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Discussion Starter · #1 ·
Hello all, I puchased an 06 xterra (240k miles) a few days ago. The previous owner stated that the head gasket blew, and that oil and coolant were mixing together in the radiator. I've taken everything apart down to the intake manifold so far. The car still runs, just not great. High rev when started, and car shoots some white smoke out of the back. Previous owner said he drove for a little while, but stopped when he found out what was wrong. Here is what's been found so far:

  • Oil is leaking at the corners of both valve covers. Cannot confirm for engine gasket yet.
  • Radiator has something weird in it. Coolant yes, but it looks more like congealed fat from cooking - light tan and all.
  • The VIAS control solenoid valve has some slight fraying on it, exposing the wire.
  • One ignition coil on passenger side bank has the rubber insert on the bottom torn.
  • An O2 Sensor right below the steering wheel has oil all over it.
  • Small animal nest under intake manifold.
  • Codes:
    • P0031 - Heater Control Circuit - Low Bank 1 Sensor
      • - I'm guessing that oil covered O2 sensor might be dead. Code reader said it had voltage though.
    • P0300 - Random/Multiple Cylinder Misfire Detected
      • Probably that torn ignition coil.
    • P0430 - Catalyst System Efficiency Below Threshold Bank 2
      • My guess, has to do with the O2 sensor mentioned earlier.
    • P1148 - Closed Loop, Bank 1
      • Also an O2 Sensor issue from what I've read.
Here's my list of things to do immediately:
  • Timing chain kit, do everything in there.
  • Timing chain gasket kit.
  • Gasket kit, this thing is puddling oil.
  • Clean out the radiator of that gunk.
Finally, I need to order new ignition coils and spark plugs. Should do these while its open.
Any thing wrong with my logic here, or does anyone recognize any of these as being part of something far worse?

Attached are two pictures of the gunk in the radiator.
 

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2015 Xterra Pro-4X
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Hello all, I puchased an 06 xterra (240k miles) a few days ago. The previous owner stated that the head gasket blew, and that oil and coolant were mixing together in the radiator. I've taken everything apart down to the intake manifold so far. The car still runs, just not great. High rev when started, and car shoots some white smoke out of the back. Previous owner said he drove for a little while, but stopped when he found out what was wrong. Here is what's been found so far:

  • Oil is leaking at the corners of both valve covers. Cannot confirm for engine gasket yet.
  • Radiator has something weird in it. Coolant yes, but it looks more like congealed fat from cooking - light tan and all.
  • The VIAS control solenoid valve has some slight fraying on it, exposing the wire.
  • One ignition coil on passenger side bank has the rubber insert on the bottom torn.
  • An O2 Sensor right below the steering wheel has oil all over it.
  • Small animal nest under intake manifold.
  • Codes:
    • P0031 - Heater Control Circuit - Low Bank 1 Sensor
      • - I'm guessing that oil covered O2 sensor might be dead. Code reader said it had voltage though.
    • P0300 - Random/Multiple Cylinder Misfire Detected
      • Probably that torn ignition coil.
    • P0430 - Catalyst System Efficiency Below Threshold Bank 2
      • My guess, has to do with the O2 sensor mentioned earlier.
    • P1148 - Closed Loop, Bank 1
      • Also an O2 Sensor issue from what I've read.
Here's my list of things to do immediately:
  • Timing chain kit, do everything in there.
  • Timing chain gasket kit.
  • Gasket kit, this thing is puddling oil.
  • Clean out the radiator of that gunk.
Finally, I need to order new ignition coils and spark plugs. Should do these while its open.
Any thing wrong with my logic here, or does anyone recognize any of these as being part of something far worse?

Attached are two pictures of the gunk in the radiator.
View attachment 80798 View attachment 80799
Sounds like you have the dreaded radiator failure that is called SMOD. In this failure the transmission cooling line that runs through the bottom of the radiator has developed a leak and the coolant and trans fluid have mixed. This is what you are seeing in the radiator. This is typically fatal for the transmission but maybe you could somehow get lucky. Radiator absolutely needs to be replaced. I would not assume the previous owner was correct about the engine head gasket. Don't go there till you figure out the extend of the radiator induced damages.
 

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Discussion Starter · #3 · (Edited)
Sounds like you have the dreaded radiator failure that is called SMOD. In this failure the transmission cooling line that runs through the bottom of the radiator has developed a leak and the coolant and trans fluid have mixed. This is what you are seeing in the radiator. This is typically fatal for the transmission but maybe you could somehow get lucky. Radiator absolutely needs to be replaced. I would not assume the previous owner was correct about the engine head gasket. Don't go there till you figure out the extend of the radiator induced damages.
According to the previous owner, the radiator has already been changed to prevent this. Also, this gunk is not at all like a milk shake. It is a tan goldish color, and I can see gold flakes in the coolant. The gold flakes seem to be in the coolant at various places in the line as well. Reading another thread, it looks like and appears to be this. According them, they said that the tan goldish stuff is line sealant.
 

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Check the color and consistency of your transmission fluid. If it's pinkish and or creamy then you know that you have SMOD. The goo in your radiator looks more like the amber color of motor oil to me, but definitely check the transmission fluid.

A single bad ignition coil will not give you a random misfire. It will give you a misfire only in the cylinder with the bad coil. I would consider the possibility that your catalytic and O2 sensor issue may be the result of what's causing your misfire. You are probably running lean or rich (I would hazard a guess that it's rich). Check your spark plugs for color and condition. That can tell you a lot about what's going on.
 

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Discussion Starter · #5 ·
Check the color and consistency of your transmission fluid. If it's pinkish and or creamy then you know that you have SMOD. The goo in your radiator looks more like the amber color of motor oil to me, but definitely check the transmission fluid.

A single bad ignition coil will not give you a random misfire. It will give you a misfire only in the cylinder with the bad coil. I would consider the possibility that your catalytic and O2 sensor issue may be the result of what's causing your misfire. You are probably running lean or rich (I would hazard a guess that it's rich). Check your spark plugs for color and condition. That can tell you a lot about what's going on.
Ayup, I checked the transmission fluid earlier, its reddish. Not really creamy. Was a slight amount of rust on the dipstick, halfway up, but it looked fine to me. Also, the transmission was filled to the right spot, wasn't way over or under, so I think that SMOD isn't a factor for this one.

I checked one of the sparkplugs. Black on the tip, fair bit of oil on the porcelain, so methinks that an O2 sensor or two will need to be checked and replaced.

Thank you.
 

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Ayup, I checked the transmission fluid earlier, its reddish. Not really creamy. Was a slight amount of rust on the dipstick, halfway up, but it looked fine to me. Also, the transmission was filled to the right spot, wasn't way over or under, so I think that SMOD isn't a factor for this one.

I checked one of the sparkplugs. Black on the tip, fair bit of oil on the porcelain, so methinks that an O2 sensor or two will need to be checked and replaced.

Thank you.
Black oily plug....that's a misfire.
 

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Discussion Starter · #7 ·
Alrighty, Heads, valve covers, intake, several other gaskets, ignition coils, spark plugs, o2 sensors, oil, oil filter, coolant, all has been changed successfully. Additionally, I changed out the the hose between the valve covers, and the driver side hose that goes into the intake plenum.
With all of that changed out, I burped the car as best as I could, and now I am faced with new issues:

-P0300 still remains, despite all hoses being hooked up. I will have to check the coils to make sure all are working properly, then check other hoses to make sure they aren't cracked.
-OBDII reader keeps showing engine temperature getting up to 240* F. When it gets there, hitting the gas causes it to cool down to 228, but it climbs back up pretty soon. Thermostat? issue? Coolant not burped all the way?
 

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Here’s my guess: your catalytic converter is probably broken up causing your air/fuel ratio sensor to skew rich causing your misfire. Your cooling system is probably not properly filled and bled causing temperature issues. Remove your drivers side front exhaust tube and inspect for damaged catalyst. Make sure your radiator and reservoir caps are properly installed. Leave the reservoir cap off during bleeding and keep the coolant level slightly above the seam.
 

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Alrighty, Heads, valve covers, intake, several other gaskets, ignition coils, spark plugs, o2 sensors, oil, oil filter, coolant, all has been changed successfully. Additionally, I changed out the the hose between the valve covers, and the driver side hose that goes into the intake plenum.
With all of that changed out, I burped the car as best as I could, and now I am faced with new issues:

-P0300 still remains, despite all hoses being hooked up. I will have to check the coils to make sure all are working properly, then check other hoses to make sure they aren't cracked.
-OBDII reader keeps showing engine temperature getting up to 240* F. When it gets there, hitting the gas causes it to cool down to 228, but it climbs back up pretty soon. Thermostat? issue? Coolant not burped all the way?
Are you able to get hot air out of the heater inside the vehicle? Poor interior heater performance can mean air in the cooling system.
 

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Yep, takes about 5 minutes before the air gets warm. Not super hot though.
Luke warm air from the heater is a sign of air in the system. I've found that just removing the radiator fill cap is enough to introduce air in the system. Best to avoid that but if you have done so, remove it again after things have cooled down and fill it to the point of overflowing and put the cap back on. Then do as Blackberry advises and remove the reservoir pressure cap and run the motor to get the coolant heated up and flowing while keeping the coolant level to just above the seam of the reservoir as he said. You might hear the baby burp.
 

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Discussion Starter · #13 ·
Luke warm air from the heater is a sign of air in the system. I've found that just removing the radiator fill cap is enough to introduce air in the system. Best to avoid that but if you have done so, remove it again after things have cooled down and fill it to the point of overflowing and put the cap back on. Then do as Blackberry advises and remove the reservoir pressure cap and run the motor to get the coolant heated up and flowing while keeping the coolant level to just above the seam of the reservoir as he said. You might hear the baby burp.
Alright, I shall do that tomorrow. Thank you!
 

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Discussion Starter · #15 ·
Alright, I burped the system decently, had some nice hot air coming out of the heat vents. However, the p0300 issue was really showing itself during a test drive. It felt like I was driving in limp mode, and could barely get up to 40. Even burped, the car stayed around 220*F while driving. I will attempt to check the cat converter tomorrow, and see what's going on in there. It does sound like there is a leak somewhere near the intake plenum, but I could not find it. All those seals were replaced as well, so it'd be weird if that were the case.
Additionally, the previous owner replaced the heater core. Where the coolant meets up to the firewall, there is a small allen screw box that intercepts the coolant lines. I think this is a bleeder valve, looks like this.

I performed several of the misfire code checks in the manual from EC-349, here were the results:

1. CHECK FOR INTAKE AIR LEAK AND PCV HOSE
? Potential air leak on passenger side of plenum, but I can't find it. PCV hose between valve covers is new, and right side one as well.

2. CHECK FOR EXHAUST SYSTEM CLOGGING
X Will check tomorrow. There was a hole in the cat converter shield, but not through the converter itself.

3. PERFORM POWER BALANCE TEST
X I don't have the tool for this.

4. CHECK FUNCTION OF FUEL INJECTOR-I
? Voltage on Harness, but no continuity between injector and ECU terminal. Odd, will have to further investigate.

5. CHECK FUNCTION OF FUEL INJECTOR-II
^ Provided battery voltage, each one fired fuel.

6. CHECK FUNCTION OF FUEL INJECTOR-III
X Didn't check.

7. CHECK FUNCTION OF IGNITION COIL-
? Didn't check, but I am pretty sure these are all working, since they are new. Also, I can't rig up the setup it wants and crank the engine at the same time.

8. CHECK FUNCTION OF IGNITION COIL-II
^ Sparkplugs are all good.

9. CHECK SPARK PLUG
^ Spark plugs are all good. I rechecked gap on them.

10. CHECK FUNCTION OF IGNITION COIL-III
^ Spark plugs should be good.

11. CHECK COMPRESSION PRESSURE
X Didn't check.

12. CHECK FUEL PRESSURE
X Don't have the tool for this.

13. DETECT MALFUNCTIONING PART
X Don't know what the malfunctioning part is.

14. CHECK IGNITION TIMING
^ Idle speed is right where it needs to be according to ODBII.

15. CHECK A/F SENSOR 1 INPUT SIGNAL
X Didn't check.

16. CHECK A/F SENSOR 1 HEATER
X Didn't check.

17. REPLACE AIR FUEL RATIO (A/F) SENSOR 1
X Didn't check.

18. CHECK MASS AIR FLOW SENSOR
X Don't have the tool.

19. CHECK SYMPTOM MATRIX CHART
X Didn't check.

20. ERASE THE 1ST TRIP DTC
^ Already tried, error code, pends, then becomes full code at 2k rpms.

21. CHECK INTERMITTENT INCIDENT
X Didn't check.

I will update this as I knock these off.
 

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Alright, I burped the system decently, had some nice hot air coming out of the heat vents. However, the p0300 issue was really showing itself during a test drive. It felt like I was driving in limp mode, and could barely get up to 40. Even burped, the car stayed around 220*F while driving. I will attempt to check the cat converter tomorrow, and see what's going on in there. It does sound like there is a leak somewhere near the intake plenum, but I could not find it. All those seals were replaced as well, so it'd be weird if that were the case.
Additionally, the previous owner replaced the heater core. Where the coolant meets up to the firewall, there is a small allen screw box that intercepts the coolant lines. I think this is a bleeder valve, looks like this.

I performed several of the misfire code checks in the manual from EC-349, here were the results:

1. CHECK FOR INTAKE AIR LEAK AND PCV HOSE
? Potential air leak on passenger side of plenum, but I can't find it. PCV hose between valve covers is new, and right side one as well.

2. CHECK FOR EXHAUST SYSTEM CLOGGING
X Will check tomorrow. There was a hole in the cat converter shield, but not through the converter itself.

3. PERFORM POWER BALANCE TEST
X I don't have the tool for this.

4. CHECK FUNCTION OF FUEL INJECTOR-I
? Voltage on Harness, but no continuity between injector and ECU terminal. Odd, will have to further investigate.

5. CHECK FUNCTION OF FUEL INJECTOR-II
^ Provided battery voltage, each one fired fuel.

6. CHECK FUNCTION OF FUEL INJECTOR-III
X Didn't check.

7. CHECK FUNCTION OF IGNITION COIL-
? Didn't check, but I am pretty sure these are all working, since they are new. Also, I can't rig up the setup it wants and crank the engine at the same time.

8. CHECK FUNCTION OF IGNITION COIL-II
^ Sparkplugs are all good.

9. CHECK SPARK PLUG
^ Spark plugs are all good. I rechecked gap on them.

10. CHECK FUNCTION OF IGNITION COIL-III
^ Spark plugs should be good.

11. CHECK COMPRESSION PRESSURE
X Didn't check.

12. CHECK FUEL PRESSURE
X Don't have the tool for this.

13. DETECT MALFUNCTIONING PART
X Don't know what the malfunctioning part is.

14. CHECK IGNITION TIMING
^ Idle speed is right where it needs to be according to ODBII.

15. CHECK A/F SENSOR 1 INPUT SIGNAL
X Didn't check.

16. CHECK A/F SENSOR 1 HEATER
X Didn't check.

17. REPLACE AIR FUEL RATIO (A/F) SENSOR 1
X Didn't check.

18. CHECK MASS AIR FLOW SENSOR
X Don't have the tool.

19. CHECK SYMPTOM MATRIX CHART
X Didn't check.

20. ERASE THE 1ST TRIP DTC
^ Already tried, error code, pends, then becomes full code at 2k rpms.

21. CHECK INTERMITTENT INCIDENT
X Didn't check.

I will update this as I knock these off.
Sounds like you're making progress. Yes that is a nice Z1 bleeder at the firewall. Not to worry about the 220 degree run temperature. My 2015 runs at 220. It's not going to match the thermostat temp.
 

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Discussion Starter · #17 ·
Alright, today I checked some more things. Checked the intakes, yada yada. My dad has an exhaust check tool that goes in through the o2 sensor slot, so I went and used that. Upstream driver side had barely any pressure on it, which should be good. Passenger side upstream though, the pressure spiked and maxed out. Took the cat converter on that side off, and I guess? that it is filled with crud. Couldn't even shine a light through it, so I assume that it is clogged.

Any budget replacements? Possibility of cleaning it? I see full sets on Ebay for $250... In Tennessee, so emissions aren't a concern.
 

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Alright, today I checked some more things. Checked the intakes, yada yada. My dad has an exhaust check tool that goes in through the o2 sensor slot, so I went and used that. Upstream driver side had barely any pressure on it, which should be good. Passenger side upstream though, the pressure spiked and maxed out. Took the cat converter on that side off, and I guess? that it is filled with crud. Couldn't even shine a light through it, so I assume that it is clogged.

Any budget replacements? Possibility of cleaning it? I see full sets on Ebay for $250... In Tennessee, so emissions aren't a concern.
I've heard that you can install a bypass pipe and then possibly an anti-foul adapter (for spark plugs) to lift the O2 sensor out of the exhaust stream a bit, and it should still work.

But I'd like to hear back from others on whether this is just an internet myth or not.
 

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Here’s my guess: your catalytic converter is probably broken up causing your air/fuel ratio sensor to skew rich causing your misfire. Your cooling system is probably not properly filled and bled causing temperature issues
most importantly, I’m going to go ahead and awards points to blackberry for this
 
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