Cool trans or cool oil?

[serpa4]

Was thinking of adding either an engine oil or trans cooler one at a time as money allows. Which is more important? I do haul 5,500 in the bed and a 5,000 lb boat at the same time several times per year.
I have electric fans which work 90% of the time unless its really hot and I'm hauling all 10,000+ lbs. Which would help to bring engine coolant temps down more, oil or trans? I think that is the real question: which helps more with engine temps? I don't think either will make any significant difference on engine coolant, but every little bit helps.

 

[hondarider552]

IMO id do a engine oil cooler.

 

[Killerbee]

Which would help to bring engine coolant temps down more, oil or trans? I think that is the real question: which helps more with engine temps? I don't think either will make any significant difference on engine coolant, but every little bit helps.

An EOC, hands down. No comparison really, not even a close one. You are discussing between 2 fluids, one with a 2 gpm flow rate, the other with a 15 gpm flow rate. A large cooler can be used for either applcation, but there is 750% more cooling ability with the EOC. I have had real good luck significantly cooling the engine with oil, the TD-EOC was developed specifically for the dmax. It lowers coolant temps because there is an intimate interface of heat exchange between the coolant and the oil.

You will find also, anything that lowers the temps of the coolant, or the oil, also lowers tranny temps. The TD-EOC reduces trans temps 10-20 degrees. By contrast, I know that a TOC will have no significant effect on engine oil temp.

One more thing, you need a large EOC, and thus it needs thermostatic control. Oil overcooling is a BAD thing.

 

[Mike L.]

An EOC, hands down. No comparison really, not even a close one. You are discussing between 2 fluids, one with a 2 gpm flow rate, the other with a 15 gpm flow rate. A large cooler can be used for either applcation, but there is 750% more cooling ability with the EOC. I have had real good luck significantly cooling the engine with oil, the TD-EOC was developed specifically for the dmax. It lowers coolant temps because there is an intimate interface of heat exchange between the coolant and the oil.

You will find also, anything that lowers the temps of the coolant, or the oil, also lowers tranny temps. The TD-EOC reduces trans temps 10-20 degrees. By contrast, I know that a TOC will have no significant effect on engine oil temp.

One more thing, you need a large EOC, and thus it needs thermostatic control. Oil overcooling is a BAD thing.

I disagree. The EOC will have no effect on trans cooling and if you are towing a load, especialy with converter unlocked, you will put a tremendous amount of heat into the radiator by way of the trans fluid. An EOC will do nothing for that.
I like the idea of an EOC, but to say it's an end all be all for our trucks is not true.

 

[Killerbee]

I answered factually. It is easy to back up. The amount of heat that can be created by the transmission from just viscous generation, is minute compared to the combustion heat offloaded into engine oil under high loads. 10 fold at least.

 

[Mike L.]

I answered factually. It is easy to back up. The amount of heat that can be created by the transmission from just viscous generation, is minute compared to the combustion heat offloaded into engine oil under high loads. 10 fold at least.

Then back it up on a truck, not a keyboard. We can do a test on a hard working truck switching your EOC, my trans cooler and TxChristophers set up and watch the engine and trans temps. It would only take a couple of hours to prove or disprove. I have already done this and found that no matter what you do to cool the engine, you still need a trans cooler if you work the truck hard.

 

[McRat]

Which would help to bring engine coolant temps down more, oil or trans?

IMO:

Neither will bring engine coolant temps down unless you are already overheating, which is very rare on LBZ's. Engine coolant pretty much stays ~200 on LBZ's.

If you are already overheating, a bigger trans cooler won't change things. An oil cooler might help, dunno. The conventional solution for overheating coolant is a bigger radiator.

But if my theory is correct about the cause of piston cracking (excessive piston temps), then an oil cooler could improve your odds by keeping piston temps down.

A trans cooler is a very good idea if you are towing heavy, are desert driving, or running up and down mountains. Oddly enough, the only time Blue overheated the trans was going DOWNHILL in steep mountains during high RPM grade braking with the stock cooler. In this case, putting a bigger trans cooler on Blue was a safety issue.

 

[McRat]

Was thinking of adding either an engine oil or trans cooler one at a time as money allows. Which is more important? ...

This really depends on what is overheating, your engine, or your trans.

 

[Killerbee]

Which is more important? I do haul 5,500 in the bed and a 5,000 lb boat at the same time several times per year.
I have electric fans which work 90% of the time unless its really hot and I'm hauling all 10,000+ lbs. Which would help to bring engine coolant temps down more, oil or trans? I think that is the real question: which helps more with engine temps? I don't think either will make any significant difference on engine coolant, but every little bit helps.

This is his question, highlighted in bold. Mike, I am completely willing to take your challenge, a TD-EOC, vs any trans oil cooler, to answer it. I would suggest a privately negotiated side wager, on friendly terms, just to make it more interesting.

I respect your position, and won't argue, just like you said, on a truck.

Clarifying: his question does not ask, "which will better cool my tranny?"

 

[Mike L.]

This is his question, highlighted in bold. Mike, I am completely willing to take your challenge, a TD-EOC, vs any trans oil cooler, to answer it. I would suggest a privately negotiated side wager, on friendly terms, just to make it more interesting.

I respect your position, and won't argue, just like you said, on a truck.

Clarifying: his question does not ask, "which will better cool my tranny?"

The trans cooler will not bring engine temp down unless the trans ran hot enough to put heat into the radiator. You said that your EOC brought engine temps down as well as trans temps and I disagreed. I feel that a properly plumbed EOC without any drain back is very benefiacial but a larger radiator will bring coolant temps down a lot more. A good trans cooler is just a preventative of adding more heat by way of a hot running trans. As far a betting, I will take your wager that your EOC does no signoficant cooling for the trans. I will also make you a wager that a bigger radiator will bring coolant temps down further than an EOC.

 

[Killerbee]

I agree with that whole statement.

And his question has been answered. An EOC is more valuable to engine temps than a TOC.

I have seen, and heard many feedbacks, that the TD-EOC reduces trans temps. But it can only do so by virtue of the oils interaction with coolant in the stock ht exchanger. If coolant is cooler then there is more capacity for the coolant to cool the transmission. A TOC will do a much better job of cooling the transmission than anything that works through a 3rd party heat exchange mechanism. We agree, with semantic differences only.

 

[SIKDMAX]

All I have to say about this is :rofl:

I side with Mike.

 

[MMLMM]

I look at it this way.

The radiator is cooling the coolant and trans. fluid.

If you can bring down the trans fluid temp any amount, the radiator will not be dissipating as much heat to the coolant.

Hot trans fluid = Hotter radiator = Hotter coolant.

Now with the trans fluid and radiator cooler, will the coolant be cooler? Hmmmm, only a test would show, BUT I bet it take the coolant a little longer to get as hot....and once the coolant and radiator get hot, the trans temp will prolly rise for the fact that the radiator is not doing a good job of cooling it at that point.....



Also Trans temps can always be better (cooler). Especially when towing.
As far as engine oil in our trucks...Are they really getting hot enough to worry? Are we using the correct viscosity if not?

 

[Killerbee]

As far as engine oil in our trucks...Are they really getting hot enough to worry?

logged 340 F. Others have logged higher. Under heavy load, oil temp goes out way ahead of coolant.

If the truck had an engine oil temp gauge, this discussion would have a much different tone.

 

[MMLMM]

logged 340 F. Others have logged higher. Under heavy load, oil temp goes out way ahead of coolant.

If the truck had an engine oil temp gauge, this discussion would have a much different tone.

LOL ok. yea, 340 is quite warm....I guess we need to log our trucks and see what temps the oil is running.

 

[racinmike77]

yea 340 is way too hot most oils break down before that.

 

[Mike L.]

IMO coolant and oil have seperate jobs to a certain point, but they do cross over. Coolant will cool the block and heads and that will affect the rest of the engine, but it's the oils job to cool the pistons rods and crank,and cam. If you are going to knock down engine temps you have to cool the block and that's not the oils job. The coolant does that. This is not to say we don't need an EOC, which I believe us hot rodders do with our tunes. I don't believe a bigger radiator will help save LBZ pistons, but I do believe an EOC will. On the other hand, I don't believe an EOC will significantly drop engine temps, not to say it doesn't work; but it's not it's job.

 

[specialagentPK]

Killerbee


What problems does overcooling the engine oil present?

 

[Killerbee]

Mainly making it difficult for the engine to reach operating temperature. Thermostat control fixes that though.

There is also the issue of lubrication quality. Most automotive oild are designed for optimum lub properties at temp sensitive viscosities. Our oil is suppose to be 200-210 F. If cooler, then it is more viscous, and that will lower flow rate and at the same time, you get worse hydrodynamic lubrication, and more viscous drag than is desireable.

One other problem, if oil does not get a chance to reach that temperature, you quickly develop sludge problems, moreso in cold and wet environments.

 

[moss6]

Noticed this thread and thought I would share some of the things I have found through my experiments on my LBZ concerning cooling issues.
I installed a Setrab engine oil cooler before I had a temperature gauge on the and have always wondered how hot the oil gets in a truck without a cooler. What I have seen with the cooler (this with the oil temp sensor installed in the engine oil drain plug) is that non towing temp. is around 195 Summertime, and you have to run a while before it reaches that. Winter seems to drop it 10 to 15 degrees. I have seen no change in fuel economy since the cooler was installed so to me that disproves the idea that the oil needs to be 200 to 210. I do run 5W40 Delvac 1 so that may be a factor. The high extreme that I have seen since the cooler install was 241 degrees and that was in the Summer pulling a 16,000lb fifth up the long steep grade of La Veta pass in Colo. against a strong headwind. I believe EGT's were in excess of 1400 also. Something quite noticable is that computer calculated oil life is consistently at least 4000 miles longer since the install so I wonder if the computer isn't picking up oil temp somewhere and factoring it in, or possibly that overall things are cooler because I also added a Setrab auxilery radiator to keep water temps down when towing.
And by the way, adding the Mike L transmission cooler has completely taken any concern of high trans temps out of the equation; no matter how hard you push it.
Cheers
Randy