Chevy & GMC Vans

wkastro wrote:70-75 deg F over ambient

That's equal to 40℃. Same as me.

I am going to throw in my two cents.

First, my bias is to remove the cooler from the radiator loop so that you have cooler only. Here is why:

1. No risk of coolant/oil (tranny fluid) mixing. With coolant in radiator, there is this risk and it happens.
2. With the radiator inline, the fluid is being raised to whatever temp the coolant resides. Engine overheating? Great. Cooking the oil.
3. Two additional connections vs. a simple connections at two points.

Now, I have seen here and other sites that some are concerned that the tranny is running "two cold". This seems odd to me. Does everyone wait for the tranny to get up to temp before driving? Probably not. Well, if one feels that the fluid needs to be cooked before hand, they should run a heater on the bottom of the pan and/or wait for the tranny to heat up (could take a while you know).

Bottom line, the radiator does nothing or next to nothing to cool. In fact, it can actually impede the cooling function as the fluid is cooling the minute it comes out of the transmission.

So why did you buy a giant cooler if only to fight with the radiator?

I plan to pick up a deep pan (four additional quarts) and a monster cooler. The tru cool is ok and fits. I don't plan to tow a giant trailer.

Think about Chevy and their penchant to pinch pennies no matter the wiseness over the penny. Why would they put in a cooler separately? That's another 100 bucks and besides...they are selling you the new transmission...right?

Toyotas did this too by the way...so it isn't just Chevy.

We redesign so much else ....why leave it the way that least benefits the transmission?

A final note on the whole "we need to precook the transmission oil". The oil is super thin. Much thinner than the oil in your motor. You drive that cold right? The oil is flowing at cold conditions. For you cold weather folks (Cheyenne and North) wait one minute...then cycle the transmission through all the gears while in the driveway. Then off you go. If it isn't cycling...well...then it is really, really cold.

http://autos.yahoo.com/maintain/repairq ... 123_0.html
I've always plumbed the fluid thru the radiator first. If your engine is operating normally the trans fluid will be cooled by some margin before it goes to the aux cooler.

Meterpig wrote:1. No risk of coolant/oil (tranny fluid) mixing. With coolant in radiator, there is this risk and it happens.

I think this risk is pretty low, and certainly no greater than leaving it stock. I'm more likely to smoke an extra deep pan on a rock.

Meterpig wrote:2. With the radiator inline, the fluid is being raised to whatever temp the coolant resides. Engine overheating? Great. Cooking the oil.

Where are you going if your engine is overheating? Your engine will cook before your oil does.

Meterpig wrote:3. Two additional connections vs. a simple connections at two points.

I don't know how you came up with this. Leaving the radiator in the loop you only need to undo one connection and make two. If you take the radiator out, you have to undo two and make two.

Meterpig wrote:Now, I have seen here and other sites that some are concerned that the tranny is running "two cold". This seems odd to me. Does everyone wait for the tranny to get up to temp before driving?

Most people are able to just start up and go. If you're in a really cold climate, you will experience delayed shifting. Also, your torque converter will not lock below a certain temperature, reducing your fuel economy.

Meterpig wrote:So why did you buy a giant cooler if only to fight with the radiator.

At $250 for a extra deep pan, I think the cooler is far better bang for your buck.

Meterpig wrote:Now, I have seen here and other sites that some are concerned that the tranny is running "two cold". This seems odd to me. Does everyone wait for the tranny to get up to temp before driving? Probably not. Well, if one feels that the fluid needs to be cooked before hand, they should run a heater on the bottom of the pan and/or wait for the tranny to heat up (could take a while you know).

Actually Toyota does run a trans fluid heater in the Tundras.

Meterpig wrote:Bottom line, the radiator does nothing or next to nothing to cool. In fact, it can actually impede the cooling function as the fluid is cooling the minute it comes out of the transmission.

True the fluid is cooling as it comes out of the tranny but without the fluid running through the cooler, what do you do to control temps when towing? I know for FACT that the radiator will keep the tranny at around 180* as long as you are not towing. I have tested this with a temp gauge and driving. My temp tests are posted in this thread...just gotta read the whole thing.

Meterpig wrote:A final note on the whole "we need to precook the transmission oil". The oil is super thin. Much thinner than the oil in your motor. You drive that cold right? The oil is flowing at cold conditions. For you cold weather folks (Cheyenne and North) wait one minute...then cycle the transmission through all the gears while in the driveway. Then off you go. If it isn't cycling...well...then it is really, really cold.

If the tranny runs too cold, you will not get 4th OD or 3rd with the TCC locked. This may not be true in an older 700R4 that is not electrically controlled, but it is true in a 4L60E with a temp sensor.

timelessbeing wrote:

Meterpig wrote:1. No risk of coolant/oil (tranny fluid) mixing. With coolant in radiator, there is this risk and it happens.

I think this risk is pretty low, and certainly no greater than leaving it stock. I'm more likely to smoke an extra deep pan on a rock.

Meterpig wrote:2. With the radiator inline, the fluid is being raised to whatever temp the coolant resides. Engine overheating? Great. Cooking the oil.

Where are you going if your engine is overheating? Your engine will cook before your oil does.

The engine can run at 225 degrees if the coolant can withstand that heat as Evan's coolant can. I don't want to run my transmission that high if I can avoid it...but won't stop anyone else.

Meterpig wrote:3. Two additional connections vs. a simple connections at two points.

I don't know how you came up with this. Leaving the radiator in the loop you only need to undo one connection and make two. If you take the radiator out, you have to undo two and make two.

I will concede that it is one additional point. Still more.

Meterpig wrote:Now, I have seen here and other sites that some are concerned that the tranny is running "two cold". This seems odd to me. Does everyone wait for the tranny to get up to temp before driving?

Most people are able to just start up and go. If you're in a really cold climate, you will experience delayed shifting. Also, your torque converter will not lock below a certain temperature, reducing your fuel economy.

In that cold of a climate, the transmission and the radiator will heat at roughly the same rate. If one is thinking it will take longer, cycle the gears or put it in gear (once a bit of time has passed) and press on the gas just a bit. It will heat up quite quickly.

Meterpig wrote:So why did you buy a giant cooler if only to fight with the radiator.

At $250 for a extra deep pan, I think the cooler is far better bang for your buck.

210 for deep aluminum pans, less for steel pans. Steel pans can withstand a bump or two. I do agree that there is a risk. Someone needs to design skid plates for the astro.

LiftedAWDAstro wrote:

Meterpig wrote:Now, I have seen here and other sites that some are concerned that the tranny is running "two cold". This seems odd to me. Does everyone wait for the tranny to get up to temp before driving? Probably not. Well, if one feels that the fluid needs to be cooked before hand, they should run a heater on the bottom of the pan and/or wait for the tranny to heat up (could take a while you know).

Actually Toyota does run a trans fluid heater in the Tundras.

I was unaware of that...but I would think that Toyota is aware that many owners are now driving their vehicles without a thought about warmup at all. Heck, I see people all the time start a vehicle and dump the gas pedal. Insane. I am speaking to owners on this site-not soccer moms.

Meterpig wrote:Bottom line, the radiator does nothing or next to nothing to cool. In fact, it can actually impede the cooling function as the fluid is cooling the minute it comes out of the transmission.

True the fluid is cooling as it comes out of the tranny but without the fluid running through the cooler, what do you do to control temps when towing? I know for FACT that the radiator will keep the tranny at around 180* as long as you are not towing. I have tested this with a temp gauge and driving. My temp tests are posted in this thread...just gotta read the whole thing.

I did read your posts. I am not referring to non-towing temps-only towing temps. I am also speaking to extreme towing-that over 2500 pounds or so. So yes, the radiator is usually fine for grocery getting.

Meterpig wrote:A final note on the whole "we need to precook the transmission oil". The oil is super thin. Much thinner than the oil in your motor. You drive that cold right? The oil is flowing at cold conditions. For you cold weather folks (Cheyenne and North) wait one minute...then cycle the transmission through all the gears while in the driveway. Then off you go. If it isn't cycling...well...then it is really, really cold.

If the tranny runs too cold, you will not get 4th OD or 3rd with the TCC locked. This may not be true in an older 700R4 that is not electrically controlled, but it is true in a 4L60E with a temp sensor.

Agreed. Here is what I have read on this subject. Many claim that this could be a problem-but have never really replicated the problem. My 4runner does hold the gears until the oil reaches a temp. I think, on a really, really cold day it once did it for two miles. And this was only due to starting and driving the vehicle within one minute.

Now, here is something interesting I have found.

Transmission Cooling: You must have a transmission cooler in your radiator regardless of what someone has told you for the transmission to last. Auxiliary coolers are just that, in addition to. Water cools 32 times better (faster) than air always, period. The transmission fluid comes directly from the torque converter at a much higher temperature than the water in your radiator and is cooled to the water temperature fast. Then it goes to the auxiliary cooler to be cooled far below the water temperature. If you don't need a cooler in your radiator why does GM spend all that money doing so? If you wanted to cool a red hot piece of steel fast would you stick it in water or air, see the point. For the best cooling you need both water and air cooling for the transmission to be cooler than the motor.

They make a good point that water cools faster than air, however, they don't point out that at 30-70 mph air will indeed cool quite quickly. Here is an easy test. Take your hot sunglasses after sitting in the front window and stick them out the window as you drive down the road at a mere 20 mph. They will be cool in a block.

They also say "fluid comes out hotter than the radiator". OK, so my radiator is running at 190-200 degrees. That's a lot hotter than I want my tranny to run consistently.

Meterpig wrote:Someone needs to design skid plates for the astro.

Someone DID, and if I lived near Lifted I would be paying him a visit with beers in hand. He makes all kinds of goodies like rock rails too.

Meterpig wrote:OK, so my radiator is running at 190-200 degrees. That's a lot hotter than I want my tranny to run consistently.

I would say that's at the top end of optimal range.

timelessbeing wrote:

Meterpig wrote:OK, so my radiator is running at 190-200 degrees. That's a lot hotter than I want my tranny to run consistently.

I would say that's at the top end of optimal range.

I don't know how accurate my gauge is...but it runs right around 190. Maybe it runs hotter than older vans?

timelessbeing wrote:

Meterpig wrote:Someone needs to design skid plates for the astro.

Someone DID, and if I lived near Lifted I would be paying him a visit with beers in hand. He makes all kinds of goodies like rock rails too.

Really? Have a link?

Meterpig wrote:Really? Have a link?

Use the "Search" button at the top right corner of the page. That button will be your best friend on this forum
viewtopic.php?f=14&t=85
viewtopic.php?f=7&t=5634

Right after I asked...I searched. and found it. Thanks.

The Ultimate.

now i have to look again to see where i found it. but in some documentation (or website) i think it was state that GM says the tranny is supposed to run at 190deg. mostly on this thread i see that everyone wants it cooler than that.

I still want the aux cooler for towing (if i ever get to that). Now to come up with the source of that number.



But if so, is it just a matter of cooler is better. I gather from some comments and literature that running to cool is bad as well as running too hot... no.?