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Discussion Starter #1
I have an FX35 with 128K well maintained miles, most at the dealer. About two months ago, car overheated; dealer changed the radiator.

Two weeks later, overheating occurred again; dealer then told me there was air in the system and all should be o.k.

Overheated again three weeks later, and dealer could not duplicate the problem.

Tomorrow going back to dealer since it almost overheated again yesterday.

As part of my investigation, I note that the coolant overflow tank gradually fills with coolant, without allowing coolant to return to radiator when car cools overnight. Eventually, the overheating occurs when the overflow tank fills; then coolant is expelled from overflow tank.

Overheating has occurred at various speeds; once when driving at steady 35 mph, once when driving at 50 mph, then again when decelerating from 65 down to 25 off a highway ramp. When overheating occurs, check engine line comes on and flow of fuel through gas pedal is barely possible (probably a computer safety device to prevent engine damage).

The day after the overheating occurs, FX runs fine until the next time.

Dealer has stated that they also have another FX with about 130K miles which overheats all the time, and they can not diagnose the problem.

Anyone have a suggestion as to what may be the cause? Dealer claims they already checked water pump, all pressures, etc. I found something on-line about the radiator cap gasket failing over time that might cause overheating, but they changed the radiator cap during the last visit.

Anyway back tomorrow for a loaner vehicle; this time I will instruct them to keep the vehicle until it is diagnosed and repaired, since the overheating occurs without warning.

Thanks,

TAXEFX
 

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I'm no mechanic, but most of my overheating problems (in other, older cars) have been related to a thermostat, usually stuck closed.

Did the dealer look at that item?
 

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Agreed... the engine cooling system on all cars hav ethe same or similar components. When troubleshooting is easiest to start with the cheapest things first and the things you can change yourself. In order of troubleshooting:

coolent level and mixture (not just straight coolant)
radiator cap
thermostat
fans (does car overheat at idle, cool down at highway speed)
water pump

Your problem sounds like a thermostat. When it is running hot, does the large top hose from radiator to engine swell up?
 

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I second the thermostat. I had an overheating problem on my ol' Lincoln Continental. Thermostat stuck shut, replaced, worked just fine after that.

Very hard to believe that they wouldn't think of this...
 

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Discussion Starter #5
According to my original invoice, the thermostat was changed when the radiator was changed.

Vehicle left at dealer on Monday morning; informed them that I do not want it back until fixed. Have not yet heard a word from them yet; there is something in the cooling system that sends coolant to the overflow tank, and then fails to return coolant to radiator, i.e., no vacuum.

I find it almost impossible to understand that Infiniti can not ascertain a quick solution to this problem.

In any event, I have transportation in the form of the provided loaner car, so they can take as long as necessary.

Thanks for all the input so far.

TAXEFX
 

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Maybe the radiator cap? That usually keeps the system pressurized. You describe what sounds like no pressure in the system. Most people forget about changing the cap. A bad rubber ring in that could cause the problem you describe.
 

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I also had an overheating issue relating to the thermostat on an older car of mine. My mechanic took it out, added heat and found it wasn't activating until about 120 degrees over the norm.
 

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I have the same exact problem with my FX35 overheating as described in the June 10, 2007 comment .... have replaced the radiator and and then the thermodstat twice within a couple of months ... overheated over and over again without a warning. My dealer in central jersey has no clue at this point. I would like the northern jersey infiniti dealer to talk to my dealer ... to compare notes ... can you please let me know what town in northern jersey that you are dealing with. And if you already solved the problem ... that would be great ... I gave my dealer the keys and have a loaner for the past three days. So far ... nobody has a clue what to do next.
 

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Discussion Starter #9
Overheating Still Continues - No Solution

JPFX35, I just replied separterly to you regarding your posting.

As an update to all, my FX35 is still overheating. It's going back to Lynnes Infiniti in Bloomfield, NJ for the fifth visit for same issue. At least they supply me with loaner vehicles each time, and appear to be genuinely interested in resolving the problem.

I have registered my issue with Infiniti Consumer Affairs at 1-800-662-6200 to see if they can assist further.

Last visit, Lynnes had my vehicle for three weeks but claimed they were unable to duplicate overheating. However, the coolant still does not return to radiator from coolant recovery tank when engine cools.

Will keep all posted.
 

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This happened to a POS Mitsubishi Galant I had when I was in high school and it turned out to be a bad water pump.
 

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Keeping my fingers crossed

OK ... So far, so good. The dealer had my car for about 1 week. They determined that the radiator cap is the root cause of all of my overheating problems. So they replaced it. I have had the car for three days now ... and no problem so far. Also, I am noticing that the temperature gauge is holding at a level just a little bit below where it was for the last few months when I was having this intermittent overheating issue. Maybe this is going to work !

I am still a bit confused .... As I stated in an earlier posting, the radiator was replaced (around Mother's Day weekend of this year) ... I would have assumed that a new radiator cap would have come with it ... I can understand why my old radiator cap would fail at 100K miles .... but is it possible that the dealer would even think of using the old radiator cap on the new radiator ? The service rep said that this was the case. If this is true ... then I have confidence that the problem is resolved. However, if they are not telling me the truth ... then I have reason to be worried. Can anyone shed some light on what happens when a radiator is replaced ? .... does it come with a new cap ? or does the dealer have to go get one off the shelf ?
 

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johnmax said:
Maybe the radiator cap? That usually keeps the system pressurized. You describe what sounds like no pressure in the system. Most people forget about changing the cap. A bad rubber ring in that could cause the problem you describe.
Winner!!!!

Whats my prize? :lol:
 

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JohnMax was, is and always will be the man when it comes to the mighty FX!!!!
 

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geltz said:
JohnMax was, is and always will be the man when it comes to the mighty FX!!!!
(bows)
 

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Discussion Starter #15
Overheating not yet solved

I'm happy to hear that JPFX35's overheating problem was solved by changing the radiator cap. I have the exact same problem with my FX but my dealership claims that they have "tested" my radiator cap and found no fault with it.

Now they say that they want to change the head gasket, according to the advice they've received from Infiniti's "Tech Line" for whatever that's worth. They also have another FX35 with the same issue currently undergoing the head gasket replacement, so I have instructed the dealer to report the results of that repair to me before they begin work on my vehicle.

Based on my research however, and what I've learned here, it still looks like it is the vacuum seal on the radiator cap.

Will contact Infiniti Consumer Affairs for more assistance.
 

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Maybe you should just cough up a few bucks for a new cap and see if that fixes the problem. If that works, it's a lot less inconvenient than going through all that other engine work. Plus you don't know what might happen when everything else is taken apart. The delar makes a lot more money changing head gaskets than screwing on a new radiator cap, so they're happy to do the gasket routine. Check the simple things first.
 

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A new cap is probably a separate piece

There are very specific checks for radiator,cap and head gasket...very surprised that the Techs just don't go down the list...but then few of them even know what can be done with a Consult... so why am I surprised
 

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SAME PROBLEM BUT NEW CAP DIDN"T WORK

I have 76K and my FX has the same problem. I tried 2 caps, put in new radiator, 2 thermostats and a block sealent. Now they want to replace the head gaskets but there are no other symptoms indicating the head gasket is bad.

I also hear a bubbling or gurgle behind the stearing wheel. It occurs everytime during acceleration.

My overflow tank in now empty now, the radiator is filled but now it's not overheating?

Any ideas
 

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OK ... Back to square one. I have driven about 700 miles since my radiator cap was replaced ... and since then it looks like the engine is running cooler than it had for months according to the temperature guage.

However, today on my way home from work, I notice a gurgling sound behind my steering wheel, while I was starting up my fx35 and driving out of a store parking lot along the way home. When I got home I checked under the hood and the overflow tank was over the MAX line. Also .. I noticed that it was bubbling inside.

Tomorrow morning I am driving back to the Infiniti Dealer. I am really getting tired of this.

JPFX35
 
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My 2003 FX35 has also begun overheating and it looks like there is either a design or manufacturing fault with the engine .

Symptoms- same sporadic overheating as other members. After replacing the radiator cap (Infiniti acknowledges that this is a common failure item) overheating again happens for no obvious reason.

Fluid ends up in expansion tank , engines runs hot. I let the engine cool, return fluid to radiator and car runs just fine for several hundred miles or perhaps weeks until the next episode.

Car has ALWAYS been main dealer serviced, 81k miles and 4 1/2 years old. Never abused.

Infiniti dealer has been reluctant to replace thermostat ( my request) or water pump / radiator. They suggested it needed a new engine for $7k! Also they gave me Infiniti's consumer complaint line to register and they would push from their side.

Finally after several discussions on why this car might need a new engine, I got into a conversation with the service manager that made it all fall into place.

They are reluctant to go the obvious replacement route thermo/radiator/water pump etc because they know it won't fix the problem. Seems that water ways in the engine block are likely jamming up and creating the sporadic problem. ( the sporadic nature surprises me and would have thought a thorough back flush would have cured this, but evidently no).

They know of =several= similar examples where replacement of all the normal culprit pieces has not cured the problem and a replacement engine has been needed.

Now the service manager was vague enough not to commit directly to these statements but I am 100 % certain of the information he was giving me.

He's caught between a rock and a hard place- defending/ignoring a yet unacknowledged flaw in the car , yet not wanting to compound the issue by letting the customer throw good money after bad.

My only hope is that Infiniti does the right thing. I have already offered to pay for a strip down and will eat that cost plus the new engine, if they can show me that it was my fault this happened. No takers yet.

I acknowledge that this car has done 81k miles ( 11 k over warranty), however these miles are highway miles for a car that has solely been main dealer serviced at all the correct intervals. This car should not need a new engine, so soon.
 
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