: #Hi James, # I would replace the thermostat, again, I've found many bad ones, #especially from Pep Boys. Make sure the radiator caps is holding at #least fifteen pounds to prevent the bottom hose from collapsing via a #clogged radiator. # God Bless America, Bill O|||||||O #mailto: snipped-for-privacy@aol.com

Bill,

The OP could also toss the thermostat into a pot of boiling water to see if it opens fully.

/herb

In article , SnoMan wrote: #A clutch fan is centrifical and bimetal thermostat controlled. It #engages when the bimetal control lets fluid into clutch disc area #faster than centrifical force can remove it. This is why it can #sometimes cool better at low speed because the centrifical forces are #not purging fluid from it faster than it is being replaced. Also at #low speeds the engine is making less power on average and needs less #cooling generally. When you put a big V8 in a small car the cooling #system has to be just right for it to keep its cool. I would consider #a electric fan as a last resort because it cannot come close to #matching the air flow capabilies of a engine driven clutch fan. To do #so would require more electric power than you vehicle can produce to #sustain it.

The WJ's v8 has a electricly driven fan in addition to the mechanically driven fan.

/herb

I know that but the electrical one has no where near the cooling capacity of the engine driven one. For it to do so it would require more electrical power than the cars system can produce and sustain

----------------- TheSnoMan.com

Is the temp gauge electrical? I have not seen anybody suggest an electrical/gauge problem. Maybe I missed it.

Years ago a buddy had an old Dart with odd overheating symptoms. He temporarily rigged a ( calibrated, borrowed from work ) digital temp gauge and determined there really was no overheating. I don't recall whether he identified the exact problem but he changed the gauge and rewired. Problem solved.

FWIW, doug

On the old Darts if you lost instrument panel ground all the gauges would self destruct. Nasty problem.

Earle

The electric fan in a hybrid fan system is only intended to provide airflow for the condenser at idle and low speed and the effect is gone by 25 MPH vehicle speed.. It is rated in the 200 -250 W range.

A typical engine driven fan in a typical V8 SUV or Pick-up runs up to around 5 HP which equals 4.3kW, far exceeding the alternator capacity. Big blocks and diesels even more ...

Bi-Metal controlled fan clutches either work or they don't work, the bi-metal adjustment mentioned elsewhere is either compensating for poor initial calibration or the addition of additional heat exchangers in the airstream (large aftermarket transmission oil coolers for example). The amount of fluid in a clutch is pretty small so a small leak quickly kills the clutch function.

Intermittent cooling system problems are nearly always related to thermostat function or lower hose collapse at high RPM.

My WJ came from the factory with just an electric fan and it has never overheated or run hot for that matter...

Service manual is not the gosphel and one reason why there are so mnay TSB's and updates on them because they are not always 100% correct. Spinning it will just tell you if there is still fluid in it, not if it is calibrated properly

----------------- TheSnoMan.com