Exhaust reroute heat questions

I actually just purchased embossed aluminum heat shielding myself planning to do something similar Although I'm probably going to be pretty OCD about forming it to the contour of the Transfer Case so it doesn't look tooo out of place.

I'm also going to run some heat shielding underneath the cab as well as wrap the Parking brake cable.

 

I do kind of wonder why engineers ran things the way they did, I do see a few potential reasons though;
- Radiant heat onto T-Case
- Serviceability of Driveshaft
- Radiant heat onto driveshaft

 

I "Think" they just plug in the Obd II and call things good, visual inspections are generally only on older vehicles.

I'm just counting the days until my drop down bed step gets torn off.. I'll probably grudgingly remove it whenever I get around to replacing the bumpers.. Finding the right bumper for me has been hard though.

 

IMO you're overthinking this. I have no issues with my reroute and it's been on 1.5 years so far. A bunch of guys have done it and I've yet to hear about an issue due to it. My Borla kit did come with a heat shield for the control module though.

The factory y pipe is a huge exhaust restriction so if anything the reroute should reduces temps dude to increased flow. And there is still a good amount of distance between the piping and any components, but heat wrap or ceramic coat if you're that worried about it. I didn't check the before or after numbers and I don't really care. Factory y pipe is an awful design - Toyota has kind of always sucked with their y pipes though, this is nothing new.

 

I think the Borla Y is a better option. The URD Y doesn't line up well from what I've read.

The factory y is a pea shooter at best.

 

There's a lot of parts/design recycling within Toyota to reduce development time/cost. 3rd gen ran it this way because 2nd gen ran it this way. 2nd gen ran it this way because the 4Runner ran it this way. 4Runner ran it this way because the fuel tank is much closer to the T-case, leaving a narrow gap between the fuel tank and T-case actuator. On the 4Runner a reroute isn't as beneficial, because the fuel tank protrudes a couple of inches below the frame.

 

Sooo, the fiberglass wrap may have actually been making things worse.

I tore that off and clamped on an improvised heat shield today and the surface temps are all around 150-160 after driving on the highway and the exhaust pipe temps are slightly lower then the passenger side whereas it was near double when wrapped. The exhaust right where it exits the cat temps at 230f, 190 near the hanger opposed to near double that when I had it wrapped.

The portion of the Control module that's shielded by the heat shield temps at 130 whereas the outside edge towards the unshielded portion of the pipe temps at 160f.

Driveshaft only tempted at 150f, which is down 25% or so from when I had it wrapped, so I'm not as worried .

I'm definitely going to proceed with my plan to better shield the Module and brake cable. Maybe extend the heat shield under the cab as well.

 

I wrapped mine and it’s close to the transfer case. Been there for 7-8 years never had an issue.

 

If you’re really worried about the higher temps, you can always add some DIY heat shields to the wrapped pipe.
I have an old sheet of aluminum (~20 or 22G) in my shop that I’ve used to make shields to mount right on top of fibreglass wrapped exhaust pipes. I attach it tight to the pipe (and at least halfway around the pipe) with stainless or galvanized mechanics wire with safety wire pliers.
Works well for deflecting heat and also for protecting the wrap from getting shredded by road debris.

 

Here's my incomplete solution,
I'm going to finish it tommorow by extending the heat shield that runs under the cab,

Will take some temps after driving around and likely pull off of relocate the clamp on heat shield depending what sort of temps the driveshaft and stuff along the drivers side frame is

 

OCD may be partially at work here.....

 

So , while all of this work may have been a moot point, I'm seeing a huge drop in temps of my fuel lines, TC module, parking brake cable, parking y split plate, brake lines and u joint with this setup.

Dropped temps by around 30-40%

 

^A different view of my reroute. Closest point is 4.5" from the actuator case, then the pipe angles away from the actuator as it runs to the passenger side. That's enough distance to avoid needing a heat shield.

 

I expressed my concern to the old guy at the front desk that has been doing exhaust's for probably 40+ years. He just chuckled and said "you have at least 3 or 4 fingers in between the transfer case and the re-routed pipe, you are fine." I can't discount his experience or anyone else's here that has not had any issues, so despite my misgivings, I am just leaving this one along and chalking it up to my paranoia/OCD.

 

Would like to make a heat shield like your where did you get the heat shield ? Or what should I type in to look for it? And did you buy and thread in some bolts to the transfer case or pull one out and reinstall it ?

 

I "think" i used the following
- Aviation tin snips
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$10 M8 x 20mm Flanged Hex Head Bolts Flange Hexagon Screws, Stainless Steel 18-8 (304), Plain Finish, 20 PCS

M8 x20 flange bolts, (I used existing, unoccupied, pre-tapped holes on the back of the Transfer Case)
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$23 Peastorm Exhaust Heat Shield Automotive Embossed Aluminum Heat Shield Muffler Exhaust Wrap, 15" x 39"

Embossed Aluminum Heat Shield Muffler Exhaust Wrap (I used this in two places)

- As an extension to the existing heat shielding to the left of the Transfer case, I slipped it behind the existing heat shield. It's held in place by two E-Brake line brackets (one shared with the existing heat shield)
- On the back of the Transfer Case. I created a model using a piece of heavy duty cardboard first to make sure it would fit and then used that as a template to cut out a piece, making sure that there was large enough drain hole at the lowest point for water and reasonably sized gravel. I used a tapered punch for the bolt holes
- crimped all of the edges over and lightly hammered them to prevent sharp burrs.​

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$40 Thermo-Tec 11650 1' X 4" Pipe Shield

Thermo-Tec 11650 1' X 4" Pipe Shield (Placed on the exhaust underneath the driveshaft U joint)
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$11 6mm - 1/4" Self adhesive Aluminum Heat Reflective Fiberglass Sleeving Side Entry High Temperature Protection for Hoses, Wire Harnesses, Exhaust 39"(1 Meter)

6mm - 1/4" Self Adhesive Aluminum Heat Reflective Fiberglass Sleeving (On the e-brake line in sections where it's now directly above the exhaust)

This brought the surface temp of everything down to something I'm more comfortable with for plastics, rubber and compound materials.

 

I tried to use some of the fiberglass exhaust header headshield wrap around the relocated section of pipe, but that was acting as a giant radiator and making surface temps much worse in the surrounding areas.

 

Thank you for this !