Trans cooler LINE question

[davew833]

The cooler I have is about 12" x 7" x 3/4" thick-- it is a factory trans. cooler I pulled off a mid-'90s Ford Explorer. I had originally purchased it as a supplemental cooler, but would this be sufficient in size to use by itself mounted between the radiator and condenser as suggested?

[Huskymaniac]

Why not place a cooler in parallel with the stock cooler? That would be an even less restricted flow.

[svxfiles]

Originally Posted by Huskymaniac

Why not place a cooler in parallel with the stock cooler? That would be an even less restricted flow.

You could do that.
I have seen a number of them done that way, usually with a pair of T fittings.
I still like the simplicity of a separate cooler.

[Trevor]

Originally Posted by Huskymaniac

Why not place a cooler in parallel with the stock cooler? That would be an even less restricted flow.

Several have done so. What must be appreciated is that the fluid will take the path of least resistance and if this is the stock cooler, the added unit will not be fully effective.

[svxfiles]

Originally Posted by Trevor

Several have done so. What must be appreciated is that the fluid will take the path of least resistance and if this is the stock cooler, the added unit will not be fully effective.

Without trying to argue with you, the resistance of the stock cooler is substantial!
So unless your replacement transmission cooler was for a mini-bike it would flow more!

[Trevor]

Originally Posted by svxfiles

Without trying to argue with you, the resistance of the stock cooler is substantial!
So unless your replacement transmission cooler was for a mini-bike it would flow more!

There is no argument unless that is what you intend.

My post states exactly what you are saying, please read again and comprehend, i.e. --- “fluid will take the path of least resistance and if (and only IF) this is the stock cooler, the added unit will not be fully effective.

For the illiterate. Therefore, if you fit the cooler from a mini bike, it is likely to have the most resistance and it will not be fully effective.

[Huskymaniac]

OK, this is where my engineering degree comes in handy. Flow is pressure drop divided by resistance. If the components are in parallel, they will see the same pressure drop. The flow through each is totally independent, assuming the pressure drop is not appreciably changed as a result of adding the new component. The total flow will now increase as the flow through the new component is simply added to the flow through the old component. The pressure drop that can be provided by the "pumping" system will be affected by the total resistance provided but how much depends on the capacity of the pressure source to supply that flow. In this case, I would assume the pressure drop would not drop appreciably due to the added path for oil flow. Now, if the new component allows for a large increase in flow but does a crappy job cooling, that could be a problem since the fluid will spend most of its time flowing through the crappy cooler.

[Cam]

Originally Posted by Huskymaniac

Now, if the new component allows for a large increase in flow but does a crappy job cooling, that could be a problem since the fluid will spend most of its time flowing through the crappy cooler.

You have quite a way with words

[Trevor]

Originally Posted by Cam

You have quite a way with words

Kia ora Huskymaniac,

Accurate words, and you have again demonstrated excellent common sense and made a very, very good point.

I have only one cooler mounted between radiator and condenser and consider this the best option on several counts. However the matter is certainly open to interesting debate.

In any event, I believe that the most important factor to monitor is line pressure, rather than temperature. Accordingly, I have a permanently mounted pressure gauge constantly in view.

[kwren]

Originally Posted by Trevor

Several have done so. What must be appreciated is that the fluid will take the path of least resistance and if this is the stock cooler, the added unit will not be fully effective.

If the stock cooler is less restrictive than the added unit, throw the added unit in the trash and replace it with one that works like it is designed to work.

Keith

[kwren]

Originally Posted by Trevor

In any event, I believe that the most important factor to monitor is line pressure, rather than temperature.

Trevor, a serious question... or two...

The pressure you are concerned with would be which? Where is your gauge connected to the transmission line? before the cooler or after it?

What exactly are you looking for in line pressure?

Is temperature not a concern?

Thanks,
Keith

[Trevor]

Originally Posted by Huskymaniac

OK, this is where my engineering degree comes in handy. Flow is pressure drop divided by resistance. If the components are in parallel, they will see the same pressure drop.

Not correct. N.B. The components do not have the same resistance.

If the components are in parallel they will "see" the same incoming pressure. The one with the most resistance will cause (not see) the greatest pressure drop, within the parallel circuit. Therefore that with the most resistance, will flow the least fluid. That with the least resistance, will flow the most fluid.

I must conclude that your exam papers were sadly of the tick the box type, rather than requiring written answers.

The flow through each is totally independent, assuming the pressure drop is not appreciably changed as a result of adding the new component. The total flow will now increase as the flow through the new component is simply added to the flow through the old component.

Agreed, somewhat, sort of.

Adding an additional path must appreciably reduce the resistance and therefore appreciable reduce the pressure drop. The total flow will increase as a result of reduced resistance overall, due to two paths in parallel.

The pressure drop (drop? The actual delivered pump pressure.) that can be provided by the "pumping" system will be affected by the total resistance provided but how much depends on the capacity of the pressure source to supply that flow.

Broadly understood, and the factor here relates to the volume of flow which is what you are getting at. The two paths in parallel, in total present less resistance overall to the “pumping system”, so that the volume of flow will be increased. The pump will be pumping against a reduced head and less pressure will be created. However I doubt that this will be of any importance, in view of the level involved.

In this case, I would assume the pressure drop would not drop appreciably due to the added path for oil flow.

The drop in pressure involved would be small and insignificant in view of the increased path available for oil flow.

Now, if the new component allows for a large increase in flow (While starving its mate.) but does a crappy job cooling, that could be a problem since the fluid will spend most of its time flowing through the crappy cooler.

Spot on and a very interesting observation as well as piece of text.

I get pissed off when several here accuse me of being arrogant/haughty, simply because of my use of precise language. Nothing else provides accuracy, or in fact is of any use when in comes to technical descriptions. I am simply an engineer conversant with English as of necessity, having had in-depth experience in writing technical and legal text. Those so ignorant they do not appreciate this and understand, rattle your dags.

[Trevor]

Originally Posted by kwren

Trevor, a serious question... or two...

The pressure you are concerned with would be which? Where is your gauge connected to the transmission line? before the cooler or after it?

Keith, a serious answer or three.

It surely is obvious that the cooler or external circuit is not involved. As I stated my gauge measures line pressure and is therefore correctly connected directly to the transmission, via the special port provided for this purpose.

What exactly are you looking for in line pressure?

Pressure! What else could I be looking for in “line pressure”.

Is temperature not a concern?

Temperature is most certainly a concern. But fluid temperature without any loss of line pressure is not. Line pressure is the really crucial factor involved in transmission damage and failure. The transmission can run hot no problem, but if hot to the extent that the fluid vaporises and results in a pressure drop, all hell is loose. The pump can not move vapour and the solenoid and sundry valves will not satisfactorily control vapour. A pressure gauge registers the vital issue.

It is significant that the temperature gauges usually fitted, record the temperature of the fluid during exit, not that deep within the transmission.

Cheers, Trevor.

[kwren]

Originally Posted by Trevor

Keith, a serious answer or three.

Pressure! What else could I be looking for in “line pressure”.
A pressure gauge registers the vital issue.
Cheers, Trevor.

It is feast or famine with you, Trevor.

I was hoping you would have a gauge that maybe would have some numbers on it and you could expound on what the pressure gauge as supposed to read for normal transmission operation, and what the numbers actually mean... maybe could have added normal and different than normal readings that would actually be informative.

If your gauge is say, an economical version, and has no numbers I can understand that. Especially if the amount of pressure is irreverent, as long as a small amount of pressure exists.

Thanks for the reply...
Cheers back,
Keith

[Trevor]

Originally Posted by kwren

It is feast or famine with you, Trevor.

I was hoping you would have a gauge that maybe would have some numbers on it and you could expound on what the pressure gauge as supposed to read for normal transmission operation, and what the numbers actually mean... maybe could have added normal and different than normal readings that would actually be informative.

If your gauge is say, an economical version, and has no numbers I can understand that. Especially if the amount of pressure is irreverent, as long as a small amount of pressure exists.

Thanks for the reply.. Cheers back. Keith

Dear Keith,

My gauge certainly has “some numbers on it”, is quite respectful in every way and is in no way "irreverent" towards me or my SVX.

I am happy to say that my gauge is “an economical version,” and in spite of you thinking that it could be still be a gauge even if it showed a blank face, it brazenly shows its numbers. What is more it is kind to viewers in the US, as well as me down here, by simultaneously flashing a double smile. Very clever and very well numbered.

Its SVX mate does not have a transmission problem and therefore for me, it does what is correct. I have put a little touch of red make up on its face to help with this.

What the numbers actually mean, together with relative test procedures is published in the in the Subaru manuals. Right now I do not have the time to set them all out here, and the pressured gauge won’t lend a hand.

However it is surely obvious that particularly, “if the amount of pressure is irreverent,” a small amount is most certainly a grave problem and the tranny could be close to death.

Again, cheers, Trevor.