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  • 3 weeks later...

I've got this exact problem on my rb25 180. Reading 91 water temp and 98 oil temp on defi gauges after coming off the highway and stuck in traffic. Otherwise it's at about 85 water temp and 89 oil temp regular 60km/h cruising.

My order of things goes like this;

Just Jap 100mm FMIC->

Greddy oil cooler with thermostat mounted behind the intercooler

Twin 12" skew blade thermo's pushing onto the air con condenser ->

Then approx 1.5cm back is the PWR 40mm aluminium radiator.

On my setup there is 4cm clearance between the radiator and the belts. I also have the nismo thermostat, N1 Oil pump and the standard water pump. All parts are new, so there's no mechanical failure of parts in the equation (checked). I also have washers behind the back of the bonnet and a radiator cooling panel.

This is the setup the previous owner had. The PWR radiator is a vertical item, and i'm wondering if changing to a crossflow design is going to make any difference. Previous owner had overheating problems with a Neo RB25. This time around, changing to the lower compression R33 RB25 didn't make all that much difference.

Unfortunate thing about RB25/26 is that the space for the fan assembly is very limited. Only thing i can see that would work would be to ditch the air con condenser and mount the twin 12" thermo's directly to the radiator. Being in Queensland and with the hot weather approaching i'd like to avoid doing that.

Is it possible to simply purchase a smaller air con condenser, or is there a side effect to doing this - eg air con won't become as cold or hot as quickly as it should?

Edited by silman

hey guys i had the same problem. all i did was switch to an r32 GTR radiator (was brand new) and got rid of my condenser and flush mounted 2 12" thermos on the front of the radiator running constantly, also running the stock thermostat. looking into a vented bonnet now aswell to lose some of the under bonnet temp as at the moment i have the bonnet slightly raised at the back but after goin for a good thrash and lifting the bonnet its like a friggin sauna, like the heat gets trapped under there.

He's got an Rb26 so the bleeder screw is on the drivers side of the engine above the plenum next to a little yellow sticker that says do not open when hot..

I doubt you would have any air still in there. A pocket would normally cause problems soon after you do a coolant flush. Shortly after it will find its way out.

  • 5 weeks later...

I'm running a RB20DET in my 180SX, don't have any overheating problems.

I've got a twin 13" fan setup.

- One in front of the condenser pushing air in

- One at the back of the radiator sucking air out

as per the Craig Davies diagram, works a treat....

Front of Car | FAN | -->> ||Condenser||Radiator|| -->> | FAN | -->>

With the A/C running on a hot day, I've never seen any overheating problems, but then again in summer I only run stock boost.

Hope that helps...

Cheers,

Johnny

my rb26 silvia.. Just jap radiator.. two 12inch thermos on the front of the radiator were condesor normaly is.. i actualy had a problem with the water being cooled to much and thermostat not opening (bottom hose was always stone cold.. changed it to 1 thermo on constantly and the other on a switch for when sitting in traffic.. dont have any over heating problems.. sits on about 86degrees almost all the time.. occasioanly see's 90 but thats about it.. rear of bonnet is raised about 15mm so yer..

I used to run 2 x 12" thermo's.

They were ok up until ~30degree's and sitting in traffic with the a/c on.

2 x 12" thermo's sucking don't work; pulling the fan off I measured the were pulling air through ~30% of the radiator. They have a huge dead spot in the middle of the fan due to the motor.

Sucking.....

A single 16" will be better than 2 x 12's... Its not the airflow that is as critical its the surface area covered.

A good stock fan works well OR 2 x 12" thermo's sitting on a shoud so they draw air through the whole of the radiator.

I currently run the stock clutch fan and have replaced the std aircon fan with a single 14" cheapo from Ebay. The cheapo from Ebay works awesome, it runs the S shape blade so its quiet and pushes a hell of a lot of air. I still seeup to 95degree's sitting in traffic witht he a/c on. With the a/c off the car will run up to 8degree's cooler depending on traffic conditions and how hot the day is. Its amazing how much hotter the a/c makes the car run.

Normal temps even on 4degree mornings is what it should be 82-84degree's.

If yours is running cooler than 80degree's it has an issue and WILL be running in the cold enrichment and retard table. Which isn't a good thing for power and especially economy. :thumbsup:

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