What the fludge *is* this thing...seems not to be described in wsm.

On line from coolant reservoir to radiator.

(in my best game show voice)...

"The first contestant with the correct answer will receive an all-expenses paid trip to sunnyyyyyy Duluth, for the festive fall Thanksgiving turkey beheading celebrationnnnn..."

:P

 

And while we're here...do these plastic coolant reservoirs just decide to go *pop* after they get so old...should I be getting a new one as a preventive measure? (doing a PM rehab on my 84 euro)

 

Coolant pressure sensor: 928 641 513 00

 

My car (well, neither of them) have one.

 

Hi the bottle needs a do over, shes gettin ready to burst captain!
Inline coolant pressure sensor,

 

OK, so what connects to it, and where is the warning if the pressure is too high? (or low???) - Ruf

 

DITTO!

 

Is that "Whole Husk Colon Cleanser" in the background? Does it work on injectors or exhaust port?

John Fagerlund
'89GT

 

Very effective on exhaust ports, but sometimes difficult to get past the intake...



Wow. A coolant pressure sensor. Yes, one must wonder what the brain does with that information. What's it gonna turn on, off or open up?

At $70, I don't think I will replace it - but I will do the reservoir at $115, it's a rather mission critical part. Thank you all...except that last guy...

 

ties into the coolant level switch presumably to delay checking coolant level until pressure (heat) is in the system...

 

WallyP stated in (this thread):

Without the pressure switch:
If the cold coolant level is low, the level switch will set the "low coolant" warning after twenty seconds. The driver can switch this warning off. As the engine and coolant warms, the coolant expands, and if the engine is stopped and restarted, there will be no low coolant warning, even though the cold level would be too low.

With the new pressure switch:
When the central warning system sees first a low coolant signal from the level swith, and then pressure from the pressure switch, the system will store that sequence, and will set the "low coolant" warning on subsequent starts, even though the level of the warm coolant is over the minimum.

If the pressure cap is removed, releasing the pressure, the central warning system assumes that coolant has been added, and the warning is removed until the next cold start begins the warning sequence again.

So, to repeat - the purpose of the pressure switch is to maintain the "low coolant" warning even on subsequent warm starts with expanded (but still low) coolant. It is a simple pressure switch - the central warning computer takes the level signal and the pressure signal and decides what to do with them.

...from the Annual Service Info for the '84 model.

 

Having recently had my reservoir replaced in 'emergency circumstance' , I can confirm that they can give up the ghost very suddenly, and that it is wiser, and certainly much cheaper, to shop around and have a spare ready for replacement ahead of time...

Phill.

 

I know all too well what that is because my 88 S4 just busted that switch last weekend while running my A/C for the first time - split the damn thing at the seams! Why do you need to know what it is?

 

As Bill points out they do fail , they do leak...

 

Mine failed and leaked, I deleted it. '87 S4 with 65000 miles.