85 N/A Coolant Question

[xX RB Xx]

My 300zx has a coolant problem. The car runs at a good operating temp and it doesnt leak any coolant while its running.

but

when I turn it off it leaks coolant from somewhere on the motor.. it doesnt leak from the radiator or any of the hoses. Its leaking about halfway down the motor and on the bottom of the engine.

Im not sure what it is. any help.

[AZ-ZBum]

My 300zx has a coolant problem. The car runs at a good operating temp and it doesnt leak any coolant while its running.

but

when I turn it off it leaks coolant from somewhere on the motor.. it doesnt leak from the radiator or any of the hoses. Its leaking about halfway down the motor and on the bottom of the engine.

Im not sure what it is. any help.

You sure it isn't condensation from running the air conditioner?

[xX RB Xx]

You sure it isn't condensation from running the air conditioner?

yeah im sure.. im not a total tard..I can tell the difference between the two. Sorry I should of worded my question better

fyi.. my ac blows out warm air.

it is coolant. Its green.

After i turn the car off its starts to leak.. when its done, its a pretty good puddle.
Modified by xX RB Xx at 11:34 PM 8/27/2009

[bigred240sx]

where under car is it after it drips. possibly one of those caps that keeps coolant in the block has come undone or loose.

[xX RB Xx]

^ that is what i was thinking..

but

i havent had the chance to jack the car up and look where its leaking. Its hot and fresh coolant.

[bigred240sx]

gotcha i would say you can tell without jacking but i forgot you have lots less room to work with than my s30. but those caps are my guess.

[xX RB Xx]

so your saying the core plugs are my problem.
Modified by xX RB Xx at 1:38 AM 8/28/2009

[Perrenial Badass]

Could be a freeze plug if it's gotten cold enough there. It's usually pretty obvious when one pops out though I suppose that one could be damaged abnormally.

There are a couple places it could be leaking out of. Is it on the driver's side, passenger's side, or front of the block? There are a few bolts that, if memory serves, are just used to block off some hole to a coolant passage. evildky should be able to confirm if ZBum can't from these pics:

Passenger's Side



Driver's Side

[xX RB Xx]

Its on the passenger side i do believe. before i got the car it had been sitting for a while, but the owner said that he had driven it a few times. I can assume it maybe the bolt came loose.

[bigred240sx]

the plugs are just a thought. but i wouldnt rule them out. but yea the bolts perrenial pointed out could also be it too. i wouldnt rule anything out yet since you still neeed to jack it up and check.

[evildky]

excellent responce perrenial! wow, pic's and everything, I was thinking freeze plugs as well, I've seen these nearly rust through on vg's

also leaks can be tricky to locate as the leak will cling and run, could be a hg leak, not comon buy pocssible, gould be a freeze plug in the valley running around

if you can't locate it , get it on a lift and pressurize the system

[xX RB Xx]

^ god i hope its not the hg.. im trying to get it too my buddy's shop to get it checked out since i dont have any tools right now.

[xX RB Xx]

Well i went and got my system pressurized and we found where the leak was coming from. Its either coming out of the water pump or out of the hose that runs right about the water pump..

we weren't exactly sure where its coming down but we have narrowed it down to those two.

i hope that it is just the hose, i should tried putting it back on there but i had to go to work and had to leave.

[Perrenial Badass]

Okay. Rubber hose above the water pump would be my guess, since the WP would have more issues if it was going out. Might be a good time to replace all the external coolant hoses. I replaced all of them on my Z except for one that ran from the intake manifold to the plenum, because it was hard to get to and wasn't cracked or anything. Big f***ing mistake on that one, blew out, then once I rigged it back up to limp home, the rest blew out. Somehow or the other the hose became so soft that it started ripping like wet paper.

The problem wasn't so much that it blew out, but it put coolant right on top of the hot block. After I spent a week getting all the grime I could physically reach out of the engine bay.

[xX RB Xx]

Okay. Rubber hose above the water pump would be my guess, since the WP would have more issues if it was going out.

you wouldnt have happen to have a picture of what that looks like do ya?

Im going to get some new hoses on Wednesday, I dont depend on the car to get to work or anything, so im not in a huge rush. and plus i dont have any extra money until then. I might as well replace my Radiator cap too.. it didnt look very well when i took it off.

[Perrenial Badass]

There is a small tube behind the timing belt cover, and a short hose from the thermostat to a pipe... that connects to another rubber hose leading to the radiator. The small tube is the most likely I'd think since it's not something somebody would think to replace when they did the other hoses. It also happens to be right above the water pump.



The second one is one that my friend had problems with. It is near the water pump so it might make you think it's the pump. My friend had this little hose bow out on him. To replace it, buy the cheapest hose you can find in that size and cut a short piece. You can also buy it from Nissan for $31574872495345.36.

[xX RB Xx]

thanks man that helps me out alot.

but would that explain why it leaks sometimes when i turn the car off and other times it doesnt. that is the only thing that puzzles me.

[kasilvia]

Sounds like a radiator cap to me. The key to what you said in all this is that it operates fine while driving. The cap is meant to hold pressure in the system, and when it reaches a certain pressure it bleeds to your resevoir, a non pressurized recovery bottle. As the car cools, the coolant returns to the radiator as the system draws a vacuum from the resevoir. When the cap is bad and the car is off, if the cap isnt pressurized, your system boils over into the resevoir and overfills it. Next time you turn it off, check to see if it overflows from the recovery bottle on the passenger side. Had the same problem with my 87. It could be disguising itself as coming from the motor if it is boiling over and overflowing while you're driving and splashing onto the engine. If it was leaking from that low, it would leak while running. Big puddles have to come from a big source.

[xX RB Xx]

the radiator cap is bad/ im getting a new one at nissan on wednesday, be we pressurized the system and its leaking from somewhere other than the cap.

[kasilvia]

That sucks. You can put a dye in the system that is flourescent under ultraviolet light. That way when you pressurize, you can source the leak easier. Odd that it only leaks when the engine is off.

[xX RB Xx]

yeah i know.. i drove it to get something to eat and it didnt leak when i turned it off.. but i did smell coolant when i was driving.

The temp gauge stays right on top of the F when i drive, so i dont really know.

[kasilvia]

When you pressure tested it, how quickly did pressure drop? How far down did it leak? If there is any air in the system, it will appear to leak down, but it will stabilize after its dropped a few pounds. Ive fallen victim to that before. I deal alot with cooling systems where I work. I would carefully inspect all the coolant hoses that run around the manifold, and along the sides of the block on the passenger side. Do you have access to a lift?

[xX RB Xx]

I dont know. i wish i knew, i didnt preform the pressure test, i went to a buddies shop and he did it. I know that it is leaking from somewhere around the water pump area. It maybe the hose that runs down over the water pump.

I dont have access to a lift right now, my buddies shop doesnt have one. I did get a warning light tonight, I couldnt tell what it was, it was the 3rd one from the end, and on the right side set of warning lights

[xX RB Xx]

^ i just checked the FSM, and its my coolant light that came on. Im kinda surprised it still works actually.

[evildky]

there si a sensor int he bottom of the coolant overflow resivior

[kasilvia]

Could be the water pump itself. it has two "weep holes" on it. One on the top, and another on the bottom. When the shaft seal goes bad, it will weep out of one or both of those holes. about the size of an 1/8 inch drill bit.

[xX RB Xx]

there si a sensor int he bottom of the coolant overflow resivior

my coolant resivior is hooked up to anything. It's just chilling there.

[evildky]

I was referring the the dash light, not the leak

[xX RB Xx]

Oh I know you were. Is the a another coolant sensor? My coolant resivor is empty

[evildky]

empty resivior = coolant light on, add coolant to resivior and the light should go off