Kingjerd

Ok my 88 Runner has a newly rebuilt 22re with around 4500 miles on it. Stock rebuild. Stock cooling system with new water pump, t-stat (180 degree I think, but i really dont remember for sure), radiator cap. The block and head were both all cleaned up in and out at the machine shop during the rebuild. Its a 5 speed with the stock gearing as far as I know. Is running 31 inch BFG All Terrain T/A KO's.

I bought it with a sunpro water temp gauge already installed with the probe on the drivers side rear of the block and the factory temp gauge has never worked. (Just stays in the midle and has never moved)

When driving around town the temp hovers around 180-190 no matter the driving style.

When I get on the highway its a whole different story. When Im in 5th gear at any given speed just cruising on flat ground the temp creeps up to 220+ (I dont let it go higher for fear of hurting the head gasket.) Up hill obviously makes it climb faster. If I downshift to 4th and cruise around 65 it cools down. Im assuming this is because the engine, even though spinning faster, isnt working as hard due to the higher gearing in 4th vs 5th.

No way the 31's are too tall for the stock drivetrain. Right? In traffic is stays cool so I know the fan is pulling plenty of air through the radiator and at speed it should be flowing even more air. Could it be timing? Or are the 31s making too much work for it?

Thank fellow yoter heads!

gottadog

iTrader: (3)

Could be the radiator, heater core thermostat off the top of my head. My old 85 did that and it ended up being the radiator. Small crack in the top tank plus it was just loaded with crap, reducing its efficiency. New rad after dumping the cooling and back flushing and it was a new truck. I don't have the part number off hand but toyota has a dual plunger stat that helps. Its expensive for what it is, but worth it.

Good luck dude!

Kingjerd

Kinda what my gut was telling me. The radiator is the only original part of the cooling system and after 281,000 miles im sure it is all kinds of gunked up. Thanks man! Guess i just wanted some clarification before i dropped money on parts or flushing materials.

Mr.Utah

Strange situation here; slow down to 65, you must be doing 80 bro!

I would think some kind of cooling restricting problem. Take out the t-stat completely, seal, road test at high speed. If still bad I would also guess your radiator is bad or your have a leak in radiator cap.

Make sure you have the proper coolant mixture before anything!

racerflea

Before u spend 100 plus on a new radiator buy a new 5 dollar radiator cap... the reason os if the old cap allows the system to loose pressure than ur temp is gonna jump up

Kingjerd

@ Mr. Utah.....Hahahha i dont really slow down much from 70....i just downshift to 4th and drop to around 65. The truck doesnt really mind since im barely above 3000rpms in 4th at 65. Typically ill use 1-4 to get to 70 then go to 5th to cruise at 70. Gotta keep up with the SoCal traffic.....everyone is in such a friggen hurry around here....back home they all take their time and enjoy the weather! I think that would suit my truck better too!

@racerflea....i got a new radiator cap when i rebuilt the motor but ill definitely try another one before dropping big money on a radiator. Start cheap is the only way i can afford to work!

Thanks to all!!! Looks like i have a few morw details to check out before im 100% sure but im already kinda thinking its the radiator. Gotta keep plugging away.

Mr.Utah

Ok Bro, Old school here, I would think it is either the radiator cap loosing pressure, leak in the coolant system, a bad thermostat, or ultimately a bad radiator?

Gamefreakgc

If you've used the green coolant during the life of the truck, it will corrode the metal in the radiator and some metal piping. Toyota trucks use the red coolant, around here I can only get it from the dealer. I bought mine with green in it but switched to red before anything was too damaged.

You can tell if it's badly corroded if you flush the coolant and you've got a lot of brown, rust-looking deposits in the fluid. Also you can look down the cap, easy to tell. Corrosion thickens the walls of the radiator, not allowing the fan and outside air to cool off the fluid inside.

If you do get a new radiator do a proper flush of the engine (almost half of the fluid stays in the engine, see service manual) and put the red in to preserve the life of your new one.

MudHippy

No. That's pretty much all wrong(except for the last half-sentence).

1. Toyota switched to using their red coolant, in all their engines(new or old), in 96. Before 96 they filled all their engines with green coolant from the factory. So, as a matter of fact, no pre-96 trucks used red coolant originally. And even the later models that do use it, don't require it to prevent any kind of damage. Well, any kind of damage caused in any short term sense atleast(as in maybe over 100s of thousands of miles, but probably not before).

2. You do not usually see brown, rust-looking particulates in the coolant unless it's been WAY watered down(or the engine has a cast iron block and head(s)). It's more common(on engines with blocks & heads made of dissimilar metals, such as cast iron and aluminum) to see black, pepper-looking flakes of corroded aluminum in the coolant(once it's lost its ability to prevent corrosion effectively). This is due to the aluminum components of the cooling system tending to corrode/erode before(or instead of) the iron/steel, brass/bronze, or copper components. Because aluminum is a relatively softer, and more electrically conductive metal (making it highly susceptible to corrosion/erosion damage by electrolysis when used in cooling systems).

3. It's not corrosion that gets deposited on the interior surfaces of the cooling system(especially in the radiator, but everywhere else too). The white, calcium-looking deposits you see inside your radiator when you open up the radiator cap are composed of silicates. And that is the result of using silicate-based coolant(green or any color). This is why Toyota red coolant is silicate-free. And that is basically the only reason it's any better to use in your/any engine, compared to using silicate-based coolants in it. Because after becoming clogged internally with silicates, the radiator(and to a lesser extent the entire cooling system) eventually loses too much of its ability to radiate/conduct heat well. Thus, the cooling system becomes significantly less efficient in cooling the engine.

That much is almost right. But if you open the coolant drain plugs on the block and radiator(see the service manual) virtually no coolant stays in the engine. The heater core will still be full of coolant though.

Back to the topic...

OP, the OEM thermostat opening temperature is 195°. But, even if you installed a 180° thermostat, what you're describing sounds pretty much normal to me . Though, I'm not going to say there isn't a problem. I am going to say that it's probably not a very significant one if there is. Meaning, I doubt the dual-stage thermostat would make any difference, and changing the radiator probably won't help all that much either. But...I could be wrong. It's just my opinion...of course.

Turd Furgeson

If it's heating up at highway speeds your radiator is plugged. Especially if it's got 281,00 miles on it with who knows how much previous maintenance. Take it to a radiator shop and have them flow test it,or pull a tank off and run a rod through the tubes to see for sure how many tubes are plugged,or restricted. Keep in mind though that once they take that tank off you're gonna need to buy a new radiator,or have yours re-cored if your tanks are in good enough shape. That core probably won't survive a rebuild with that many miles/age on it. Personally I would re-core it (as long as it's a quality core,and assembled by a good radiator repairman) and as long as the tanks aren't starting to crack. Re-coring can get expensive compared to a new cheap complete radiator,but in the end will be a WAY better radiator when done right with the right core. These are the ones we use http://www.pacificradiator.com/cores.php Yours would be a PC style core (typical oem tube size,spacing,but better than oem materials-thicker) or an upgrade would be a TQ style core that has bigger 3/4" tubes for more tube to fin contact. It kinda depends how wide you headers are as to how many rows (and tube type) you can fit in it.

Luvmeye22re

Radiators aren't THAT expensive... get one, yours is due with that kind of mileage. I'm a firm believer of "if it ain't broke don't fix it" but I also believe that if it old enough where it "should be broke but ain't" it's almost time to fix it before you end up doing an HG. Cooling system issues drive me nuts!

Rebuilt engine, new radiator cap, water pump, cleaned block etc... There isn't much more that can be wrong.

Just for giggles are there any engine codes that may have popped up and disappeared or any that were there previously that haven't been addressed?

Kingjerd

Actually ive never had a cel. But yesterday it did come on for seemingly no aparent reason. Obviously theee was a code but i dont have a reader and never made it by auto zone. I personally hate it when the cel comes on with no other symptoms...id rather thee be sonething obvious that went wrong so im not left wondering whats up. The light went away after turning the truck off and letting it sit at the motorcycle shop while i browsed around. Came vacknout after 20 minutes and started right up with no moe cel.

I truely appreciate all the input everyone!

xylicon

I've ran both the stock 195F thermostat and the dual stage thermostat. My cruising temps are a little lower with the dual stage according to my autometer gauge.

What I noticed with the stock 195F thermostat is that during a cold start when my thermostat would first open my autometer gauge would go up to 205 then back to 180, it would continue this cycle about 3 to 4 times before becoming stable at around 190F.

The behavior of the dual stage thermostat is quite different. During a cold start, when the thermostat first opens my temp goes up to 150F then it seems to close, then about 30 seconds later it opens again this time hovering just about 180F and that's where it stays. It's a lot more stable compared to the stock OEM thermostat, and my cruising temps are a little lower.

/2cents

Kingjerd

Ok so last night I was looking around the engine bay and the lower radiator hose had one single drop of coolant where it meets the radiator. Yes it was EXTREMELY minor (in over an hour there was just a single droplet hanging under the hose, it didnt even drip) but a leak is a leak and any leak means the coolant system cant pressurize properly and keeps the lower boiling point. I the overflow tank was low as well....i filled it to the recomended level. This morning it wasnt very warm out and I wasnt driving long enough to really heat it up fully. At lunch ill see how she behaves when its hotter and I have a few errands to run. Illl make sure its up to tempurature before leaving the base and hitting the highway to head to the house.

Ill replace the hoses this weekend when I have it apart to flush it and to check the T-stat and see where it goes from there.

Turd Furgeson

If it's the original radiator, the top and bottom necks are made out of steel and they are soldered into the brass tanks. As the steel rusts and corrodes the solder joint suffers. It's really common for that solder joint to fail to the point where the neck (usually the top one) almost comes out (or completely comes out) and you will end up with a leak at that solder joint as a result of the solder deteriorating. A lot of the time when I take that top neck out to re-do it,the tank is actually starting to crack around the hole that the neck slips into.

Turd Furgeson

You know,I really need to have someone come down to where I work and take pictures,and/or video of what I do in the radiator repair field. Especially when it comes to toyota pickup radiators and make it a sticky on this forum or something. I'm starting to feel like a broken record when it comes to radiators and sometimes I get into arguments with people in the auto repair field on this site about radiators. I've only been repairing,rebuilding ,re-coring,and building them from scratch for just over a decade now. Seriously I'm gonna try to get a sticky thread about radiators going in the future .

Kingjerd

Radiator Classics on eBay....Got me a new in box V6 2 row radiator since Im planning on towing my motorcycle trailer up and around the mountains of SoCal all year. $67 with a lifetime warranty! Cant beat that.