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Discussion Starter · #1 ·
Ever since I converted my 4th gen from automatic to manual my water temperature gauge takes forever to get to the middle mark. Most of the time it stays on the 1/4 mark unless I start driving like a madman. When I used to have my auto tranny, it only takes a few minutes for the water temp to reach the middle mark...by the time I left my driveway, it's in the middle already. So does this mean that auto trannies put a little bit more stress on our engines than manual trannies?
 

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Maybe a little more since it is never fully disengaged but on the other hand the shifts are easier and no revving or downshifting. Probably comes out about even, I think.
 

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auto trannies rely on the engine's cooling system for cooling, so my guess is that the auto tranny causes the coolant to heat up quicker than in a 5 speed.
 

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Discussion Starter · #4 ·
G_Loc said:
auto trannies rely on the engine's cooling system for cooling, so my guess is that the auto tranny causes the coolant to heat up quicker than in a 5 speed.

hmmm good point.
 

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G_Loc said:
auto trannies rely on the engine's cooling system for cooling, so my guess is that the auto tranny causes the coolant to heat up quicker than in a 5 speed.
I don't believe that would make a significant difference, I think something else must be going on here.
 

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G_Loc said:
auto trannies rely on the engine's cooling system for cooling, so my guess is that the auto tranny causes the coolant to heat up quicker than in a 5 speed.
Actually, the Honda auto tranny on the 4th gen has two cooler lines hooked up to the bottom of the radiator to help cool the automatic tranny fluid, but it's a completely seperate system than the engine's antifreeze system, so it shouldn't impact the antifreeze at all.

I did the auto to manual swap as well, but I didn't notice anything as significant as you are seeing...
 

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dont think the tranny swap caused this to happen...check to see if your thermostat is bad, maybe it is open 24/7 and the motor is running colder?
 

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sharkcohen said:

Actually, it was the first thing that came to mind for me. The tranny cooler core is integrated into the bottom of the radiator. I could see it making a significant impact on coolant temps.
I seriously doubt there is a significant difference in the first 15 minutes of driving. No doubt in my mind that coolant temp comes up before Auto tranny fluid temp does.
 

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The Auto transmission get a lot hotter than the coolant in the radiator.

The auto trans actually heats up the raditor coolant.

If you were to replace your stock radiator, then you'd find that your car engine temp would also go down from where it generally was. (Because you'd added more cooling surface by removing the ATF cool build into the auto radiator.)

By the same token, you should also see a difference in your temp (as you said) by just removing the AT.

Synthetic ATF (Mobil 1, AMSOIL, Redline High Temp DIII) will lower your AT temps for those who still have an Auto.

The 5th Gen SS Auto has problems for many reasons, but the heat causes significant ATF wear. This is why we're seeing a need to change the ATF every 15,000 - 20,000 miles.

Gerhard
 

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buy a tranny cooler

they're only like $70 from Pepboys and such
 

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Discussion Starter · #12 ·
92 SI Ludester said:
dont think the tranny swap caused this to happen...check to see if your thermostat is bad, maybe it is open 24/7 and the motor is running colder?
I checked my thermostat and it was ok. Anyways you guys have good points, I think that since the tranny cooler is below our radiator, it greatly affects the coolant temp.
 

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Hmmm, now I'm wondering if I should get a larger (appropriately sized) tranny cooler and just bypass the stock core in the radiator to help keep my coolant temps down for my JRSC setup.

Hmmm, now I need to do some datalogging to see if my coolant temps are higher now now that I've bypassed my current external tranny cooler from the system. Perhaps it has been my tranny cooler that has kept my coolant temps down, and not my snazzy Mugen cooling parts.
 

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sharkcohen said:
Hmmm, now I'm wondering if I should get a larger (appropriately sized) tranny cooler and just bypass the stock core in the radiator to help keep my coolant temps down for my JRSC setup.

Hmmm, now I need to do some datalogging to see if my coolant temps are higher now now that I've bypassed my current external tranny cooler from the system. Perhaps it has been my tranny cooler that has kept my coolant temps down, and not my snazzy Mugen cooling parts.
You can never have to much cooling.

You can also never go wrong using 100% synthetic products for all of you lubrucation needs. Since you're generating all that extra heat by boost whoring.

-grin-
 

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HI HO said:
Sorry, I still don't buy it.
Why wait, I'll just type it out:

1) The transmission temps should never be below 175 degrees F.

2) For ever 20 degrees over 175F your ATF is, it will break down 50% faster. So if it will last 60,000 miles at 175F, then at 195F it will only last 30,000 miles. (...only 15,000 miles at 215F)

3) Honda Prelude SS Auto transmissions generally run at about 230F or so.

4) The coolant is generally at 195F to 210F.

5) The coolant cools the ATF and is also warmed by the hotter ATF fluid.

6) Synthetic fluids are generally better at thermoconduction. Therefore, they are better at transfering heat more efficiently.

7) Using an external transmission cooler allows for better cooling of the transmission. There is, however, a point at which the heat traveling off the cooler would warm engine coolant as much as if it were still passing thru the OEM ATF cooler. For that to be the case it would have to be a very large surface.

8) Due to the lower proximity of the aftermarket cooler to the engine cooler (radiator), the engine coolant is not warmed as much as it would be with the OEM configuration.

It pretty much makes sense.
 

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HI HO said:


I seriously doubt there is a significant difference in the first 15 minutes of driving. No doubt in my mind that coolant temp comes up before Auto tranny fluid temp does.
I tend to think they are related... I suspect that the tranny temp is initally warmed by the coolant. Once up to temp the friction in the ATF causes heat and the tranny begins to warm the engine coolant.
 

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HI HO said:
Where are the comments from all the other tranny swappers confirming that they experienced the same thing?
I have never swapped but my temp gauge reads about the same. Sometimes it will read full then go back down another light. I don't think that it is a 1/4 temp or anything. A more accurate temp gauge would be able to tell me what my car is usually at. I think its just a hair under from lighting up the last one. That is why it goes back and forth somethimes.
 
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