Alternative Hi-Flow T-stats for the 2LTE? 3RZFE maybe?

[GTSSportCoupe]

Did a bit of aftermarket parts crossing for the 3RZFE t-stats. These don't appear (from web pics) to have rubber in the opening part, which I believe allows more flow. All are 56mm diameter so need to be turned (lathe) or ground down to 52mm to fit properly.

Opening diameter similar to a Tridon Hi-Flo for 2LTE: Beck Arnley 143-0720 Moto rad 298-180

Massive opening diameter - may not work at all or possibly could work with housing modification: Stant 14108 Gates 33798

 

[Nas90tdi]

Agreed on the Tridon. I am running one now, but I no longer trust them. The one that failed on me would only open max about 3 MM at full expansion. I caught it immediately so, it didn't do any more damage to my already cracked head. But, had I not been right down the road from my house and not been watching the gauge it would have certainly cooked my motor.

 

[GTSSportCoupe]

Agreed on the Tridon. I am running one now, but I no longer trust them. The one that failed on me would only open max about 3 MM at full expansion. I caught it immediately so, it didn't do any more damage to my already cracked head. But, had I not been right down the road from my house and not been watching the gauge it would have certainly cooked my motor.

After focusing on these things for a couple days earlier this week I came to visually recognize the attributes of the better quality ones. Tridon is definitely low on the quality scale. Look for ones with heavier gauge springs and a deeper spring basket.

I'll be swapping my Tridon out anyday now for the 3RZFE one I modified to 52mm on the lathe. Just need time.... I'm pretty excited.

I've been looking for smaller water pump pulleys now.... To over drive the pump just a tad for more flow. Just need to find the 'right' one. Something like this: FJ40 Water Pump Pulley - F & 2F Engine (2 Groove - SWP) Might go so far as to make one from scratch.

 

[GTSSportCoupe]

Popped in the 3RZFE t-stat yesterday evening. I measured the inside width of the housing and it was close to 48mm wide. So I don't think we can put the larger opening version of the 3RZFE t-stat in the stock housing (as per my earlier experience - the opening component of that one is so wide coolant would have a hard time getting around it in the housing.).

I also measured the depth from the center of the t-stat rubber gasket to the bypass opening in the housing. It's about 42mm. Recall I measured the 3RZFE fully open to be about 44mm. So this means the t-stat will close off the bypass a bit earlier, and not open as much as it potentiality could. Although I think in reality it'll just compress the rubber gasket as it expands; and still open nearly all the way. It'll actually put a little more pressure on the bypass opening...which I feel is a good thing.

So initial thoughts? This t-stat is a whole different beast!! I'm very excited to see how it performs on a hot day with the truck under load. Although it's a 82C t-stat, the temp gauge sits rock solid lower than with my previous (and pretty new) 82C Tridon. And interestingly, in a pot on the stove the 3RZFE didn't even start opening until 82C. So that tells me I'm getting much more effective flow already. Downside is I may loose a bit of efficiency running cooler.

I'll try to do a run up one of the big long highway hills near me this weekend and report back. Also, I'm towing the following weekend, so that will be the real test!

I'm very happy so far!

Another thing I noticed with my Tridons; they both say 'moto-rad' inside of them; so thats who makes them in case anyone was curious.

Pic from this morning:

 

[GTSSportCoupe]

Hooked up the trailer and went for a tow up a long steep highway grade yesterday. Ambient temperature was only around 17C (63F).

The 3RZFE t-stat behaved exactly like a good condition Tridon. I was hoping for better, but that was a bit unrealistic (in retrospect) as the opening diameter/distance is basically the same as the Tridon. Anyhow, at least we know the 3RZFE is a good option for the motor. Gives more part options, and higher quality options than the Tridon.

Still trying to get my hands on a spare t-stat housing, and I can try some other ideas. Maybe revisit the huge opening 3RZFE t-stat version or the 1KZTE one that ATEB (Vancouver shop) was using.

I am beginning to wonder if the build up of heat is in the cast iron of the head and the coolant temp is just reflecting that fact though. If this is the case, improving the t-stat diameter beyond a point may not help much. Heat in the cast iron would make sense given the slow steady build of heat going up a long grade, and the couple minutes it takes to cool down once cresting a summit. If it was just the coolant in the head holding the heat, I think it would heat up faster and cool faster than what I've seen.

Part of what is bringing me to this conclusion ^^ is I remembered that all Toyota IDI turbo motors have this same heat problem no matter what thermostat they have. Lots of complaints of turbo 1HZ's getting hot when towing. Same with 1KZTE, and 3B turbo's too. All those motors have MUCH bigger thermostats and they still get hot. It all comes back to having a pre-combustion chamber in the cylinder head, and the heat loss that comes from that.

Anyhow, I still believe Evan's coolant is the best option to truly protect these motors. It keeps the head temp more even, and will continue to effectively carry heat away even when temps get high (where water could start leading to super heating in the head around pre-cups because of localized vapor barrier).

Here is a picture from yesterday afternoon showing factory gauge after cresting a summit while towing. This is about how things always are when I've towed up a long hill. (Factory gauge never goes over half when I'm not towing BTW.) What's really nuts is I've done this multiple times every summer for the past 8 years and not cracked the cylinder head. I chalk it up to the Evans.

I never got around to installing an aftermarket temp gauge, but I think this temp is around 100-110C or so.

 

[GTSSportCoupe]

Also, I should mention now that I figured out Tridon are made by Moto-rad, I also figured out the Moto-rad part number is pretty much the same; just take the Tridon numbers without the letters, and search with 'Moto-rad'.

So for example, I recently bought a Tridon Hi-flow 180F (82C) t-stat. The Tridon part number is TT2322-180. The MotoRad part number is just 2322-180. For those that want to run these, just buy the Motorad version and save yourself some money and shipping. Incidentally, this t-stat is also used for the Mazda RX7 with the 13B rotary engine. Maybe I should look for a racing t-stat for that motor and try it in the 2LTE, haha.

 

[GTSSportCoupe]

So, for one last kick at the can, here is what I think I might do. I'm going to thread the bypass hole in the t-stat housing. I'm going to install a brass plug into it. Then I'm going to remove the t-stat completely, and try towing again. If the motor gets just as hot, I know the t-stat is not the problem. If the motor runs much cooler, I know we're onto something in looking for a higher-flow t-stat.

 

[John in Utah]

I get my last thermostats in tonight so I will have some updates very soon. I’ve already done some initial flow testing using a 2lte housing and stock stat with some interesting results, but I’ll save that for when I have all the data to share. Hopefully one of the two 3rzfe units I got is the oversized one.

@GTSSportCoupe you are welcome to Have my housing once I finish my tests

EDIT: just saw your last post, for what it’s worth I’ve found a roughy 55% flow rate increase between empty housing (bypass blocked) and stock tstat in the full open position

 

[GTSSportCoupe]

EDIT: just saw your last post, for what it’s worth I’ve found a roughy 55% flow rate increase between empty housing (bypass blocked) and stock tstat in the full open position

Hey John, that is very interesting; thanks. Not as much difference in flow as I would have thought actually.

Thanks for the offer of the t-stat housing. I have a couple lines on local ones, so should be ok...

 

[John in Utah]

I received a handful of thermostats today for various toyota engines and years - based on the ideas in this thread and others I picked up the stock 2LTE stat (most of us are probably running), a later 2LTE/5L version, and what I thought would be two 3rzfe variations. Unfortunately the 9091603101 isn't available in a red TEQ box that I could find, and the Taiho brand I ordered is identical to a Toyota 9091603120. I also grabbed a 2TRFE unit that would have come from a 2nd gen taco, and just for the hell of it a 2UZFE one as well.

Here are the initial measurements from the collection of thermostats. You can see the stock flange diameter is 52mm but I found the 56mm diameter thermostats to fit in the housing very snuggly without modification. Based on orifice diameter alone the 2TRFE stat looks the most promising, I was worried the additional height on the 3rz stat would keep it from opening fully compared to the 5LE part, but upon closer inspection the bypass block off plate on the 3RZ and 2LTE parts is stepped (so it nests in the bypass hole) vs the flat plate on the 2TRFE part - so the 3RZ stat actually extends a similar amount as the 2TRFE. Hard to tell from the photo but the 5LE and 2LTE thermostats are visually identical. Its interesting that the 5LE part was the only one to come with a rubber grommet around the flange - I did an informal test of leak rate without the grommet installed on a closed thermostat and there is a slow trickle of water out of the outlet, but not enough to keep the engine from warming up normally (I assume).

PARTS SUMMARY
Part Number	Engine	Chassis	temp (C)	Flange dia (mm)	orifice (mm)	height (mm)
163405010	5L/5LE	LN1205	88	52	32	60
9091603099	2lte/3L	LN106	88	52	32	60
9091603120	3rzfe	RZN200	82	56	34	65.5
9091603093	2trfe	TGN11	82	56	36	60
9091603100	2uzfe	UZN210	82	64	42	69

I got this water outlet housing in a box of 2LTE parts I picked up when I did the oil cooler swap on my 3L. I plugged it up the best I could with old hose and misc bolts and plugs.

Then I bolted the housing to the bottom of a 5 gal bucket. There is a hole in the bottom of the bucket that roughly matches the housing port where it bolts to the cylinder head. I did not include the bypass in this hole.

The test stand is far from perfect, but I made an effort to keep everything equal between tests. Leak rate from the misc housing holes and where it bolts to the bucket are pretty minor, and nothing to worry about since the rate should be consistent the whole time. The goal was to establish a baseline using the empty housing (simulating running the engine without a thermostat and with no radiator bypass). Then the baseline can be used to compare flows between thermostat part numbers - specific volumetric flowrates are not of interest here since we really only care about how good one thermostat is compared to another.

The crux of the thing was figuring out how to run cold water through a thermostat that's only supposed to be open at boiling temp. It took some trial and error but I finally found a suitable method of shimming the thermostat with some cross sections of PVC. I used a butane torch to heat the stats since I can't get water to boil above 93 C here. A couple interesting conclusions already cropping up here:

• Too much heat and the thermostat won't want to close fully again when cold, I think due to spring deformation. So be warned about heating them up this way for testing and then using them
• Every one I heated with a torch got far more open than the physical housing geometry would allow, making me wonder why toyota wouldn't design a deeper housing to increase flow range? Might be possible to drill out the bypass hole deeper to allow for more movement.
• The 3RZ part responded far faster than any other I heated. Note that I didn't control the heating process and just held the stat just out of the flame of my torch. The 2TRFE was the slowest to respond.

Messing with the shim to get the height of the thermostat just right - you can see here what I mean when I say they will open much wider than the housing will allow:

Alright, so that's all fine and great but it really means nothing without some data, so here you go:

FLOW TESTS
	Empty housing	2LTE	5LE	3RZFE	2TRFE
Test 1	19.15	28.36	28.65	28.88	32.9
Test 2	18.85	28.5	28.03	28.03	32.6
Test 3	18.65	28.53	28	28.09	32.56
Test 4	18.75	27.9	28.13	27.5	34.43
Test 5	18.6	28.72	27.99	27.63	34.32
Avg	18.8	28.402	28.16	28.026	33.362
Normalized	1	0.66	0.67	0.67	0.56

I ran each test 5 times and averaged the results. The values are representing the seconds it takes for the housing to discharge a given amount of water out of the bucket. I filled the bucket to the same point each time before pulling the cap off the outlet and starting the timer. I stopped the timer when the water reached another, lower level. Volume is arbitrary as long as it is the same each time. I filled the bucket most of the way up for my starting mark and let it drain almost completely for my ending mark, in an attempt to add as much resolution to the results as possible. I normalized the average time in seconds using the empty housing as a baseline, so flow through the housing becomes 1 and each thermostat tested is a fraction between 0 and 1, where the closer the thermostat's value is to 1 the closer it is to being "perfect". Needless to say but the 2UZFE thermostat will not fit without significant mods to the stat and the housing, and even then I doubt it would even be able to open once bolted down inside.

Well it's not hard to see that I really didn't discover anything groundbreaking. The 2LTE, 5LE, and 3RZ stats all performed close enough as to make no difference. The 2TRFE, which looked so good based on initial measurements, didn't perform nearly as well as the others (though I'd still venture a bet that it doesn't make a noticeable difference in the truck). In reality the cylinder head is full of small passages and constrictions that surely limit flow well beyond what an empty thermostat housing is capable of - and I imagine the toyota engineers knew this.However I am anxiously awaiting any testing others do with the thermostat removed entirely - I'd love to be proved wrong!

At the end of it all I will most likely run the 3RZFE stat like the one @GTSSportCoupe has already installed and tested, if only to get an 82 instead of an 88 opening temp. And because I believe the temperature response to be quicker than others I tested.

 

[GTSSportCoupe]

Well, there you have it! Nice job @John in Utah . Thank-you for doing this. Can't argue with data!

I think my testing pretty much agrees with what you've found. I was hoping for a miracle from the 3RZ t-stat, but not so much.

I do really like your idea of increasing depth of the bypass hole to match a t-stat that opens more. This might be more effective than a wider opening in a t-stat. I may pursue this at some point. This could work for a 1KZ sized t-stat.

One thought I still have. Does running one of the t-stats without the rubber seal in the opening part give it more flow?

Also, I used a die grinder to remove those bumps of aluminum in the t-stat housing just behind the t-stat in my truck. In an effort to unrestrict flow a bit. Not sure it helped or not.

 

[John in Utah]

I can try all that. I will see if I can pry the rubber seal out and at least do the 3rz and 2lte stats again.

Interesting that I don’t remember those bumps being in my 3L housing. I might try porting the housing once I do the tests without the seal. I can also attempt to drill out the bypass hole, but it looks like it makes a hard 90 so I might not be able to go much farther.

Thinking about this more it would be really helpful to have a temperature reading at the lower radiator hose. I think this would help us quantify the question of if the head is truly unable to transfer all of its heat to the coolant. If the lower water temp doesn’t rise proportionally to the temp of the water exiting the the head I think that would indicate the problem isn’t as simple as cooling capacity.

 

[GTSSportCoupe]

I can try all that. I will see if I can pry the rubber seal out and at least do the 3rz and 2lte stats again.

Interesting that I don’t remember those bumps being in my 3L housing. I might try porting the housing once I do the tests without the seal. I can also attempt to drill out the bypass hole, but it looks like it makes a hard 90 so I might not be able to go much farther.

Thinking about this more it would be really helpful to have a temperature reading at the lower radiator hose. I think this would help us quantify the question of if the head is truly unable to transfer all of its heat to the coolant. If the lower water temp doesn’t rise proportionally to the temp of the water exiting the the head I think that would indicate the problem isn’t as simple as cooling capacity.

I agree, monitoring more on the engine would really allow a better understanding of the problem. I was day dreaming of running a half dozen or more thermocouples to a temperature logger while I go on a hard tow sometime. Could monitor several points in the cooling system at once, and I'm sure it would tell a story.

Another big factor for some of us is how much heat the auto trans dumps into the coolant. The trans cooler is right at the bottom of the rad, and would heat the coolant up right before it returns to the engine. I know when I'm towing I try as hard as I can to keep it in 3rd lock-up as long as possible. When it drops to 2nd and out of lock-up, it has quite a noticeable impact on coolant temps. There is a manual trans LJ78 for sale near me right now...I must say I have been a bit tempted.

 

[GTSSportCoupe]

At the end of it all I will most likely run the 3RZFE stat like the one @GTSSportCoupe has already installed and tested, if only to get an 82 instead of an 88 opening temp. And because I believe the temperature response to be quicker than others I tested.

Hey John. I did a bit of part searching this morning, and found that one of the newest 2LTE/2LT/3L/5L/5LE thermostats that Toyota has made (and is still using in current models like the LJ150) is an 82C t-stat. Every other L series t-stat I could find was 88C Anyhow, the 82C one is part number: 16340-54040 . It might be one of the best factory fit early opening OEM options out there... So temperature response would be probably the same as the 3RZFE one.

 

[GTSSportCoupe]

Also, I found a picture of what the ATEB shop used to do. They swore this was the fix for the 2LTE heat problem. They added a spacer to the t-stat housing, and installed a 1KZTE t-stat. Presumably it opens a lot more and allows more flow - and the spacer is the key to allowing this.. I believe they open at a much lower temperature too.

 

[John in Utah]

I agree, monitoring more on the engine would really allow a better understanding of the problem. I was day dreaming of running a half dozen or more thermocouples to a temperature logger while I go on a hard tow sometime. Could monitor several points in the cooling system at once, and I'm sure it would tell a story.

Another big factor for some of us is how much heat the auto trans dumps into the coolant. The trans cooler is right at the bottom of the rad, and would heat the coolant up right before it returns to the engine. I know when I'm towing I try as hard as I can to keep it in 3rd lock-up as long as possible. When it drops to 2nd and out of lock-up, it has quite a noticeable impact on coolant temps. There is a manual trans LJ78 for sale near me right now...I must say I have been a bit tempted.

It still amazes me what you cruiser guys can put that engine through and still maintain decent water temps. I can barely get my truck to stay below 100 degrees up a grade and that’s with a lighter chassis and manual trans, not to mention without more fuel, boost, towing, inferior coolant, etc.

I do believe the hilux/surf LN series has a cooling capacity / airflow problem - on top of the same engine issues the LJs face - and if I can remedy that I will finally feel comfortable jumping to Evans. But that’s a whole other discussion.

I think I will tap my new radiator for a lower (output) temp sender to help add context to the thermostat discussion. They’re cheap enough and I would be able to repurpose it for exploring IAT and oil temp later on. I’ve always wondered how much heat the CT20 adds to the oil when running it without the water lines.

Doesnt the 1KZTE thermostat sit at the water inlet to the engine and that’s why the temp is so much lower? 71 degrees I think, 90916-03121. Shouldn’t be hard to make that spacer but I’m not sure running the engine that cold is desirable

 

[GTSSportCoupe]

It still amazes me what you cruiser guys can put that engine through and still maintain decent water temps. I can barely get my truck to stay below 100 degrees up a grade and that’s with a lighter chassis and manual trans, not to mention without more fuel, boost, towing, inferior coolant, etc.

I do believe the hilux/surf LN series has a cooling capacity / airflow problem - on top of the same engine issues the LJs face - and if I can remedy that I will finally feel comfortable jumping to Evans. But that’s a whole other discussion.

I think I will tap my new radiator for a lower (output) temp sender to help add context to the thermostat discussion. They’re cheap enough and I would be able to repurpose it for exploring IAT and oil temp later on. I’ve always wondered how much heat the CT20 adds to the oil when running it without the water lines.

Doesnt the 1KZTE thermostat sit at the water inlet to the engine and that’s why the temp is so much lower? 71 degrees I think, 90916-03121. Shouldn’t be hard to make that spacer but I’m not sure running the engine that cold is desirable

I just looked at the rad core size of an LN106 vs LJ78, and they're very similar. LN106 is 508x472x48mm. LJ78 is 524x480x48mm. Although some LJ's I've seen have up to a 54mm core - but maybe were upgraded in Japan before they came over.

I'm surprised an LN106 would have a hard time cooling being its not turbocharged. Have you serviced your fan hub with new silicone oil? I found that made one of the largest differences for me. Do the LN106's have a decent fan size? A/C condensor in the way of the rad? Is your rad clean and in good shape?

Yes, you're right about the 1KZTE t-stat being at the coolant return location. I think a lot of efficiency would be lost running that cool in the L series outlet location.

 

[John in Utah]

I’ve been through everything pretty thoroughly, including the hub and bigger 5L fan, but you can’t fit a cruiser size fan in there as far as I know. AC blocks most of the upper rad and of course mine has a big Australian roo bumper on it so that doesn’t help. I should have mentioned I didn’t see any issues before I put a turbo on, but my fuel has stayed the same and I’m only running 7 psi. My factory gauge is pretty much static between 75 and 95 degrees, so I’m not sure what fluctuation I saw before adding an aftermarket gauge (which went on with the turbo) This is also what makes me question the oil temp post turbo and how that impacts coolant. My new rad core is 50mm so we’ll see how that does.

If you can test your truck and see improvement with the empty thermostat housing and the bypass plugged it might be worth it to make a spacer for the 3rz thermostat so it could open farther.

 

[GTSSportCoupe]

I’ve been through everything pretty thoroughly, including the hub and bigger 5L fan, but you can’t fit a cruiser size fan in there as far as I know. AC blocks most of the upper rad and of course mine has a big Australian roo bumper on it so that doesn’t help. I should have mentioned I didn’t see any issues before I put a turbo on, but my fuel has stayed the same and I’m only running 7 psi. My factory gauge is pretty much static between 75 and 95 degrees, so I’m not sure what fluctuation I saw before adding an aftermarket gauge (which went on with the turbo) This is also what makes me question the oil temp post turbo and how that impacts coolant. My new rad core is 50mm so we’ll see how that does.

If you can test your truck and see improvement with the empty thermostat housing and the bypass plugged it might be worth it to make a spacer for the 3rz thermostat so it could open farther.

Ah, right, I forgot you had added a turbo; they do add a lot of heat. Also, you're right about the factory gauges in the Hilux's; they have quite a big dead spot. Here is what some people do to fix that (doesn't matter for you as you already have an aftermarket gauge): Temp Gauge Mod My temp gauge in the LJ78 doesn't have a dead spot; it's very linear as the motor heats up - much like the pictures on the right side at that link.

I have a lot of crap in front of my rad too. A/C, intercooler and aux trans cooler. I managed to design my bumper to still allow decent air flow.

These motors do have piston oil squirters (coolers). So yes, when the pistons heat up, it will most certainly be wicked away by engine oil - then picked up by coolant. Might be less substantial than a direct injection diesel would see though?

One interesting thing I just remembered about these motors. When the heads crack, the rear most cylinder four is always the worst. It gets progressively better toward the front of the motor; often with cylinder one not being cracked at all. This means the rear cylinders likely run much hotter on average. Maybe because they're not getting enough coolant movement past them?? Again pointing to flow issues.

Picture from the manual:

 

[mattimooseprime]

Is there a water port anywhere on the head in the rear that's blocked off?

Cummins 6bt's suffer from the same rear cylinder heat issue and to solve this in my current engine swap, and a family members dodge, I moved the heater inlet hose to the rear-most head water port. I just took the plug out of it and installed a brass nipple for the hose, and put the plug up front where it no longer needed to come from.

that would certainly help move some hot water out of the rear of the engine, and may assist with cooler overall temps? Might even make the heater work better!