RAMROD84

Working on a 95 4runner v6. i installed a new rebuilt motor. New parts include,

• motor
• water pump
• timing belt and all timing components
• t-stat
• coolant tube that goes into the valley under intake manifold (old one had 2 pin holes)
• radiator cap
• all belts
• temp sensor

i flushed the radiator with water seemed to flow good. tested 3 thermostats in a pot, all opened at 180. burped the system to the point that there was no more air bubbling out and rad was full.



problem is the temp gauge goes up to 3/4 which seem to hot to me. top of radiator is hot bottom stays cold. seems as if the thermostat isnt opening to allow flow. with the heater on the gauge sits below 3/4 once heat is off goes back up. clutch fan work as it should. made sure the thermostat was installed correct a 12 o clock position. when i run the motor with thermostat out gauge sits at half. when i pulled the thermostat out i added fresh coolant. after i ran it for a while i drained the radiator and the coolant was dark more brown which leads me to believe that the radiator has gunk in it and some of it washed out because there was flow in the system? could a clogged radiator keep a thermostat from opening? checked the oil and its still clean, did the lighter test and passed. level is normal. no white smoke from exhaust. my last option is the radiator but id like to get others opinions on what might be happening. iv been at it for 3 days now so help as soon as possible would be appreciated.

rworegon

With the radiator cap off and the engine up to temp, does coolant flow through the radiator? You should see some motion... A clogged radiator will not likely keep the thermostat from opening, but it will cause temp to stay up due to poor cooling efficiency.

The coolant return hose to the engine is at the bottom of the radiator so the bottom of the radiator will always be cooler.

RAMROD84

With the thermostat in and motor up to temp i dont notice flow through the radiator. With the thermostat out there is flow through the radiator.

RAMROD84

iv been reading that if the timing is off it could cause it to overheat. could this be true? i made sure the timing was set right but could it be that the valve timing is off. id just like to figure this out so i can get it out of my shop already. im loosing my mind with this thing.

RAMROD84

Bump. Any ideas or possible solutions anyone?

TNRabbit

Does it run hotter when you're driving down the highway? If so, I'm betting it's the radiator.

What caused you to replace the engine in the first place?

RAMROD84

It does alittle, but its never gone into the red on the gauge and overflow has never overflowed. Replace due to blown head gaskets.

Took it to toyota they installed an oem thermostat. They said its flowing with the thermostat in now. But still heating up past normal. They also said there is exhaust gases in coolent which I don't get cause its a new motor. Possible defect in head gaskets or heads? Could I presssure test the system and see if it holds pressure? Still wonder about the timing?

RAMROD84

so i pressure tested the cooling system and it held the same pressure for a good while. took the timing belt off and redid it. fired it up and it still goes up to 3/4 on the temp gauge. took it for a drive and it didnt heat up past 3/4. and a few times when i came to a stop it seemed to go down to 1/2 and then back up to 3/4. only thing left i could think of is radiator partially clogged? or the temp sender is reading wrong? with it idling and temp up it still seems that the thermostat isn't open cuz i don't notice any flowing. yet the bottom hose feels a bit warm to the touch now after the drive. thinking about buying a new radiator but the only thing is its $150 at o'reilly. since its about my last option im gonna have to do it. any input or help?

justin_4runner

are u running the same rad as before the swap? i would go to one of the kent wrecking yards and get one for 50 bucks, also something to think of, do u have any mud or anything that might be in the fins not letting it cool good? also the exhaust gasses in the coolant is not a good thing makes me think that defective head gaskets or cracked of bad head. one way to see if its a clogged rad is to pull it and flush it out fill from bottom hose and let water threw, see what comes out also look in at cap and see if any ports looked clogged. u can also get a heat gun lazer type and see what the temp is all over the rad. see if u have some cold spots vs hot areas. that will also show if its not flowing good.

RAMROD84

Same radiator as before the head gaskets blew. Theres brown crap in the engine bay and overflow bottle from when old motor over heated. Could the previous owner have used some leak stop crap with the old motor and cause the radiator to partially clog? Iv flushed the rad a few times but could still be clogged in some parts. I live ellensburg now so kent would be to far of a drive. Not sure if the junk yard out here has one

93toyrunner2

Radiator repair shops charge $50-$80 here to boil it out and clean up the coils.

RAMROD84

So I put in a new radiator in and its still goin up to 3/4. also it still seems as if the thermostat isnt opening. dont notice any flow through the radiator and the bottom still stays cool compared to the top of radiator.

ksti

Just a thought, did you check your fan clutch to see if it is working properly?

RAMROD84

Yup its working. At this point everything in the cooling system is new. Thermostat isnt opening. Air behind it?

toyotanick

if there are exhaust gases in the coolant it normally means that it has a blown head gasket and with a remand motor its normally due to not so perfect block decking which is sort of common. the head gasket may not actually be blown, it might just be that they gasket is not thick enough to fill the void that is there due to decking issues

oldirtydirt

v6 22re

RAMROD84

Agreed!

RAMROD84

Ill be back at it tomorrow. If I cant figure it out ill be pulling the heads off.

justin_4runner

u might want to put a sensor or put a temp sensor that shows what temp it running, might not even be running as hot as u think..

93toyrunner2

If the temp gauge never goes above 1/2 without the thermostat, then trapped air is going to be the problem. I purchased a radiator filling/burping funnel by Lisle at the auto parts that attaches to the top of the radiator, and used it to burp my system several times before it finally flushed out the air pocket. I had my truck on an incline, as well as up on ramps, while doing this. Now my gauge is back at 1/2 all the time when running for more than 3-4 minutes. It can be aggravating, but persistence is the key.