Engine/Transmission (1998.5 - 2002) Trans. flush now higher temps

[DWest]

Recently had my local shop flush my trans. and temps went up 25 degrees. They flushed trany then dropped the pan and changed the filter. Temps went from around 100 to 125 or higher empty. Use to run with the trailor at 120 125 now go over 150. Probe is in the bottom of the pan. Have double deep pan. Plenty of oil flowing through the cooler as we checked that. What gives. DW

 

[FLynes]

When I had my '05 (different trans, I know) I put a double deep Mag-Hytec on it and had gauges. I ran at 135-140 empty consistently and 145-150, sometimes 160 loaded going uphill. What you're saying doesn't sound unusual to me, but then again you have the 47RE or RH, and it might be different than the 48RE. As for the increase in temp, the only thing I can think of is that, when they flushed your transmission, some junk might have gotten stuck in a passageway, causing the temp to go up. I'd have it looked at again by whomever did your flush.

 

[DWest]

Other 47re temps

Mine is a 47re and runs those same temps now. I also have the double deep pan with the probe in the bottom. Do others run these same temps? If not I'm thinking about a remote mounted cooler with an electric fan, any other ideas? DW

 

[SGrasmick]

Best guess why the trans temps went up is because the viscosity of the new oil is much higher than the old oil causing more friction and a slightly higher temp. I wouldnt be concerned about spending the money on the remote coolers, Call some companies like suncoast and you will find that 250 is not a terribly high temp when towing, my 2000 ran 180 empty and 220 pulling the trailer with a suncoast and my 2001 runs 140 - 170 empty and 240 when pulling 18k pounds.

 

[CNeubauer]

The other possiblity is when it was flushed there was some crud somewhere in the transmission or lines that got broke loose and is now partially plugging one of your cooler lines or the cooler itself. I know a couple transmission builders who say not to flush transmissions for that very reason unless it's done on a regular basis since new.

 

[rweis]

I think the transmission has a thermostat that tries to get the transmission fluid to 150* before it opens fully. My 47RE will slowly ease up to 150* and then sit right at 150*. I have an aux cooler, and I have removed the check valve in the transmission line going to the water heat exchanger, so I know I have good flow.



Maybe flushing caused a blockage that was in the thermostat line internal to the transmission to clear and now it is functioning like it should. Seems that the transmission has a minimum normal operating temp at 150*.



That's my take at least.



Bob Weis



The post before me said 250* is not unusual, I think that was a typo and it should have been 150*.



I have completely (transmission & TC) drained and wiped it out every 12k and I am pretty sure it is clean inside and out.

 

[RPayton]

I have an 04 and empty it runs 175 moveing and up to 200 in town. With a trailer 10,000 lbs. it can get up to 230 ? Normal ? I have been told yes. Just my two cents worth.

 

[DWest]

Fluid flow rate

I checked the flow rate of fluid through the cooler and it was well above acceptable levels, so all is well in that regard. Seems the temps are within others so all must be fine. Maybe the thermostat that controls oil flow was stuck open before the flush? Will stop worrying now. Thanks! DW

 

[Joe Mc]

My trans will creep it's way to 150 and never gets any higher I'm guessing there may be a stat but never heard of that - anything's possible? Anyone know for sure about a trans stat? Where is it located? Thanks

 

[John - K5AWO]

The transmission does NOT have a thermostat. What you are seeing is the cool oil gradually getting warmer until it is at the temperature of the BOTTOM of the radiator. This is because the oil cooler for the transmission is in the lower portion of the radiator and under light load 150* temps are about normal for the low side of the radiators.

when you load the engine heavy, like in towing, the engine is throwing off more heat load, and the radiator temps start to climb. 180* on the bottom side of the radiator is not abnormal and higher depending on how hard you are pushing it.

Oil temps up to 230 are not considered to be abnormal during towing conditions, and the manufacturers don't get overly concerned until they start going over 250-270 on a short heavy pull.

It is for this reason that the manufacturers quit putting gauges on cars. People got scared when they saw those higher numbers.

The "feel good" factor is a lot nicer on the lower temps for sure, but don't get alarmed if you are seeing temps in the 180-230 range when towing.

Here in the Phoenix metro area, our ambient temps reach 115 for more than six weeks at a stretch. My transmission temps are consistently at 170-180 empty. They will never be the same temps as the ambient because the radiator water is hotter than that.

 

[rweis]

Thanks John, I was never really sure why the transmission temp went to 150* and then just sat there. For grins I'll IR the lower radiator and the water / transmission fluid tank exchange to see what those read.



One thing about TDR you always can learn something new just about every day.



Thanks,



Bob Weis

 

[Joe Mc]

Thanks for clearing up the trans stat or not question. Didn't seem to make sense as it would restrict flow unless it was somehow on the coolant side ???

 

[Fishin Guide]

You should never flush transmissions. As stated, it routinely lodges innocent particles in the wrong places. I have seen more than one trans fail after a flush.



While there is no therrmostat, there is a anti drainback valve located on the output line where it enters the heat exchanger. It's possible the issue is right there. Check and replace if necessary.



If you have an internal blockage, it could be in the VB or other passageway. An immediate increase in temp with no other changes is a sign that something is wrong.



It may be nothing, it may be a bigger issue.



Dave