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Transmission Fluid Flow Rate through Radiator problem?
My new transmission is (still) overheating on long highway drives.
Transmission shop tested the t-fluid flow rate through the radiator at 1 quart every 30 seconds. The transmission itself however will push times that amount, 3 quarts every 30 seconds, all by itself and also through an aux t-cooler. My radiator is only 2 years old. When I first started having transmission overheating I found the radiator was shot and had it replaced and later put in a tran cooler too. So the questions is... What should be the t-fluid flow rate through the radiator? In other words... is my radiator restricting t-fluid flow rates below spec? 1993 4Runner, V6 3L, Auto, 4x4, 170K Thx Dave-in-Denver |
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#2
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Transmission Fluid Flow Rate through Radiator problem?
> wrote in message oups.com... > My new transmission is (still) overheating on long highway drives. > > Transmission shop tested the t-fluid flow rate through the radiator at > 1 quart every 30 seconds. > The transmission itself however will push times that amount, 3 quarts > every 30 seconds, all by itself and also through an aux t-cooler. > > My radiator is only 2 years old. When I first started having > transmission overheating I found the radiator was shot and had it > replaced and later put in a tran cooler too. > > So the questions is... > What should be the t-fluid flow rate through the radiator? > In other words... is my radiator restricting t-fluid flow rates below > spec? > > 1993 4Runner, V6 3L, Auto, 4x4, 170K > > Thx > Dave-in-Denver > I do not recall ever seeing a specification for transmission fluid flow rate through the radiator. The flow rate will vary depending on pump output. I would see if the coolant temperature drops after it exits the radiator and cooler. -- Ray O (correct punctuation to reply) |
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Transmission Fluid Flow Rate through Radiator problem?
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#4
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Transmission Fluid Flow Rate through Radiator problem?
On Wed, 13 Jun 2007 16:00:45 -0500, "Ray O"
<rokigawaATtristarassociates.com> wrote: > > wrote in message roups.com... >> My new transmission is (still) overheating on long highway drives. >> >> Transmission shop tested the t-fluid flow rate through the radiator at >> 1 quart every 30 seconds. >> The transmission itself however will push times that amount, 3 quarts >> every 30 seconds, all by itself and also through an aux t-cooler. >> >> My radiator is only 2 years old. When I first started having >> transmission overheating I found the radiator was shot and had it >> replaced and later put in a tran cooler too. >> >> So the questions is... >> What should be the t-fluid flow rate through the radiator? >> In other words... is my radiator restricting t-fluid flow rates below >> spec? >> >> 1993 4Runner, V6 3L, Auto, 4x4, 170K >> >> Thx >> Dave-in-Denver >> > >I do not recall ever seeing a specification for transmission fluid flow rate >through the radiator. The flow rate will vary depending on pump output. I >would see if the coolant temperature drops after it exits the radiator and >cooler. I have not seen a flow rate either but I also agree the pump output will variy some with engine RPM and is not a fixed rate. As mentioned above the tempature drop is the bigger concern and if OP had over heating tranny problems if engine was running hot too it would take the tranny with it unless you had a aux external cooler. DO not get carried away with aux cooler size though as many do because you can overcool oil and reduce flow rate because oil is thicker when cooler. ----------------- TheSnoMan.com |
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Transmission Fluid Flow Rate through Radiator problem?
>
> I do not recall ever seeing a specification fortransmissionfluidflowrate > through theradiator. Theflowratewill vary depending on pump output. I > would see if the coolant temperature drops after it exits theradiatorand > cooler. > -- > > Ray O > (correct punctuation to reply) Thanks Ray O, Tranny shop said they tested t-fluid flow with "operating temp" fluid using the same RPM's for three flow tests; 1) just tranny which produced 3 quarts in 30 sec. 2) tranny and aux-cooler which also produced 3 quarts in 30 sec. 3) tranny and radiator which produced just 1 quart in 30 sec. Do not know if they had a measured both the in and out temps... will ask. Have to presume their logic is.... if there is a restriction or fault in the radiator flow then the t-fluid will not cool... especially when the tranny wants a 3 quart rate. Thx Dave-in-Denver |
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Transmission Fluid Flow Rate through Radiator problem?
>
> I have not seen aflowrateeither but I also agree the pump output > will variy some with engine RPM and is not a fixedrate. As mentioned > above the tempature drop is the bigger concern and if OP had over > heating tranny problems if engine was running hot too it would take > the tranny with it unless you had a aux external cooler. DO not get > carried away with aux cooler size though as many do because you can > overcool oil and reduceflowratebecause oil is thicker when cooler. > ----------------- > TheSnoMan.com Thanks SnoMan, I will ask about the in/out temp drop. Engine has never run hot... temp gauge rarely varies once up to temp. Have to presume that OP in tranny has been pushing against what we presume to be a low flow problem in the radiator since the radiator was new 2 years ago, and since the new tranny was rebuild 6 months ago. (FYI the new tranny work Soooo much better than the old one and it still does.) Aux cooler was picked out by tranny shop... it looks smaller than what I would have picked out... so my guess is that the tranny shop follows your advise too and does not over do it on aux size. Thx Dave-in-Denver |
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Transmission Fluid Flow Rate through Radiator problem?
> wrote in message oups.com... > > >> I do not recall ever seeing a specification fortransmissionfluidflowrate >> through theradiator. Theflowratewill vary depending on pump output. I >> would see if the coolant temperature drops after it exits theradiatorand >> cooler. >> -- >> >> Ray O >> (correct punctuation to reply) > > Thanks Ray O, > Tranny shop said they tested t-fluid flow with "operating temp" fluid > using the same RPM's for three flow tests; > 1) just tranny which produced 3 quarts in 30 sec. > 2) tranny and aux-cooler which also produced 3 quarts in 30 sec. > 3) tranny and radiator which produced just 1 quart in 30 sec. > > Do not know if they had a measured both the in and out temps... will > ask. > > Have to presume their logic is.... if there is a restriction or fault > in the radiator flow then the t-fluid will not cool... especially when > the tranny wants a 3 quart rate. > > Thx > Dave-in-Denver > If that is the case, then there is a problem in the radiator. The transmission part of the radiator may have been rebuilt incorrectly, the cooling fins are obstructed so that sufficient air does not flow through them, or something has clogged the cooler part internally. -- Ray O (correct punctuation to reply) |
#8
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Transmission Fluid Flow Rate through Radiator problem?
>
> Every turn in a line, additional cooler, fittings, ect, will cause some > resistance in the hydraulicflow. Did the trans shop test theradiatorflowbypassing the additional cooler? I have never seen a hydraulic > cooler fail from the inside from corrosion, or buildup restrictions > except for component failure that restrict/plug the line with debris. > Make sure that the trans temp indicating system is operating correctly > like Ray said. Check the temp with an in line gauge. Check the actual > trans pumpflowas well. Thanks Ph@Boy, Well the old tranny sure had it problems and your comments make me think that perhaps some debris from it could have caused the restriction in the radiator. And that junk was not cleaned out as part of the tranny job.... causing overheating and perhaps introducing old debris into my new tranny.... Yuck. Good suggestion to test the tran temp sensor... I will ask. Check the actual tranny pump flow... well I guess that the tranny shop was happy with the 3 quarts in 30 seconds... but I will ask them if it actually meets volume and SPI specs. Thx Dave-in-Denver |
#9
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Transmission Fluid Flow Rate through Radiator problem?
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#10
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Transmission Fluid Flow Rate through Radiator problem?
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