Chasing Overheating Issue...

I'm thinking buildup/blockage inside the radiator decreasing its effectiveness in warmer weather

 

it’s a fairly new radiator maybe 6 month old/ 2l miles.

 

Your ''fine sand'' is likely silicate residue.

 

The sand. When I was younger, I got convinced I needed a new fangled billet coolant filter. At some point I took if off to see what it caught, there was a tiny bit of sand in it. The collective gear head opinion was that it’s from the sand casting when the block was cast.

 

I have nothing new to add to this discussion other than I would second the recommendation of flushing with distilled water a couple of times and see what comes out.
This is a question of ignorance, but is there a difference in head gaskets over the years? Is there any chance a water passage is blocked from the gaskets?

 

I saw where the radiator is fairly new. Lower the coolant slightly below the tubes in the radiator and look for a build up on the tube ends. Your radiator may need to be boiled out by a radiator shop.

 

I would second checking the condensor. Also check the ac pressures. Is high and low side within specs. i live in south florida, our normal temp readings very from 200-220 deg over that i would get concerned. Putting a secondary electric fan in from of condensor is not a bad idea. A good one you can set to come on at a certain temp, say 200 and should maintain that or go lower. would also help the ac greatly.

 

Your first post mentioned a Brand new cooling system...what does that included? Radiator and water pump? Or just radiator? What about the heater core? If you have sediment in the coolant, maybe it is really collecting in the heater core and there is a blockage there? As Someone said before, flush, flush and more flush, until absolutely clear.

I am thinking it is something thermostat related, I know you said you already replaced, but try again and double check.

Also what about your full list of mods?

On a footnote, as you can see I have 2 large offroad lights that significantly block my radiator and I have no overheating issues in South Texas with daily 106 heat (I have the towing package radiators). I know AZ is slightly hotter, but I as a reference I think our Tacomas coolant system is very effective and well made.

Good Luck, and we are all here to help out best we can.

 

Towing package radiator isn’t a thing. They all have the same radiator

 

Let me clarify, mine has the towing package transmission cooler...so there is an another small radiator in front of the main coolant radiator on the driver side.

 

105 today in S TX, and mine stayed in the middle of the temp gauge. for those of you with an ultragage, what actual temperature does that equate to??

 

EXACTLY, not actual sand, but rather decomposed coolant debris and engine corrosion debris.

 

South Florida, temps are pretty warm currently. My truck still operates at 190*f max coolant temp. I run a dedicated trans cooler and no transmission fluid enters the radiator.

I have purchased the items to do a flush and fill of the cooling system. Recently, I tried that billet thermostat housing setup. Total waste of money as it is improperly designed. During that install, when draining coolant, I too had silica sediment in the bucket. Previously over the years of ownership since new, the truck has had two flush and refills in the 95k miles since new.

For this flush and refill, I will accomplish a Thermocure flush with distilled water. Then second distilled only flush, followed by refilling with 50/50 Peak coolant. Yes, again, I will remove both engine side drain plugs for a complete flush.

On a side not, while contending with the POS billet thermostat housing, the increased temps from that had me question my oem radiator. That was replaced with an all aluminum radiator from URD. Even now with the oversized cooling system, temps are the 190*f as before.

 

-I agree with more flushing to remove silt/silica that could be plugging up the new radiator.

-Also, with the engine good and hot (before doing additional flushing) check around the seams of the new radiator where the tanks are crimped/glued to the core and look for any signs of moisture.

-After the final flush and fill is completed, you might add a bottle of Water Wetter for good measure.

$14 Red Line 80204 WaterWetter Super Coolant - 12 Ounce

https://www.amazon.com/Red-Line-802...locphy=9028784&hvtargid=pla-334077729758&th=1

 

Interesting comment to note on Amazon's page, I did find one that may be helpful to some TW owners:

"...After doing a crap load of research on the topic of coolant mixtures and temperatures associated with different mixtures, I decided to drop the coolant mixture down to 25% coolant, and 75% distilled water. I actually got this ratio from Redline's technical sheet on this product. If you read the information on this product and look at the dyno testing they did, you'll see that they saw the biggest temperature drop when this product was added to pure water, and the temperature climbed slightly with more and more antifreeze added. That's exactly what's supposed to happen.

Modern cars use a 50/50 mixture from the factory so that the cooling system can operate in any climate. A 50/50 mixture gives you optimal protection from freezing while not raising the temperature too high. If you were to just run straight anti-freeze the temperature in the cooling system would spike dramatically. But if you were to run just straight water all the water would boil out, you also would have no corrosion inhibitors.

Basically what I'm getting at is that if you want to see results with this you should run a 75/25 mixture and a bottle of this product. And read the technical sheet on this product...

Happy tinkering."

 

Welcome to the forum


Running only 25% coolant only gives freeze protection down to about 10 degrees above zero. While 10 degrees sounds really cold and obviously not that common in AZ it isn't unrealistic that the OP might encounter a temperature that cold on a weekend getaway trip for example.

Some years ago a friend was scraping his windows (northeast) as his truck warmed up, he heard several odd cracks and suddenly steam erupted from under the hood.

He knew his old antifreeze wasn't quite the best and thought "it should be ok".
It was a carburetor equipped truck running on fast idle, the engine was cold so the thermostat was still closed.
The truck had a towing package with a full fan shroud and a big 7 blade fan.

The cold winter air rushing through the radiator with no circulation (closed thermostat) pulled the temperature of the substandard coolant low enough that it froze, water expands about 9% when frozen - the radiator obviously expands 0% and it burst the radiator core in multiple places.

He got lucky, only the radiator was damaged - about $400.
I did have some small satisfaction mentioning the high cost of deferred maintenance.

 

TY! This place is a wealth of information and the main reason for purchasing my new (to me) old taco. Best of luck! @AZTaco-86 [OP]

 

Another problem (arguably larger) with running a reduced percentage of coolant is reduced corrosion protection.

Coolant doesn't wear out in the sense that it becomes "freezable" so much as the additives that provide corrosion protection become depleted.

Modern engines are mostly made of aluminum which is highly susceptible to corrosion, the coolant "works harder" to protect these engines than the heavy cast iron engines of the past.

The only thing protecting the head gaskets is the additives in the coolant, replacing head gaskets is an expensive job, coolant service is fairly inexpensive by comparison.

 

One thing I have learned is new doesn't always mean its good.
I had a Volvo in the shop once with a similar complaint, the temp would spike after a run on the highway and coming to a stop. The radiator had been changed the prior winter due to a leak so I was sure it was an airflow problem. We proceeded to replace the fan clutch since you could not hear the roar of it kicking in. Then I went after the antifreeze/water concentration. Still had the issue.
Long story short it was the radiator. I don't know what brand it was but it simply could not transfer enough heat fast enough when sitting still after a heavy load on the system.
I feel your pain, cooling seems to be a pretty straight forward system but strange things will throw you for a loop.
I also had a temp spiking issue that was related to the plastic impeller on the water pump not being tightly secured and was spinning on the shaft. It was intermittent too, it drove me nuts.

 

Damn.