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M35 coolant bleed

Sack87

By Sack87,
in Four Door Family & Wagoneers

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Sack87 Community Regular

Sack87

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Why the f**k can't I bleed this f**ked up cooling system. I'm about to drive this flamin mongrel into a pole. 

I have tried every single way possible for over a week and still it overheats or spews all the coolant out of the radiator funnel. I've searched on here and tried all the tricks you guys have used, all the tricks the 350z guys use, the old fashioned way and nothing works. 

I'm running the coolant bypass mod and have a tap on that with a funnel filled with coolant and it just continues to blow bubbles or fills up with coolant. 

I then tried the funnel in the radiator and cracking the bleed but the coolant just starts unloading when it gets hot. 

WHAT THE f**k AM I DOING WRONG. 

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https://www.sau.com.au/forums/topic/476333-m35-coolant-bleed/
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Sack87 Community Regular

Sack87

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Thermostat is part of housing so impossible to get it wrong. I did a full engine rebuild so it was bone dry. 

What's weird though is that it will sit on 104deg when driving but if I fluctuate the engine under light load in a lower gear, it will drop down to 93deg then rise back up. 

  • 3 weeks later...
MrStabby Grand Master

MrStabby

Posted
Posted

I had the same symptoms and came the conclusion it was not a bleeding problem after re-filling the viscous clutch and installing a bigger radiator stopped the overheating. If i had realised the viscous clutch was stuffed first, I wouldn't have changed the radiator unless i could confirm I still had overheating.

So check if you're viscous clutch is ok first (see the link in my sig). I'm still using the 6000cst fluid - never go around to trying the 3000.

Sack87 Community Regular

Sack87

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21 hours ago, MrStabby said:

I had the same symptoms and came the conclusion it was not a bleeding problem after re-filling the viscous clutch and installing a bigger radiator stopped the overheating. If i had realised the viscous clutch was stuffed first, I wouldn't have changed the radiator unless i could confirm I still had overheating.

So check if you're viscous clutch is ok first (see the link in my sig). I'm still using the 6000cst fluid - never go around to trying the 3000.

Haha funny you say this. I literally just refilled the viscous hub last night with new 10000CST oil and now it moves a f**k tonne of air. Not much was in there. 

I figured it had to be an airflow issue as it was hot at 1200rpm but would cool down at 3500rpm

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  • 2 weeks later...
Sack87 Community Regular

Sack87

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Posted

Soooooo.

I still have the issue and it's frustrating as f**k.

Either the fan is not working when hot or the water pump is not pushing the coolant around enough. 
FAN THEORY: After about 1min of high idle it goes from sounding like a jet to a mouse fart and doesn't pull f**k all air in.
WATER PUMP THEORY: If i drive it above 4000rpm in say second at 70kmh, the coolant temp drops 10 degrees in 30 seconds. So I'm thinking that it's flowing more coolant through the radiator, the temp sensor is actually getting more coolant passing over it and therefore getting a better reading.

Although, these two problems are related whereby increasing RPM should increase fan speed and will increase pump flow so it could be either.

Any suggestions or does someone have a spare viscous hub I can try out in Perth?

Blakeo Rising Star

Blakeo

Posted
Posted
On 4/16/2019 at 1:48 PM, Sack87 said:

Soooooo.

I still have the issue and it's frustrating as f**k.

Either the fan is not working when hot or the water pump is not pushing the coolant around enough. 
FAN THEORY: After about 1min of high idle it goes from sounding like a jet to a mouse fart and doesn't pull f**k all air in.
WATER PUMP THEORY: If i drive it above 4000rpm in say second at 70kmh, the coolant temp drops 10 degrees in 30 seconds. So I'm thinking that it's flowing more coolant through the radiator, the temp sensor is actually getting more coolant passing over it and therefore getting a better reading.

Although, these two problems are related whereby increasing RPM should increase fan speed and will increase pump flow so it could be either.

Any suggestions or does someone have a spare viscous hub I can try out in Perth?

Chill out mate, its a car everything can be fixed. 

Firstly, the clutch fan is suppose to disengage at a certain engine RPM speed. I hope you haven't overfilled the viscous clutch.

I would be getting the coolant vacuum bled. Its a 100% certain way to make sure that its bled correct. Usually I will leave the car on the vacuum pump for a good half an hour before introducing coolant into the system. This is fool proof method. 

When you built the motor, did you pump coolant thru the block first to make sure there was no blockages? Generally you would do this when cleaning/prepping the block. 

Doing the vacuum bled will also confirm if it has a head gasket leak. May also be worth doing a leak down test.

Sack87 Community Regular

Sack87

Posted
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Figured it out after driving it home in the wind and rain with the temp not dropping at, so it had to be a flow issue and not a fan issue.

I put a VQ35 one in there as it was listed as fitting. Yes it looks identical from the outside but the thermostat itself is different. I never pulled the VQ25 one off my old motor so I had no idea on the difference between them.

The 35 (left) is longer but has a smaller opening, so it's not allowing enough coolant through compared to 25 (right)

 

IMG_20190421_153428.jpg

IMG_20190421_153439.jpg

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