Billet Aluminum Thermostat Housing for 4.0L 1GR-FE

No such thing as a stupid question. But one thing is for sure, we all would be a lot more ignorant if we did chance being judged now and then. Most of these guys are pretty solid and enjoy helping. This even while enduring the redundancy of having answered the same questions over and over through the years. I know that I am indebted to the kindness of many here. The main thing to me is that we help when we can and enjoy the "Fellowship of the Taco!"

 

Unfortunately no it will not fit the 3.5L but we have that in the works as well!

 

We will be out running around at Hammers! I’ll have some housings with me!

 

I'll bring my old housing with me then.. maybe we'll run into each other.

 

Excellent! no rush but were here.

 

Is there a difference with the housing if you have the towing package? Rock Auto has a housing with and without the towing package.

 

Curious, those of you that installed the billet thermostat housing AND the 180*f high flow thermostat, if you run an oem radiator, what temps are you indicating on your Scangage?

I recently installed the new replacement billet housing with a 180*f high flow thermostat. Coolant is 50/50 and not old. Fully serviced coolant. Previously, with oem thermostat, Scangage would indicate a stable max temp of 190*f.
With the installed billet setup and 180*f high flow thermostat, idle temp is 193*f, around town lesser rpm indicates 195/197*f and at 60mph the temp runs at 199/200*f.

Concerned, I purchased a new Motorad 180*f high flow thermostat, installed and verified, temps were as I posted previously.
Messaged Cody but no reply.

Seems the high flow thermostat acts as a restriction to flow since when measured, the oem thermostat opening is larger than the Motorad 180*f high flow.

 

@1GR-FE<3R Any updates on a redesigned housing for the supercharged crowd? I don't currently have a SC but might add one in the future and I'd prefer to only buy this part once. Part can't be found on your website, and the eBay listing doesn't mention anything about fitting (or not fitting) SC applications. TIA!

 

Will say that this billet aluminum thermostat housing, while a nicely made part that fits well on non supercharged engines, caused increased operating temps of 10*f, using the 180*f high flow set up, compared to an oem thermostat and plastic housing.

The 10*f increased temps were local driving and no highway driving. So temps may have increased even more.

Coolant used is a 50/50 mix and not old, was replaced along with flushing of cooling system. Total miles is 92,000 since I bought it new.

Yesterday, ordered a new double row all aluminum radiator.

I suspect that Toyota had a pretty good engineering team design the oem cooling system to work as an assembly. Single row radiator, along with oversize thermostat, worked well. This billet setup with a smaller thermostat, just does not seem to have the capability to flow thru the thermostat adequately to cool as well as oem.

 

Noticing your comment about the Motorad. I don't have the billet housing but a few years ago I replaced the original thermostat with a Motorad from Rock Auto. The temp was originally 185F and with the Motorad it went to 195F.
I ordered a new Aisin thermostat and replaced the Motorad (RA gave me a refund) and the temp is back to 185F.

 

Thank you. Will consider that. Radiator is ordered. Even though oem has not failed, it is getting pretty up there in age.

Will report back, but not opposed to getting another brand thermostat if temps remain elevated. I did try a second new Motorad 180*f high flow, with the same results.

 

Installed new CSF radiator. Made no additional changes. For testing, reused the same coolant as has been run with the oem thermostat, the billet housing with the supplied 180*f high flow thermostat, and the billet housing running a second replacement 180*f high flow thermostat.

For my truck, the coolest operating temp, once up to normal temp, with oem radiator and oem thermostat and housing, was a stable 190*f as noted on the Scangage.
With the billet thermostat housing, with either 180*f high flow thermostat, the oem radiator or the newly installed CSF radiator, the temps fluctuate, typically 193/195 at idle, at part throttle 45 mph around town cruise is 195 /197, and higher steady speed of 60 mph 197 / 200.

All temp readings are via the permanently installed Scangage.

To summarize, on this truck, no supercharger installed, my opinion is the MotoRad thermostat is the likely suspect of why the temps are increased.

Have not yet decided a next step to bring temps back down to a stable 190*f.
Location is South Florida, not summer yet, but has been warm.

 

Ditch the billet thermostat housing and buy the Aisin thermostat assembly. AISIN THT003


BTW do you have a light bar installed just below the grill?

 

No light bar. That is an Avid Brush Guard most likely you are seeing.

Only non oem obstruction is the dedicated trans cooler. But that has been there for many years. No trans fluid runs thru the radiator. Oem trans cooler became a power steering fluid cooler.

 

Temps fluctuate while driving, 200 degs is not a big deal

 

Will reinstall the oem thermostat and housing that still functions fine, maintains 190*f max temp regardless and is stable at 190*f once warmed up.

That will offer up valid numbers regarding what is happening.

 

Had time today and drained coolant, then removed the billet thermostat housing with the Motorad 180*f thermostat.
Reinstalled my oem Toyota thermostat and plastic housing that has 92,000 miles on it.
Reserviced the coolant with the same coolant that was removed.

So, as expected, the temps indicated on the Scangage returned to the previous temp of 190*f max and stable.
The 190*f stable temp is 10*f cooler than common driving temp displayed with the billet setup.

Currently I will just shelve the billet aluminum housing setup. Not worth running 10*f hotter.

Want to also add, the oem thermostat design and engine housing utilizes a disc that blocks flow for control of the water flow. The Motorad thermostat does not have that provision. Not knowing the water flow path, it may or may not be having an effect on controlling temps.

 

Finally had time to research why my engine ran hotter and with fluctuating temps when the billet housing and Motorad high flow 180*f thermostat is installed (actually tried two thermostats with the same results).
These 1GR engines utilize a Double Valve type thermostat as oem. The disc diameter at the end of the thermostat is important, as is the discs location and travel when going from cold to 180*f.

Explaining, when the engine is cold, the actual thermostat is closed, and the disc has the water bypass port uncovered. This allows the engine to warm up quickly by recirculating coolant without sending any to the radiator.
As the engine temp gets to 180*f, the thermostat opens while at the same time closing off the bypass port. This allows water to flow from the engine to the radiator, and back to the engine.

If the bypass port is not capable to be closed, heated coolant circulates back thru the engine without being cooled in the radiator.

The oem thermostat has a much larger disc to block flow as needed, sending coolant to the radiator. The Motorad thermostat had a smaller diameter disc and is not capable to block the flow as needed.

This explains why my truck ran temps that were fine at idle, yet as rpm and load increased, the temps ran 10*f hotter than the oem thermostat at 60 mph cruise on flat highway. Simply, a portion of the engines heated coolant was being recirculated back into the water pump / engine without passing thru the radiator.

Reinstalling the oem plastic housing and thermostat restored the temps as they were.

Note in the photo, the difference between the two Double Valve thermostats. The Motorad has the smaller disc on the end, while oem has the larger disc, capable of correctly controlling heated water flow in the system.

All the best to those using this well machined part. Mine sits removed and on the workbench. Not worth having localized overheating within the engine.

 

I've been battling borderline over heating issues on my last couple of trips. While climbing my temps have been over 230, hot enough to where my OEM needle was getting close to H. My transmission temp hit 250 this weekend on a climb in 97 degree weather with my engine temp over 230 (can't remember the exact engine temp because I was so focused on the trans temp). I've been thinking about billet radiator, upgraded trans cooler, pusher fan etc... but in the back of my mind I've been wondering if this billet thermostat might be the issue. The problem is that right after I put it in I switched to 35s so I thought the increased load must be the problem. @PMK post is definitely making me switch back to OEM to see if that solves it.

 

Swap back, and see if there are changes.