Overheating.....

[Bow]

OK. I have a question for you 240sx owners...

I have a '91 S13 Hatch, KA24DE

In December, I found a hairline crack in my stock radiator (Original, 220,000 miles) end tank, near the top hose.

I picked up a CX Racing radiator (Aluminum 2" core).

Before I installed it, I flowed water through it to make sure there was no internal blockage. everything checks good, so I flush the cooling system, heater core and all.

I then installed the new radiator, proper Antifreeze/water mix, burp the system, everything looks good, 13PSI Radiator cap installed.

Overflow bottle filled to max, just to for the extra air that is ALWAYS in a KA24DE that you can't get out.

I took it out that night, and it starts overheating.... Take it home...

Next day, I jack the front end up and burp it again.. nope, still overheating...

Fast forward to tonight.

I figure maybe the thermostat is old.. pick up a new one on the way home and install it tonight.

Refilled the coolant

Let it idle for 30 minutes

Burp the system

Fill the overflow

Take it for a run...

Still overheating.

The only real coolant system I have is the Heater core (Engine starts overheating, Heat to Max, fan to Max to help cool it down).

Nissan Datascan tells me the coolant temp is up around 250 degrees F

The bottom hose isn't warm... at all...

Top of the radiator is PLENTY hot...


Sooooo...

What is my next move?

Water pump? I figure the water pump is working, because it moves coolant through the heater core...

Suggestions?

[iworshiplemons]

Water pump, generally, is fine unless it's either leaking or falling off.
Hate to say it, but.. headgasket?

It's possible you're not overheating. Try changing your water temp sensor - it can't just be your gauge as datascan is getting the signal too, so it speaks of the temp sensor.
There's two, ones for gauge one's for ecu, I forget which is which. FSM?

Aftermarket temp gauge would be helpful.

[Bow]

Well, The stock gauge and the Datascan are both showing it, and yes, that is 2 different sensors.

The one thing I haven't done yet is relieve the sensors by pulling them to make sure the air is out of them...

But I'm not sure that is it, because the temp drops on the gauge and Datascan with the heater on ...

I agree, when the water pump heads south, it pees out the weep-hole (my KA24DE Frontier did that a couple months back, after 235,000 miles, that is acceptable)

My concern is the bottom hose not heating up... that radiator isn't THAT good.

As for the head gasket, I don't think so, it runs like a raped ape, pulls like a *******, and the oil is Gold/Brown, like it should be.. no milky tint... no oil in the coolant either....

The other thing i should add.. the CHT (Cylinder Head Temp) gauge I have in there never hits 200 degrees... and the sensor is back by the #4 cylinder...

And even though I am the FSM-thumping preacher, its coolant section sucks. :/:

[Projectgofast]

I would remove the thermostat and test it without one, it sounds like your not getting any flow through the radiator, I would take a look at the water pump, how long do you drive before it gets hot? also did it have this issue before you installed the new rad? If it wasnt running hot before I would not worry about BHG, when it dose get hot is coolant bubbling out of the overflow?

[Bow]

I would remove the thermostat and test it without one, it sounds like your not getting any flow through the radiator,

That is my first thought too... but I checked the flow before I installed it...

I will probably try pulling the thermostat back out and run it without one.. I'll also unhook the electric fan sensor to let it heat up quicker...

I would take a look at the water pump, how long do you drive before it gets hot?

I'm pretty sure the water pump is working, as it flows water through the heater core.

It will idle for ever and never heat up, driving it, about less than a mile...

also did it have this issue before you installed the new rad? If it wasnt running hot before I would not worry about BHG,

Nope, I didn't have this problem before the radiator swap, and I don't drive it hard enough to blow a Head Gasket, it pulls like a Ba$tard, so that isn't it...

when it dose get hot is coolant bubbling out of the overflow?

Yeah, after my test hop last night, there was more coolant in the overflow then when I left to drive it, and this morning, it had sucked the overflow almost empty, back into the engine...

I'm thinking I have a big-*** air lock in the engine somewhere...

Thanks for the ideas

[vp4prez]

sounds like it could be the proverbial bubble/pocket locked up in the motor somewhere. i remember working at a firestone a while back and working on an explorer that kept do this to me. didnt fix it until the old man told me about it. even then, its a matter of being patient enough and letting it run without the cap on and you standing there with collant squeezing the damn hoses.

[MJDalton]

Just a thought, It is possible to get a bad thermostat. I had people bring them back to AutoZone all the time.

I'm not convinced you have an Air Pocket. You said the bottom hose is cold. If it was just an air pocket and the thermostat was good you would still get circulation. The thermostat is on the bottom hose. It clearly appears to not be opening.

I think your on the right track by taking it out.

Good Luck Bow

[iworshiplemons]

Everything you've said points to thermo. Make sure it's installed right and, indeed, working. They are like six bucks anyway, so no big deal.

Let us know an update!

[Bow]

Yeah, I'll probably pull it and run without it tonight, if I get a chance... see what that does...

if nothing else, it might help get the air out of the system, until I put it back in anyway...

I hate plumbing

[noxis08]

you could cheat and use a water/air separation tank of course it would be a shame if you spend ~100 bucks on a part and it didn't work :(. I know you say your only safety is using the heater but its possible that the heater core may be clogged try bypassing it and see if it changes anything.

[Bow]

you could cheat and use a water/air separation tank of course it would be a shame if you spend ~100 bucks on a part and it didn't work :(. I know you say your only safety is using the heater but its possible that the heater core may be clogged try bypassing it and see if it changes anything.


But I didn't have this problem until I changed the Radiator...

I don't see how the heater core could be clogged if it works, and cools teh engine down, I'd say it's flowing quite well, no?

[noxis08]

But I didn't have this problem until I changed the Radiator...

I don't see how the heater core could be clogged if it works, and cools teh engine down, I'd say it's flowing quite well, no?

Your probably right about that however bypassing it would eliminate the possibly of a bad unit.

[Bow]

Update!

SWEETNESS has come to my garage...

I guess last nights belch session with the overflow bottle, and a quick run tonight to heat it up and using the bleeder screw again paid off.

I filled overflow bottle to the "Max" line again and took it on a short run tonight (just to the gas station for lawn mower gas), it seemed to check good on the short 1 mile to and back run, but I wasn't trusting it 100%.

So when I got back to the house, I used the bleeder screw to burp it until it was puking coolant (I have done this routine about 20 times in the past 3 months, but never had a lot of time to work on it)...

After mowing the lawn, I took it out for a run up 290 tonight, and beat it like a rented mule...

10 mile round trip at highway speeds and above... and datalogged it as an Excel file if you are interested... 4 Megs

I'll see if I can upload it...

My Booze burning Ba$tard is Back! :/:

[Projectgofast]

Good to hear you got it sorted out, I hate problems like that, after reading your reply I figured it was air, based on the bubbly overflow

[MJDalton]

Congrat's Dude. Glad to hear that is behind you now. :D

[iworshiplemons]

Yay!
I'm interested in the excel file.

I want to see what kind of "beyond highway speeds" you do.
Lol.

[Bow]

If Anyone cares, here is some of the data captured on the Test Run.. I graphed it:

http://riley-music.com/BowsStuff/240SXWebShots/OverheatTestRun.JPG

Damn traffic was heavy on 290 last night...

[iworshiplemons]

lol 100mph

crazy how much water temp goes down when you start going fast.

[MJDalton]

Thank Bow that looks really god now. I need to get my system installed

[Bow]

lol 100mph

crazy how much water temp goes down when you start going fast.

Yeah, traffic was too heavy, and my Radar detector when off.. see how fast it dropped? LOL

Funny, I downshifted from 5th @70 to 3rd and hit it (see the RPM jump), then hit 4th...

Yeah, the water temp went down to 157 at the lowest point while running that fast

[Trippen]

Bow only 100 damn man thought you could go faster then that.....lol

[Bow]

Traffic man, Traffic... you know how 290 can be....

And a bit of faith in the Radar Detector when it trips in KA mode ;)