Blurr

for as long as I have owned my 4runner the temp needle has never budged higher than the middle of the gauge. I know this is typical and our 4runner temp gates are often regarded as nothing more than a dummy light but this has recently changed for me.

yesterday in the middle of a 150 mile round trip drive i saw my temp gauge spike up to the redline two separate times. it was after driving about 70mph and immediately slowing to a crawl due to traffic. the needle would bounce around when i would speed up and slow down and eventually it went back to the middle after the traffic let up and i could get back to 60-70mph. i know that the engine would normally heat up in a situation like this but my temp gauge never moved in the past. i pulled over, no coolant leaks, nothing looking out of the ordinary. i cracked the radiator cap and coolant sprayed out so i know that the radiator system wasn't dry. after i got back home i let it cool down and looked at the coolant level and it was full and looked normal.

I replaced the radiator about a month ago but i have put over 1000 miles on it since, most of it during 90+ degree weather, and the temp gauge never moved until yesterday. the thermostat has about 25k miles on it but it isn't behaving like i have seen stuck thermostats behave in the past. the fan is moving freely.

has anyone experienced anything like this before? anything else I should look for?

BigBluePile

iTrader: (3)

What do you mean by "the fan is moving freely?" Like when you spin it, does it take some effort or does it move effortlessly?

Blurr

i mean that the fan spins like it always has

BigBluePile

iTrader: (3)

Ok, well, if the clutch fan isnt' engaging that might be causing your hot flashes...lol! Reason I'm asking is because I dont run a clutch fan anymore, I have an electric fan plus an aftermarket temp gauge. When I come off the highway(the efan never runs, obviously due to the freeway speeds) to an intersection to stop I can watch the temp gauge(aftermarket one) move up, fan come on and the needle will return to where it was. So, if your clutch fan isn't engage right, it might cause a delay in cool down. Make sense?

So, again, does your fan spin around or not?

Blurr

yes the fan seems to be spinning just fine.

Lumpy

Well after 1K miles I'd rule out an air pocket. If you say the fan is alright then we'd have to take your word on it. The stat could be bad? I don't know may have a clog somewhere but I'm with Blue on this and it could be the clutch. I can hear my fan when I'm at a light and just start moving...So I'm not sure if mine is sticking but she has not gone over 1/2 way. Just gets loud when stopped and start once your moving it quites down. Now my 22re does not do this. I need a stat it's stuck open so I never hear the fan.

Blurr

i don't think i have ever dealt with a faulty fan clutch. what are some symptoms to look for?

Lumpy

Well with mine at startup the you really can hear the fan running then it slows down and it's normal. After it gets up to temp and I'm at a red light and start moving again you can really hear the fan when I get up to bout 10-15 mph it quiets down.

I'm thinking if you let it get up to temp and shut it off and try to spin the fan it should have resistance to it. While it's idling and coming up to temp you should be able to tell when the fan speeds up and slows down just by watching it.

BigBluePile

iTrader: (3)

Ok, I think we're confused about the spinning thing. Lets make a comparison: Ceiling fans, bare with me here. If you can reach up to a ceiling fan as it sits not spinning and push against one of the blades it should spin around for a bit and THEN stop. If your clutch fan does this, that's bad! lol! Now, your clutch fan is fluid coupled and engages by temperature(I can't seem to find 4crawlers info on this, you might have to search a little...) and when you try to spin it, it'll only go about a half a turn or so and immediately stop. Thats good!!! As Lumpy said, thems fans is LOUD!! LOL!! On start up, or during a hot condition, you should here that sswwoooOOOOOSSHHHH sound and then it'll diminish as the system cools down.

Blurr

ok, i'll take a closer look at how the fan works at startup and after the engine warms up. i definitely recall the 'wooosh' when it first starts but i'll check it again to see if anything is different.

freddy

so, what hapend?

Pigman

I have seen thermostats act up like the symptom your describing, especially after market, as cheap as factory t-stats are, that would be the fist thing I would do. Over the years I have never had any long term service out of "aftermarket" t-stats, but thats just me! As descibed above with the engine at operating temp , you should feel some resistance in that fan clutch, maybe not a lot but some none the less. Hope that helps.
Pigman

Pigman

I did forget to mention, seems like a bad fan clutch is going to give you more of an overheat condition at slower speeds and in town driving(lack of air flow) as oposed to higher speeds due to the airflow thru the radiator because face it your doin 70mph. At slower speeds that fan is sucking the air thru the radiator, make sense???
Pigman

BigBluePile

iTrader: (3)

yes. That's what the OP said.

Blurr

i think the fan clutch is ok. when cold i can move it but it does not spin and i still hear the WOOOSH when i first start it up then it the fan slows down.

over the weekend i drove just city streets with heavy stop/go traffic during the hottest parts of the day and the temp gauge stayed right in the middle. however when i took it on the freeway, even for just a few miles going 60-70, the temp gauge would shoot up to the red as soon as exited the freeway onto the city streets. way too strange.

the t-stat is from the dealer. it is a $5 part and wouldn't hurt to replace but i'm skeptical that it is the culprit. thank you for all of your comments so far. any other thoughts?

DupermanDave

did you actually order the thermostat yet? Im about to order one and dont want to be surprised when it's $37. Went to a subaru dealer for a "$17 part" (as the internet called it) and it was $50.

BigBluePile

iTrader: (3)

Well, which radiator is it? Is it really thin? Or is it a three core? It sounds like it does fine in the city. Too me it sounds like the fluid isn't getting cooled fast enough, idk. Try the thermostat and check it and the old one before you put it in.

Blurr

dupermandave - i haven't ordered it yet and you're probably right in that it will be more expensive at the dealer (i can't remember what i originally paid) but I'm sure Napa has one for much cheaper.

bigbluepile- the radiator I put in 1k miles ago has the plastic top and bottom but is the same thickness as the original radiator. how do i know if it is a three core? i agree that the coolant doesn't seem to be adequately cooled. what i don't get is if the radiator is not doing its job why am i seeing problems 1k miles later? shouldn't i have had these symptoms much earlier on?

BigBluePile

iTrader: (3)

I forgot about the 1k mileage thing...hmmmmm.

Well, I think I'd try thermostat still, heck might even change out the temp sender while you are in there.

freddy

any news?