Transmission temps and cat plate correlation?

I just returned from our yearly to the lake vacation, (approximately 165 miles one way) and noticed an interesting variation from last year to this year.

Let me begin by saying that both last year and this year consisted of towing the same boat, with a similarly loaded truck. The ambient temperature being similar, A/C engaged and same roads to same location. Prior to last years trip I bought and installed Nicks transmission cooler kit and found the pan temps staying mostly in the upper 190's, if I remember right only a couple times hitting 201.

This spring I bought and installed Valhalla's front and rear catalytic converter theft
deterrent plates, and on this years trip my transmission pan temps ran probably around 5 degrees higher than last year, staying mostly around 203.

The only other difference is that last year I believe I ran in S-5 almost exclusively and this year used S-6 mostly. Both trips were made with Tow/Haul engaged.

Has anybody else noticed any similar increase in pan temps after plate install?

 

I have the Desert Eagle cat protection/ skid plate. It seems to have increased the tranny temps at least 5 degrees.

FYI. I’m not running a tranny cooler.

 

Maybe insulating your cats with some high temp heat shield insulation would help.

Some products will block up to 70% of radiant heat from escaping from the insulated part. That would probably help.

 

@Green Thunder Interesting you have a similar situation as I, this would seem to indicate that the plates do indeed trap some heat inside.

@Coal Dragger Thanks for the suggestion, but I am not really concerned with the slight temperature gain. If my pan temps stay under 210* I've no concerns. I just found it interesting and wondered if others have experienced similar temperature gains after installing plates.

 

I do not belive tow haul works in sequential modes.

 

Oh it most certainly does! Has the same effect in drive as S mode, difference being S limits tranny top gear to whatever S gear you choose. I can't say with certainty there are no other differences but I don't seem to notice any.

 

i see the same temp rise

adding a trans cooler to my list

 

It's hard to compare since you used S6 this year and S5 last year. If the torque converter was unlocked more in S6, then that would also cause a rise in ATF temp.

 

I think it’s impacting airflow, so you get less air rushing past the cats while driving.

Agreed. I only recently started towing exclusively in S-D mode. That’s cut my tranny temps significantly.

 

This! I haved tried different gears when towing and watch what the trans temps did. Going from S5 to S6, the temps would rise 5-10 degrees.

 

There is no doubt any large plate that would lessen airflow and reflect heat, even minimally, would result in a higher temperature of the components it is covering up.. No need to argue that. Now how much is the question and is it enough to even be remotely concerned. It sound like very little and no concern.

 

It's not an issue. I just towed a 4Runner roughly 35 miles in regular drive with tow/haul and the max I hit is 213 in Florida heat. I have front and rear cat plates along with an RCI engine skid and Trans cooler.

 

with my old man style driving on hwy - I hit 213 in no traffic @ 59mph

it's hot in Houston.

I have both plates

 

I agree with others that its both less airflow and your change to S6.

 

Yep, posting on an older thread but I figured I'd share my experience after recently installing RCI components on 2023.12.22.

Current Setup: Supercharged 5.7, CSF radiator, tow package with trans cooler pinned open, Magnaflow OE style intermediate pipes/cats, front diff skid plate (comes with RC 6" lift), & RCI trans/TC skid and cat protectors. Currently monitored with ScanGauge 3 (previously with OBD Fusion)
*Trans temps provided are pan/post-cooler F° temps (assume TC lockup for highway)

Pre installation of RCI skid/cat protection:

• City driving*: 135-165
• Highway*: 165-180
• ECT: 185-205
​

Post installation of RCI skid/cat protection:

• City driving*: 150-185
• Highway*: 175-222
• ECT: 185-213​

Notes: Although the increase in temperatures were found post-RCI installation, the alarming things were the conditions in which I reached the highest temps on my recent trip back from UT->CO. Ambient temp was 9° and I was at 70mph headed East up to the Eisenhower tunnel (watch TFL Truck Ike Gauntlet YouTube videos for a better understanding). At the top I had a pan temp of 220° and 213° ECT (usually 190°/205° respectively). I have NEVER seen either of those reach that high - especially at such low ambient! As I coasted down, ECT dropped to 185°, however, TC temps hit 230° (pan reached 222°) as lockup is not engaged during deceleration. Even on hot summer days, I have not reached those temps.

I frequently drive I70 between CO & UT which means I'm 70mph up/down Eisenhower with max elevation of 11,158 feet. I am most always hauling something - usually dirt bikes and gear. With my most recent trip (over new years weekend) it was 350lbs of garden pavers in the bed for weight, plus 15 gallons of extra fuel - about half of what I haul with the dirt bikes & gear. So seeing such high temps under such cold conditions is new.

At one point on my recent trip, the ambient temp was 0° and I was driving 80mph. ECT was 197° but trans reached 216°! At lower speeds of 55-60mph and temps between 0°-5°, I witnessed significantly better results with trans at 177° and ECT of 185°, but still higher than expected for ambient temperatures.

My theory and conclusion is that the skid plate and cat protectors have affected heat dissipation under all conditions as well as created stagnant air at higher speeds, thus insulating the trucks belly with a pocket of hot air and exacerbating poor cooling.

 

Thanks for posting this. I’m currently trying to decide if I want to get a full RCI package with engine skid, tranny skid plus cat shields or just get the front engine skid.

Do you think it’s mainly the tranny skid and cat guards that trap the heat? I live in an area that goes triple digits much of the summer so I definitely don’t need more heat.

 

At this point what I have to offer is speculative and anecdotal, but I can say things staid cooler prior to adding the skid plates and cat guards.

I lived in Gilbert for a bit and can relate to your temps! Perhaps you've already considered this, but there's that brutal radiant heat coming from the road during the day. I would suspect that would only compound the deficiency in removing component heat.

Although the operating temps I have experienced are not out of range, my concern is where they'll be when I'm not traveling through subfreezing weather. As soon as it warms up, the skid plates will have a visit from the business end of my plasma cutter for some thoughtful ventilation.