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Overheating With Aftermarket Rad And Fan

SkylineBNR32
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SkylineBNR32 Rookie

SkylineBNR32

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I'm having a little problem with the engine on my GT-R overheating. If I let it sit and idle in even mild (18-20 degrees celsius) temperature, the coolant temp almost goes through the roof and my oil temp climbs up to 110 degrees c. The current setup is a Koyo 2 row aluminum rad measuring 26" x 18" x 2 1/4" and the fan is an electrically controlled 14" fan which is much smaller both in diameter and blade size to the stock fan. However, the rad is twice as big. Would the extra coolant not keep the motor cool? If not, what fan should I find to fix this overheating problem. I think I have figured out the oil temp problem, being that I put in 0w40 synthetic which I had a bad feeling about anyway. Im changing it out after just about 200 km to 10w40 synthetic because I don't trust that lighter oil. Could the overheating also be cause in part by the lighter oil? Is it possible that I have already damaged my turbos by running the lighter oil? By the way, the motor is stock with the factory boost restrictor removed and HKS pod filters and a 3-inch Apex'i cat back exhaust. Also, I am getting a stumble on accleration after 5500 RPM. Does the factory ECU actually retard the performance so much as to get a bad miss and very rich conditions? Any help would be appreciated because I am not experienced enough with cars to figure this out without expert advice.

sh@un Grand Master

sh@un

Posted
Posted

Now I assume you do realise that the water-pump is driven off the same pulley that the factory viscous/thermatic fan is mounted to, yes?

If this isn't being driven, you have no coolant flow. If it is being driven, is it slipping badly? That could cause the water in the block to have too low a pressure. Both these would cause high oil temps, too.

110deg C oil temps at idle are ridiculously high.

Part-time electric thermo fans are garbage for hi-po engines like RB26's, the engine bay should have a constant supply of fan driven air to keep heat-soak down. Plus the mechanical fan pulls air through the intercooler.

And finally- always use a radiator fan shrould. The radiator won't be as efficient without one.

Hope this helps.

BHDave Grand Master

BHDave

Posted
Posted

Did you buy the car with the current radiator setup on it, or have recently swapped it and the overheating issue has started since the swap.

Does it overheat when driving on the freeway or at a reasonably constant speed?

If it doesn't cook when driving there are a couple of quick things to check,

1) that the fan has the blades around the right way to pull the air through the core (or push if you have it on the front)

2) That the factory thermo mounted to the front is still working (it should kick in at about 90 degrees).

I suspect that it is an airflow issue and the single 14 can't pull enough air through the core as it's a pretty thick unit

On a general maintenence front, it's worth checking that the thermostat isn't stuck shut if it overheats no matter what and also run a flush through the system to clean out any scale and shit from the block.

Abo Bob Grand Master

Abo Bob

Posted
Posted

How quickly does this happen? I suspect the thermostat if it happens quickly.

A 14" fan will not pull enough air through even if it's working properly but on cool days driving along it should still be fine. I think some of them can be wired backwards which can spin the fan in the wrong direction.

Stock fan or 16" thermo, stock is better.

SkylineBNR32 Rookie

SkylineBNR32

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Thanks for the comments. My first thought was that the stock fan would be much better as it is about twice the size of this electric fan, which is definitely a piece of junk, the problem with the stock fan is that when the engine is reved the blades bend forward and smashed the crap out of the rad before. had to get a new one ordered in, however it was installed at a body shop and not by me. is there a stock sized fan that would not bend like this that I could mount on the water pump pulley?

SkylineBNR32 Rookie

SkylineBNR32

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I have one more question. Where is the connector for the outside temperature sensor located? The manual says to disconnect this sensor with ignition on to force the Auto A/C into heat mode but the picture in the book really sucks and I can't figure out where this connector is located.

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