# 1995 4cyl Pickup - overheating



## neytas2000 (Jan 15, 2006)

I have a 1995 4cyl 4x2 pickup. It is overheating even after I replaced the thermostat. What else can it be. the radiator is not leaking and all hoses are secure and free from cracks. what else can i look for?

fyi - it does need an alternator belt, but i'm not sure if thats related. maybe one of those pulleys are connected to something that has to do with the cooling... any help will be appreciated. I am trying to fix this myself to save some $ and then all I want to do is sell it to the first offer.

good truck otherwise. 1st time anything has happened in 11years. (98K miles)


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## dvdswanson (Nov 6, 2005)

do you have any fan belts on the truck? you need a fan belt to turn the water pump. now if you do have a belt on, check to see if you need to bleed off the air in the system. have you pressure tested the system?


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## mitchell35758 (Oct 21, 2005)

FWIW
I had replaced a thermostat in my old elantra. It overheated after replacing it. Turned out that the thermostat was defective and stuck in the closed position.


Some vehicles you can run them without the thermostat for few purposes. One of them being to make sure there is nothing else causing the problem. I don't know if you can do it on that truck, but if you can and do try it and it still overheats then you know for sure that there is something else wrong. Or you can test the thermostat by boiling it in a pot of water and checking ot see when it opens and shuts while monitoring with a thermoeter. Thats how I found out I had a bad (but brand new) thermostat on the old elantra. 

Just thought I would mention this.


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## mcm4090 (Jan 20, 2006)

It is possible that the thermostat is installed upsidedown. There is a bleeder hole on the thermostat that needs to point up.


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## japtruck (Jan 6, 2006)

I think he said that he was overheating even before he replaced the thermostat....

I'm assuming that you could have a problem with the water pump. They don't always leak when going bad. You could also check if the fan clutch is engaging.


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## mitchell35758 (Oct 21, 2005)

japtruck said:


> I think he said that he was overheating even before he replaced the thermostat....
> 
> I'm assuming that you could have a problem with the water pump. They don't always leak when going bad. You could also check if the fan clutch is engaging.


I understand that. When I had my problem in my elantra, it was overheating before I changed anything.I want to say that replacing the thermostat every two years is in the maintence schedule for those cars, can't recall though. Read about someone having a similar problem and it was caused by the thermostat. SO, I replaced my thermostat. I had doubts that it was the problem because IT WAS STILL overheating. I pulled the new one out and tested it. SURE ENOUGH it was a defective part. Bought another one and put it in and it fixed the problem. 

I am not saying this is the same problem, just thought I would mention it before he goes one step further into spending money in parts. I know I would want to be damn sure I don't overlook something before moving on the real expensive stuff.


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## MrFancypants (Nov 18, 2005)

First off, do the fans come on? If they do, then at least you know the temp sensor is working and the ECU is cycling them on correctly.

Next, have you properly bled the system of all air? When you replaced the tstat did you replace all the coolant and bleed the system correctly?

Your water pump could certainly be bad -- especially considering the age of the motor. Are there any coolant leaks around the WP?

The radiator could also be gunked up, and the tstat you put in could also be faulty. Always use OEM thermostats. The crappy copies you get at the local parts store are NOT very good quality. Hold a genuine Nissan one next to it and you'll see the difference. Hopefully you installed it right side up, but even still the bleeder hole can get clogged with RTV if you use too much.


- Greg -


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## neytas2000 (Jan 15, 2006)

This is all awesome information... I am a true Novice
1 - What does ECU stand for?
2 - How hard is it to bleed the system?
3 - Where is the water pump?
4 - Is it hard to change the water pump?
5 - Does the water pump run from the same belt as the alternator? thats the one thats broken as well...


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## mitchell35758 (Oct 21, 2005)

neytas2000 said:


> This is all awesome information... I am a true Novice
> 1 - What does ECU stand for?
> 2 - How hard is it to bleed the system?
> 3 - Where is the water pump?
> ...


1. Engine and/or Electrical Control Unit
2. Haynes or some other manual and it should not be bad
3. Front and center looking dead on at the engine(95% sure, somebody correct me if I'm wrong)
4. Not detailed information, but answers this question to some extent.
http://experts.about.com/q/Nissan-Repair-825/replace-water-pump.htm
5. I think so, I believe it is on my 04, and they really haven't changed much as far as the engine is concerned.








This is supposdly the picture of the 95 nissan hardbody water pump.


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## CT_Nismo (Dec 25, 2005)

Have you check your brakes? Dragging brakes can put an extra load on the engine. But you will see this is bad mpg and poor performance.

Are you sure that the radiator flow channels are open? Crud will block them but you will see it from the filling port.

Are either of the radiator hoses collapsed due to vacuum?

Are you losing radiator fluid due to a manifold gasket leak? This is easy to check.


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## JZ82 (Jan 13, 2006)

The fan is attached to the water pump. Test your coolant for the proper mixture. You need to have 50/50 split with Antifreeze and distilled water. If you have too much of either, usually of the water, the boiling point is lowered which can cause overheating.


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## MrFancypants (Nov 18, 2005)

JZ82 said:


> If you have too much of either, usually of the water, the boiling point is lowered which can cause overheating.


Actually if there's more than 50/50 water you lower boiling point but increase heat transfer. The highest boiling point isnt necessarily desired. You need a balance of heat transfer and boiling point. Depending on the application, it can be a good idea to run more water than antifreeze (like 70/30).

You can also get a bottle of Redline Water Wetter. It has surfactants in it that inhibit boiling and help with heat transfer. Make sure you follow the mix directions though to ensure the correct ratio.

Last, you can try a performance radiator cap. I believe the Frontier has a 1.1 bar cap (pretty much standard for Nissans). You can cheat with a 1.2 or 1.3 bar radiator cap and effectively raise the boiling point of the cooling system without changing the coolant mix. This again lets you get more heat transfer with a higher boiling point.


- Greg -


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## CT_Nismo (Dec 25, 2005)

I think Neytas's overheating problems is beyond antifreeze concentration, and pressure cap.

From this board, I am learning every day the influence of aftermarket vendors has on car enthusiasts. That any particular part, gizmo, or additive actually works is subordinate to believing the story that it works. If someone was to try and sell me Redline Water Wetter on the concept that it inhibits boiling, I would walk away. 

Fundamentally it is ambient air that cools the engine. Engine coolant, radiator, hoses and all the other stuff are just intermediaries used to move the heat to the radiator where it can be cooled by the air. Well, you ask, "why even have this middleman, why not cool the engine with air just like the Beetle." If you can answer this question, you will know why Redline Water Wetter does nothing.


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## mitchell35758 (Oct 21, 2005)

CT_Nismo said:


> I think Neytas's overheating problems is beyond antifreeze concentration, and pressure cap.
> 
> From this board, I am learning every day the influence of aftermarket vendors has on car enthusiasts. That any particular part, gizmo, or additive actually works is subordinate to believing the story that it works. If someone was to try and sell me Redline Water Wetter on the concept that it inhibits boiling, I would walk away.
> 
> Fundamentally it is ambient air that cools the engine. Engine coolant, radiator, hoses and all the other stuff are just intermediaries used to move the heat to the radiator where it can be cooled by the air. Well, you ask, "why even have this middleman, why not cool the engine with air just like the Beetle." If you can answer this question, you will know why Redline Water Wetter does nothing.


Cooling is limited by energy (heat) density. Air cooling can be a difficult thing. If you have a piece of the engine that is getting hotter than the rest of the engine, it is hard to cool it down because air itself has low heat density. Depending on the speed of the air cooling the engine, the air can heat up to almost as hot as the hot spot, thus making it the efficiency of cooling the rest of the engine very low. In clearer words, there is only a small mass of air to carry the heat away. To counter this you would have to blow more air but that takes more power and makes more noise. The problem with getting enough air to those parts to maintain the temp of that part will cause the rest of the engine to run cold. Liquids tend to have a much higher heat density and so a trickle of the fluid can keep the part cooler. Air cooling can be difficult when it comes to this because sometime the hot spots occur in locations that the air can not get to. Hot spots can form any where in the engine and we not even know about it because as the coolant flows, it is keeping the rest of the engine at operating temperature. The temp gauge will read as normal. The problem with liquids is that when they reach one of these extreme hot spots, they are going to boil, then turn to gas causing a momentary blockage which just lets the hot spot get even hotter. Having these small and tiny overheating spots within the engine can cause a significant engine wear over time. It is almost like a cycle, the coolant hits the spot that has become hotter and then it boils and turns to gas causing another very quick(extremely quick) blockage that lets the hot spot get even hotter. The coolant that has become a gas mixes back in with the coolant as there is still going to be circulation throughout the engine. The method of air cooling eliminates these small blockages because there is nothing to boil. Air is already is the state of a gas. 

The components of a liquid system do weigh more in weight, but the air systems are more expensive and the cost benefit is in favor of liquid cooling. 
Liquids have less temperature rise as they absorb waste heat. The coolant temperature varies under the operation of the engine. The more even temperature of liquid coolants means better component tolerances can be maintained. It might be possible to achieve good temperature control with air cooling but it will be at the expense of more complicated and heavier temperature management.


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## OBYWAN (Dec 6, 2004)

*OVERHEATING 4 CYL*

Your 4 cyl needs to have the air purged when you replace coolant in your radiator. The procedure is pretty straight forward. On the left side of the engine ( below the intake manifold) you'll find a brass screw. Loosen or take out the screw and then add fluid till it starts to percolate out of the screw hole. Put the screw back in and your done. If you lose coolant because of a leak or whatever, air will be sucked into the radiator if it gets below the level of the air purge screw. This might have been your problem. Just a thought. By the way, I've posted up this solution before. I suggest whoever reads these posts and does their own maintenace should print out this post for the future. The air bleeding solution also applys to the v6. The bleeder screw for the v6 is on top of the manifold in the right rear. :cheers:


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## CT_Nismo (Dec 25, 2005)

Mitchell,

You have figured out two of the critical attributes. Heat capacity, the energy it takes to cause a 1 deg rise in temperature. Air is about on fourth that of water. Density, mass per unit volume; air is must less dense than water (1000X). There is a third attribute that is also important. Hint: why do we wear woolen sweaters to keep warm? Why do we insulate houses with fiberglass. Why does holding a piece of steel in one's hand feels colder than a piece of plastic when you know they are at the same temperature?


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## azrocketman (Oct 5, 2005)

neytas2000 said:


> I have a 1995 4cyl 4x2 pickup. It is overheating even after I replaced the thermostat. What else can it be. the radiator is not leaking and all hoses are secure and free from cracks. what else can i look for?
> 
> fyi - it does need an alternator belt, but i'm not sure if thats related. maybe one of those pulleys are connected to something that has to do with the cooling... any help will be appreciated. I am trying to fix this myself to save some $ and then all I want to do is sell it to the first offer.
> 
> good truck otherwise. 1st time anything has happened in 11years. (98K miles)


Under what conditions does the engine overheat? Are ambient temperatures hot or cold? Are you carrying heavy loads, towing, or is it just you in the truck? Will it overheat while idling? Stating the conditions might assist the group in identifying possible problem areas.


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## azrocketman (Oct 5, 2005)

CT_Nismo said:


> I think Neytas's overheating problems is beyond antifreeze concentration, and pressure cap.
> 
> From this board, I am learning every day the influence of aftermarket vendors has on car enthusiasts. That any particular part, gizmo, or additive actually works is subordinate to believing the story that it works. If someone was to try and sell me Redline Water Wetter on the concept that it inhibits boiling, I would walk away.
> 
> Fundamentally it is ambient air that cools the engine. Engine coolant, radiator, hoses and all the other stuff are just intermediaries used to move the heat to the radiator where it can be cooled by the air. Well, you ask, "why even have this middleman, why not cool the engine with air just like the Beetle." If you can answer this question, you will know why Redline Water Wetter does nothing.


As an owner of two 1966 Corvairs I can say that air cooling's primary advantage is that I do not have a bi-annual coolant change. The downsides include lots of sheet metal around the engine to duct the air, a mediocre heater, high engine temperatures (over 300 degrees F), high oil temperatures (it provides some of the cooling), and pinging in hot climates (like Tucson) on pump premium. The difficulty in maintaining a constant operating temperature creates emission control problems which is why air cooling, for the most part, is history. By the way air cooling can use a fair amount of power. A Corvair cooling blower (fan) pulls over 15 horsepower with the engine at high rpm's.


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## CT_Nismo (Dec 25, 2005)

Rocketman,

I remember the Corvair all too well. My friend had one in high school and we had lots of fun with it. Twice, under hard braking, we did 180 (rear engine weight imbalance). I cannot tell you how many times we fished out the fan belt (the one that turns 90 degrees) to reinstall it. For all its faults, it was freedom for us youngsters so it cannot be all that bad.


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