Gen 4 into Gen 3 swap fail

This is engine coolant circuit? I'll attach both.

4th gen into 3rd engine swaps do seem to have overheating problems a lot. Something in the plumbing revisions is not working well? @Ragingfit says "cut the jiggle pin" IIRC, which is a little node on the thermostat? With my very vague comprehension, this seems like a work around, probably prolongs warm up, but maybe it works.

 

I did this swap ran into your issues.

1.make the engine look as much as possible liek the gen 3
I cut the lower mounting bracket on the EGR cooler and let the four bolts do the holding 2 on the exhaust and ttow on the intake is all yo need.

2.get the American version of the outlet for the head get rid of all the other plumbing it is of no use as your car does not know how to use it and plug the hole on the front of the engine with ahose and bold, I did.

3.cut the jigle pin on the thermostat trust me. overheating will occur, this is how I handled it. side note yo may need to bend slightly the egr cooler throttle body line so hoses dont rub. in adition I grinded off about quarter inch off the egr mount so it dont rub and short the temp senor.

4. filling and burping procedure. connect a see through hose to the bleeder valve if you have one on top by the egr cooler if you dont have one get one add it as toyota I suspect removed it to force you to go to them to install a pump or coolant. now open the valve and fill the coolant till it comes out of the bleeder valve as it is the highest point close valve. run the engine and monitor it. Monitor and if it get to 203 turn it OFF EMEDIATELY better to be super safe than sorry. run the engine if you have a gauge to see the temp let it get to 185 to 195 and open the bleeder till all the air bubles come out. drive the car around the block have the AC on as it will run the fans and ensure your car does not over heat. rinse repeat. park the car ALWAYS HAVE THE RESERVIOUR CAP ON WHEN YOU OPEN THE BLEEDER ELSE YOU WILL SUCK AIR BACK IN from the return hose. IN ADDITOIN HAVE A HOSE CLAMP WHEN BLEEDING i FOUnd THIS HELPED FROM SUCKING AIR BACK IN FROM THE RESERVIOUR TANK. SEE PIC i WILL POST LATER. it took me 10 time doing this to finaly
feel all air is out. warm up car to 185 to 195 bleed air. for some reason there will always be bulbes in the system. but a sure fire way to know if the system is good as in my case is car normal temp is 190 to 195 and will flux up to 197 to 201ish maybe 203. Fans will kick in after temp is at 203 for at least five seconds. then should go down with in like ten seconds. if it goes above 203 pull over shutdown car turn on AC and let it cool. be safe not sorry as these pumps cost 300 and up. once you get your car to 190 to 195 and never over 203 you are good. to go.

 

@C-in-DC having a 2010, he probably does have the bleed valve. I would think if you don't just pulling off one hose right there where the bleed valve was, you achieve the same as putting in an aftermarket bleed valve: you're basically letting air escape as you pour in coolant. Just disconnecting a hose and pouring coolant till it comes out is a little messier, that's all.

 

Besides that, Toyota already seems to have decided that their degas-bottle cooling system does well enough what they designed it to do even without a bleed valve. I wondered, and Elektroingenieur confirmed, that when they dropped the bleed valve, they did not add any other instruction to the repair manual for pulling a hose or any such thing. They simply dropped the reference to the bleed valve (and also the reference to draining from the stopcock on the back of the block, which usually gave you about a tablespoon of coolant after you'd contorted your arm nine different ways to reach it).

They left the instructions to simply fill to the B line and let the system swap the air for the extra coolant as it was built to do.

If a lot of people doing this mod are seeing overheating issues and cutting the jiggle pin as a workaround, that makes me wonder if the bypass loop is somehow not doing its job, maybe because of plumbing differences between the generations that haven't been properly accounted for.

The thermostat does need to see some hot coolant go by, in order to detect the temperature and open. That chicken-egg problem is supposed to be solved by the bypass loop—the paths that include the heater core, EHRS, EGR cooler, and throttle body, but not the radiator, and return to the smaller bypass nipple on the inlet elbow, the one the thermostat doesn't block off when closed.

That bypass function isn't supposed to be the jiggle pin's job. The pin's really just there to give air a place to go while you're filling and bleeding, but after that the water pressure's supposed to hold it closed. If it ends up being critical in normal engine operation, something else somewhere isn't right.

 

yes but you cant do this while you bleed hot coolant.

 

Ok so here are the pics.
1.see the bleeder and bubles do that about ten times stop to drive car around the block each time.
2.cap the inlet at the timing chain cover I used old hose and a bolt.
3.remove gen 4 stuff and replace with stock gen 3 including grinding off part of the EGR pat that sits on top off temp sensor.
also grind off the bracket on egr just use the front and back bolts for intake and exhaust manifold been like this for a year no problems.
4.when bleeding use a clamp , keeps air from being sucked back in. reach out to me I can explain process furhter.
5.if you are stuck with what you got then punch a hole in the grey thingy as you can see has major restriction causing air to be trapped and flow to be low end result overheat.
6 in addition I grinded off 2 MM from the white plastic part of the temp sensor keeping it flat also the connector has a yellow spacer remove it and it will give you and additional 3 MM for connector to go down and not touch EGR. Sorry no pic

 

^ @johnnychimpo there's duplicate, maybe even triplicate, in the above. Have a look? Appreciate the pics.

 

I should have taken a pic but just wanted my car up and running but on the Gen 4 there are zigzag plates in the cooling jacket that may cause the plumbing issue you speak off. kinda like this.

 

Those are internal to the engine though. They may qualify as a difference in plumbing, but not the kind that would explain this apparently-common overheating problem that people are running into after putting Gen 4 engines in Gen 3 cars (and trying to solve by cutting jiggle pins, which strikes me as grasping at straws).

The Gen 3 engines didn't overheat in the Gen 3 cars. And the Gen 4 engines didn't overheat in the Gen 4 cars (even if they had baffles in their water jackets). Nobody had to dig out any of their thermostats and cut jiggle pins. But it sounds like people keep putting a Gen 4 engine in a Gen 3 car, and fudging the external plumbing and hoses in whatever way seems to make the number of hose ends match the number of nipples, and boom, the thing persistently overheats. It doesn't seem to be just one or two people's bad luck.

I'm suspecting the bypass path—the one that goes from the cylinder head water outlet, involves the heater core, EHRS, EGR cooler, and throttle body, and returns to the thermostat elbow through the smaller, bypass nipple, which is never closed by the thermostat. That is how the thermostat is able to see the temperature of flowing coolant while it is still closed, so it can open as that temperature goes up.

There were several changes between Gen 3 and Gen 4 in the plumbing of that path: what water outlet connections are on the cylinder head, where the EGR cooler comes in the sequence, whether it also does tee duty before and after the EHRS, whether the EHRS supply pipe has a tee coming off, and those are the ones I'm thinking of offhand.

It doesn't help that a lot of people seem to be getting JDM Gen 4 engines that come with the electric flow shutting valve, which apparently is shut, without a Gen 4 ECM telling it to be open. In a Gen 4, that doesn't cut off the bypass flow, because there's that other pipe coming around the engine from the timing cover. But if that's been blocked off with a bolt and the flow shutting valve is shut, that's a problem. (Drilling out the shutting valve is one way to attack the problem, but probably better to just buy the US version of the water outlet fitting, the one that doesn't have the shutting valve.)

I was also wondering if there could be any difference in the thermostat elbow, maybe in the size of the bypass nipple's passage, but it looks like that elbow has the same part number.

 

IF you swap from gen 3 to gen 4 I advise get the engine as native as possible IE make it gen 3 as best you can replace what you can to make it stock idealy the return outlet get rid of the electric valve thing. then cut the jigle pin, just do it, dont risk a $300 water pump.
Then bleed cooling system repeat till the engine never goes above 203 that is the limit in my eyes. if it goes above 203 there is still enough air in the loop to cause an over heat. Please stress test your car once you think you got it dialed in get on the freeway use power mode crank the heat get the car up to 195F turn off the heat and step on it. get the rpm to 2800 ish if your car can keep it bellow 203 you are good as I did this and mine went up to 204 then 207 208 and came back down. Impellers start to warp at 208 then degrade due to imbalance caused by the warp causing car to reach 208 and above with more frequency until failure and you wont know cause high temp light wont go on till its too late till you get a premature failure. in these swap if your car goes between 203 and 208 in normal conditions you have air in the loop and may get caught on a hot day in heavy traffice overheating.

 

A native Gen 3, of course, doesn't have its jiggle pin cut. So I might go further and say, if you do cut the jiggle pin to get it not to overheat, then maybe don't consider it "dialed in" until after figuring out why it was overheating really, and getting it to where you can put an intact thermostat back in and it still doesn't overheat.

 

I've only did a few hundred coolant changes so I'm no expert.
I've changed the engine coolant and inverter coolant 3 times and never had a problem.
But I found the biggest problem is the system is filled to quickly.
It take me about 10 minutes to fill the engine coolant. Pouring VERY slowly, and only about
1 quart at a time. Once the overflow tank starts filling up, I squeeze the hoses several times.
When the coolant level goes down, I fill slowly again, and squeeze the hoses again.
When the coolant no longer goes does, I fill to the "B" mark. I leave the pressure cap off and
start the car. I let the car run until it turns off. Usually about a minute give or take.
I let it sit, and put all the tools away and clean up.
Then I drive the car around the block, about .7 miles. When I check it in the morning, it's just above
the seam on the tank. And stays there until I change it.