engine overheating, need help.

[TheOne]

ok, first things first, its a 95 nissan 240sx, its got 170k miles.

what happened: goin down the highway the heater hose that goes from the block(on the back, down of the intake manifold to a tube), got a hole on it from a shop that did a bad install of the hose(over tightened the clamp), and well enough coolant got out of it and overheated the engine till past the H, when we went to coast it, it was put on neutral and the engine stalled.

what we've fixed(the owner of the car and i), we replaced the water pump cause it started leakin, we replaced the hose that leaked in the first place, we also replaced the spark plugs & wires(the plastic down where it meets the spark plug melted on all 4 of'em), the oil cause it smelled cooked, the thermostat, and we flushed the coolant.we did a compression test and numbers came out(compression done with instructions from FSM, car warmed up)#1 - 160#2 - 170#3 - 170#4 - 170

while we replaced the water pump, we also wired the A/C fan to work with ignition(1 of the how-to's in 240sx.org install page), and so we removed the mech fan and fan shroud.

now the problem: after 15 mins of the car idling(this is after warmed up, normal temp, so maybe add another 3-5mins), it will start to overheat, the fan kicks into hi mode, and it tries to get the temp back to normal, but it just doesn't.

what am askin is, could it be the headgasket?, or just that there may still be some air bubbles in the coolin system?compression is not really tellin us that it could be that, we also did our best to bleed out all the air from the coolin system.

ps. there is no smoke comin out of the exhaust and from what we could see of the pistons, there is no coolant in there.

sry if this may seem long, but i had to describe in detail to get a better answer.

[TheOne]

BUMP

plz, i really need to know what else can we check as my friend needs his car, its his only.

[JNM240]

Well, if you are JUST using the A/C fan, and no other after market electric fan setup, then that is your problem right there. There is no way the stock A/C fan will cool your coolant down without the help of the mechanical fan. Put the mechanical fan back on, or invest in some flex a lites, then see if it still overheats.

[DjPantsSpecR]

wow...

i have two s13s, and both of them only use the AC fan... neither of them ever overheat.

as for the problem, it sounds a lot like air bubbles in the system, so search that because ive explained it a million too many times. its such a common problem on KA if they are not refilled properly after major coolant loss.

additionally i'll add that some believe nissan headgaskets to be on the weak side as overheating goes. maybe the material they use has a high tendency to creep when overheated. so maybe the headgasket is blown, but i dont think so

but your compression kinda sucks, the way a warped head does. I bought my car with one.

with that said: you will probably need a burp funnel to get all those air bubbles out, and maybe 15 minutes to an hour of bleeding with that to get all the air out.

[InsanityInc]

Your compression looks basically fine. If your headgasket were leaking, the compression would be like 100 130 170 170 or something similar to that.

[nismo dreaming]

Well, if you are JUST using the A/C fan, and no other after market electric fan setup, then that is your problem right there. There is no way the stock A/C fan will cool your coolant down without the help of the mechanical fan. Put the mechanical fan back on, or invest in some flex a lites, then see if it still overheats.

believe structure240sx was runnin that fan full time on his 240sx with over 500hp and some racing, so i'd doubt its the fan, and he's just 1 example.

well we re-did the whole coolant per the FSM instructions and it still overheated, but this time i touched the lower radiator hose and it was cool, so we are replacing the thermostat for the 2nd time.

plz somebody help, this is my daily driver and only car.

ps. this is my vehicle, TheOne has been helpin me through this.

[Ekinchheng]

IIRC one of our users had a similar problem. Did you try to shake the engine around? Like drive it left and right so all the colant could get inside the engine.

[nismo dreaming]

We installed the coolant properlly. The lower radiator hose never seems to get hot so the thermostat isnt opening. I am going to replace the water pump again today and hope thats the problem. Also, i am going to put the mechanical fan back on just for grins. If anyone has any other suggestions, plz let me know.

Thanks..

[DjPantsSpecR]

i really wanna stress that you can do exactly what the fsm says, but unless you get a burp funnel and go through this procedure you might not get all the air out.

put the burp funnel in the radiator neck, chances are it wont fit right, so wrap the end up with electrical tape to seal

fill it about half full. its important to have the water level here over the water level anywhere else in the motor, this is the reason why these bubbles get trapped in the first place.

then you simply run the motor and add coolant as needed. sometimes it takes an hour of idleing and racing the motor to get all the air out. i wasn't just saying this to hear myself talk...

if the air bubbles never stop coming out, or the water level constantly overflows after a while, sometimes this is an indicator of warpage or headgasket failure.

now with that said... i would give this a try, it costs three dollars and some water, rather than replacing a bunch of crap you have no idea if its wrong. if the water pump isnt leaking out of the weap hole its probably not the culprit but im not going to say its not.

also did you install the thermostat correctly? I'm not sure if its possible to get it backwards, but its definately possible to forget to put the air hole on the housing up. this is a minor difference, and is also probably not the culprit

additionally, because no one ever said before, but if you are using the FSM i bet you have the heater turned all the way up, that make a world of difference too

good luck man. i dealt with an overheating 240 for many many months. i have five headgaskets as proof.

[TheOne]

yeah i've had my share of overheatin too.

we tried askin the auto parts stores here(autozone/o'reilly), they don't carry a burp funnel for some reason, i know what it is and how to use it cause my brother had 1, it was called spill free, but he's gone and well, he took it with him and i can't find it anywhere to buy.(he bought it from a snap-on truck that goes to dealers)

now were thinkin that it could be the radiator, maybe it really did get too hot and damaged it, you can feel on the upper rad hose that the plastic itself got bubbles on the inside. this happened to my stock rad in 1 of the overheats, i replaced it and well the overheatin stopped, when i checked it the plastic had bubbles formed on it.

you think it wouldn't show in the compression test that the headgasket may be leakin?

[DjPantsSpecR]

Actually now that i think about it, although it isnt so uncommon for a motor to have one weaker cylinder compression, it is also a pretty good way to indicate that one IS leaking. Especially if you are checking after overheating it. I wouldn't be too surprised, now that i think about it, that you blew the headgasket. Its a pretty good indicator on an other-wsie fairly strong 170k motor

i bought the car with a warped head, i learned that after i did a second headgasket to it. I overheated it consistenetly every day for at least six months. I blew a hole in an upper hose, a lower hose, an upper radiator tank, and another upper radiator tank. it became pretty-much undrivable when it would expell exhaust out of the overflow tank.

The thing would drive for a while, then over-heat and come back down within about 15-20 seconds, then go back to normal. Is that something that is occuring? because this was an extreme case of air bubbling when it was actually large amounts of exhaust that would get trapped. So obviously yours will not be as extreme. But this is what i mean by when you are burping it air will not stop coming out. Eventually my air bubbles being burped were the size of the burp funnel, and it would spill too much coolant to even use. No fun at all. Sorry, the point of this story was that the head was only warped over .009. which is just out of what the fsm says is the decking limit of .008. Some serious abuse be me and whoever may have had the car before me, adn only that much. But only that much makes the car worthless too...

I would strongly try to get ahold of some burp funnel, i see em all the time at corner autostores like checker/schucks/kragen and the like. It also helps to shake the car while doing this as some one suggested, but i would just do it by hand, adn make sure not to get hit in the head by the hood on the downstroke...

thats the craziest radiator problem ive ever heard of, but i dont doubt it, i'm not down with the plastic endtanks.

on a sidenote. On my s14 auto-radiator-equiped s13 i've never had any problems with air bubbles after breifly using the burp funnel. This radiator is a twin row, and this includes filling a bone-dry rebuilt motor.

[JNM240]

But dont you think that if he had a blown headgasket it would shoot coolant out of the radiator with the cap off from the pressure? When the car is running, can you see coolant movement from the radiator filler neck? If so, then the w/p is doing its job. From there, the top hose is hot but the bottom is cold, so my first place to look would be the thermostat. Im sure its brand new, but did you try boiling it before you installed it, just to make sure it opens properly? If its not the fan and its not the w/p, and it isnt shooting coolant out when runnin from built up exhaust pressure in the cooling system, i would seriously have to look at the thermostat.

As from before about the electric fan: my S13 has 1 A/C fan, its about 6-8 inches in diameter, and doesnt even cover half of the radiator. Even if this were on all the time, i doubt very seriously it would be able to cool MY car down. If people have done this modification to their cars before with success, great, i just look at mine and think there is now way it would work.

[DjPantsSpecR]

no, from experience, you have to have a blown headgasket and seriously warped head for the coolant to just leak out of the radiator neck. it wont violently shoot or anything unless its ina burp funnel full of coolant, and you ahve serious, serious problems.

a blown headgasket can look like a few bubbles even. and you dont need to have white smoke out the exhaust to have a blown headgasket either, because my car never smoked, except eventualy out of the overflow resevoir.

a boiling resevoir (or seemingly boiling, it actually just bubbles) is a good sign of a serious problem

i agreed a long time ago it could very well be the thermo. People have gotten "brand-new" malfunctioning thermostats before, it happens, and unless he bought an oem one i wouldnt count this one out.

i bet he didnt buy an oem one, as they are ridiculously expensive compared to what you can get at like autozone. its entirely possible its a malfunctioning unit...

As for your fan question. I'm not sure exactly what your car has, but i use that fan on both s13s and it has no problem. I've never overheated once with them. These cans deliver some serious power, often times even more than most aftermarket fans you can buy. How do you think Altima's get it done? same motor, one fan runs constantly. i dont think the other runs constantly, just when the AC is on. Either way these S13 fans of very nice.

just to verify, i'm not saying its ablown headgasket either, but it does sound a bit like one, ands always a good thing to figure out before you waste a bunch of unrelated money

[nismo dreaming]

Well everyone, the headgasket finally blew. Thanks for all the support but as i went to move the car into the garage, the idle was extremely ruff. My heart sank and i started to move to the dip stick. MILK. It turns out that it was a headgasket all along. Thank you all so very much for your support. Jason.....
Modified by jaytheman88 at 7:39 PM 3/6/2006

[MikeMurphy]

Bummer!

Best of luck in the future!

PS. JNM240, the stock rad without ANY fan in most cases can keep a car cool in most climates. I cant even remember the last time my AC fan turned on. Having a fan, even a small one, is more than enough.