Hi y'all,

Just got my 3.4 swap 2nd generation 4Runner back on the road right as a heat wave hit here in NorCal, and I was wondering what engine coolant temperature is normal. With AC on in stop-and-go traffic and 100 F air temperature, I was reading as high as 230 F when I pulled over to let the old girl cool off. After warping the head to smithereens on the original 3.0 3VZE due to overheating, I obviously don’t want to repeat my mistakes. Since then, I turn the AC off in slow traffic and blast the heat, but obviously this isn’t a long term solution for a daily driver. The radiator is a CSF all-metal brass unit that I put in only about two years ago, and the cooling system should’ve been bled of air at the shop. I believe I put the jiggle valve upright when I did the thermostat, and I also replaced the water pump with an Aisin unit at the same time. I currently don’t have the fan shroud installed as it doesn’t fit properly with the mismatched fan from the 5VZ, and I plan on doing an electric fan conversion. Let me know if these temperatures are normal given the situation, or if there’s something glaringly obviously wrong with my setup (most likely the fan shroud I assume).

 

Personally, I would be concerned with 230 degree temp. I would make sure it's accurate and check it with a mechanical gauge or temp gun instead of the dash gauge only.

A fan shroud is a must have in my opinion. Will your shroud work with a 3.0 fan? I know the 3.0 fan fits the 3.4 fan clutch because that's what I'm running. I did a 22RE to 3.4 swap and I'm running the same 3 row brass radiator for my 22RE in my 88 pickup. I had to fabricate my shroud. I'm in AZ and mine doesn't run hot. It did start to creep up in temp ONLY above 65 MPH and I found it was my winch and bumper blocking air flow at high speeds. I modified the bumper and that fixed it.

IDK if the jiggle valve position really affects the temp. I always "assumed" it should be positioned up at 12:00 and ran it there for many years without problems. I recently found out it's supposed to be at the bottom at 6:00 and installed my new T-stat there. I haven't run it yet because my engine is going in my current build that is not quite finished.

If your radiator is clean my guess is you have an air flow problem across the radiator. Maybe a GOOD electric fan setup would help. I personally never had good cooling with electric fans but I haven't tried any of the newer ones. My 22RE radiator with shroud and 3.0 fan cools my 3.4 here in the desert so I would think your larger radiator should too. I also had my radiator rodded out. It is pretty old though.

Since I don't see freezing temps here, I run a 60/40 coolant ratio most of the time but I haven't run hot even with 50/50. I'm running the old school green coolant since I have a brass radiator and heater core and tubes. Back when I did the swap the Toyota red coolant specs said it didn't protect brass. IDK if that is still the case today. I've been running the green since my swap and I think it was back in 2011.

Good luck with it and be sure to post up your solution.
Scott

 

Thanks for the reply, Scott!

After reading your message, I went out and bought a new 3.0 fan to fit my 3.0 shroud, installed everything, and took it for a test drive. With the AC on full blast on a 92 F degree day, I took it down a 10 mile stretch of stoplight-riddled road and nearly floored it at every light just to stress test it and see how it did. With my scanner plugged into the ODBII to read the temperature, by the end of the drive, the coolant temperature got to 225 F momentarily. I used to have access to a FLIR thermal camera; would’ve been nice to corroborate these readings. However, under normal driving, it basically never broke 210 F, and earlier in the day when it was cooler, it was sitting right around 195 F. I’m running the Toyota red coolant, which I checked beforehand — crystal clear and absolutely no signs of corrosion. It was also completely full under the cap, and the coolant in the expansion tank was at the proper level. I also have a completely stock front end, so airflow is likely adequate. I would be interested for someone who tows with their 3.4 to tell me if these elevated temperatures under heavy load are normal. But considering that the typical operating temperature is back in the normal range, unless someone says otherwise, I’m going to consider this fixed.

- Ben

 

Hopefully you're good to go Ben. Thanks for the follow-up. Dead end threads suck. One other thing to consider, especially if you're driving an auto trans is the extra heat it puts into the radiator. I have a manual trans so much less heat load on my radiator than an auto equipped truck.

Also, I saw a few threads on the 3.0 fans. A regular fan blade type VS the one with the ring around the perimeter. "Supposedly" the one without the ring is better so that's what I bought. I really don't know if there's a difference though.

 

Hey Scott,

It's only about 85 F today, and I noticed that after some stop-and-go with the A/C on that the ECT popped up to 220 F before settling back down to about 210 F. I read that, like you pointed out, having the jiggle valve in the 12 o'clock position instead of the 6 o'clock position can add about 10 F (I don't recall what orientation I installed it in -- definitely going to check). Also, I definitely agree with your point about the A/T adding heat load to the radiator, and the A/C seems to exasperate the ECT, so I realize that I should give the condenser fan a test (as I noticed corrosion on the solder joints to the fan motor). I checked the fan clutch as well, it spins freely when cold and has a decent amount of resistance after sitting for about 30 minutes. So basically, I need to check the thermostat, make sure the condenser fan is working, and check the fan clutch when hot. It's hard to tell if the fan is working just by sound; I have a whiny power steering pump that needs rebuilt/replaced (I performed the flush as well as cleaned out the reservoir filter).

Even so, something still doesn't isn't sitting right with me, because 220 F, even with the above issues, seems too hot for normal driving. I read that head gasket leaks can be a cause of overheating issues. I checked the engine oil on the dipstick and under the cap, and the oil is golden on the stick and gray on the under the cap with no sign of the milkiness characteristic of a badly blown gasket. There's also no sign of any blue smoke when I accelerate.

HOWEVER, I noticed oil dripping down the driver's side bellhousing. Before I performed the swap, I cleaned everything up very thoroughly with brake clean, so I am sure that this leak started in the last 500 miles or so since the swap. I took some videos and picture to try to figure out if the head or valve cover gasket is the culprit, but I can't quite tell and was wondering if you or anyone else could give me some input. Here are the links to the full videos:

Video #1

Video #2

The 3.0 that I originally pulled from this car is known to have head gasket failure in a similar location because of the heat from the crossover pipe drying out the gasket material, and I was wondering if something similar might have happened here (even though ORS does not suggest wrapping their crossover pipe with exhaust tape).

Here are the photos:


1. Block - bell housing interface on driver's side. ORS crossover pipe visible in top of image connected to exhaust manifold.

2. Block - head interface near cylinder 6 (nearest driver's side)

3. Alternate view of image #2

4. Alternate view of image #2

5. View of block - head interface under exhaust manifold near cylinder 4

 

Just a quick remark to note that ignition timing out of spec can contribute substantially to excessive heat rejection into the coolant.

 

That's too oily for me to see the SOURCE of the leak(s). You have to clean it and recheck maybe when idling with a mirror or whatever you can to get a clear view. It's obviously coming from up high somewhere. Rocker cover or cam plugs. You can also have engine oil leaking from the rear main seal but you wouldn't see it up there obviously or trans oil from the front seal inside the bell housing. I don't remember if there are oil plugs on the rear of the block that can leak. I never rebuilt one of these. Just installed and have been running them. IDK if it related to your heating issue. May just be time to reseal it.

As far as wrapping the exhaust, I wrapped mine back when I did my swap. No rust out issues for me but I live in the desert. I have gotten it wet from water crossings or even washing my engine. I was more concerned about damage from the heat to my wiring and cables as well as a ton of heat into the firewall and floor. I wrapped from where it attaches to the manifolds to my CAT and after my CAT to my muffler. I made heat shields for above the muffler and CAT. I cut up and refit my original cross over and the rest of my exhaust is built from a universal kit of mandrel bends. Just aluminized mild steel. No rust yet. I used DEI header wrap.

IDK how to check timing on these. I thought the ECM did it? Mine's always ran great so I haven't had to troubleshoot much. Maybe there would be a code if timing was off?? I'd have to read up. Maybe millball can offer more. He's usually spot on in his replies that I've read. Do you have any codes? It runs good otherwise? Just too hot?

A head gasket leak can be checked with a kit you can buy that checks for combustion gasses in your coolant. Sometimes it can test negative if it's a small enough leak and just starting to leak. Or you can pressure test your cooling system. If you're losing sleep over the possibility, have it tested or buy the kit and do it for peace of mind.

Another thing to consider is if your radiator is actually clean. Mine looked spotless and I changed my coolant per the book and used distilled water. When I did my swap, I took it to get checked at a local radiator shop. They rodded it out and said it had a lot of plugged tubes. The tops looked clean and the bottom was plugged. I don't remember the number they told me in percentage plugged. It was a long time ago.

You definitely need airflow through it so it's good that you're checking your aux fan.

Don't give up, you'll get it figured out.

 

I went out in the garage to take a look at my engine. You may just need to reseal your rocker covers for a good start on the oil leaks.

I included pics of my wrapped exhaust just to show you the condition after many years. Only that bottom section has new wrap on it. I had to cut, turn and weld that section. The top is the same stuff I put on back around 2011. You can see I used plain mechanics wire back then. I added the new stainless band recently.

 

My 88 22RE 3 row brass radiator, 3.4 fan clutch with 3.0 fan and my home built shroud cools it so your larger rad should too.

 

I felt up on the aluminum heads and there seemed to be a substantial amount of oil above the gasket, it's just more visible on the cast iron, so I am leaning more towards valve cover gasket. That would make more sense as there are no other obvious signs of a head gasket leak (no coolant consumption, etc.). There is also has been a steady ATF leak from the transmission and transfer case the whole time I've owned the truck, and based on the amount of fluid on the front propeller shaft, it seems likely that it's slinging oil all around the bellhousing and back of the engine.

I'm not sure how to check timing either -- I'll read up on it. I too was under the impression that the ECU controlled the timing. The only codes are for the evaporative system that's not hooked up yet and for low catalytic efficiency, as I just have the original cat in there. I bought a high flow cat to build a new exhaust around though. I'll probably avoid the wrap so as not to void my warranty with ORS, but it's good to know that I could wrap it.

I am going to wait at least for my first paycheck to throw anything more at the truck in terms of time, tools, or parts. But the head gasket leak check kit seems like a good idea just to rule it out.

I am also 99% positive the radiator is good; it has less than 1000 miles on it as I replaced it after my OEM radiator cracked (which destroyed my 3VZ).

Since I am only noticing the elevated temperatures when the A/C is on, my next most likely cause is the condenser fan. Ran out of time to check it today.

Thanks for the words of encouragement...feeling ready to throw in the towel on the old girl.

 

Sounds like your radiator is good and you have a good plan forward. Good luck with it. I hope you get to enjoy your swap.

The good thing about oil leaks is that it's better than a rusty undercarriage and you can wash it off when you feel like it.