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1990 Nissan Pickup - Overheating/No Heat
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Britches
New User
Feb 24, 2008, 2:47 PM
Post #1 of 10
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1990 Nissan Pickup - Overheating/No Heat
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Hello,
I have a 1990 Nissan pickup. Right now it has no thermostat and runs no higher than the "C" on the temperature gauge. If the thermostat is installed, it runs hot. Here's a timeline of what's happened to it as well as what's been done to it:
1. Timing chain wore a hole in the timing chain cover causing the truck to overheat.
2. Timing chain cover was replaced and a new timing chain kit was installed.
3. Truck was overheating so we turned the heat on to help cool engine and no heat came out of vents.
4. New water pump and thermostat were installed.
5. Truck was still overheating and still had no heat so I had someone check for blockage in the lines and none were found.
I really want to get the thermostat installed so I can get it up to operating temperature. Why does it run hot when the thermostat is installed and why is there no heat?
Thanks in advance!
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jespo
User
Feb 24, 2008, 5:00 PM
Post #2 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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You need the t-stat for the heater to work  . So open the radiator cap, start it, look inside the radiator see if the fluid is moving, if not the radiator is blocked. Usually it would be the t-stat but because you don't have one it can't be that. Also look at the upper and lower radiator hoses see if they squeeze shut by themselves, if so replace. Make sure radiator is full of 25% water and 75% anti-freeze or all anti-freeze. A bad tune up would also make it over heat. No oil will make it over heat. Bad carb will make it over heat.
(This post was edited by jespo on Feb 24, 2008, 5:21 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 24, 2008, 5:59 PM
Post #3 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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Partially agree with jespo. No t-stat will run a flow of coolant more than useful to just the front of the engine and can be overheating where not detected. Boiling coolant won't transfer heat nor does air in the system.
The radiator is suspect. I'll suggest just 50/50 anti-freeze as higher concentrations don't transfer heat well and alone can cause overheating! NEVER USE STRAIGHT ANTI-FREEZE! Without water anti-freeze will turn to slush when cold and with water stays a liquid.
T-stats are mandatory as they also allow for mixing of the coolant within the engine to be a uniform temp and without one they may only cool locally where the gauge reads the temp. An engine that boils at one end and overheats at the other is highly subject to damage from uneven expansion of metal parts,
T
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Guest
Anonymous Poster
Feb 24, 2008, 11:58 PM
Post #4 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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You need the t-stat for the heater to work . So open the radiator cap, start it, look inside the radiator see if the fluid is moving, if not the radiator is blocked. Usually it would be the t-stat but because you don't have one it can't be that. Also look at the upper and lower radiator hoses see if they squeeze shut by themselves, if so replace. Make sure radiator is full of 25% water and 75% anti-freeze or all anti-freeze. A bad tune up would also make it over heat. No oil will make it over heat. Bad carb will make it over heat.
If the radiator was blocked, wouldn't the truck overheat with the thermostat out? I assumed the radiator wasn't blocked because I figured if it was, the truck would overheat even without the thermostat in. However, without the thermostat, it runs super cool. With the thermostat, it overheats.
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Britches
New User
Feb 25, 2008, 12:00 AM
Post #5 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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If the radiator was blocked, wouldn't the truck overheat with the thermostat out? I assumed the radiator wasn't blocked because I figured if it was, the truck would overheat even without the thermostat in. However, without the thermostat, it runs super cool. With the thermostat, it overheats.
 You need the t-stat for the heater to work . So open the radiator cap, start it, look inside the radiator see if the fluid is moving, if not the radiator is blocked. Usually it would be the t-stat but because you don't have one it can't be that. Also look at the upper and lower radiator hoses see if they squeeze shut by themselves, if so replace. Make sure radiator is full of 25% water and 75% anti-freeze or all anti-freeze. A bad tune up would also make it over heat. No oil will make it over heat. Bad carb will make it over heat. |
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Britches
New User
Feb 25, 2008, 12:02 AM
Post #6 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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Someone suggested it might be a blown head gasket. What are you guy's thoughts on this?
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dave284
Enthusiast
/ Moderator
Feb 25, 2008, 3:33 PM
Post #7 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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Signs of blown gasket, steam from exhaust pipe/sometimes rough running/overflow of antifreeze, do a compression check when in dout, you could have a bad temp sending unit?,does this vehicle have a fan clutch.The last time I ran into a problem like this I had found several cooling passages clogged up with corrosion thru out the heads and block
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slipperyslope
Novice
Feb 25, 2008, 4:37 PM
Post #8 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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If the engine wasn`t overheating before the timing chain episode,and wasn`t severely "cooked" when the timing cover wore through,I would think there is most likely air trapped inside the cooling system. Is there a bleed valve anywhere on the engine? If so open the valve with the engine off and add coolant to the system.IT COULD TAKE A WHILE! If no bleed valve see if there is a small hose up high on engine that can be removed to allow air to be bled off. It`s worth a try.
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Britches
New User
Feb 26, 2008, 2:38 PM
Post #9 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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I'm not sure if this helps, but my mechanic said that both the lines
going to the heater core are still cold even when the engine is
overheating.
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Guest
Anonymous Poster
Apr 18, 2008, 3:29 PM
Post #10 of 10
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Re: 1990 Nissan Pickup - Overheating/No Heat
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Just wanted to thank everyone for their help and advice! The problem has been fixed! He flushed the system, installed the thermostat, and bled the system. Now the heat works and the system doesn't overheat. Thanks again!
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