1997 3.4 Limited Overheating issues...

[4runningfun]

Alright guys,


I know I havent really posted here, Ive been a long time lurker, and also a previous member of TTORA for the better part of a decade.

I have a 1997 4Runner Limited. It has an auto transmission, and currently has 211,000 miles on it.

Now, I purchased this 4runner almost exactly a year ago with 178,000 miles on it. Here are the events that have happened in the last year as follows:

2 weeks after purchasing it, the A/C compressor seized up. I went broke purchasing this beautiful piece of toyota machine, so I snipped what looked like a fresh belt and carried on about my way without A/C...

about 1 week after the A/C compressor seizing up, it slowly developed a rough idle, and one particular morning before work, (bare with me on trying to describe this) it sort of hydro-locked.... as in the starter made three cranks and then seem to hit a unpassable wall. I let off the starter, and attempted to start it again only to act as if it had a dead battery, but did not. a third attempt turned the engine over enough and it fired up.

at this point, i dumped the oil, to find it extremely milky and runny... blown headgasket. I made arrangements with a reputable mechanic, hauled it in, and they confirmed it... both headgaskets were popped in their usual locations,

the good news was the head was in good shape. it hadnt been overheated, it hadnt been driven far after developing issues. my mechanic went through using OEM toyota parts, and replaced the head gaskets, and also replaced the timing belt, water pump and t-stat. he had the head resurfaced, and I trust his work as he is well known as a "toyota-nut" in the area. ... he also replaced my a/c compressor and recharged my air.

after getting the runner back from the mechanic, all seemed great, it produced great power, it was crisp when starting.. we took it on a 1500 mile road trip to the oregon coast and back...

In mid august around here in north-central idaho, it tends to be insanely dry and very hot (95-110 degrees). My work commute consists of roughly 35 miles one way, with a 8 mile, 6 to 7% grade that i usually hit around 4:30 or 5 pm (about the hottest part of the day).. if i pull this hill at any speed over about 58 mph, on a day thats 90+ degrees... my 4runner will overheat.

this has been an ongoing issues that has carried over from last summer. now that it is june, and we are receiving rather warm weather (it was 97 degrees today) my 4runner got warm on the way up the hill, and i had to slow down, crank the heater, and take it easy the rest of the way up the hill.

When winter came on, I found out that my heater produced lukewarm air. in november, we took an air compressor, and blew into the outlet port of my main heater core, blowing out a bunch of nasty gunk. it was too cold to be able to run water into it, we put it back together, put fresh coolant in it, and my heater would work, however weak. out on the highway in winter. it would not be able to heat the cabin. in town at slow speeds, it could pump out mildly warm heat... nothing to write home about though. however the engine temp always stayed at dead center. (for the record, the rear heater does not pump out any good heat at all.)

Since the head gasket work was done, I have replaced the Thermostat with a stant from napa, I have always changed the oil on time at 4k miles or earlier. I have also replaced the radiator cap, along with all the routine maintenace stuff (air and fuel filters, plugs, wires.) I checked to make sure the radiator is not plugged, the muffler was replaced in march. we replaced the rear main seal, and clamped the heat shield on the crossover pipe as it was rattling (took me forever to diagnose that one). the downstream o2 sensor was replaced in february following a CEL indicating it was faulty.

Why is my truck still overheating???? ... I'm completely out of ideas.. and the past year of ownership has been absolutely dreadful.

Can anyone please give me any other ideas as to what could be causing this?

Thank you for your time.... and I apologize for the novel...

 

[cashmoney]

Have you checked the fan clutch?

 

[jeremyc74]

Fan clutch sounds like a good possibility to me. Does it overheat when idling for long periods?

It would help to plug into the diagnostics port with a scanner and monitor the actual temperature while you're driving around.

 

[BrianSD_42]

I would suggest you get a guage & code reader asap and plug it into the port that is by the gas pedal. You can buy one for like $35. One option is the Bluetooth OBD2 reader on Amazon for $20 to use with your phone.

It would help a lot to know the real temps here. Looking at the dash is not effective.

I believe the dash gauge for overheating into the red doesnt show hot until it gets to 230+ F.

I would consider anything over 215 abnormally hot (but not specifically dangerous) for a properly working and cooled 4Runner V6.

I have run my truck in the mountains when it was 106 F outside, in 4WD going up hills and it never went above 205.

 

[4runningfun]

Have you checked the fan clutch?

Fan clutch sounds like a good possibility to me. Does it overheat when idling for long periods?

It would help to plug into the diagnostics port with a scanner and monitor the actual temperature while you're driving around.

I would suggest you get a guage & code reader asap and plug it into the port that is by the gas pedal. You can buy one for like $35. One option is the Bluetooth OBD2 reader on Amazon for $20 to use with your phone.

It would help a lot to know the real temps here. Looking at the dash is not effective.

I believe the dash gauge for overheating into the red doesnt show hot until it gets to 230+ F.

I would consider anything over 215 abnormally hot (but not specifically dangerous) for a properly working and cooled 4Runner V6.

I have run my truck in the mountains when it was 106 F outside, in 4WD going up hills and it never went above 205.

Thanks for the replies,

as for the fan clutch, I believe it is in good working order, I have considered the possibility of it being faulty, and when i first drive it after it sits for a while i can hear the fan whirl for the first few minutes before the clutch starts to slip and lets go. i figured this was normal operation. the other thing i took into consideration was I didn't think the fan would do as much as wind would at 60 mph wind through the grille. i figured going speeds that fast would be sufficient to cool the radiator..

I have zero issues cruising in town anywhere between 25 and 35 mph. I have no issues cruising down a highway at 55-65 mph, even with hills involved. the temperature always stays steady dead center.

Now when it comes to grades, it will pull a grade within normal temp on any average day of the year. but as soon as i start seeing warmer days, my temp climbs.

I have a scangauge on order. it should be here by the end of the week. I agree with the dummy gauge not being accurate enough to tell whether im in danger or not, just past experiences have taught me that if temperature is fluctuating, the vehicle no longer has the ability to completely control the temperature of the engine.

My experiences with my tacoma have shown me that these trucks can handle the heat. it can manage to pull the very same hill, in hotter conditions with 35s without heating up one bit...

I've also had a gearhead friend of my recommend replacing my catalytic converter.. this does kind of make sense to me.. being that blown headgaskets can cause cat and o2 sensor failures, and a partially plugged cat can overwork the motor, and hold in heat when more is being demanded from the motor...

would you guys agree that theres a possibility that my cat could be the culprit as well?

 

[BrianSD_42]

Well I would think it shouldn't be that hard to get the cat tested.

Doesn't the smog test check the cat? I live in sunny CA and always assumed they were checking this with each smog test.

 

[4runningfun]

Well I would think it shouldn't be that hard to get the cat tested.

Doesn't the smog test check the cat? I live in sunny CA and always assumed they were checking this with each smog test.

Here up in this area of Idaho there is no smog testing requirements. I've never had to worry about it.

EDIT: as far as getting it tested.. the last muffler shop I took it to, they beat on it a couple times and said it was fine... I'm glad I didn't have them do anything more... it was a joke of a shop.

 

[psraff]

I think I read you have a napa tstat. Get a Toyota one and put in. My temps dropped 10 to 20 degrees in some cases due to running an auto parts store tstat.

Scangauge is great. Also the right bluetooth adaptor and the Torque Pro app.

 

[4runningfun]

I think I read you have a napa tstat. Get a Toyota one and put in. My temps dropped 10 to 20 degrees in some cases due to running an auto parts store tstat.

Scangauge is great. Also the right bluetooth adaptor and the Torque Pro app.

After I put it in I also read several posts relating to the OEM tstat being superior, and the importance of having it in the 6 oclock position.

I was meaning to get a cheap blutooth adapter from amazon to work with torque pro.. but I broke the screen for the second time on my LG and have yet to get it fixed.

for now, my iphone will get the job done. as far as I knew the last time I looked into it, Torque Pro is only available to Android.. is this still true?

I have plans to also replace my radiator. with the amount of miles I have put on, and the 4runner getting up in age. I think it would be a wise move overall.

Cat will get tested tomorrow. today was an oddball day as I didn't have to make the commute to my office, therefore didnt face the infamous grade that stands between us.