Weird cooling issue

[phil_long]

Hello gents!  I wanted to post this up because I'm having an issue that's a bit odd to me. From what I've read before about the cooling system, when cruising on the highway our cars should remain cool(er) than stop and go traffic. I seem to have the opposite going on as it seems when I'm on the highway, my car runs a bit warmer than usual, but when I slow down and get into stop light driving, it cools better. Just the other day(low 80's) I was on the highway, and the car got up to about 188. That's pretty warm seeing that it cooled back down to 172 when I got off the highway. I am running the F-Body radiator with the Dual Fans(LOVE EM) and I've NEVER had a cooling issue with this setup. Sitting still this combo cools until the fans kick off.


I had a theory and I wanted to know if I was way off base with my thinking: I haven't fixed my TC issue as it is still NOT locking up.  I've noticed that when I'm trying to maintain speed on the highway(65 MPH or so) I'm damn near/constantly going into boost. Coupling that with more load in 4th gear I figured the engine is getting warmer due to the work needed to maintain speed. Am I in the ball park with my thinking?


Also, does a L/U TC generate more heat when it's unlocked at cruising speeds? If so, how does the heat from the tranny cooler effect the cooling ability of the radiator itself? Thanks!

[PacecarTA]

the heat from the trans is directed to the coolant with the trans cooler in the radiator, if trans fluid is hotter than coolant the coolant will be heated 
are you running a seperate trans cooler?

problem with a lockup is its usually not very efficient unlocked 
NL are designed to couple better , not 1:1 as a lockup will locked but still better

have you replaced the thermostat lately

[phil_long]

I am NOT running a separate cooler for the tranny.  Seems like that's the issue right there. The T-Stat is a 160 and it functions as it should. I figured that about the TC. I have to figure out why it's not locking.

[larrym]

Is the fan setup to pull air into the engine compartment rather than push air out?
With the fan pushing and the car at speed there would be no flow.


Mobile larrym

[Forzfed]

I am NOT running a separate cooler for the tranny.  Seems like that's the issue right there. The T-Stat is a 160 and it functions as it should. I figured that about the TC. I have to figure out why it's not locking.

I think Paul nailed it!  How old is your rad?  Is it stock or a stock re-core?  Good idea to run a big cooler for the transmission.  A bigger transmission pan is a good idea also.

[earlbrown]

All transmissions need an external cooler.

If you're running warmer on the interstate it might not be a heat load issue, it might be a flow issue.

If you have a stock rad that's clogged up, it can flow enough to reject around town heat, then be a cork when the engines spinning the water pump faster.

an easy way to tell is to pop the thermostat out and see if you still run hot on the interstate. 

[phil_long]

I stated in my original post that I had the F-body Radiator with the Dual fan setup.  It isn't 2 years old yet. I installed back when my timing chain had broken.  You guys dont remember?? Lol.  Just kidding on the memory part.  Lol.  But I got rid of all the stock junk then.  The dual fans are def pulling in a ton of air, not pushing.  I wasn't aware that people could set it up to push air. 

[phil_long]

And, the tranny being on an external cooler I believe will fix my problem.  I wasn't aware that the tranny cooler in the radiator would effect the actual coolant, but I learn something everyday.  I'll work on getting that tweaked.  Thanks guys 

[Scoobum]

I have the F Body rad and the twin fans. When I drove my car on the highway it would run warmer than around town. This was my theory. The F Body rad appears to be thinner...thus holding less coolant. At highway speeds the RPM's are higher...thus moving the coolant through the system much quicker. With there being less coolant capacity...and it flowing through the rad so quickly...it doesn't get a chance for the heat to dissipate.

[larrym]

I have seen the wired backwards before....

[Steve Wood]

The faster the coolant flows thru the radiator, the faster it has to go thru the block to get back to the radiator so the cooling is equal.  In reality, the faster it flows, the more stable the water in the water jackets will be as the internal pressure is higher so there is less chance of steam pockets forming plus the velocity creates more turbulence in the radiator tubes so more heat is removed as the transfer to the walls of the tubes increases.

Some of these aftermarket fans have badly designed shrouds so air flow is blocked on portions of the core that are not in front of the fan opening.  Larry has a good point.  Be sure the fans are pulling air thru the core and not running the wrong way and pushing air from the back of the core toward the front against oncoming air flow.

As I am in boondocks, I would unplug the fans and hit the highway to see if the temperatures were the same at 70 mph without the fans as they were with them running.

A torque converter that is not locking up will certainly generate more heat than one that is working correctly.  And running the tranny cooler thru the one in the radiator and then thru an external cooler has always raised the temps in my cars about 10 degs in the summer even when the converter is locking up properly.

And, why haven't you fixed the lock up?   http://www.vortexbuicks-etc.com/tcc_lockup.htm

[Scoobum]

That blows my theory to shit. Steve...why did I see 178 degrees on the freeways...and 167 around town? The fans in my car have enuf velocity to drag a small child through. I have a separate trans cooler...and don't bother with an oil cooler.

[Steve Wood]

Simply, I don't know

But, the engine works harder to push one of these bricks down the road at highway speeds in OD than it does at lower speeds and lower gears for the most part.  Harder work translate to more heat generated.

If you run 50% coolant, it will probably run 10 degs warmer than it will on straight water.

If you run 70% coolant, it will run even hotter.

If you run straight water with a surfactant like purple ice or rmi, it may run 15 degs cooler than on 50% coolant.

If the electric fan has a shallow shroud, the air flow will have to make a 90 deg turn when it comes thru the core to escape the opening around the fan(s).  The better fans have doors that open in the shroud to relieve the pressure at higher speeds to beat that problem.

If the fan sees less voltage at speed, it pulls less air.

A high volume water pump will increase the pressure in the block and prevent steam pockets which don't transfer heat to the coolant stream and this ultimately heats things up.  A good coolant system sees 50-60 psi in the block if I recall correctly as compared to 15-17 psi in the radiator.  Kinda like sticking your thumb over the end of a water hose.  You get a lot more pressure behind your thumb than in front.  That is the primary function of the thermostat--build higher pressure in the block due to the restriction as well as create a more turbulent flow to the radiator tubes.  Of course it warms the engine up quicker which is desirable.  It's purpose is not to slow water down thru the radiator.  As I said earlier, we have a closed loop system so the same amount of cooling occurs no matter the speed of flow.

Removing the tranny cooler from the radiator tank lowers the temp but placing it in front of the radiator core forces the hot air off the cooler to pass thru the radiator core and that area of the radiator does not do any effective cooling.  If it is in front of the core, it should be at least an inch in front to allow the air stream to straighten out and flow more effectively thru the core.

If the Radiator is not sealed on both sides and the bottom, air will take the path of least resistance instead of going thru the core which tends to look like a brick wall at speed and the radiator will not cool nearly as well...

Like, I said, I don't know!

[Scoobum]

Great info...thanks so much.

[daveismissing]

Good stuff!   
That should be a stickie.

Now watch Earl pervert the statement above.