Overheating problem...sorry

[grinevb]

So before I get started, this is my first post and wanted to introduce myself along that way.
Just bought 240sx three months ago and I love it. Thats all you get.


Anyway, so every imaginable problem that you can think of in the cooling system of a 240sx, I have it. Gonna give you a list of specs, and stuff done to it.
I have a 1992 KA24DE with 113k on it
- New OEM Nissan Thermostat
- New water pump (AutoZone)
- New Mishimoto Radiator
- Stock rubber radiator hoses
- Cooling fan hooked up to a switch
- Bled the system correctly (took me forever to understand that fact that it needs to be done over and over for many hours, before I thought if the radiator would burp once it was done, I was very wrong), I know I bled it correctly because I see the coolant (50/50) circulating throughout the system. Also upper hose is hot while lower is warm, or something like that.
- Checked the compression of the engine and got (150) (155) (155) (155-160), I'm guessing thats good? (I'm not a mechanic, slowly learning)

So, the car is still overheating and I'm thinking of two possible problems.
First, it might the the sensor itself, but I don't think so. Because, the sensor corresponds with the engine, meaning when I romp on the gas pedal after 4krpm the temp goes down and then goes back to normal operation temps (this is at idle). I'm gonna go somewhere to get the actual temperature.

Second, I think that there is too much pressure in the system (? not sure if that is possible? I don't know too much). I see a LITTLE bit of coolant leaking out of the lower hose, not enough to drastically change temps because the level of the liquid stays the same. Now, I notice coolant on the top of the radiator around the cap which is why I think there is too much pressure. ALSO I see the coolant going into the reservoir tank and not going back into the radiator, which is not stock the PO just put random one in. If there is a certain way the tank goes please tell me and how the hose runs please tell me.

I think I got it all, I have use the search and it has helped but everyone's problems were mostly air issues or there problems were resolved, etc...

Any question, ask because I'm sure I missed a few things.

[cbeuglas]

First remember that this is a closed pressure system. Of coolant is leaking out of a hose then air is getting in that hose. Any air in the system could cause overheating. Fix all leaks! Second you should receive a clutch fan (stock). Your stock electric auxiliary fan on a switch does not pull much air. Also remember that the stock guage is crap as it only reads cold, normal, hot. If you are waiting for it to start showing above normal to cut the fan on its probably to hot already.

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[cbeuglas]

Also when you bleed the system make sure the car is running and the heat in the car is on full blast.

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[cbeuglas]

Fill it. Use the bleeder screw to let air out. Pour in more coolant/water. Keep doing that until coolant is coming out from the screw. Start and run the car with the heat full blast. Let it cool back down and repeat all above again. I usally do this cycle a couple of times. Filling as you go. Fix all leaks!

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[cbeuglas]

Get a new cap also if it is leaking

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[TougeSR20Kid]

It would also be highly advisable to do a coolant flush, KA motors have iron blocks and if not taken care of (i.e. propper coolant, mix and servicing) they rust. This rust can get everywhere in the system and cause bullshit to happen.

Those are good compression numbers so I wouldn't worry about headgasket, but like the guy above said any leak will add air and is not good. Fix that first, do a coolant flush *properly!* dont just add water and call it good, and if possible use a vacuum bleeder or one of those ones where you put the resivoir on top of the radiator cap. Also helps if the radiator cap is the high point, so if doing it on a slant make sure the front end is going uphill.

Finally no the temp gauge is not bad, those things only fail one way and that is they stop working or they intermittently stop working. I don't think I've ever seen a temp sensor send a higher signal than true in any car.

[grinevb]

First remember that this is a closed pressure system. Of coolant is leaking out of a hose then air is getting in that hose. Any air in the system could cause overheating. Fix all leaks! Second you should receive a clutch fan (stock). Your stock electric auxiliary fan on a switch does not pull much air. Also remember that the stock guage is crap as it only reads cold, normal, hot. If you are waiting for it to start showing above normal to cut the fan on its probably to hot already.

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I usually turn the fan on right away because honestly i don't really know when to turn it on...
Also, my fan is on the radiator, not really sure if you would call that a clutch fan or an e-fan? Confused on that part...

[grinevb]

It would also be highly advisable to do a coolant flush, KA motors have iron blocks and if not taken care of (i.e. propper coolant, mix and servicing) they rust. This rust can get everywhere in the system and cause bullshit to happen.

Those are good compression numbers so I wouldn't worry about headgasket, but like the guy above said any leak will add air and is not good. Fix that first, do a coolant flush *properly!* dont just add water and call it good, and if possible use a vacuum bleeder or one of those ones where you put the resivoir on top of the radiator cap. Also helps if the radiator cap is the high point, so if doing it on a slant make sure the front end is going uphill.

Finally no the temp gauge is not bad, those things only fail one way and that is they stop working or they intermittently stop working. I don't think I've ever seen a temp sensor send a higher signal than true in any car.

I've gone through lots of coolant so its probably not even a month old, but I order new silicon hoses ($50 hope thats a good deal?) and once I install them I'm gonna do another coolant flush. When I was bleeding it I put the car up on ramps + my driveway is already slanted so its even higher. And my bleeder screw snapped. I've read around and was told that it's not completely necessary, it not using it worked for me. ALSO, took out the t-stat, both hoses, and ran a hose through both ends and they came out clean so it being dirty could not be the problem (but I could be wrong, soo...).

Also, side note. Will I have to re-burp the system if I install new hoses and do a coolant flush? I don't really wanna go through that again, took too long.

[grinevb]

Get a new cap also if it is leaking

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The radiator came with a Mishimoto cap so I'm relying on them for providing with a working cap.

[grinevb]

Fill it. Use the bleeder screw to let air out. Pour in more coolant/water. Keep doing that until coolant is coming out from the screw. Start and run the car with the heat full blast. Let it cool back down and repeat all above again. I usally do this cycle a couple of times. Filling as you go. Fix all leaks!

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No AC or heat unless I'm driving but I do have it on full blast when doing this

[TougeSR20Kid]

ALSO, took out the t-stat, both hoses, and ran a hose through both ends and they came out clean so it being dirty could not be the problem (but I could be wrong, soo...).

Also, side note. Will I have to re-burp the system if I install new hoses and do a coolant flush? I don't really wanna go through that again, took too long.

Ok perfect that works too, and then once full just add straight coolant and no 50/50 cus theres gonna be about a gallon of water in the motor

You have to re-burp the system any time you replace any part to make sure there are no air pockets

The radiator came with a Mishimoto cap so I'm relying on them for providing with a working cap.

Mishimoto caps are shit get an OEM one they're not expensive and way better

[grinevb]

just replaced the hoses and still having overheating issues. I re-bled it but I'm not sure if I did it right because I don't see the coolant flowing, but it won't burp on me. Mishimoto just sent me a new cap but after changing the hoses I don't see coolant spraying out of the cap.

There are no leaks around the hoses and not leak out of the cap but I see coolant spray/drops all around the radiator. I'm gonna post up a video if I can to show

[grinevb]

https://www.dropbox.com/s/3mjsevyas8h5jn8/Video%20Nov%2025%2C%205%2033%2051%20PM.mov?dl=0

here's a link if this helps

[that1guywithans13]

Your not bleeding it righhtt. Search up drill thermostat 240sx and you'll get the procedure needed. These engines are a pain in the ads to bleed and the only luck I've had is to drill extra holes on the top portion of thermostat and remove jiggle valve. Bleed for 30 min revving engine to 2.5k in increments of 30 seconds every 5 minutes or so

[grinevb]

Still having problems. It looks like there is a leak SOMEWHERE, I can't tell where. I say that because I see coolant sprayed (it's dried out from the heat of the radiator) on the radiator. Looks like there is too much pressure? I've said this before I think.
Trying to do a leak down test but the autozone leak down tester doesn't fit my mishi rad, so I'm waiting on a bud to borrow his.
Is it possible that the belt is not turning the water pump? This happened once to me but the car started to over heat and the belt start to squeal really bad. The sequeal used to be just when i started and if I revved the engine higher then it would go away or I would just have to turn the wheel (I assumed it was power steering that made it squeal because my pump is out).

[grinevb]

I also just installed silicone hoses

[mishimoto]

Ok perfect that works too, and then once full just add straight coolant and no 50/50 cus theres gonna be about a gallon of water in the motor

You have to re-burp the system any time you replace any part to make sure there are no air pockets



Mishimoto caps are shit get an OEM one they're not expensive and way better

Hello Zilvia!

I apologize if you had issues in the past with our caps TougeSR20Kid. We have recently redesigned our caps to eliminate any leaking that a handful of customers were experiencing. For any customer who has a problem with our caps, please feel free to contact us directly at [email protected] and we will be happy to send out a replacement!

Thanks!
Pat

[sincity_sil80]

Op did you end up finding a resolution to your issue?

[grinevb]

no i still haven't. took out the thermostat and car doesn't overheat but for some reason smoke/steam comes from the engine bay. I have no idea where it's coming from.

[grinevb]

today i'm going to put the t-stat back and maybe try bleeding it again. the last time i bled it, i think it worked not sure because it stopped bubbling from the rad cap, but I didn't see the coolant flowing.

[grinevb]

but i have successfully bled the system once (i saw coolant flowing from the rad cap), but it went back to overheating which then made me believe there is a leak in the system.