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Hi all, I just purchased a 2016 RS400 about two months ago. A few days after buying the car I noticed the fluid in the expansion tank for the intercooler was low. I filled it up, checked it a few days later and it was still good. This past week I checked it again and it was empty. I filled it up again and it seems to be holding but maybe dropping very slowly? I have checked for leaks by examining the various hoses that make up the system. I've also removed the splash guard under the car and check it for leaks, nothing. I sure hope it's not somehow leaking into the turbos. Has anyone else on here had this issue? I did a thorough search but couldn't find an example of anyone having the same issue (except on some forums for other make/model cars). I guess I'll need to take it in to get looked at, but any information some of you might have would be much appreciated. -Matt
 

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Do you have the ability to do a pressure test on that system?
 

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So the engine coolant may change its level but the intercooler coolant should be pretty much at a constant level. And no, it's not going to the turbos since it is a separate fluid circuit.

And just to be clear, we're talking about the smaller coolant reservoir tank on the right side, correct?
 

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Discussion Starter #4
Do you have the ability to do a pressure test on that system?
I don't have a cooling system pressure tester but could probably pick one up. I was just curious if anybody knew whether this is a common problem on these VR30DDTT motors. I guess I'm hoping it's just a small leak in the plumbing somewhere and not leaking into the engine.
 

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2018 Q50 Red Sport 400 AWD
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So the engine coolant may change its level but the intercooler coolant should be pretty much at a constant level. And no, it's not going to the turbos since it is a separate fluid circuit.

And just to be clear, we're talking about the smaller coolant reservoir tank on the right side, correct?
So you're saying an internal leak in the heat exchanger would not have the potential for this coolant to enter the intake air and make its way through the turbos and into the engine to be burned? I understand this coolant circuit would not contaminate the oiling system and thus not reach the turbo bearings, but I think depending on where the leak is this coolant could be ingested into the engine.
 

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Discussion Starter #6
So the engine coolant may change its level but the intercooler coolant should be pretty much at a constant level. And no, it's not going to the turbos since it is a separate fluid circuit.

And just to be clear, we're talking about the smaller coolant reservoir tank on the right side, correct?
Yes, the smaller tank for the intercooler coolant. I read on Audi and BMW forums that a consistently dropping level in intercooler coolant with no apparent leaks is indicative of it leaking into the intake and being burned.
 

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2017 Q50 Red Sport 400 RWD
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So the engine coolant may change its level but the intercooler coolant should be pretty much at a constant level. And no, it's not going to the turbos since it is a separate fluid circuit.

And just to be clear, we're talking about the smaller coolant reservoir tank on the right side, correct?
Might want to define 'right'. ;) Right as in PS, or right as in when facing the engine bay with the hood up, looking down at the two tanks.
 

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So you're saying an internal leak in the heat exchanger would not have the potential for this coolant to enter the intake air and make its way through the turbos and into the engine to be burned? I understand this coolant circuit would not contaminate the oiling system and thus not reach the turbo bearings, but I think depending on where the leak is this coolant could be ingested into the engine.
The intercooler is post-turbo. Depending on the leak location, it might drop back into the turbo (due to gravity perhaps?) or just get sucked thru the throttle body and into the intake plenum and wherever it may reach. The OP issue seems to have slowed down so I don't think it's that huge leak but still worth to be checked out.

Yes, the smaller tank for the intercooler coolant. I read on Audi and BMW forums that a consistently dropping level in intercooler coolant with no apparent leaks is indicative of it leaking into the intake and being burned.
That is a possibility and that can easily be checked IMO. The hard part is probably choosing whether to disassemble left or right side first. You can also do a few hard pulls (or whichever action that would activate the two water pumps) and check its level again.

Might want to define 'right'. ;) Right as in PS, or right as in when facing the engine bay with the hood up, looking down at the two tanks.
I always use the same as the car manufacturer labels as L or R - that is, referenced when you're sitting inside the car. But who else knows I always refer L / R that way, right? Hence, the word 'smaller' :p
 

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The intercooler is post-turbo. Depending on the leak location, it might drop back into the turbo (due to gravity perhaps?) or just get sucked thru the throttle body and into the intake plenum and wherever it may reach. The OP issue seems to have slowed down so I don't think it's that huge leak but still worth to be checked out.
I guess I never really thought too hard before posting, about when the air is cooled, pre or post compression, but when I stop and actually think about it, I was aware post turbo is when it happens. Three turbo motors and I have never taken apart any of the induction system over the years. I'm ashamed.
 

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I guess I never really thought too hard before posting, about when the air is cooled, pre or post compression, but when I stop and actually think about it, I was aware post turbo is when it happens. Three turbo motors and I have never taken apart any of the induction system over the years. I'm ashamed.
Man it isn't late yet. You still have a turbo in your car (twins in fact) and you still have plenty of opportunities. Just call Avedis in case you get stuck in the process ;)
 

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Discussion Starter #11
The intercooler is post-turbo. Depending on the leak location, it might drop back into the turbo (due to gravity perhaps?) or just get sucked thru the throttle body and into the intake plenum and wherever it may reach. The OP issue seems to have slowed down so I don't think it's that huge leak but still worth to be checked out.



That is a possibility and that can easily be checked IMO. The hard part is probably choosing whether to disassemble left or right side first. You can also do a few hard pulls (or whichever action that would activate the two water pumps) and check its level again.



I always use the same as the car manufacturer labels as L or R - that is, referenced when you're sitting inside the car. But who else knows I always refer L / R that way, right? Hence, the word 'smaller' :p
Thank you I will try getting on the throttle a little more to see if that makes the coolant drain faster. I see you've to a 2016 RS as well. Have you found yourself having to add any fluid to the intercooler fluid tank? I think I will bring it in to the shop so at least they can pressure test the system. There are a lot of VR30DDTT owners on this site so I think if this issue was common on these cars it would have been brought up before.
 

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Thank you I will try getting on the throttle a little more to see if that makes the coolant drain faster. I see you've to a 2016 RS as well. Have you found yourself having to add any fluid to the intercooler fluid tank? I think I will bring it in to the shop so at least they can pressure test the system. There are a lot of VR30DDTT owners on this site so I think if this issue was common on these cars it would have been brought up before.
Only when I drained it after the heat exchanger upgrade and after the dealer brought the engine down for turbo replacement that I had to refill it back to max level (also the engine coolant). It wasn't a lot, probably took a few hundred milliliters.

It's pretty rare actually. If anything related to coolant, it's always the engine side.
 

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Discussion Starter #13
Only when I drained it after the heat exchanger upgrade and after the dealer brought the engine down for turbo replacement that I had to refill it back to max level (also the engine coolant). It wasn't a lot, probably took a few hundred milliliters.

It's pretty rare actually. If anything related to coolant, it's always the engine side.
Okay, thank you for all of the info. I took of the engine cover and inspected all of the hoses and such (going into and out of the intercoolers). Wow, there's a lot going on with the intercooling system on these cars! I was wondering if one of those intercoolers had a small crack somewhere on the inside, it could allow coolant to slowly leak into the air flow and be taken into the engine. Right now I only seem to be losing a few tablespoons of fluid every 2 - 3 days. I will monitor it for a few more days and take it in to the dealership if the issue persists. Unless somebody knows a good Nissan/Infiniti mechanic in the Phoenix area? From the looks of it, DIYing an intercooler replacement doesn't seem too hard. They're easily accessible without much fuss.

Sorry to hear about your turbo. That makes me a little nervous too as I'm not under warranty. How many miles did you have on it when the turbo went out on you? I am guessing that's a $$$y repair?!
 

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Okay, thank you for all of the info. I took of the engine cover and inspected all of the hoses and such (going into and out of the intercoolers). Wow, there's a lot going on with the intercooling system on these cars! I was wondering if one of those intercoolers had a small crack somewhere on the inside, it could allow coolant to slowly leak into the air flow and be taken into the engine. Right now I only seem to be losing a few tablespoons of fluid every 2 - 3 days. I will monitor it for a few more days and take it in to the dealership if the issue persists. Unless somebody knows a good Nissan/Infiniti mechanic in the Phoenix area? From the looks of it, DIYing an intercooler replacement doesn't seem too hard. They're easily accessible without much fuss.

Sorry to hear about your turbo. That makes me a little nervous too as I'm not under warranty. How many miles did you have on it when the turbo went out on you? I am guessing that's a $$$y repair?!
Yes our engine bay looks somewhat messy and spaces are tight. Hopefully you get your issue sorted soon.

I take it you have over 70k miles on the car already. My turbo had been leaking oil for maybe almost two years before I brought it in. It was still under warranty so i didn't pay for anything. I just wish they replaced the other turbo as well. It would be costly to replace a turbo since they'd need to drop the engine down and approx 2 days work.
 

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I had the same problem, bought the car and after a week I noticed the expansion tank for the Heat Exchanger was empty. I took it to the dealer for service and they refilled it, happened again after a couple of weeks. Went back again and got it refilled, it has been holding since Mid November. Hasn't happened again.
 

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Discussion Starter #16
I had the same problem, bought the car and after a week I noticed the expansion tank for the Heat Exchanger was empty. I took it to the dealer for service and they refilled it, happened again after a couple of weeks. Went back again and got it refilled, it has been holding since Mid November. Hasn't happened again.
Thank you! That's good information. I will be keeping a close eye on it.
 

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Hi all, I just purchased a 2016 RS400 about two months ago. A few days after buying the car I noticed the fluid in the expansion tank for the intercooler was low. I filled it up, checked it a few days later and it was still good. This past week I checked it again and it was empty. I filled it up again and it seems to be holding but maybe dropping very slowly? I have checked for leaks by examining the various hoses that make up the system. I've also removed the splash guard under the car and check it for leaks, nothing. I sure hope it's not somehow leaking into the turbos. Has anyone else on here had this issue? I did a thorough search but couldn't find an example of anyone having the same issue (except on some forums for other make/model cars). I guess I'll need to take it in to get looked at, but any information some of you might have would be much appreciated. -Matt
Hi, i have the same issue that you had before and yet didn’t know the reason of water dropping!
Would you please advise of you found the solution? And what was it ?
 

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Discussion Starter #18
Hi, i have the same issue that you had before and yet didn’t know the reason of water dropping!
Would you please advise of you found the solution? And what was it ?
To be clear this is just about the intercooler fluid level. I brought it to the dealership and asked them to pressure test the system. They checked for leaks and said it was not leaking anywhere. I had to add a little more fluid a few times after that, and eventually it stayed steady. My car had been in a flood before I bought it so I think whoever did the rebuild/service before I bought it didn't properly fill it using a lift tool (or bleed/burp it). See this related thread, it seems to be an issue others have had as well. It appears even the dealerships often do not properly fill the system.

 
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