Aknightwhosezni

a couple days ago i was driving along and i noticed that my needle was on h... the engine was starting to lock up and become unresponsive... i said ok... this is simple... new thermostat will fix that... wrong... i bought another thermostat just to see if this one was falty and stuck it in some boiling water and it opened right up... then i said... hmm... must be the water pump.. its drivin on a belt with the fan... took it off... no gouge marks inside... it turns... must be working... i have full water in it and the reserve is to the max line.. it still overheats.. i have NO water leaks... and like i said... this has NEVER happened before... it just hit out of the blue.. any help would be appreciated..

jerryp58

The boiling point of water is around 200 degrees; the thermostat should open before that, but at least you know it wasn't stuck shut.

When was the last time you did a "flush & fill"?

The hoses aren't collapsing are they?

When the engine is cold, if you start it with the radiator cap off, do you see the water in the radiator move when the engine reaches operating temp? Be careful if you do this; watch out for the fan, the hot radiator, and put the cap on before you shut the engine off.

You don't have any signs of water in the oil (foaming), do you?

Just some thoughts.

__________________

Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd

Aknightwhosezni

lol... i did about 3 or 4 of them thinking its the radiator getting clogged... there is no water in the oil and the hoses do not collapse... and the water is moving..

Aknightwhosezni

anyone know of anything else i can do?

jerryp58

I'm not familiar with the fan on your '97; is it electric or mechanical? If mechanical, could the clutch be bad?

I would question the gauge (you could test it with a thermometer), but it sounds like you're pretty sure the overheating was real because of the engine response.

Nothing blocking the radiator?

Any timing, ignition, or sensor issues that could be making the engine run lean?

Any exhaust blockages?

Is it an auto that uses the radiator to cool the tranny fluid? If so, could the tranny be getting really hot?

I'm reaching here, but just thought I'd throw these ideas out there.

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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd

Aknightwhosezni

the fan is on a clutch... and it is fairly tight.. the radiator does have the tranny running through it... nothing is blocking it... timing and ignition is almost perfect... i get 26mpg (not running lean) and nothing is blocking it...

now... right before i parked this when it was hot... i would step on the gas and the rpms would go up.. but nothing(no acceleration) happened... just like it was in neutral...

the tranny works and doesnt leak anything,nothing that is audible that is wrong with it.... but... i did experiment today... i left it in my driveway and ran it at about 3200 rpm... the temp stayed the same...a little below half... then when i went around the block it shot straight up... i thought nothing of it... wow... im going to check the fluid level now... thanks.. ill edit this post with the results..

*EDIT* the tranny and oil levels are just fine..

jerryp58

How "tight" is it? It should move fairly easily.

Will it overheat if it's just sitting idling?

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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd

Aknightwhosezni

you can move it easily... but when it heats up it tightens up... anywho... i took the thermostat out.. (the last of three) and decided to see what it would do if i didnt have one in... im happy to say that it never went past half way since i took it out... i just put the housing back on with no thermostat... the thermostat is supposed to open up at 170 deg for normal operating temperature... this being texas and summer im not to worried about too low of a temp for my water... but come winter i will need to find a solution for this... the clock is now ticking... and it wont overheat if its idliling..

Yontrop

Indeed. I'd keep it like that until you find a solution. That's ok for summer, but it does need to be fixed by winter.

Here's a thought... are you installing the thermostat backwards?

__________________
ASE-certified technician by day, metal musician and computer nerd by night, and avid Nissan HB lover

1997 D21 XE KA24E 2WD 5-spd - 190,000mi

Will

I know you said the water is moving but the needle 1/2 way on the gage seems way to hot,even for Texas. Just barely reading on the gage would seem closer to normal with no thermostat.

Aknightwhosezni

there is absolutely no way you could possibly install the thermostat in backwards.. before this whole incident the needle was always at about quarter..... like i said... its fine until winter... but i am most likely going to replace the radiator..

and after i took the thermostat out i noticed a power boost that is a little more than noticeable(spelling)... that was cool... before i would have to floor it and it would start slower and then the power would kick in at about 3000... now... i step on it and the power is there.. anywho..

Aknightwhosezni

well... i bought a new radiator... itl be here in about half our... hope it works

Aknightwhosezni

I found the problem.... there is a crack in my heads.. the truck gets to normal temperature and then the metal expands... making the crack bigger... when the water seeps through it hits the hot metal and evaporates... so you dont see a leak anywhere... or water in the oil.... this is ass... now i have to take everything back apart...dammit.. im selling this mofo when im done and then buying a 240... im done with this 2 year [engine] project..

jerryp58

Bummer.

Did you change the radiator? Could the cracked head have been caused by the initial overheating you observed? If so, the radiator may have been the original problem.

Sorry it wasn't something simple.

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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd