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Hi Guys,

I am new here.  This is a great site.  I have an R33 GTR Vspec.  I replaced my cracked stock rad and fan with a Mishomoto rad and fan shroud.  The car did not overheat with the stock rad but did with the Mishimoto.  We tried cutting out the fan shroud so that the aircon fan could blow through the rad but the car would still overheat even at idle on a 25 deg day.  We switched back to a factory fan and overheating is gone.  But now I notice coolant on the top of the rad and it seems to be pushing through the Mishimoto rad cap on hot days. Looking at the setup I can't see how the coolant overflow bottle can work, as the overflow hole is above the point where the cap seals, see below photo.  So it seems like the coolant is heating up, expanding and then has nowhere to go except past the cap seal.  You can see the red coolant on the top of the rad.  I can't remember if the setup is the same on the stock rad.  Can someone with a stock rad check for me?  I also noticed that the coolant was boiling in the hoses today, which was 30+ deg.  Is this normal?  Any advice is appreciated.

 

rad.JPG

rad2.JPG

rad3.JPG

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the spring loaded inner part of the rad cap seals in the lower surface and the top of the cap seals against the top lip that over pressure outlet is in the right spot. You have another problem methinks. Is the spring loaded low section actually firmly touching the lower surface? Is the upper rubber seal seated properly in the cap. Remember the a/c condenser gets mucho hot so a/c fan is blowing more hot air thru the radiator on a hot day at standstill.

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Thanks Rusty. 

Overflow hose and spout are clear. 

Quote

Is the spring loaded low section actually firmly touching the lower surface? Is the upper rubber seal seated properly in the cap.

The cap doesn't feel very tight on the 2nd twist so maybe the upper rubber seal is not seated properly - is the cap faulty?  A faulty upper seal would explain the coolant leak around the filler.   What is weird is the cap came with the rad and both are new.  What to do?  Replace the cap?

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2 hours ago, georgev said:

Thanks Rusty. 

Overflow hose and spout are clear. 

The cap doesn't feel very tight on the 2nd twist so maybe the upper rubber seal is not seated properly - is the cap faulty?  A faulty upper seal would explain the coolant leak around the filler.   What is weird is the cap came with the rad and both are new.  What to do?  Replace the cap?

Only one way to find out ...caps are not that expensive

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1 hour ago, KiwiRS4T said:

Only one way to find out ...caps are not that expensive

Its certainly possible the wrong one found its way on at the factory

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The mishimoto radiators and fans are absolute junk. You're better off buying a cheap ebay radiator and using the stock fan. We've had multiple cars come in with these setups and idling they see around 107*C temps. 

From what I've been told the radiators don't have a divider in them so the coolant doesn't make it through the whole radiator and just circulates straight up instead of going across, up and then back across.

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On 1/6/2019 at 6:35 AM, klutched said:

The mishimoto radiators and fans are absolute junk. You're better off buying a cheap ebay radiator and using the stock fan. We've had multiple cars come in with these setups and idling they see around 107*C temps. 

From what I've been told the radiators don't have a divider in them so the coolant doesn't make it through the whole radiator and just circulates straight up instead of going across, up and then back across.

I agree that the fans are rubbish.  It does not move enough air.  I replaced the Mishimoto cap with a new NISMO item and the leaks have stopped.  But it does feel like the mishimoto rad is running warmer than the stock radiator did.  The a/c used to work the same at idle and cruising.  Now there is a noticeable difference between a/c temp at idle and cruising.   

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On 1/4/2019 at 8:57 PM, Rusty Nuts said:

Also check the overflow hose and spout are not blocked, mud wasps are bastards.

Does the overflow hose only work one way, from the radiator to the overflow bottle?  Or is it designed to pull coolant from the bottle into the rad when coolant is low?

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Does the overflow hose only work one way, from the radiator to the overflow bottle?  Or is it designed to pull coolant from the bottle into the rad when coolant is low?

Works both ways. Designed to let coolant expand and enter the o/flow bottle, then gets sucked back into the rad as the coolant cools down and contracts.

 

This is all a function of the radiator cap.

 

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Mishimoto is pretty much overpriced eBay special radiators.

I would find a suitable Tridon radiator cap, I can't say which one you need though.

Also any aftermarket fan shroud or electric fan setup generally never works on Nissans.

Nothing beats the OEM 200 to 600kW fan lol.

 

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On 1/13/2019 at 9:16 PM, admS15 said:

Works both ways. Designed to let coolant expand and enter the o/flow bottle, then gets sucked back into the rad as the coolant cools down and contracts.

 

This is all a function of the radiator cap.

 

So does that mean you can just keep the overflow bottle at max level and the rad will always have enough water?  Or do you guys remove the cap and fill the rad from there?  I'm used to cars with no rad filler just an overflow bottle so I am not sure.

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14 hours ago, Dose Pipe Sutututu said:

Mishimoto is pretty much overpriced eBay special radiators.

I would find a suitable Tridon radiator cap, I can't say which one you need though.

Also any aftermarket fan shroud or electric fan setup generally never works on Nissans.

Nothing beats the OEM 200 to 600kW fan lol.

 

I've learnt the hard way!

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So does that mean you can just keep the overflow bottle at max level and the rad will always have enough water?  Or do you guys remove the cap and fill the rad from there?  I'm used to cars with no rad filler just an overflow bottle so I am not sure.
Fill from the radiator. The overflow bottle should be above the min mark when cold and below the max mark when hot.

Sent from my A1601 using SAU Community mobile app

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Mishimoto has a pretty bad wrap in the Subaru community. It's always hit and miss but a common problem is their caps are garbage as Klutched said. I put a Mishimoto thick mofo in my misses Subaru because it was the only one we could get on short notice that actually fit and used the factory radiator cap and touch wood it hasn't been a problem since October. 

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1 hour ago, Predator1 said:

Use the stock rad cap. The aftermarket caps are shit esp the ones that come with the radiators. 

I would be very careful recommending this.

E.g. if you were to splash out on a nice premium PWR radiator, you'll run into issues using the stock radiator cap. You need to use the CB16110 from Tridon or the Stant equivalent, I assume the same with these run of the mill ling long specials.

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On 2/4/2019 at 1:05 PM, Dose Pipe Sutututu said:

I would be very careful recommending this.

E.g. if you were to splash out on a nice premium PWR radiator, you'll run into issues using the stock radiator cap. You need to use the CB16110 from Tridon or the Stant equivalent, I assume the same with these run of the mill ling long specials.

Sorry, yes, you’re right. Although my personal experience has proven that a cheap radiator caused issues when using the supplied cap.. issues such as higher temp.. didn’t let it overheat.. easily fixed by sticking stock cap which did fit. Had very similar issues with another friends car.

 

also, the stock piping may not last with the increased pressure.. .9 bar over 1.3.. another reason to recommend the stock, or equivalent cap.

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