Ohio4Runner

Hello wise ones. Before you tell me to search the archives, please know that I have read everything twice. I am out of ideas.

The problem: temperature rises at idle. It does not overheat, but it begins to move up noticeably, to the right side of the thermometer pic on the temp gauge. Once I am moving, it comes back down right away.

I recently installed a new (aluminum, 3-row) radiator, new fan clutch (fan pointed in the right direction, ie a pull-fan), new fan belt (which is at the proper tension), new thermostat, new coolant (shelf-stock, not Toyota - I know), and new hoses. I have burped for weeks, trying to get every last air bubble out of the system.

I changed all these items because my original radiator failed and blew the top off. The truck had not had cooling problems before. Before it failed, the truck had been running at normal temperature. The top cracked AFTER I shut off the engine.

What now?

Thanks all, I really appreciate the help.

wyoming9

iTrader: (1)

New Radiator cap with all the new parts ??

Did you change or at least clean your sending unit ??

These factory gauges are pretty poor Have you checked the temperature with a infra red heat gun??

Automatic or manual ?? AC ??

Ohio4Runner

Yes, I did change the radiator cap along with the other parts.

Did not touch the temp sending unit.

Automatic, 3.0 VZ, 4WD, A/C. Sorry, I seem to have left out a few key details.

wyoming9

iTrader: (1)

I would guess your not running a separate trans cooler??

That is dumping heat into the cooling system

Ac condenser is also dumping heat .Have you cleaned the condenser that gets filled with dirt and road grit over time

Plus the added heat from the concrete and black top

Then add a temperature in the high 90`s

Then if the coolant was left in way to long block can have lots of rust Hard to really know.

It could also be the sending unit is getting old and tired and the resistance is not what it once was.

A few ideas to think about.

Have you ever figured out what caused the last radiator to fail ??

Ohio4Runner

RE: the old radiator, my very unscientific assessment is that it was old and corroded along the top, so when I turned off the engine, the coolant was no longer circulating and therefore heated up from the engine temperature. When the contents of the cooling system heated, they expanded, and cracked the top corner right next to the upper hose. The rupture occurred about 3 minutes after I shut the engine off.

You are correct about the transmission line, I am going to check the fluid today. Also going to check the idle speed, it is running low right now which would cause the coolant to circulate more slowly at idle.

If that has no effect, I will check the AC condenser and the sending unit. (Do I need to drain the whole cooling system to change the sending unit?)

Pretty sure it isn't rust...I did the head gasket about 4 years ago and cleaned it like new. I didn't see too much rust when I drained the system to replace the radiator.

Thanks!

Terrys87

iTrader: (1)

I wonder if your new radiator is sufficient. From my experience if it cools down while driving, it just isn't getting enough air flow. I have gotten the same symptoms as you have with a dirty, clogged or poor radiator but when driving the air is moving better then when sitting.

I too don't have a lot of confidence in the temp gauges.

Odin

Are you still using the fan shroud? They help at idle and very low speeds.

Ohio4Runner

Yes to the fan shroud.

Adjusted the idle speed higher, as it had crept down to about 550 RPM. This helped a bit, but it still gets warm.

Checked the transmission fluid, the level looks good.

I am thinking it may be the gauge? For a couple reasons. First, it reads all the way warmed up within about 30 seconds of operation. Second, the other day I had 35 minutes of stop and go in 90+ degrees. Temp read normal until 20 minutes, then started to creep high. It did so for about 5 minutes, then came back down to normal and stayed there for the final 10 minutes. It has repeated this pattern of creeping up and then staying back at normal a couple other times. Is there a story here? Regardless, I have ordered a new sensor.

Is it possible that the aluminum radiator just doesn't exchange heat as efficiently as the steel one did, even though it is 3 rows instead of 1?

Odin

Did you replace the thermostat with a Toyota dealer thermostat or aftermarket?

I don't have a clue what the stock temp thermostat is on a 3.0 but could you have possibly installed a higher temp thermostat?

AKHeathen

when it creeps up, rev the engine and see if you hear the fan roaring. honestly, if you went through all that trouble i would have installed an electric fan. i'm not a fan of power robbing clutch fans, lol.

Ohio4Runner

Definitely can hear the fan roaring.

Good news so far is, the coolant isn't boiling in the reservoir.

AKHeathen

does it ever go into the red?

Ohio4Runner

Nope, just creeps a little to the right of the thermometer.

AKHeathen

then just run it. sounds good, it's just not passing a whole bunch of air at idle. on the stock cars, we used to rev them up and spray down the radiators after a set because cooling at idle is not even close to efficient and heat will creep up. this is usually fine because idle alone doesn't make too much heat.

Turd Furgeson

Your old radiator was not steel,it was copper fins with brass tanks,tubes,and headers with steel sidebrackets. The parts store people always mess up when they say "3 row" aluminum radiator. Your original v6 radiator had 3 rows of 3/8 or 1/2 inch brass tubes. The aluminum radiator you have now Is most likely 1 row of 1,or 1 1/4 inch tubes,maybe 2 rows of 3/4 inch tubes. The parts store people don't know what they're talking about,the computer probably says 3 rows because it's supposed to be equivalent to a 3 row copper/brass radiator.

ctheiss

Check your water pump. The fan blades might have rusted away and it's not circulating good until you get the rpm's up which makes the fan spin faster.

Odin

Not a bad suggestion.
If anyone has allowed the coolant to get old and nasty or you have bad grounds you could have had an electrolysis problem that has partially eaten up the water pumps impeller blades and is now hurting the flow of coolant.
Electrolysis usually hits aluminum the hardest and the impeller blades are likely steel. If it's got really high mileage that can contribute





Testing for electrolysis is incredibly easy but is often overlooked.
Testing information can be found at
http://www.sancarlosradiator.com/Vol...ectrolysis.htm

AKHeathen

that video does show signs of elecrolysis, but does not tell you how it is happening. (this is a huge issue with large engines with broken or missing radiator grounds) basically, the electrolysis itself can't be measured with a multimeter as it leis in the realm of electrostatic and ionic measurements.... but i'll put it in a way easy to understand: the airflow draws electrons from the radiator to land on the engine and builds up a static bias on the metal of the engine. the only way to return the electrons to the radiator is through the coolant, so it does so, breaking down the metal in the process. much like rubbing your socks on carpet to build a bias and then touching something with fewer electrons. you get shocked. think of the block as you. this measurement is measuring the continuity of the coolant as basically a conductor breakdown in the form of content in the coolant.... so basically, electrons are pulled from the radiator to the engine, then flow back through the coolant. good new coolant takes high voltage to do this, but as more metal is broken off in the coolant it gets easier and increases coolant and elctrolysis. when you find this condition, you should properly ground the radiator to prevent it from occuring. i've seen the difference first hand, where the same engine in the same vehicle has had the newer one ravaged by elecrolysis sometimes unusable 2x where the older one is uneffected because the radiator is grounded, in 30k cat engines. electrons flow from the radiator to the engine and need to get back to the radiator somehow.

Ohio4Runner

Hmm, the electrolysis idea is one that had not occurred to me. Recently my one-year-old battery would not start the vehicle - everything went absolutely dead at the same time. Turns out that the negative terminal had a fair amount of corrosion built up, so once I cleaned it off, everything was like new again.

How would I rig a ground for the radiator? Would it be as simple as running a 10-gauge wire from one of the radiator bolts over to the battery ground on the fender?

And, I think Mr Ferguson has the answer above. I think it is simply a case that the new radiator is inadequate. There is plenty of airflow even at idle - if I hold a piece of paper in front of the grill, the airflow pulls it pretty firmly against the grill. When I shopped around for the replacement radiator, the two price points were $150 and $600. Both said "3-row". One truly gets what one pays for.

I am going to look into getting the original radiator rebuilt. If they can work around my hurried epoxy job on the crack, maybe I can put it back on and get another 20 years out of it?

I am also going to change the sensors, just because I can.

AKHeathen

on the original radiator, the shroud or mount bolts would work fine for a ground. either battery, body, engine, or frame, if your grounds are attached, it will reach the engine. on the aluminum, make sure it's metal contact that reaches the radiator coolant, many can have plastic tanks that wouldn't do any good to ground there.
usually, they say, "x-core" not row..... at least they used to. like "3-core 2inch radiator" 2-core/4-core, etc, and come with a sheet of paper stating like 3/8" cores vs 1" cores or whatever.