L322 Viscous Fan Speed

After doing my coolant pumps (electric and Mechanical) Tstat and temp sensor the 4.2 has been spot on in temp....

… however..

the Viscous fan has become a bit more roar-y at low speeds to the point its stating to annoy me.

if I put my toe down the fan quietens off, but back off and it gets roar-y again

I plugged the IID tool in and brought up the live data for the Viscous fan (cool huh) and it shows when at lower RPM an approximate 10-25 rotational speed above the engine RPM on live data. when I the down the VC fan speed then comes into line or under the engine RPM.

The VC fan is electric on the 4.2 pulled the plug and reseated still doing it and it seems to be over cooling a bit. I'm guessing that undoing it and leaving it aside when doing the pumps has unsettled the internals on a probably old and worn VC fan clutch.. though a VC fan reading over the engine RPM?

appreciate any thoughts from the LZ RR boffins !

Bin it and fit a electric fan from a 2008 mercs c200. It's a monster fan.
Err maybe...

I am just wondering how a viscous fan can be electric. A viscous fan should never reach engine speed.

wammers said:

I am just wondering how a viscous fan can be electric. A viscous fan should never reach engine speed.

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Could be that the simple Bi-Mettalic strip for controlling engagement has been replaced by over complicated electronic control.
If it's running at over engine rpm, then it must be due to the pulley ratios, it sounds like the viscous mechanism is fecked.

Yep the L322 viscous fans are special

See there’s quite a bit in the mix to control it too.
How fast it should run in relation to the engine I don’t know. Will dig in manual a bit more later see if I can find anything useful.



J

Datatek said:

Could be that the simple Bi-Mettalic strip for controlling engagement has been replaced by over complicated electronic control.
If it's running at over engine rpm, then it must be due to the pulley ratios, it sounds like the viscous mechanism is fecked.

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Possibly correct. Normally a pure viscous fan should never run at more than 85% engine speed. Whilst driving at cruise speeds the engine is cooled by ram air, only if the car slows should the viscous fan engage to a variable extent subject to temp to remove latent heat from the system.

I'm pre-empting a discussion here!!!
@wammers and @Datatek ....
Stop!!!

Please for the love of God don't!!

Designers no matter how inept put it in there and it works..

L322 is speshul

On mine, I occasionally get "reduced engine performance" showing on the dash.
When this happens, the fan goes into its maximum locked state and roars to about 3k rpm engine. In this condition, the temp drops to about 1/4 on the gauge rather than just off centre.
From the limited reading I've done, it's an extra cooling strategy if it thinks the engine is too hot.
My thinking, judging by the work you've done is that you have a temperature sensor issue somewhere.
On gap tool, there is an advanced menu for faults, can't remember exactly which ones I select but you will get a shed load more faults showing. If I do that and clear them it then works OK.

Wazzajnr said:

From the limited reading I've done, it's an extra cooling strategy if it thinks the engine is too hot.
My thinking, judging by the work you've done is that you have a temperature sensor issue somewhere.

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Could be possible I would agree.
Somewhere else in the manual it says if the coolant sensor is duff it uses the oil temp sensor ,if that’s duff it uses a default number.
But it doesn’t say what the fan controller does in those situations

J

I'm assuming it would take the primary reading from the CTS.

Further reading it seems default number is = to 119°. With that it should lock up the fan and hence over cool. And probably throw a EML or fault message of some sort.

The are some codes related to the fan hopefully a look around with the Gap plugged in May show some.

J

Mark Piercy said:

I'm pre-empting a discussion here!!!
@wammers and @Datatek ....
Stop!!!

Please for the love of God don't!!

Click to expand...

Go back to sleep or get another beer

wammers said:

I am just wondering how a viscous fan can be electric. A viscous fan should never reach engine speed.

Click to expand...

Electronic would be the appropriate word. indeed.. let alone spinning above engine RPM!

ukadamwest said:

let alone spinning above engine RPM!

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Hummm missed that bit

Did you perhaps damage the sensor on the front of the fan when you took it off?
I have not been in amongst mine so don’t know.

J

marjon said:

Hummm missed that bit

Did you perhaps damage the sensor on the front of the fan when you took it off?
I have not been in amongst mine so don’t know.

J

Click to expand...

Is there a sensor on the front of the fan?

Datatek said:

Is there a sensor on the front of the fan?

Click to expand...

Maybe, how do you read this?



J

marjon said:

Maybe, how do you read this?

View attachment 187890

J

Click to expand...

I read that as hall effect device is used to detect fan speed. The sensible way of doing that would be to mount the hall effect device on a stationary part and the passive trigger on the rotating part, however there is very little that is sensible in the L322 electronics so who knows, the whole thing is bonkers, a variable electric fan would do the job as is the case on many other vehicles..

Datatek said:

Go back to sleep or get another beer

Click to expand...

And I thought you were my friend...waaaahhhh...

Datatek said:

I read that as hall effect device is used to detect fan speed. The sensible way of doing that would be to mount the hall effect device on a stationary part and the passive trigger on the rotating part, however there is very little that is sensible in the L322 electronics so who knows, the whole thing is bonkers, a variable electric fan would do the job as is the case on many other vehicles..

Click to expand...

Maybe so........ However.......... it’s an L322 and we have to live with it and learn it.
The BECM was a magical box of tricks....... why?

I used to run a variable speed water pump with electric fans on a car, so yes many “better” ways of doing things,

But this is what we have, and need to try and work it out.

J