Things you should know about our FX35's and all the over heat issues

D

duncan351

Member
Location
Texas
Car
2003 FX35 AWD
Name
Duron
Hey guys this is my 1st post on this forum but my wife encouraged me to share my knowledge with you guys. I bought my wife an 03 FX for Christmas. It was described to me by the previous owner that his wife was driving the fx to work and one day it just overheated without any warning. First problem they ever had with it and have owned is since new. They had it towed to a shop and they told her she needed a new engine which is how I got pulled in to the situation. The customer called my company to get a quote on an engine rebuild. After talking for a while he asked me if I was interested in buying the fx. He didn't want to invest the money in it and want to buy a BMW X5( Like that's going forward, going backwards IMO). So I bought it and trailered it to my shop. The first thing we did was replace the thermostat and I noticed black flaky stuff in the coolant which I knew was the viton coating from the head gaskets. So I bought some Blue Devel and ran it through to the cooling system. I could tell compression was bleeding into the cooling system. The blue devel solution worked for about 4 mths or so then it blew the radiator and burned the motor UP!! I ended removing the motor and replacing the heads and block along with a new radiator. It runs great now with 300+ miles on it. But the entire problem started from the factory head gaskets. They are a terrible design and will give up eventually on most of the early model fx's. When I rebuilt the engine we used Victor Rienz head gaskets which the entire gasket is coated in Viton versus the factory which only has viton covering around the combustion chamber only. For some reason this a serious problem and deteriorates over time then compression leaks into the cooling system pressurizing it and pushes the coolant into the overflow tank. This is my 4th or 5th VQ35 engine I've rebuild in 8 years or so. Most people are not willing to spend the money the rebuilds because all these engines failed from the exact same problem which is over heating. I always have to replaced the heads and get a new short block because the engines got so hot heads are warped to the point they are no good and the block warps too.

The other major problem is the factory temp gauge is a SERIOUS POS!!! The Service manual says the gauge is in the Cold when 122* or colder, middle position is 156*-233*, hot is *266. This is ridiculous, you really don't get much of a opportunity to get off the road and shut your vehicle off before your engine is toasted. I bought a Scan Gauge II for the FX and mounted it cleanly in it so my wife can see the actual temp that the ECU see's that way she doesn't have to depend on the factory gauge which will cost you an engine one day. But for those with good running motors I would highly recommend the scan gauge. It is digital, clean, and i have the display calibrated to the same orange color as the factory interior without having to put a ricer gauge in a luxury SUV.

Sorry for being long winded but have I read sooooo many over heating stories where people reported their problems but no explanation for why they had their problems. I felt compelled to explain the situation to members here. I could clearly see there wasn't much info out there on the net about what really is going on internally with these engines.
 
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is the overheating problem that you saw isolated to only the fxs? i still drive an 02 qx4 wit 150k and have not seen any major issues other than some leaks at he vc gaskets.
 
duncan351 said:
Hey guys this is my 1st post on this forum but my wife encouraged me to share my knowledge with you guys. I bought my wife an 03 FX for Christmas. It was described to me by the previous owner that his wife was driving the fx to work and one day it just overheated without any warning. First problem they ever had with it and have owned is since new. They had it towed to a shop and they told her she needed a new engine which is how I got pulled in to the situation. The customer called my company to get a quote on an engine rebuild. After talking for a while he asked me if I was interested in buying the fx. He didn't want to invest the money in it and want to buy a BMW X5( Like that's going forward, going backwards IMO). So I bought it and trailered it to my shop. The first thing we did was replace the thermostat and I noticed black flaky stuff in the coolant which I knew was the viton coating from the head gaskets. So I bought some Blue Devel and ran it through to the cooling system. I could tell compression was bleeding into the cooling system. The blue devel solution worked for about 4 mths or so then it blew the radiator and burned the motor UP!! I ended removing the motor and replacing the heads and block along with a new radiator. It runs great now with 300+ miles on it. But the entire problem started from the factory head gaskets. They are a terrible design and will give up eventually on most of the early model fx's. When I rebuilt the engine we used Victor Rienz head gaskets which the entire gasket is coated in Viton versus the factory which only has viton covering around the combustion chamber only. For some reason this a serious problem and deteriorates over time then compression leaks into the cooling system pressurizing it and pushes the coolant into the overflow tank. This is my 4th or 5th VQ35 engine I've rebuild in 8 years or so. Most people are not willing to spend the money the rebuilds because all these engines failed from the exact same problem which is over heating. I always have to replaced the heads and get a new short block because the engines got so hot heads are warped to the point they are no good and the block warps too.

The other major problem is the factory temp gauge is a SERIOUS POS!!! The Service manual says the gauge is in the Cold when 122* or colder, middle position is 156*-233*, hot is *266. This is ridiculous, you really don't get much of a opportunity to get off the road and shut your vehicle off before your engine is toasted. I bought a Scan Gauge II for the FX and mounted it cleanly in it so my wife can see the actual temp that the ECU see's that way she doesn't have to depend on the factory gauge which will cost you an engine one day. But for those with good running motors I would highly recommend the scan gauge. It is digital, clean, and i have the display calibrated to the same orange color as the factory interior without having to put a ricer gauge in a luxury SUV.

Sorry for being long winded but have I read sooooo many over heating stories where people reported their problems but no explanation for why they had their problems. I felt compelled to explain the situation to members here. I could clearly see there wasn't much info out there on the net about what really is going on internally with these engines.
Click to expand...
Thanks for the info

Sent from my SGH-T889
 
On most cars though, if something goes wrong with the cooling system, it's pretty sudden. It never goes up gradually; one minute it's working, the next your temp gauge pegs. Agreed that the OEM temp gauge doesn't do much. When I had improperly bled the system and it was overheating, it would go from normal to maxed out in about 50 ft.

At least the FX has a temp gauge. My 335 doesn't even have a gauge. If the waterpump fails, a yellow warning light pops up and you have about another 15 seconds before the red light pops up and the car goes into limp mode. If you don't pull over immediately, you risk engine damage.
 
Welcome and thanks for the detailed info, hope I dont have to get into head gaskets anytime soon.
 
I have seen this head gasket problem on earlier version VQ engines and it doesn't matter what its in. I have done a 04 or 05 I35, quite a few 03-04 350Z's, and now this FX. I honestly can't tell you when the changes took place in the VQ motors but I believe the Head gaskets and head bolts were changed in 2005 and up.

---------- Post added at 03:02 PM ---------- Previous post was at 02:59 PM ----------

I own a machine shop too, so all the heads that are serviceable are taken there to pressure test, resurface as needed, valve job and new valve seals installed however when you have a block that is distorted we toss them and rebuild with a good working core short or long block.

---------- Post added at 03:17 PM ---------- Previous post was at 03:02 PM ----------
shadow191 said:
On most cars though, if something goes wrong with the cooling system, it's pretty sudden. It never goes up gradually; one minute it's working, the next your temp gauge pegs. Agreed that the OEM temp gauge doesn't do much. When I had improperly bled the system and it was overheating, it would go from normal to maxed out in about 50 ft.

At least the FX has a temp gauge. My 335 doesn't even have a gauge. If the waterpump fails, a yellow warning light pops up and you have about another 15 seconds before the red light pops up and the car goes into limp mode. If you don't pull over immediately, you risk engine damage.
Click to expand...

True however most common vehicles the gauge is more leanier than the FX. In most cases when your temp gauge starts to move towards the North Pole and have enough time to get off the road and shut the vehicle off but on the fx as I was explaining in my first post the middle (totally warm, normal position) position of the gauge moves a little but its deceiving if your driving down the road and trying to glance over to you gauges too. It really doesn't move out of what we would consider the normal temp area in the sweep of the gauge until than after 233*. I'm sorry but that's just too dam late and by the time you get out of traffic to get off the road, that engine is toast. Alot of shops just try to replace head gaskets and sometimes replace the heads however if they aren't checking the deck on these particular engines, my experience is they just aren't holding up very long having cooling problems they are constantly fighting or burning oil because the entire block is warped.
Yea, Bimmers are terrible. I had a customer 8 hours away transport his 750Li to my shop replace his motor because of our reputation and savd him major $$$. His motor was shot from a bad water pump so had to replace it with a low mileage one. Hard to belive a $100K car doesn't have better warning systems or even a temp gauge.
 
Thanks for the info, you have really educated me on something that is important. I went online (Amazon, Ebay) and I'll be getting a Scan gauge II for sure. From what I read about it, it seems to be a must for anyone who wants to stay ahead of the curve when it comes to information about motor issues.
 
My mechanic e-mailed me back in 2013 when I asked about buying a used 03-06 FX35/45, in a nutshell, he wrote: .....We service a lot of them and they are less than admirable vehicles. For an unknown reason we see a lot of them with oil leaks which doesn't make sense unless there is a difference in engine bay temps. The engine is the same as it is in other Nissans, but we don't see that problem in the sedans.......
But in the end he did say get it checked out ( and clean CARFAX report) and if YOU like it, you will have a nice driving car.
And in 2014 I got a 05 45 anyway with no real problems......yet.:good:
 
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Yeah I got a clean carfax with mine, still have it from when I bought it. This will most likely be my last winter with the fx though. Time to move on in the spring/summer.

Sent from my SM-N920V
 
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