WillRadford

First of all I got to say that I love this forum. Last month while I was tearing my heads off (V6 3.0) to get a valve job done I found some threads in here that really helped, especially with getting the camshaft sprocket bolts off. All went fine with that project and I am very happy with the way she runs now (more power, no more rough idle, better gas milage). BUT, the reason why I come here today doesn't have to do with that, it has to do with overheating.

Rig: '94 4Runner v6 3.0 170k miles.

Symptoms: Overheats only when pushing her hard (driving with A/C on going up hills). Doesn't matter if its on the freeway or going 30 mph. Temp is easily brought back down if i shut the A/C off or let the rpms drop down.

Here is what I know: Last year I got a new radiator put in, as well as water pump when timing belt was done. Thermostat is new and good. Radiator cap is new and good. Cleaned the dirt and grease off the fan clutch. Ran cleaner through the radiator twice, which by the way was coming out a little dirtier than I would have expected it.

I took it in to a radiator shop last weekend and all they could find was a supposed leaky hose that they replaced when they did a pressure test.

So Im stumped. I want to say that I need a new radiator but that wouldn't make a lick of sense, unless the shop that did my timing belt last year gave me an old radiator and just said it was new. Any thoughts anyone?

Thanks,

Will

digdug

Sounds like the fan clutch is bad to me. I had very similar symptoms on my 2001 dodge dakota and replaced the fan clutch and radiator cap and that fixed it right up.

To test the fan clutch, you need to get something (i.e. broom handle) and stop the fan from being able to turn. start the truck and let it come up to temp with the AC on. With it still running, remove the broom handle to let the fan go free. It should try and lock up, causing a lot of fan noise as it tries to catch up with the temp and cool it down. If it just spins kind of lazy like and makes no effort to lock up you have a bad clutch.

WillRadford

Thats kinda what Im thinking, is that the fan clutch needs replacing. Does anyone know how that thing works? Is that spiral thing on the outside of it like a thermostat that turns it on? Why does the fan engage right when you start the engine but shut off after a few seconds?


There is also one more thing that I think may be a related problem, but I wanted to see what you guys thought. The other day while driving up the canyon, the car felt like it was kinda pulsing, where the engine would have slightly less power(kinda like there was an extra load on the engine), then go fine, then slightly less power, and on and on at a fequency of about a half to a whole second, whenever the hills were steep. At first I had no idea what this could be, but maybe it is the fan clutch engaging and disengagine on and off? Any other thoughts?

yota_krazy

In your post you noted that your coolant looked a little dirty. That is possible that you have a blown head gasket, but with your symptoms id lean more towards the fan clutch too.

Your last post said that it was kind of pulsing which would also make sense with the fan clutch as it was slipping and bogging your engine down then catching up. Thats my 2 cents

gonzo

Just a thought. How much off-roading do you do? Is the radiator packed with mud?. Or seeing you have a/c how about mud in the condenser. Also is the electric fan for the a/c working?
good luck

Crymson

Try switching to an electric fan or installing an engine oil cooler. Both have worked wonders for my 3VZE cooling issues. I run my rig hard, 4-6k rpm for 8-15 minutes at a time winding up mountain roads. Without the fan I would have to back off every now and then and let the temps get down to a reasonable level. The electric fan helped a little, keeping temps down longer, ultimately leaving the same result as without one. The oil cooler mounted in front of the radiator, has made a significant impact. Damned near full throttle, high rpm run for 15-20 minutes, and the engine doesn't break a sweat, temp gauge never exceeds 50%.

ZUK

iTrader: (1)

Will- I would be suspicious of the radiator. This is the problem with having someone else work on the rig.....you don't know for sure what they did. A new one on-line is about 120. If it keeps over-heating you will have a headgasket issue.

Poul D'eau

You might also want check your transmission, cuz its fluid is pumped through the radiator to cool it as well. If the level is good and its nice and Red you are ok... but if its brown.... you get the idea...

I'm leaning towards the fan clutch but "heating up going up hills" made me think of that as an outside shot.

Even if the tranny fluid is ok it wouldn't be a bad idea at some point to drop the pan so you can clean off the magnets and clean the filter.

WillRadford

So on Tuesday after work I went to Napa, bought a new fan clutch and installed it. I let the engine warm up and I started driving around up hills with the A/C on, and I immediately noticed the loud wirrrrr of the fan when the radiator got hot, and then it would go off when the radiator cooled off a little. My old fan clutch never got the fan blowing this hard when it heated up so I thought I solved the problem. But, the evening I was testing it, it was only about 80 degrees out. Yesterday after work it was about 100 degrees out, and when I drove home with the A/C on all was fine until I had to go up the big long hill when the needle started to climb past the half way mark. Nooooooooo!!!

So I now know that I'm getting maximum airflow across the radiator, but the heat just isn't transferring off the radiator fast enough when Im driving hard. Or, I guess it's possible that the coolant isn't pulling heat off the engine fast enough. I don't know. I need to know if my radiator is working as efficiently as it should be.

Crymson: Tell me about that oil cooler you installed. Did you just mount a little oil radiator thing up in the grill and run an oil line through it? I already have a cooler for my transmission up there, I guess I could do the same for the oil if it would help.

Crymson

The kit is manufactured by PermaCool and is available for under 100 dollars. You can choose either a sandwhich style adapter for the oil filter or a remote mount setup.

There was some "creative" modification to route the oil lines through the grille area. I am switching to the remote style kit as the sandwhich filter style makes changing and installing oil filters which was a pain in the ass on the 3.0, a living nightmare. A thermostat is also going in to bypass the cooler when temps are lower than 180 degrees, but thats not until I find the time to tool around on my vehicle.

Sorry for low quality pics, I seem to have misplaced my digi cam.




You may have noticed the neoprene foam I fashioned into a shroud to direct the airflow into the radiator. Although this does help cooling i'm not sure of how much since I put the cooler and the foam on around the same time.

They can be pruchased at www.summitracing.com

More information can be found at this address: http://www.perma-cool.com/Catalog/Cat_page07.html

gonzo

Whats it do w/o the a/c on?
Is the electric fan behind the grill for the a/c coming on?