2jz swap slowly overheating

[Deofol]

Hi everyone,

I'm in the process of trying to acquire Craig’s 2zj swap '89 supra.

http://www.supramania.com/forums/showthread.php?t=69381

As it looks now I'm going to have to find a way to ship it to me, or find someone with a trailer and trailer it back to Dallas.

As some of you may have know, Craig did this swap and then took a job in Dubai. He isn't able to do anymore work on the car, and as far as I know from talking with him the swap is pretty much done, and the car is running pretty good. It just needs a tune (maf T pro). There is one problem we have run into though.

Basically, the car slowly overheats at highway speed/cruising. I was told that tooling around under 45-50mph, everything seems to run normal, however once you hit the freeway and stay at a sustained speed the needle slowly climbs. So driving back from Houston isn't an option.

Currently it is running the stock radiator (7M), and Craig believes all it needs is an aftermarket radiator to keep the temps normalized. Unfortunately he has left for Dubai now, so I'm stuck trying to figure out what to do.

Does anyone have experience with this swap, and does a simple radiator seem like the easy fix. It looks like a great deal, and this will be my first MKIII, so I'm very excited about the work already done. But also am a little nervous trucking the car back here not knowing exactly what I'm getting into. lol. :1zhelp:

Any advice or ideas are welcomed please.

Thanks in advance!
Billy

 

[WhtMa71]

From the looks of it, it does not have a fan shroud. Id probably try to address that situation first as a fan shroud is needed for the cooling system to work properly. Or you could try your luck with some e-fans.

 

[tlo86]

i had a brand new radiator on mine (GTE swap) and it cools just fine, i also have the clutch fan and shroud.

it could be possible if he has his old radiator still its all gunked up, to which it can be cleaned. did he throw a new thermostat in? might have a BHG too if he didnt put the Gte headgasket on right

 

[Deofol]

Not sure about the thermostat. I do know that he replaced the headgasket. "full gasket set, stock TT 1.3mm headgasket and ARP studs". I imagine he did everything right there, seems like the build thread he put a lot of effort into doing everything right, and not rushed.

I guess it's just tweaking everything out. The car doesn't have hardly any miles since the rebuild. Like less than 100.

I did ask about the fan shroud, and apearently the 2JZ fan didn't line up like the 7M, so the shroud had to be removed. So I'm not sure if its better to go with a electric fan setup or try and tweak the existing shroud.

Without having the car in front of me, I guess I'm SOL. I'm looking for a way to ship the car now.

 

[Marotta1]

The fan shroud shouldn't really be an issue at higher speeds because you would have so much air running through the radiator your not depending on the fan.

Just to get the car home, you might want to try taking out the thermostat. It should run cooler that way. Also if you ran straight water that would cool better. It has better thermal transfer properties. Just make sure it doesn't have BHG.

 

[tlo86]

the shroud doesnt fit right?

mine fit fine and there is less room to work with on a gte. and it should fit even better because it should be an N/A fan that is closer to the block as my gte fan is closer to the radiator.

when you receive it i would get the BHG tester just incase. i would also replace the radiator, or at least clean it and flush with new coolant. i wouldnt run a/c either on the trip

 

[tlo86]

The fan shroud shouldn't really be an issue at higher speeds because you would have so much air running through the radiator your not depending on the fan.

Just to get the car home, you might want to try taking out the thermostat. It should run cooler that way. Also if you ran straight water that would cool better. It has better thermal transfer properties. Just make sure it doesn't have BHG.

i was thinking the straight distilled water too just for the trip heh, liek a quick clean and pour

 

[suprastanger507mgte]

i had a brand new radiator on mine (GTE swap) and it cools just fine, i also have the clutch fan and shroud.

it could be possible if he has his old radiator still its all gunked up, to which it can be cleaned. did he throw a new thermostat in? might have a BHG too if he didnt put the Gte headgasket on right

I would have to say a gunked a up radiator too. Fan shrouod will defintiley help as well.

 

[HommerSimpson]

At highway speed its over heating...?
Radiator is pluged... and or no thermostate and the coolant is flowing to fast to cool down...
or thermostate is stuck open.....

Imho

 

[jdub]

Yep...I'm thinking it's a thermostat that sticks in a partial open position. The lack of a shroud and a *possible* clogged radiator would make it worse. You do need a shroud.

If you replace the thermostat, make sure it's the stock temp for the 2JZ. Toyota TSSC's "look" for a specific coolant temp range for normal running conditions. Also, cut the jiggle valve off the new thermostat...you will get a small amount of flow all the time and any pressure build up behind the stat will not interfere with operation.

 

[WhtMa71]

If you go pick it up bring a new thermostat with you and a new radiator..or one that you know isn't plugged.

Or if you were to go there, let the car get up to operating temp and use an infrared heat gun and look at different parts of the radiator. If there are any cool spots on it then you have a clogged radiator.

 

[HommerSimpson]

What you can try.... is back flushing the system.... not very hard to do... yank the stat... just bolt housing back up dont worry about it leaking...

take hose off top of radiator... put garden hose in end heading towards thermostate.. duct tape hose clamps rags... you get idea... take and put another hose hopefully you have something laying around on radiator and point it down..so you dont make a mess..

turn on full blast and jump up and down on hose to... it helps break shit loose...
Yes i have back flushed thousands of radiators... but most was with a gun that pumped 120psi air in with the water..
I Worked several years For a Radiator shop.. Roded out quite a few radiators to....
Mainly look and see what all comes out... if its clean.. well its prob not cloged.. if lota shit comes out.. rust ,scalle and such...
Just an idea to try before you spend money...

 

[IJ.]

Missing undertray and front plastics?

 

[HommerSimpson]

Missing undertray and front plastics?

the camaros and firebirds that have that 2 inch black air dam looking thing..Had many people come in asking why car ran hot on highway..
they had removed or tore off going over curbs that little airdam and would run hot..

 

[IJ.]

My car runs +5c if I drive at highway speeds with the undertray off.
(My cooling system is large and perfect)

So on a car that where the cooling isn't optimal it can cause the above symptoms.

 

[HommerSimpson]

i have no undertray but have planed on building one as it needs to feed rad,engine oil cooler and trans cooler and front brakes...

but with no tray 180 deg no mater what speed or how hard i drive it...

 

[jdub]

Another thing to look at...is timing set correctly. Improper timing can affect coolant temps a lot like this.

 

[Deofol]

Wow, thanks for all the ideas everyone! I definitely feel a lot better about this having such a great community a post away! If it wasn't for this forum, I'm pretty sure I would have just gave up.

I looked at shipping services, and found one for around $300 to get it trailered to Dallas. But I'm thinking I might be able to find a friend with a truck that I can talk into letting me take it on Saturday. Truck, UHAL carrier and see what I can do. Hopefully things should be a little clearer when I get the car to the house and have some "one on one" time with it.

Being that he replaced the head gasket I'm hoping that isn't the issue and its just something simple like a fan shroud, stuck thermostat, radiator, etc.

 

[gtsfirefighter]

Hey Billy, congrats on picking up such a nice car. If you know someone with a pick up you can rent a uhaul "auto transporter" for about $60 bucks a day. You can be down there and back in 9 hours. It's been several years since I've seen his car so can't wait to catch it at a meet if DFW ever has one again.

Could it needing to be tuned have anything do with it overheating? Fuel mixtures being off? Maybe too lean? I'm ignorant of Maft Pro and the likes but was just curious.

 

[hottscennessey]

I run a 2JZGE-T with 16+AFR's at cruise, stock radiator, 2JZGE mechanical fan (no shroud), and no undertray. Obviously I need to beef up my cooling system a little.. but my car doesn't overheat. It used to get a little hot when beating on it but then I replaced the HG, and that was that. I doubt that the air/fuels being lean will cause overheating.

It sounds to me like:
bad thermostat
advanced timing