Hi folks,

I live in NC and am having trouble with the current heat wave we are under. The truck wants to overheat if I sit at idle for longer than 5-10 minutes. I'm hoping it's just the thermostat, so am planning to replace it this evening.

My question: Is there any advantage to getting the lower temp thermostat? I'm assuming that Nissan would have put a lower temp thermostat in if the engine was supposed to run cooler, but just wanted some opinions.

She's a '93 King Cab 2.4L with 193k miles. Thanks!

I know out here in Cali its pretty typical to just remove the thermo, because it never really gets cold enough for it to matter that its been pulled. Just keeps the fluid flowing all the time.

quote:

Originally posted by blaisearts:
I know out here in Cali its pretty typical to just remove the thermo, because it never really gets cold enough for it to matter that its been pulled. Just keeps the fluid flowing all the time.

I don't think it's typical to remove your t/stat.

I wouldn't go to a colder one to mask a symptom being caused by something else..

934x4, check your fan clutch. If it's never been replaced- it's due to be.

YOu can check it : w/ the engine hot( and OFF), the fan should be hard to turn. If it easily turns, then it's not locking up like it should when things get warm.


Check out one of the vendor/sponsors on the homepage. Mention the N4W discount when getting a quote for the fanclutch.

ANd check your local dealer for the price- it will probably be 20% higher( or more) and you have to go shag it. The sponsors will ship to your doorstep.

Good luck.

I have to agree with hillbille on this one. Your problem definitely sounds like a failing fan clutch. If is were a thermostat problem, it would overheat even when you are moving.

Check the clutch as bille described.

Too many people pull the t-stat, or go to a colder one to treat a symptom. Running without a t-stat keeps the engine from reaching the temperature that it was designed to run at. The ECU detects this and supplies a rich fuel mixture to feed the cold engine. In most cases, it never "warms up". Poor fuel milage generally results. Don't fall into that trap.

hey guys,

Thanks for the quick responses. I don't plan to simply remove the thermostat due to the exact issues you've raised (poor fuel economy, etc).

So with the fan, the clutch was replaced a a few years ago and I'm pretty sure the fan is running. I've been hearing it a lot lately.

I left work this afternoon with the intention to hit Advance on the way home and only made it about a half mile down the road before the engine was pegged on H again. No good. I'm still thinking it's the thermostat, but am having trouble getting to it.

According to a Haynes manual I have (I know, they are hardly trustworthy) the thermostat is mounted where the top radiator hose meets the block, but I can't find it. I found another source that says it's mounted on the water pump, but I can't really get to it. Is there an easy way to do this or am I gonna have to pull a load of things off?

Thanks again for the help!

Also I know when I swap my radiator out for a larger one I'm also going to be running shrouded dual electric fans instead of the mechanical fan.

quote:

Originally posted by 93Hardbody4x4:
..... only made it about a half mile down the road before the engine was pegged on H again. .....

Your original post stated that it overheats when idling.
Faced with this new information, I have to ask YOU a couple of questions:
After it cooled, was the coolant level in the radiator low?
Was the coolant level in the overflow tank high or low?

To remove the t-stat, remove the fan shroud, power steering pump(real easy, 4 or 5 bolts), Remove the fan(4 bolts). Remove the t-stat, 3 bolts. Im probaly missing something. It was only a 30-45 min job tops. It really looks harder than it looks.

quote:

Originally posted by blaisearts:
Also I know when I swap my radiator out for a larger one I'm also going to be running shrouded dual electric fans instead of the mechanical fan.

A radiator for a v6 is about twice as thick as the four-banger one. I bought mine at Auto Zone for about $125.

Luckily my cousins work for 1-800-Radiator so I'll probably pick one up for pretty cheap. Not sure what one I'll go with. I'll probably just head over to the warehouse in Benicia and check out some v6 or v8 ones that have similar upper and lower hose locations. There's also a shroud design I've been thinking about. The idea has popped into my head watching the guys at drift events constantly spraying every radiator on the car and blowing air over them. Why not have a shroud that runs from the back of the oil and trans radiators to the front of the regular radiator so that the electric fans on the back are pulling air through a tunnel that increases in size from front the front to the back.

Hi guys,

Sorry about confusing you with the earlier posts. Originally the truck overheated when idling and I was able to keep it somewhat cool while driving to limp back, but when I drove it yesterday evening it wouldn't keep cool even when driving.

So I just got the thermostat all changed out and started it up. It was running rough and smoking quite a bit. Once again I only made it about a half mile down the road before she started overheating.

Thanks for tear down advice Bandit, you were right. I was actually able to get it off without taking the powersteering pump off though. I just took off the fan, shroud, 2 front belts and the radiator hoses to get to it.

In response to your questions Res:
After it overheated this last time, the coolant in the reservoir was high and the radiator was pretty low. Other than the reservoir boiling off, there aren't any coolant leaks though.

It's smoking an insanely large amount, reminds me of when my older brother's Landcruiser blew... It's making a "tut tut tut" noise as well.

So my prognosis is 1 of 3 things:
1- The water pump has failed. However the upper radiatior line is getting warm and I could see the level in the radiator moving after the initial start up while I was topping it off.

2- I've managed to warp the head and am getting a leak there. There isn't any residue on the dipstick though, so I don't have any evidence of coolant in the oil.

3- Catastrophic failure. Hopefully this is incorrect.

So what are your expert opinions? I'm starting to wonder if I should be in the market for a new vehicle.

High reservoir/low radiator indicates a couple of possibilities:
1) Leaky top hose that allows air to suck in during the cool down cycle while never leaking coolant because the hole is above the fluid flow. (Somewhat rare)

2) Leaking head gasket. Exhaust pressure is forcing the coolant out. This is most likey your problem, because of the smoke.
As the gasket errodes, it may begin to suck coolant into the combustion chamber during the intake stroke, thus creating tons of white smoke. Finally, the leak is so bad that coolant dribbles into the cylinder while the vehicle is parked, letting coolant into the oil pan and possibly hydro locking the engine.

Pull the head, have it pressure checked for leaks and shaved a bit to flatten the gasket surface. Follow the Hayne's manual to remove and replace the head. Pay attention; ther is a LOOSENING sequence to follow as well as a torque sequence.

Sorry for the bad news.

If it is the four-banger, it probably failed between 3 and 4.

Thanks Res, even if it is bad news I appreciate your help. You are actually the second person to tell me it's most likely the head gasket, so my worst fear here is most likely correct.

It's my daily driver so I'm a bit stuck. Let the new car search begin!

Thanks again for all the help. I'll make it a point to keep posting up here, especially if I decide to tear it down. Sadly this could be the end of an era though, that truck was my first vehicle and probably the most reliable one I'll ever own. I may cry.

Thanks again!

Paul

Whoa, dude! It's not all doom and gloom! A head gasket job is not the end of the world.
It's a bit more involved that an oil change, but I did mine on a Saturday. I borrowed my wifes van to take the head to the shop and get it shaved.

Order the gasket set and start removing the head on Friday evening. Finish removing the head on Saturday morning and take it to a machine shop. When it is ready, rent a torque wrench before leaving.
Put it back together and you are good to go.
read through that section of the manual a few times until you have it clear in your head. If you run into problems, post up here. We are happy to help.

also head gaskets are not that expensive to have done. My girl paid ~600 for the head gasket in her honda to be done. Which included the machine work expenses.

I would fix a hardbody before I would get another vehicle. Theses trucks are just workhorses.