Pressure and Flow Rate to Tranny Cooler?

[rgiles]

Anyone know what the pressure and flow rate in the lines leading up to the transmission cooler? I would assume it is much lower than motor oil flow and pressure, am I correct?

 

[Jason_25]

Well the pressure in the tranny cooler lines is determined by the tranny pump, and the pressure of the pump is caused by the governor of the tranny. So as the engine speed increases, the pump increases the pressure. So there is no real "set" pressure for the lines.

 

[rgiles]

Could anyone venture a guess as to how much pressure we are talking about? I guess I would like to know a ballpark as to whether or not the flow and pressure tends to be more or less than oil, as I want to know if an external oil filter can handle the filtering of tranny fluid without always having the bypass valve open. I'm considering one of those external Inline filters that use an oil filter setup.

Thanks

 

[Opera House]

I'll just have to measure it some day

The manual indicates that pressures, I assume at the tap off, can be from 57 to 280 psi. It had been my assumpion that the fluid that went to the cooler was the excess from the pressure regulator and the dump from other sources. There is very little in the manual and with the transmission apart it stil isn't obvious what happens with the return line after it enters the transmission. If I had to take a wild guess, it would be that it is under 30 psi max. Look at those little plastic inline filters you can buy. They can't take that much pressure.

 

[rgiles]

Thats a good point Opera House concerning the Plastid filters. Also I've heard people say that the flow rate when idling is around a quart every few seconds out of the hose to the cooler, so that would be pretty low flow rate compared to an engine oil pump. I know it took about 45 minutes to do a complete flush on my X at one of those Jiffy places.

Anyone else have any other facts or intuition on the subject?

 

[Robert]

My OBD-II scanner shows my "line pressure" at 28 PSI with my SuperChip installed. That is up by 3-5 PSI that I got without my SuperChip.

 

[Fischer]

When I talked to a tranny guy he said "If you are going to add another tranny cooler be sure to get the XYZ? low pressure." I think that my secondary trans filter works just fine. I use Mobil1 filters "High Flow".

 

[ALYZ1FLR]

cooler pres.

Give me five min. I,m running out to check my ATSG serv man.

 

[ALYZ1FLR]

A-hah!!

30 low regulated to appr. 90 high. As per atsg. Techtan man. second edition.

 

[ALYZ1FLR]

Filter

I used a flow data base from work to check flow rates from std auto motive filters and found the same filters used on our motors were more than good. I use the same filter on my remote trns filter . Purolater pure 0ne L30001 gold on engine and regular on remote trans.

 

[rgiles]

ALYZ1FLR, thanks for the info, that helps. I decided to go with a remote oil filter. Do you do this with a fleet? How much does it extend the life of the transmission do you think? How often do you change the tranny filter (external)?

 

[ALYZ1FLR]

Rgiles I am a comm. diver and our breathing air comp. use very expensive filters. I was researching filter alternatives when I found the flow data. Since I use the same filters, I change it with oil filter changes. I rebuilt my own trans. 150 thousand mile ago. No problems since.

 

[dogfriend]

Originally posted by rgiles
Anyone know what the pressure and flow rate in the lines leading up to the transmission cooler? I would assume it is much lower than motor oil flow and pressure, am I correct?

In my factory manual, there is a transmission cooler flow test. To perform the test, you disconnect the cooler return line from the transmission and reroute it to fill a funnel in the fluid filler (dipstick) tube. According to this test, you should get a flow rate of 1 liter (1.05 qt) every 30 seconds.

The test for determining if the radiator mounted cooler is leaking says to apply no more than 50 psi to the cooler, so it seems reasonable to assume that the pressure is less than 50 psi.

 

[Opera House]

dogfrieng

I love the backdoor data analysis method. There is always some pearl of data found in an obscure location. Now I remember reading that. That flow could get higher at other speeds than idle.

Something else to ponder. I was in a minor winter fender bender that dented my fender but still left me able to drive. When I replaced my bumper five days later I found the rubber hose to the cooler had severely kinked to the point that no flow looked possible. No damage ever happened to the transmission and all shifting was normal.

rgiles - so what are you doing about the 91. Did you drain off the excess fluid?

 

[dogfriend]

Re: dogfrieng

Originally posted by Opera House
I love the backdoor data analysis method. There is always some pearl of data found in an obscure location. Now I remember reading that. That flow could get higher at other speeds than idle.

The way I see it, it is just speculation unless you have a reliable source for info (most of the info in the service manual seems reliable) or you perform a test to determine the value yourself. Anyone volunteer to check the flow rate by removing the cooler line and seeing how much ATF flows at wide open throttle?

If you really need to know this, you could put a rotary flowmeter in the cooler line, but I haven't done it and I don't need to know bad enough to think about trying it.

 

[Robert]

I could sell you one

 

[dogfriend]

I think the one in the center of the picture would be adequate

 

[Robert]

Originally posted by dogfriend
I think the one in the center of the picture would be adequate

Ya sure? That is only a 2" (1.6 - 160 GPM). We go all the way up to 12" which would cover your from 150 - 15000 GPM. Of course you would have to have a very secure since it weighs about 400 lbs.

 

[Opera House]

Hmmmmmm.......I got one

Just the right size, 3/8. When I get the 92 back together, I'll try it. Have to do some plumbing anyway to hook up the remote filter. Don't you just love science.

 

[rgiles]

Re: dogfrieng

Originally posted by Opera House
rgiles - so what are you doing about the 91. Did you drain off the excess fluid?

I drained off some excess fluid by sucking it out of the filler tube with a pump, however, I don't think it is likely that this would be the problem. I haven't had sufficient time to test whether or not it fixed it, but on the cold morning I drove it afterwards, the slipping didn't occur. Because I've had a rear brake problem, I'm also holding out the possibility that the brakes are making the transmission look bad by requiring me to rev higher to move. I have got the transmission filter and gaskets from bulkparts for the 91, but I'm taking more time to diagnose. I don't drive it much right now so I have that luxury. I think I will look into the brakes first, since they might be confusing the issue. I'm splitting my attention between 3 vehicles right now so it will take time on all