Compression Ignition Addict
Join Date: Jan 2007
Location: Springfield, OR
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* Bring the transmission up to temperature. It needs to be at least 100 degrees for this test.
* Turn the truck off.
* Remove the rear line from the transmission and place it into a bucket or similar container so that you can measure volume of your flow.
* Have someone turn the truck on.
* At idle (in park), you should measure 32 ounces of fluid in your bucket - in 15 seconds or less. This is an absolute minimum number. A properly working transmission will flow that amount in about 10 seconds or less. You should not see ANY fluid pumping out of the rear transmission port.
1. If you have the proper amount of flow, your transmission pump and coolers are working fine. SO, if you are running hot and have the proper flow (with no fluid coming out of the rear transmission port), you most likely have a mechanical problem causing high heat. This could be torque converter slippage or one of many other internal problems. You may have to see a professional at this point to help diagnose the problem.
2. If you do not have proper flow, OR you have fluid coming out of the transmission rear port, you either have a cooler blockage, OR a faulty cooler bypass valve. Here's how to tell.
* Trace the forward transmission line to the front of the truck.
* Remove the line from the 1st place it enters a cooler or the radiator (if so equipped).
* Now, do the same flow test checking flow at this point.
* There are two outcomes.
1. The first is that you now have enough fluid flow- this means your cooler /coolers are partially blocked. To determine which cooler is plugged you would perform the same flow test through one cooler at a time.
2. The second outcome will be that you don't have enough flow even with all coolers disconnected. This means you have an internal pump problem.
IMPORTANT! The outcome of this test assumes that you have NO fluid exiting the rear port of the transmission. If you perform a flow test with the coolers disconnected and you get fluid from the rear port on the transmission, your cooler bypass valve is bad."
got this off of dieselsite....kinda sounds like what you're describing. maybe the trans was not up to temp and the bypass was bypassing??