Wheel well mounted oil thermostat flow ?

turbobrat930 · 07-03-2014, 05:11 AM

Ok, So I have used the search function, and still can not find what I need. Maybe, I did not search using the right working, etc...

I want to know what route the oil flows through the wheel well mounted oil cooler (to the front oil coolers). Does it allow the oil to flow all the way through the oil cooler, and then dead heads it, until the oil reaches required temp? Then opens? Or, does no oil get to the front coolers, until the thermostat opens? and instead, when the cold oil hits the thermostat, it just does a "u" turn, and sends it back?

Flow pictures or diagrams would be great!

Thanks in advance!!

Brad

uwanna · 07-03-2014, 08:51 AM

the ext thermostat to the aux cooler is always open!

Here's a cut & paste from a previous thread on the subject. Kinda says it like it is!

"Grady,

It has been a long time since I posted this thread several years ago. But I would like to share some findings regarding the oil flow in an auxuliary thermostat.

1). The opening to the oil line to the auxiliary cooler (Carrera cooler) is always open.. Meaning wide open all the time and no valve involved.
2). When the oil temperature gets high (warm) to about 180 F plus, the auxiliary thermostat comes into play.
3). The initlal cooling process of the engine oil is controlled by the internal thermostat in the motor and circulated thru engine oil cooler then to the oil tank.
4). When the engine oil gets up to around 180 to 190 F, the oil return opening (oil from the auxiliary cooler) starts to widen. Thus an inital flow of oil thru the auxiliary cooler is experienced for the first time.
5). Simultaneously, as the opening for the return oil (auxiliary cooler) increases, the valve opening for the return to the tank decreases. When the oil temp. is below the opening temp. of the auxiliary thermostat, the valve opening for engine to oil tank (let's call this as A) is fully open (100%) and valve opening from the auxiliary cooler (let's call this B) is 0% (fully closed).
6). As A starts to close, B begins to open. The openings for A and B is the same. In simple description, when A is 100% open, B is 0% open. When A is 90% open, B will be 10% open and so on.
7). The change in valve opening ratio will proceed as temp. goes up till valve A is fully closed (0%) and valve B is fully opened 100%. Valve opening is temp. dependent.
8). Don't know when valve B's maximum opening occurs. But at temp. below 180 F, valve B was fully closed.

Just wanted to share my findings from the tests made. Not very scientific but practical. Comments, remarks, critics, etc. welcome.

Tony

poorsha · 07-03-2014, 09:09 AM

boyt911sc · boyt911sc's Garage

Brad,

I will try to explain the oil flow circulation of a 911 by using the ERP picture posted by Joe Bob. From 1A it goes to 3A then to the auxiliary thermostat (AT). The auxiliary thermostat (cold engine) diverts the oil flow in two directions. One going to the oil tank and the other to the auxiliary cooler (AC). The oil line from AT to AC is always open by designed. So cold oil is delivered to 4A line to 6 line and fills the auxiliary cooler. To 7 line, 5A line, and back to auxiliary thermostat. If the engine oil temperature is below 186°F (+/-) the auxiliary thermostat slide valve is closed to the oil tank. So all of the oil from the engine is going back to the oil tank after filling the oil lines and cooler.

In short, engine oil temperature below 186°F (+/-) goes back to the oil tank and suck by the oil pump to the engine. As the oil temperature gets to the operating temperature, the stagnant oil in lines 4A, 6, cooler,7, and 5A is gradually released back to the oil tank.

The amount of hot oil being diverted to the auxiliary cooler is equal to the oil (cooler) being allowed by the slide valve after passing the cooler. Remember one thing, the auxiliary thermostat valve is closed and does not allow the oil in the auxiliary cooling system to move out until it reaches the operating temperature.

Once the thermostat valve slides to open (allowing oil from the aux. cooler) and allowing the cooled oil to go back to the tank, a corresponding equal amount of hot oil enters the cooler. The oil circulation starts at 100/0, 95/5, 90/10, etc. 100% going to the oil tank/0% circulation to the cooler..........50/50, it means 50% going to the oil tank, and 50% circulating to the cooler. And so on......

Tony

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by uwanna

the ext thermostat to the aux cooler is always open!

Here's a cut & paste from a previous thread on the subject. Kinda says it like it is!

"Grady,

It has been a long time since I posted this thread several years ago. But I would like to share some findings regarding the oil flow in an auxuliary thermostat.

1). The opening to the oil line to the auxiliary cooler (Carrera cooler) is always open.. Meaning wide open all the time and no valve involved.
2). When the oil temperature gets high (warm) to about 180 F plus, the auxiliary thermostat comes into play.
3). The initlal cooling process of the engine oil is controlled by the internal thermostat in the motor and circulated thru engine oil cooler then to the oil tank.
4). When the engine oil gets up to around 180 to 190 F, the oil return opening (oil from the auxiliary cooler) starts to widen. Thus an inital flow of oil thru the auxiliary cooler is experienced for the first time.
5). Simultaneously, as the opening for the return oil (auxiliary cooler) increases, the valve opening for the return to the tank decreases. When the oil temp. is below the opening temp. of the auxiliary thermostat, the valve opening for engine to oil tank (let's call this as A) is fully open (100%) and valve opening from the auxiliary cooler (let's call this B) is 0% (fully closed).
6). As A starts to close, B begins to open. The openings for A and B is the same. In simple description, when A is 100% open, B is 0% open. When A is 90% open, B will be 10% open and so on.
7). The change in valve opening ratio will proceed as temp. goes up till valve A is fully closed (0%) and valve B is fully opened 100%. Valve opening is temp. dependent.
8). Don't know when valve B's maximum opening occurs. But at temp. below 180 F, valve B was fully closed.

Just wanted to share my findings from the tests made. Not very scientific but practical. Comments, remarks, critics, etc. welcome.

Tony

Uwanna,

I was reading your post earlier and something struck my attention!!!! The grammar and the wordings look very familiar to me (?). Then saw at the bottom of the post the name of the writer.

Tony

turbobrat930 · 07-03-2014, 09:36 AM

Thanks to all who replied!! The reason for the post, is because I took the auz thermostat apart to clean it (after I spun two rod bearings), and I guess i did not tighten the caps with the flat slot in them enough... I have turned over the engine, in an attempt to test all the functions of the ECU and to get positive oil pressure indication before firing.
I took off the aux thermostat and one of the aux oil cooler lines was full of oil. I was under the impression that none of those lines would fill up unil the thermostat opens... I guess I was wrong! So, it just fills up, and then waits for the aux thermostat to open, causing the oil flow to complete the circuit...

Cool!!!

uwanna · 07-03-2014, 09:47 AM

Quote:

Originally Posted by boyt911sc

Uwanna,

I was reading your post earlier and something struck my attention!!!! The grammar and the wordings look very familiar to me (?). Then saw at the bottom of the post the name of the writer.

Tony

Yea, as I said, it was a "cut and paste" from a previous thread. Very good and understandable explanation! KUDOS