Pozi

One problem after another!

As many of you may know I am nearly completed with my 3.4L swap. I just got the exhaust installed but when driving it home it started to overheat. Luckily a friend lives close to the exhaust shop so I pulled in his driveway to let it cool down. After it cooled enough to let the pressure reside and get the radiator cap off I topped off the coolant in the rad. However after starting and letting it run for a couple seconds (probably 20 seconds) the water started to shoot out of the radiator (yes the cap was off). To get it home I removed to t-stat and never came close to overheating.

The next day, thinking the t-stat was bad I replaced it, filled up the rad and it started to overheat again. Now I am beginning to suspect somewhere near the rear of the engine I have one (or some) of the coolant lines crossed. I can verify the water pump is working because when the t-stat was out and the rad cap was off the coolant was freely flowing inside the rad.

Does someone have a coolant line diagram for the 3.4L? Or other suggestions?

Lone4runner

Fan clutch?

Pozi

Should of included that I have Taurus fan.

Pozi

top

mt_goat

What year is your 5VZ? The index is a mess but here is a 2003 FSM: http://www.deserted1.com/FSM/

mt_goat

Are you talking about the heater hoses? They should be crossed, with the drivers side of the body going to the pass side of the engine and vise/versa.

If you're talking about the oil cooler hoses its pretty hard to switch those up but I have some pics if that will help.

Maybe the throttle body heater hoses? Can't see that causing it to over heat.

What temp/brand t-stat did you put in? Did you test it on the stove to see when it opened and closed?

Pozi

Right. I am talking about the heater hoses near the rear of the engine.

I bought a Toyota t-stat from the dealer, installed with same result. Did not test it in the boiling water.

What has me confused is the coolant geyser it produces with the rad cap off. When I run the vehicle with the t-stat out it heats up to 1/2 way on the gauge with plenty hot air blowing out of the front and rear heaters.

mt_goat

I suspect air in the system did that. Did it happen more than once?


That would worry me because it should run cooler than normal with it out. Did you wire up the OBDII plug? If you did I'd hook it up to a laptop and check the actual engine temp reading. I've heard the gauge on the dash is not a linear read out, (it has a big range of temps that still show 1/2 way).

Are you running the Taurus fan on high or low speed? And do you have a good shroud around it?

How old is the radiator?

Pozi

Yes more then once.


Have not hooked up the laptop yet. I have is interface but still need to install. Ideally what should the operating temperature be?

Taurus fan with low speed on (temp gauge - middle) high speed connected to A/C.

The radiator does look clogged through the cap. Maybe time to have it reemed or replaced?

mt_goat

Well if it does it all the time it could be the coolant is boiling in the engine and the rapid expansion is giving you the geyser effect. The system is normally under about 10 psi with a good radiator cap and water boils at a higher temp under pressure than with no pressure. Standard opening pressure for the radiator cap is 10.7-14.9 psi.


That's a good question, I've only hooked my 5VZ up a few times and I was mainly looking at when it went into open loop. Can't remember what the temp was running. I'd be concerned if it was much over 185 though with a 180 deg t-stat or no t-stat at all. Maybe someone with more experience can jump in here. You could at least use it as a gauge though.



Yep that would do it. And I bet your shroud isn't fitting very good as well.

Pozi

Thanks for the reply Dale. I had a feeling my rad needed replaced anyway but I have been ignoring it.

mt_goat

I found the normal range in my 2001 FSM for the engine coolant temp sensor on the OBDII diagnostics: 176-203 deg F

SLC97SR5

My ScanGauge II has never shown over 205* and that's turning off the truck and then re-starting it after it has sat for 10min and all the engine bay is getting heat soaked. Intrestingly, the temp gauge shows normal temp (1/2 way up the gauge) anywhere from 137* to 202...I've never seen it budge once it hits halfway. I'm usually right at 197 for 75mph A/C driving during 95-100 ambient temps. (50/50 red yota coolant mix)

DeathCougar

iTrader: (23)

sounds like air in the system to me. Check the rad for freeflow, then you need to burp the whole system after that.