Fluctuating RPM's at constant throttle (throttle hunting, surging, gear hunting)

zulu

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Fortunately.. No metal sounds is noticed through this ordeal
 

bbyer

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I had to replace my what I call the electro-viscous fan; more complicated than the usual viscous fan in that it includes an electric clutch.

Anyway, mine tended to stay on so loud fan noise when driving - would often uncouple but when it would not, loud whirring noises from the engine compartment into the cabin.
 

zulu

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I wonder if thats what im hearing. But in my case.. Not when im on a higher gear and going faster than 50km
 

bbyer

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I wonder if thats what im hearing. But in my case.. Not when im on a higher gear and going faster than 50km
As I recall, the fan noise was at low speed but usually upon speeding up, (50 kph or so), the noise would soon stop. It was quite a few years back now so I do not recall all the circumstances but I know the fan roar was noticeable in the cabin and that it would eventually quit, only to often commence again after a short stop.

The fan assembly was not cheap either.

For whatever reason, LR uses a much more complicated system than GM does on their 350's - that fan was just viscous and operated by the feel of the air off or near the radiator.

With the LR system, you have that plus the engine computer telling the fan clutch to lock or let go.

I imagine it has something to do with emission regulations as it seems the excuses for a lot of the LR odd ball designs are emission related.
 

zulu

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Thanks bbyer. Yeah. Your description sounds about right. Sigh.. Cheaper to just turn up the volume of my radio.
 

bbyer

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Well actually the aluminum block might need the cooling one day - sourcing the Jag V8 is not quite the same as going to the junk yard and yanking a Chev 350. I regard the cooling system as a big deal - that is one reason I replace that bleeder tee as a maintenance item, kind of like an oil filter and the thermostat housing.

I might also add that bleeding the air out of the cooling system is tedious and an art - taint a Chev.
 

Dinospring

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i have this same issue with my 2005 LR3 V8, wondering if I can ignore it and how long it might run without it becoming a big problem, and what eventually would happen, transmission failure? Is it dangerous to not address it preventatively?
 

DaytonaRS7

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i have this same issue with my 2005 LR3 V8, wondering if I can ignore it and how long it might run without it becoming a big problem, and what eventually would happen, transmission failure? Is it dangerous to not address it preventatively?

drain fluid, replace filter, replace fluid.
drive a few miles.
drain and replace fluid.


alot of time dirty fluid and filter will cause this.

i cant answer how long it can go on without futher damage, but the (possible) fix isnt THAT difficult.
 

bbyer

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I’ve put 80k miles on the truck with this condition. Still does it.
I am wondering what problem you are referring to?

The thread started out with a question of what I would call surging - sort of like one was tapping on the gas pedal at low speed.

If that is the problem, see my post #16 of 2019 - two years later, still no surging so I guess replacing the oil temperature sensor located down near the oil filter on the 4.4 V8 was the solution.

Replacing the oil temperature sensor did not cost much and was pretty easy to do - yes, that is unusual and hence worth a try if surging is the concern you have.
 

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