Does the Torque Converter heat engine while idling??

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66fyssh

66fyssh

Don't Stop Believin'
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66 Barracuda, 273/904.

I've noticed when idling in Park my engine temp will sit at 180* all day long. When sitting in traffic in Drive, the engine temp will increase above 180*. It won't go above 195*, but I'm curious to know what causes it to increase. Will the torque converter cause it?

I'm idling about 850 RPM in Park and 675 RPM in gear.

Thanks!
 
yes. But perhaps not for the reason you might suspect.
In park all fluid pressure except the small lube line is dumped to the pan.
In Neutral the torque convertor is filled.
And in Drive, the forward clutch is engaged, so the TC is trying to move the car. But with the brakes applied, it cannot.So the TC does what it was designed to do;it slips. This heats up the oil. The pump sends the hot oil to the rad to be cooled by the water flowing all around the internal cooler. And the water temp. rises, as the oil cools.
Furthermore the reduced idle speed slows down the waterpump, and the connected fan. This reduces the air speed/flow through the rad, slowing the cooling rate. You might think that 175 rpm is nothing, but consider that 175/850 is nearly 21%.
 
The engine is also under a load in drive, so the engine itself builds more heat.
 
It has more to do with the fan speed and increased engine load friction, rather than tran fluid temp increased then diffused into a rad cooler... I always run an external cooler and get the same effect.
 
66fyssh said:
66 Barracuda, 273/904.

I've noticed when idling in Park my engine temp will sit at 180* all day long. When sitting in traffic in Drive, the engine temp will increase above 180*. It won't go above 195*, but I'm curious to know what causes it to increase. Will the torque converter cause it?

I'm idling about 850 RPM in Park and 675 RPM in gear.

Thanks!
Click to expand...

I see AJ gave you the long answer.
The short one is absolutely, and the engine will even warm up quicker if the trans is in gear because of the long answer.
 
Thanks guys. Great information! Just one of those "I wonder why" things that I never learned. I appreciate the input. I haven't seen it go over 200* while running yet so I should be good.

The motor is stock except for a Edelbrock 500. Factory fan.
 
if the tiny amount of load at the stop light were heating it think about how hot it should be at 60 mph.
my money is on inadequate air movement.
 
It cools off quickly as soon as I start moving again. Haven't had any issues with cooling at 60-65 mph.

Nearly 2 years ago, a radiator shop ran the radiator through their boil out tank and it flow tested OK. I run a factory shroud and a hood to radiator seal.

I haven't seen the temp rise above 195 sitting in traffic yet.
 
ir3333 said:
if the tiny amount of load at the stop light were heating it think about how hot it should be at 60 mph.
my money is on inadequate air movement.
Click to expand...
IMO, this is the most likely cause and is normal: no extra air flow inlet pressure from movement, and the fan at it's lowest speed so rad and direct engine cooling is minimum.
 
ir3333 said:
if the tiny amount of load at the stop light were heating it think about how hot it should be at 60 mph.
my money is on inadequate air movement.
Click to expand...

Actually, not. The torque converter generates extra heat at the stop light because it is slipping. It is, in effect, trying to rip the fluid apart. At 60 mph there is little, if any slippage in the torque converter and it thereforee it creates less heat.

When drag cars get on the trans brake and bring the revs up (the torque converter is slipping) you can actually watch the trans temp guages rise, and rather quickly.
 
d55dave said:
At 60 mph there is little, if any slippage in the torque converter and it thereforee it creates less heat.
Click to expand...

Just a comment on NON lockup tc's; if the torque converter is not slipping, it is transmitting ZERO power. In other words, if it speeds up to begin transmitting and then converting torque, and the speed differential between stator and impeller becomes zero (stator and impeller are spinning at same speed), no fluid movement occurs and torque transmission ceases.

At this 1:1 speed point, the system loses energy, and torque transmission/conversion resumes when either stator or impeller changes it's relative speed.
 
It's all just a giant physics equation. Heat is generated by a number of things, and it is dissipated by a number of things(variables). IMO your car is operating well within the parameters established for it. If you just want to know why or want to learn, you will have to examine each component individually to find out how they operate, and how they operate together. Not too big a deal, but too much for this thread. You pretty much got the long and the short of it in this thread.
 
You have other issues if you can't get the engine to idle at 700-750 in park with that camshaft.

175 rpm drop in gear is a big for that cam.

Look for a vacuum leak somewhere and make sure the carb isn't dripping fuel in from the boosters.
 
Thanks again errryone!! I got some schoolin' on TC's today!!

crackedback, it idles OK. Wouldn't I expect the drop in rpm with the Commando motor?
 
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