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QLDR31

RB25DET NEO Overheats after about 10mins

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Hey guys,

My auto Stagea Overheats after about 10mins of warming up and driving.

Its all pretty much stock setup, no exhaust or mods.

OEM Water pump was done about 100K ago.

Recently I got an OEM radiator cap and 82deg c thermostat.

I put an aftermarket clutch fan on it. Which probably wouldn't fix the issue as I was doing 100KMh the first time it heated up. I hear clutch fans don't do much when your doing more than 80KMh.

I changed the radiator today.

Each time I change something I bleed the coolant with the two bleed nuts then run it with the heater on and a funnel for coolant.

I use green coolant, currently from Repco.

It overheated today, and the weather isn't hot at all.

A while back the turbo started making weird noises on boost, I wonder if a stuffed turbo could make it heat up?

Any ideas? I'd like to get it back on the road. Its been off for a few months now. Besides the occasional test drive.

Cheers Brendan

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When you bleed the coolant do you extend the radiator filler up higher (with tube or tight fitting funnel) so you can definitely get out the bubbles?

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And maybe raise the front of the car?

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I concur with these guys. ^ .  It's not bled properly.

And put a 90° thermostat back in it.  Neos aren't meant to have 82° thermostats.

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2 hours ago, Ben C34 said:

When you bleed the coolant do you extend the radiator filler up higher (with tube or tight fitting funnel) so you can definitely get out the bubbles?

I bought a funnel kit which has a cap that screws on. All sealed etc.

2 hours ago, KiwiRS4T said:

And maybe raise the front of the car?

I didn't didn't raise the front of the car but its worth a try. I will slap myself silly if this fixes it ;)

I thought the sealed funnel setup would sort this, with coolant higher then the engine.

1 hour ago, GTSBoy said:

I concur with these guys. ^ .  It's not bled properly.

And put a 90° thermostat back in it.  Neos aren't meant to have 82° thermostats.

Dang I thought it was 77° or 82°. I got the chick to check my VIN when I was buying it.

The previous thermostat I  think was a Tridon, not sure what temperature but changing thermostat made no difference.

On a side note when bleeding it lots of bubbles came out and as it got hotter the funnel got fuller. I didn't really add any coolant until it was off and cooling down. I didn't think this was normal. I thought id need to add coolant.

Before I bought the funnel lots of coolant would spew everywhere when bleeding it.

The bleeding procedure I used:

-raise front of car [ADDED].

-take off two bleed bolts on NEO engine.

-using non spill funnel slowly fill until constant coolant comes out bleed holes.

-add bleed bolts

-start up engine

-turn a/c off and heater on.

-squeeze various coolant hoses.

-Add coolant if required

-Wait for it to get to running temp and minimal air bubbles out.

-Turn off engine. Once cool put on radiator cap.

 

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Yuh, the bleed screws are for bleeding while it's getting hot also.  Air will get trapped up there if you leave them closed.

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Is the heater blowing hot air constantly?

 

As gtsboy said, the bleeder screws should be cracked open when heating up to release trapped air.

 

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3 minutes ago, admS15 said:

Is the heater blowing hot air constantly?

I thought so.

4 minutes ago, GTSBoy said:

Yuh, the bleed screws are for bleeding while it's getting hot also.  Air will get trapped up there if you leave them closed.

Ok, might try with them off as well, sounds messy.

I think the thermostat is right. I took this from the R34 service manual:

R34_Coolant_Settings.png

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Don't take the bleeders off, just crack them loose a little bit

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No, what you do is you undo them a little to let the air out, then close them when coolant starts to come too.  Swap back and forth between those and the other things you're doing while you're trying to bleed it all up.  That's why they're called bleed screws.

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5 minutes ago, QLDR31 said:

I think the thermostat is right. I took this from the R34 service manual:

Actually, that is correct.  It ends up running at ~90°.  When you said "82°" I thought you meant the running temp, not the start of opening.

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go to a mechanic and get the system pressure tested. and chuck a sniffer on the rad. 

is it losing coolant, or just overheating? have you cleaned or got a new sensor for the gauge?

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Thanks guys i'll give it another go. I'll try a proper bleed.

 

1 hour ago, Trex said:

go to a mechanic and get the system pressure tested. and chuck a sniffer on the rad. 

is it losing coolant, or just overheating? have you cleaned or got a new sensor for the gauge?

I bought a pressure tester it seemed to hold 15psi in the coolant system.

Think it was only loosing coolant from the overflow bottle, eg getting too hot.

I haven't touched the senors

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Get a sniffer test on it. Could be head gasket

 

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Today I jacked up the front. Put my funnel on. Started it up. Loosened the bleed bolts. Set heater to 32°. It got up to running temperature.

The rear bleed bolt seemed to bleed ok. The front bleed bolt seemed to blow bubbles the whole time. The funnel funnel gained coolant, I didn;t put any in it..

I just had it idling the whole time. It stayed at running temperature.

The heater didn't seem to get hot. Does this mean its a water pump issue?

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I would think it means it has a blockage in the galleries somewhere.  When I bought my Neo it took a year and >6 coolant flushes to get it clean.  When it first went in there was muck blocking up all the small passages.  I had to dig the bleeders out to even get coolant to move through there.

The heater not working points to a stuck heater tap.  They get gooey crap in them and it can make it too hard for the actuator to push it.

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Give the engine little revs while the funnel is hooked up and see if it sucks coolant in. I still think you have air trapped in the system.

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Sounds like a pain in the butt.

2 hours ago, admS15 said:

Where are you located?

Southwest Brisbane

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I took it to a radiator place a while back. It sat there for five weeks and they were too busy to touch it so I grabbed it back.

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