M35 overheating

[MrStabby]

M35 overheating

In cold weather, it looses no coolant, and is fine (all winter). But after a few 35 degree plus days it looses coolant and overheats. If i top it up and drive in cool weather, it again looses no coolant and is fine. Last summer it got a new thermostat, radiator and radiator cap, and was holding pressure.

Is your M35 ok in 35+ weather?

How do i troubleshoot this, or are M35s a bit iffy under extreme temps?

[spudtatoe]

Are you going by the temp gauge in the dash? They're pretty shit, but if it's going all the way up on that there might be something up

[West]

36 minutes ago, MrStabby said:

M35 overheating

In cold weather, it looses no coolant, and is fine (all winter). But after a few 35 degree plus days it looses coolant and overheats. If i top it up and drive in cool weather, it again looses no coolant and is fine. Last summer it got a new thermostat, radiator and radiator cap, and was holding pressure.

Is your M35 ok in 35+ weather?

How do i troubleshoot this, or are M35s a bit iffy under extreme temps?

Did you bleed it right when you did the rad, thermal stat? Did you do it in winter? Were you able to trace to see where the coolant leak from?

Maybe bubbles still trapped in the system?

I dont' have problems on 35+, having said that, car already came with a Scotty cooling mod, i also just did the thicker radiator, nismo stat, new genuine nissan coolant.

[Duncan]

I know you said you changed it....but it sounds exactly like radiator cap not holding pressure....

[MrStabby]

I didnt do the work last summer, because lazy. Yes always bled. Temp gauge apparently working fine, and giving repeatable results, ie moving above normal level correlates with loss of coolant, and vice verca.

I wonder if i can get a nismo cap for it...

EDIT: R32 and M35 caps are the same so ill try the Nismo from the GTR on it

[Duncan]

Just swap it for anything that fits for a few hot days, even something crappy like a micra.  It also could be a leak that is only obvious under pressure (which it doesn't get to on cooler days) which you could check with a pressure tester.

[MrStabby]

Interestingly the M35 spout is 1.2mm higher (seal surface to cap surface) than the R32, and since force = distance x spring constant, so any cap will have less sealing pressure on the M35 compared to the R32 (for the radiators i have)

[Darkmeat]

NM35 with Scotty's cooling mod.

Lost a litre of coolant over the last few really hot days - including 4 hrs driving (half of it in Sydney traffic) in 38-40 deg. temps. With no air conditioner (another story, but I personally lost a couple of litres of coolant on that drive).

The temp. gauge sat rock-steady on half-way the whole time.

No discernible trace of coolant leak.

Topped it up with pre-mix over a week ago. Since then, temps have been in the high 20's low 30's, and it doesn't appear to be losing coolant.

Now, the temp. gauge needle sits about 1/3rd of a mm below half way. Just like it did before the heatwave.

So that missing litre made some kind of difference.

Radiator cap looks and feels in top nick. No idea where that coolant went.

Interested to see if the change of radiator cap solves your problem, Mr Stabby.

[Equilibrise]

I have exactly the same issues, however I know that the large alloy radiator is leaking from the top tank on the side (not easily visable). It doesn't leave puddles on the ground, yet drains the reservoir on hot days.

The leak, in my case, was caused by a stray current in the car - kills alloy radiators. I found the leak last time I removed the radiator and it was less than a year old when it started leaking.

[Equilibrise]

Note: you know if you have a stray current if inside the neck of your aluminium radiator has turned black.

FYI I have a 53mm koyorad

[MrStabby]

On 2/22/2017 at 11:33 AM, Darkmeat said:

Interested to see if the change of radiator cap solves your problem, Mr Stabby.

Update for Darkmeat; swapped the caps between the R32 and Stag. No apparent issues with the Nismo cap on the stag, but it hasnt been hot enough for a proper test. The new 0.9 cap from the stag leaked on the R32, so either its defective as Duncan suspected, or Stags need a greater than 0.9 cap. Seems like the standard pressure ratings are 0.9/1.1/1.3 and IIRC the Nismo is 1.3. I'll try a 1.1 on the Stag next and put the Nismo back on the 32.

 

[scotty nm35]

Seen a few leaking coolant from the back of the head lately, from mixing brands of coolant I think.

[MrStabby]

Ok, had the 0.9 cap on in 27 degrees with air con and it lost coolant. Now trying a Tridon CB18125 from Supercheap. Looks like the 18125 means 18psi/125kpa. There was also a CB16110. So tar the caps i've seen have pressure stamped on as either the bar number or psi/kpa numbers.

So cap options are;

0.9bar / 13psi / 90kpa

1.1bar / 16psi / 110kpa

1.3bar /18psi / 125kpa

[Bennyboym35]

Scotty mn35 Just been reading alot of your comments and treads, seeing if you have any of your cooling mods laying around..... and some pointers on bleeding the cooling system... I've tried a few times no luck care only over heats in hot weather, I've ordered new water pump thermostat and looking at replacing the radiator just for peace of mind but still sounds like from what I read it's air block..... only started happing after I blue the heater bypass hose on the front of the motor..

[MrStabby]

My cooling issues were blocked radiator and weak fan clutch, not bleeding issues. I replaced the radiator with a Fenix ($400), which is higher capacity/wider than the stocker (~$800). Here's how to fix the fan clutch;

Re: air block/heater bypass hose, don't know what that is, but if its bled it should be fine. Just follow the bleeding guide.