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Discussion Starter · #1 ·
Hello everyone. Could anybody help me with the following problem:
2 months ago I bought Infiniti FX50s and after the deal I changed all liquids: engine oil, transmission, coolant etc. 1 month later I cleaned the throttle valves and after assembly I noticed some gurgling sound in the dashboard when I rev up the engine. Yes usually such kind of sound means that you have an air in the cooling system and this air flows together with coolant in the heater. So I decided to look for a leakage of coolant but there were no any markers of leakage - Coolant was at the same level in reservoir. I tried to make the leakage test and apply additional pressure to the system - everything was OK, I haven't seen any decreasing of pressure on manometer and I've not seen any leakage.
I had a blown head gasket on my second car (Mitsubishi Montero/Pajero 4) and yes at that moment I had the gurgling sound in the dash and key issue was increasing of coolant level in the reservoir. But I can't see that the coolant level is increased after the ride on my Infiniti.
I've re-read the FSM several times on how to refill the coolant but looks like instruction there is useless because - I'm from Russia and on Russian market as well as on the European one - Infiniti has another cooling system: the reservoir type is circulating and we have cap with valves on reservoir instead of the one on water inlet. The pressure is different too - 88kPa instead of 137kPa.

I've tried to go to the hill to make 45 degrees corner and rev up engine there, I've tried to lift up the reservoir and open the cap to totally avoid the pressure and let the air go out of the system - but looks like everything is useless.
Does anybody has the same behavior ? Can something else make the gurgling sound in the car e.g brakes system or something else?
I should say again that I can't see the increasing or decreasing of coolant level. Engine temperature is normal - I can't see any increasing of temp on the dash and I measured it in alternative way - everything is OK. I can notice the opening of thermostat cause I touch the hoses of radiator and they are cold on the start and hot after the ride...

~ 950 KM passed since the change of the coolant...

Steps to hear the sound:
  • warm up the engine
  • turn on the fan and the heater and run engine on idle run for 1 minute
  • turn off the heater and all climate control using "Off" button
  • rev up the engine up to 2500 - 3000 RPMs.
 

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It is possible that the sound you are hearing is actually from the Air Conditioning system. The AC compressor may not be turning the coolant to a gas and may cause the gurgling that you hear. Retry the steps you mentioned but instead of fully turning off the heat, just turn the AC off. If the gurgling occurs, then it is likely a problem with the AC system.
 

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Discussion Starter · #3 ·
It is possible that the sound you are hearing is actually from the Air Conditioning system. The AC compressor may not be turning the coolant to a gas and may cause the gurgling that you hear. Retry the steps you mentioned but instead of fully turning off the heat, just turn the AC off. If the gurgling occurs, then it is likely a problem with the AC system.
Thank you for the reply, but if I understand correctly in my case A/C is always off. Usually I don't use it in a winter (only for quick defrosting of windshield) and so A/C button is not lightened. Can the compressor be used in this case anyway? Also as I understand fans should work almost constantly when A/C is on, but as I can see they are switched off and car switching them on only on high temperature.
 

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Discussion Starter · #5 ·
Have you bled the system using the bleed port on the heater hose near the firewall? It is at the back of the engine on the driver side.
Yes, I've even tried to open in on running engine - and I've even got a jet of coolant to the face (thanks God that it wasn't too hot). I've tried to bleed air according to the manual and taking into account the differences in the coolant systems. When I open the heater air hole on cold engine - sometimes there is a pressure if I don't flush it with the opening of radiator cap but there is no air ...
 

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My suggestion is to open the bleed screw, start the engine (heat to max) and run it until you see coolant coming from the valve. Monitor the coolant level at the reservoir and make sure it doesn't go empty. You may have already done this but it isn't clear in your posts.
 

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Discussion Starter · #7 ·
My suggestion is to open the bleed screw, start the engine (heat to max) and run it until you see coolant coming from the valve. Monitor the coolant level at the reservoir and make sure it doesn't go empty. You may have already done this but it isn't clear in your posts.
Yes, I've tried this procedure - I could see the coolant and closed the air hole after that. I thought "OK, everything should work fine now" - but unfortunately gurgling remains... So I repeated that procedure several times until I've got the jet of coolant to the face from this air relief hole and even after that I can hear the gurgling.

Also according to the schemes of cooling system - there is no any valve to control the flow of coolant through the heater and there is no any bypassing hose, so I'm not sure that there is any necessity to set heater on max as this only controls the air damper in the heater unit, but the flow of coolant remains the same.



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I think I heard it. Sounds like a large gulp. That is definitely very strange. Have you checked the passenger side carpet to see if any coolant has leaked inside. You would probably smell it first though. I wish I could be more help but other than keep trying to bleed it, I can't think of anything else.
 

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Discussion Starter · #12 ·
@DenisMcG yes, you're right about the large gulp.
I've looked through the heater inside and there is no any leak, btw I've applied additional pressure to the system and there was no any decreasing of that pressure, so potentially there is no leak outside of the cooling system.
I've contacted with several owners of FX50 here in Russia (with the same type of cooling system) and they said that they don't have such noise. Also I've contacted with several Infiniti specialized workshops including the official dealers and most of them say that there is such noise on some vehicles with S51 body (FX50/FX37). But they don't know how to fix that.

Currently I've ordered the CO2 leak detector and if my suggestion is right the reason of noise is the breached head gasket or microcrack in the cylinder head.
That will be very said...
 
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