marcusSRG

Hey guys,

Posted this on the 2nd Gen 4runner Mafia page on FB and got some good responses but wanted to post here. I'm sure this has been discussed previously so feel free to link me to the right thread, but I think I have a fan clutch issue. My rig is a '94 SR5 3.0, bone stock.

My rig has started to warm up a couple of times on HOT days while idling. Never to red though, maybe 2/3s the way there. Turn the AC off, give gas and it goes right back down. I've been driving around without AC on and it's been just fine. Sounds like the fan clutch right? Just to make sure I did check coolant level and it's to the full line in the reservoir (never understood why the full line was so far down there) but it is not covering the top vanes in the radiator...although that seems to be how it always is.

I'm pretty much a newb, but I've been doing some heavy reading lately and am learning a lot. I want to try and remedy this myself and not take it anywhere. Is there a recommended thread for this job?

I'm about ready to put on some bigger tires and a 4crawler lift but I want to make sure it's working as it is before I do anything to it. ALSO make note that HGs, rad, VCGs, thermo, water pump, timing belt, spark plugs and the actual fan have been replaced in the past year. Brakes too but that's obviously not related.

Thanks in advance, sorry if this has been covered a million times!

Marcus

millball

The coolant level should always be above the core when you look into the radiator cap bung.

If the cooling system is sound, the high coolant temps force a bit of coolant into the reservoir while the engine is running, and the one way valve built into the radiator cap permits that coolant to be sucked back into the radiator when the engine is totally cooled off.

If there is coolant in the reservoir, and the overflow system is sound, (and no holes/leaks in the rest of the cooling system), the radiator should always be absolutely full to the brim when inspected cold.

As a start, fill the radiator to the brim, and the overflow to its mark, run it and see what happens.

Odin

millball is on target.
A full overflow tank and a coolant level that isn't up to the filler neck kinda sounds like you may have a leak somewhere. If the overflow hose has a hole in it or fits loosely it can leak coolant and then draw in air instead of pull coolant back in from the overflow tank.
Also make sure you don't have any wet spots/leaks around any of the hose ends in the cooling system.

You might also want to either have your radiator cap checked out or replaced. Just don't throw the old one away before the new one has proven it's good. I purchased a new Stant cap that was bad right out of the box. I have very little faith in what you get in auto parts stores these days.

marcusSRG

Ok thanks guys. I'm pretty sure the rad cap is new too. And it just did something else that it does every once in a while - after interstate driving (today drove about 10 miles going 70ish) and parking for a few minutes, when I refire the engine the temp gauge immediately shoots past half-way point but goes back down to normal when I start moving....note it has never got to red in any of these situations. Probably 3/4 the way max and starts coming down.

I recently had a pressure test done after I found a pool of coolant under the truck and a blown coolant line was discovered and fixed, perhaps another one is in order.

I'll fill up the rad, check for wet spots/leaks on hoses, although I look under the car (by habit) every time I get in or out and I haven't had any visible leaks since the above incident.

So I guess fan clutch may not be the primary culprit...

millball

If you recently found and repaired a coolant leak, it is possible that the system was not burped successfully, and consequently, the cooling system was not filled full at the completion of the repairs.

Fill the radiator again and watch it for a while.

Odin

Since you said you are new to this..


While the engine is cold slide the heaters temperature control to hot and make sure the heater blower is OFF. Next remove the radiator cap and start the engine.


Look at the coolant level in the radiator. If it doesn't cover the top vanes add coolant or distilled water until it does but not more.


Wait for the thermostat to open. This will be obvious when the coolant starts rushing by the radiator neck. The coolant level may drop. When it does add more coolant or distilled water until it covers the radiator neck opening and put the radiator cap back on while it's still running. Now go for a drive down the freeway or up a few hills with the heater settings right where they are.


The next morning check the coolant level in the radiator, overflow bottle, and check for leaks.


Do level checks until you find a problem or it holds steady.
If the level keeps dropping you have a leak and if it holds steady and there are still temperature problems start looking in other places like the fan clutch or a plugged up radiator.

Also if you've removed the fan shroud that can cause higher idle and low speed temperatures because it decreases the airflow through the radiator at low engine and vehicle speeds.

marcusSRG

Thanks guys. I guess that's what I'll do. Its gotta either be a small leak somewhere or fan clutch, likely not the radiator, as that was replaced in the past year. And it doesn't visibly leak.

Also - why is the "full" line on the overflow reservoir at the top of the "skinny" part of the tank, way in the bottom?

Hey millball - let's see a pic of that "nearly mint" '95 mentioned in your sig.

kcaudill

Install an electric fan. Then you will have a couple extra hp and know for sure whats up with your cooling system

marcusSRG

Thanks. I'm going to assess my coolant levels first before I look at the fan. I added coolant this morning (as instructed above), drove down the interstate to work and now it should be cold again, I'm going to go and see what it looks like here soon.

Edit: checked and it was still above the vanes., albeit slightly lower. Will check again tomorrow morning.

YotaWoRx

I've had this happen before. I thought I had a bad head gasket because I would top off the radiator and reservoir and coolant would disappear. No visual leaks. I had a milky residue under my oil cap signifying coolant in the oil. Long story short, turned out to be a small crack in one of the heads......

marcusSRG

YotaWoRx - thx for the input. Let's hope it's not heads as I've had those and many other engine components fixed over the past year. My coolant was a little low but I had replaced a bad hose fairly recently, so hoping I can attribute it to air in the system. It took just about 1/4 bottle of coolant when I topped it off yesterday morning...but we shall see... I’ll take a look in there and see if I see any milkiness.

Anyway, I had a chance to start and stop a lot today and have some results, and a video showing my gauge spiking. Below is a timeline. *Remember, it warmed up on me last week sitting in traffic with AC blasting (3/4 the way to red) and pretty much immediately went down with driving. It also sporadically warms up past half way very briefly after starting the engine (both with AC running and not running, often after highway driving). Rode with AC off until today. Also we have been in a HEAT WAVE down here. Here's what's been going on:

-Yesterday morning: topped off coolant per Odin's instructions and drove down the interstate to work (with NO AC and heater temp gauge all the way up but fan not turned on). No heating issues.

-Yesterday afternoon: went to check coolant in rad now that truck was cool; level was the slightly lower but still covering top vanes. Drove home still with no AC and heater temp gauge all the way up but fan not turned on. No heating issues.

-This morning: checked coolant and it was at the same level covering the top vanes; drove to work still with AC off and heater temp gauge all the way up. Had to leave work on an errand about 10mins after arriving and temp rose past half way right at ignition and immediately went down when I started driving. Stopped for gas, restarted after filling, and no heat spike - gauge stayed normal. Since it wasn't acting up I turned the AC back on full blast. Drove on the highway, stopped about 45min, restart, no heat spike. Drive on highway with AC blasting, arrive at my last stop for only about 5-10 minutes, restart (still with AC on) and it spiked. Flipped the heat on and started driving and it goes right down. It's like it gets hot while off and it takes a few moments once turned on to get itself cool again. Here's a link to a video I took of it warming past halfway after the last restart (had sat about 5-10 min after going down highway and AC was on full blast):




I haven't seen the temp go up while stopped or idling since the instance last week. Sometimes I notice the fan "roaring" a bit during off-highway driving but not consistently. I will continue seeing what it does with the AC on (it feels a hell of a lot better!) and re-check coolant tomorrow AM.

Sorry for the long post but I wanted to be detailed….y’all lemme know what you think. Remember I’m pretty green with this stuff. Thx.

Odin

Fill the radiator neck clear to the top so that coolant comes out of it when you install the cap.


It's fairly normal to see a different level in the overflow bottle for a day or two. However it should normalize fairly quickly, especially in hot weather.

In the mornings before you start the engine remove the radiator cap and look into the radiator.
The coolant level needs to stay right at the bottom of the cap. - Touching it

You're sure there are no leaks? Try removing the overflow hose from the radiator. Next remove the top from the overflow bottle. Place a finger on the hose that is submerged in coolant. Now suck on the end that connects to the radiator and make sure it holds vacuum. Both of those hoses are generally neglected by most people.

I know you said the radiator cap was replaced but new ones can fail out of the box and it's not unheard of to have a new one fail within a year. If you have the type that has the release lever on top you might want to replace it anyhow. That type has been the source of leaks for me on a few cars.

Odin

That's a good thing, it normally means the fan clutch is locking up tighter so it's turning more (less freewheeling) and attempting to pull more air through the radiator.

marcusSRG

Thank you. Okay, that cleared up the level - I had thought just covering the top of the vanes was needed. Will add more in the morning and check the overflow hose.

BTW no warming in traffic on the way home. But it did warm up when restarted after stopping at the store. This was after going up the interstate and stop/go local traffic. BTW - I noticed that if I just turn the ignition on and not the engine, the temp still spikes. When the engine actually starts it may keep moving up a sec but then starts cooling down.

Odin

We can't view your video because it is set to private.

I've been wondering about the thermostat too. Do you remember what you replaced it with?
If it was aftermarket I'd be suspect of it.

Aftermarket thermostats, like the radiator caps have been known to fail right out of the box or not long after.
You do not want to everheat these engines! $$$

I would rather spend $25-$30.00 replacing the thermostat and radiator cap than have to rip the engine apart, replace the head gaskets, machine or replace the head, or worse.
It's even worse if you have to pay someone to do it for you.

marcusSRG

Sorry about that. I thought the video was set to unlisted. It is now so it should work.

Yeah I'm definitely aware you can't overheat a 3VZE. I'll check the thermo but I know the person who put it in was an old Toyota mechanic, for what that's worth.

Odin

I thought you were talking about a big spike to HOT.
In warm to hot weather the temp in the video doesn't look too bad to me but I know more of the 22RE. If a 190-195 thermostat was installed that might be a cause of the temp being where it is. Like you I would like it a little lower.

I'm somewhat of a bad customer for repair shops. I'm always suspect of the parts they install in cars trying to increase their profits. You might be able to install a 180 degree thermostat to bring it down some. If you're not willing to dig in there to see what's in it right now you'll never know.

marcusSRG

Yeah, I was trying to make sure I said it got warm, not hot. It hasn't gotten into the red once. Got towards it but never to red

Edited - thanks a lot, Siri

Odin

To me the 3/4 mark on the gauge IS HOT and hints of danger and $$$.



When the engine is off the water pump isn't pushing lower temperature coolant from the radiator through the engine.
Since the coolant is now just sitting there it starts soaking up the higher temperature from the block and heads and is shown by the higher sitting temperatures (especially in the summer) and a few seconds after you start the engine.
You'll mostly notice it when you have a mechanical water temperature gauge and a 190-195 thermostat.

Once the water pump starts pushing cooler water from the radiator through the engine and passed the gauges temperature sensor you'll notice the gauge start heading back down.

I'm not a big fan of 190-195 degree thermostats unless it's winter time. I know it's only 10-15 degrees but being at the 1/2 way point makes me a little nervous in the summer. It always seems a little to close for comfort to me.
They claim it's for better burning, lower emissions

Whatev'a

marcusSRG

Just an update: no major issues other than warming past middle on a restart after highway driving the other night. Coolant level has held steady but this morn it seemed maybe a little bit lower. But... I have been running my AC and usually keep it on recirculate...but yesterday I switched to fresh air and am noticing a coolant smell while idling. I'm starting to think heater core. How easy is that to DIY?