jdyoung

Okay guys, It's a 98 4runner, Drove it down to California last year with not an issue, the weekend after I returned I drove into Eugene Or. (2.5 hrs each way) on my way home out of nowhere the temp needle pegged on the red! I had it towed home and replaced the timing belt, waterpump and Thermostat, started her up and went to red!! Did a comp test all was well? So decided to do headgaskets and the radiator (new felpro MLS gaskets) So..... $650 later I started it up ran great for a day and then RED! Dang it! Figured at that point somehow it had either a cracked head or block? SO called B&R autowrecking bought a 3.4l popped her in and wala! went for a ride to Eugene (once again 2.5hr each way) No problems didn't go over mid way on the gauge all was well. THEN yesterday I went on a 45 min ride to get a quad with my trailer and looked down and it was in the red AGAIN? fan clutch felt a little weak so I put in a rapid-cool 18" elec. fan today just took it for a ride drove 45min out and 45 back no prob, then stopped at the local coffee stand and it idled into the red again! SO new radiator, new elec fan, new (used) engine, no water in oil or vise versa, comps at 180 across, I am lost guys please help!

FogRunner

With it giving readings of overheating in such varying conditions I would ask the question, is it really overheating or is the gauge/sender bad. To find out get a OBD scan tool that can display live data and watch the engine temp reading reported on the scan tool from the ECU vs what the gauge on the dash says. The fuel injection computer/ECU uses its own temp sensor which is independent of the gauge sensor and mounted in a different place on the engine.

I would also check how clean your A/C condenser coil is, I've seen guys go mudding and it plugs up their condenser enough got cause overheating. Wait till night time and shine a BRIGHT flashlight through the radiator and see if you see it through the front of the condenser coil.

It may not be either of those but its worth a try.

FOG

Kiroshu

I hate to say it but you should ahve taken it somewhere and had someone put a scanner on it with the temp issue just like Fogrunner said and they can go to an onboard data display in the scanner and see the temp reading. If it was staying at operating temp the whole time while the gauge was spiking red the sending unit was prob bad..... You may have just dumped hundreds of dollars into it for just a 30-50 buck sending unit... I'm not too sure where it is but try and find out where it is a get that handy Multi-meter out (if you don't get a scanner onit) and check for 12 volts on the wire with the key on if its got volts then the unit it prob bad. When this is happening ahve you tried tapping on the dash where the gauge is to see if it moves it at all?

jdyoung

I did check those options, I actuall bought an aftermarket guage and mounted it, Also the overflow was at a boil also? I did check the fins also, All clear.
I do know with previous vehicles I've owned when at operating temature I could pull the cap and very easily see the coolant rushing through the system, I pulled the cap and ran it to operating temp, took a pinch of pepper and dropped it in, Kinda just slowly moves away? Kinda wondering if even though it is a newer radiator if it is plugged somehow?

jdyoung

Also forgot to mention that I did purchase a new sender also for the factory gauge as well as the install of the aftermarket gauge.

Kiroshu

Wait at operating temp you where took that cap off and it was not curcualting? With the truck running and warm feel the top and bottom rad hoses and see if either one is still cold or both cold or hot. When it went hot the first time did you check the coolant lvl? Was the rad dry? On these engines the thermo stat is on the inlet side which on most engines the thermo stat is on the outlet. Disconnect the upper rad hose and pour coolant in until you can't anymore. You said you bought after market gauges? What where they reading going down the road. You need to get one of those gauges and or a scanner on there and drive it and see if it ever goes hot if the above don't work.

jdyoung

The coolant level has stayed the same, Hasn't went up or down? Allthough the location of the thermostat is on the outlet end of things, Shouldn't I still see a consistant flow with the cap off? What are the chances the radiator could be plugging up? It was replaced about 6 months ago. Is there a need for special coolant? I am running the common 50/50 premix from the local parts store.

Kiroshu

On these engines the themo stat is on the front of the water pump. The inlet is usually the low rad hose and the outlet the top. If the engine is warmed up you shuold see flow cause the thermo stat has opened and the water pump is now pumping it thoughtout the engine. The rad could very well be clogged you could take it and have it flushed somewhere. Now i've never seen this... but if the thermo stat its on the up under the outlet housing theres your prob.

rjaudi

Check to see if the upper radiator hose gets hot after the engine is running. The thermostat is on the engine side of the lower hose. The lower hose is the outlet and the upper hose is the inlet to the engine. That is why if the upper hose gets hot the coolant is circulating.

CodyX36

Same thing happened to my truck, just PM BigBluePile, he'll give you some coolant.

eddieleephd

What type of coolant and does the fan turn???? have you ever cleaned the fins on this radiator??

really could be a fan clutch or a clogged radiator where the air will not pass through it!!

mt_goat

Usually an e-fan will do even better cooling at idle than a mechanical fan will, IF its running and has a shroud. My guess is its got no shroud. What CFM rating does the fan have? You might have gone from a bad mechanical fan clutch to a bad e-fan setup.

Some actual temp numbers might help, as well as some pics of the radiator & fan setup. The basics are you need coolant flow and air flow through the radiator.

eddieleephd

also what temp rating is the thermostat?? and what Mt.Goat said as well. still did you ever blow out the radiator with an air compressor??
bugs and pollen and what not can prevent the flow of air through and reduced air flow will cause over heating too!

Please in the future break up your post to make for easier reading!

Blue_petersen77

The thermostat is facing the correct way right?

jdyoung

To answer all the previous questions at one time: The fan is 1400 CFM. Shroud is in place. Coolant is the typical Prestone 50/50 (states on the jug formulated to work with any color) Thermostat cannot go in backwards on the 3.4l the thermostat housing has an imediate bend to route around the belt, only allowing the thermostat to go in one way. (with the temp measuring device facing the block). The temp rating on the thermostat is unknown? Allthough the temp switch for the new electric fan is 180on and 165off.

mt_goat

That's pretty weak. I'd say you need at LEAST 2000-2500 CFM, I think mine is close to 3500 CFM (Taurus fan on high speed). EDIT: this writeup claims 4500 CFM for the Taurus fan on high: http://www.go.jeep-xj.info/HowtoTaurusFanInstall1.htm

What temps are you seeing exactly? OBDII or real temp gauge.

Kiroshu

Were not getting the whole story somewhere cause you realized you have changed the entire cooling system including the motor.... Check hoses for hot/cold touchy feely. Get temp readings and do what i told you and get an after market gauge and/or scanner and drive and see what the readings do if they do anything.

jdyoung

I went ahead and replace the thermostat today to be sure it is good, as far as the aftermarket temp guage.... I am going to install it tomorrow, After replacing the thermostat I drove out the highway to the next town (45min) and back never got above the 1/2 way point, but when I got home I sat in the driveway and let it idle for 5min and it slowely but surely went to the red? I shut it down and it is definately overheating it was boiling pretty good into the overflow. Also this morning I added a toggle to bypass the temp switch on the fan (didn't remove the temp switch just added a bypass so if I was pulling my trailer or...... I could flip the switch for added cooling and/or safety?) Turned on the switch in the drive to have tha fan stay on full time. No help. (also did research on the fan as far as CFM and multipul manufacturers state that the fan I bought is more than enough CFM for the 3.4l, Most of the sites actually show a complete list of auto's and engine by size, on the 3.4l they all ask for a fan actually smaller than mine) Thanks guys, I will keep you updated, Gonna also take the radiator out and to the shop tomorrow and have it flowtested and flushed. It's new but I have had new parts fail the same day I bought them in the past. Just want to do it so I can take it off the list?

eddieleephd

I will tell you one thing those dummies that sell those fans know nothing about our trucks and if Mt.Goat says they need like 2000-2500 CFM I would trust him over any A$$HOLE at any shop even and especially Toyota Techs!!!

Now that said maybe what you really need to do is what I did and get a FLEX-FAN that is manual and see what happens if you do not want to venture the extra $'s for the bigger Electric fan... Mine works great and I guarantee that it goes like 3000-4500CFM and stays a little below half no matter what!

FogRunner

With the exception of those diehards that do seriously deep water crossing I don't understand why people ditch the stock belt driven fan.

With a properly operating fan clutch the OEM setup pulls far more than most electric setups do. I know some argue a electric fan gives them more horsepower, well with the amp draw its pulling the altnernator uses plenty more than the fan did.

I've lost count how many times I've sat idling in my 4runner on a extra job in blistering 90F+ summer time heat with the A/C blasting and the engine temp stayed dead center of the gauge. Same thing when I had to LIVE in my 4runner after hurricane IKE, engine running round the clock for over a week, temp never got a hair over the center mark. You never realize how comfortable a 4runner is till you have to call it home sweet home.

When it comes to the OEM fan I say its not broke so don't fix it


FOG