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Could this be a head gasket problem?


Kazza
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Hi guys,

 

Had a bit of a saga over the last year and a half with my pathfinder overheating and never really getting to the bottom of it. It all started when the car overheated while climbing a hill in winter in 4x4. I didn't notice the temp gauge (because the car never had issues in the past) and it did max out unfortunately before i shut her down. After this incident, I started reading online and heard that the cooling system in the VQ35DE's can be notoriously hard to bleed. I went through all the the different weird and wonderful methods of purging air but the temp gauge still started creeping up on longer, slow climbs. Also, the coolant hoses would be rock solid (overpressured?) shortly after the car reached operating temperature, and the top hose and top of the radiator would too be hot to touch. After a few months of "managing" the problem (running my heater on full heat), I looked into it again and this time decided perhaps that I had poor circulation in the cooling system either due to the thermostat not opening properly or the radiator being blocked in some way. So I went about replacing both of these and bleeding the system again but still this did not fix my problem. Again, I went back to just managing the problem until a few weeks ago I noticed I was losing coolant at a fair rate (1/2 litre per week). I took the car to the garage and they diagnosed as the coolant crossover pipe behind the engine, passenger side gasket leak. Big job, big $$$ (I was quoted almost the value of the car to change this gasket)... i reluctantly decided to throw some K-SEAL in until I figure out next steps. The K-SEAL, to be fair, has stopped the leak for now - I'm not losing a drop of coolant anymore - and I plan to flush the system soon to remove the excess K-SEAL. But I'm still left with this concerning (however manageable) overheating issue and, what feels like, an over-pressurized cooling system. 

 

Now.. something has came to my attention since adding K-SEAL and having the small metallic particles in the coolant. In the linked video below you will see that there is a constant stream of micro-bubbles or fizzing coming up to the surface of the coolant in the funnel attached to the radiator neck when the engine is running. This may just be evidence of normal operation - the coolant flowing from the pump into the top of the rad - but I have nothing to compare it to and my mind is questioning if this may be a very small but significant enough leak of air/compression/gasses from the engine (head gasket?). And, that it may be causing the loop to over-pressurize (rock solid hoses) and also causing poor coolant flow (overheating) as a result. Note: I have none of the classic failed head gasket symptons - e.g. white smoke, milky oil/oil cap, loss of coolant into the engine.

 

Here is the link to the video; apologies if a little faint but you should be able to see the slight fizzing and displacement of metallic k-seal particles, mostly to the left of center.

 

Also summary of problem and diagnostics thus far;

- Car temp gauge rises on long, slow/low revs incline. Turning on heater and/or increasing revs brings the temp gauge back to middle.

- Coolant hoses and top of radiator run very hot (too hot to touch) shortly after reaching operating temps.

- Coolant hoses become rock solid at operating temp, but lose pressure again not long after engine shut down.

 

- Replaced thermostat and radiator

- No loss of coolant (crossbar coolant leak fixed for now)

- No air in coolant system

- Clean oil (to the eye, not tested)

- Clean coolant (to the eye, not tested)

 

Appreciate any and all input on this... its been haunting me for a while now.

 

Cheers,

 

K

 

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OEM rad caps are so cheap I'd do that first too. You can get a coolant exhaust gas test kit on Amazon for $35, or Ebay for as little as $15, so I'd do that too. Not sure I trust China eBay kits. It will at least eliminate that possibility to move on to next

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I have had thermostats go bad in a week and even had one bad out of the box. 

I would start with the coolant test kit like has been suggested. If it passes that, you don't need to be distracted by the head gasket, it will be fine. If it fails, then you have a starting point. 

It is possible that the water pump is going bad on you, or possibly the fan clutch. When the engine is hot, turn off the engine and try turning the fan by hand. It should be hard to turn. If you can turn it easily, that tells you the clutch is bad and letting the fan slip too much, so it isn't pulling enough air. 

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You deleted both your most recent posts.

 

My coolant hoses are all pretty tight at running temperature.

 

Thermostat and radiator are two that’ll cause your woes but you’ve replaced them both. Chances that you’d get a part with the exact same failure mode are slim but not impossible.

 

Did you notice any chalky looking buildup on the radiator cap?

 

Do you notice any bubbling in the coolant reservoir after the engine is shut off?

 

The steady stream of bubbles in the radiator filler neck is no bueno. Not enough to call it a head gasket though.

 

You’re no longer loosing coolant. Before using the sealant, did you notice any light misfiring when starting the engine after sitting for a while?

 

You might want to read this thread:

http://www.nissanpathfinders.net/forum/topic/43908-blownseeping-head-gasket/?tab=comments#comment-795883

 

Edited by onespiritbrain
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9 hours ago, R50JR said:

did you replace the radiator cap with a new oem part?

Forgot to mention, I replaced the rad cap with a Gates.. it looks the same and has the same PSI rating (13) as oem?

9 hours ago, colinnwn said:

OEM rad caps are so cheap I'd do that first too. You can get a coolant exhaust gas test kit on Amazon for $35, or Ebay for as little as $15, so I'd do that too. Not sure I trust China eBay kits. It will at least eliminate that possibility to move on to next

Sent from my SM-N950U using Tapatalk
 

I'll probably grab one of these kits as a next step..

7 hours ago, onespiritbrain said:

What does the underside of your oil cap look like?

Oil cap is clean underneath.. no residue.

 

5 hours ago, Mr_Reverse said:

I have had thermostats go bad in a week and even had one bad out of the box. 

I would start with the coolant test kit like has been suggested. If it passes that, you don't need to be distracted by the head gasket, it will be fine. If it fails, then you have a starting point. 

It is possible that the water pump is going bad on you, or possibly the fan clutch. When the engine is hot, turn off the engine and try turning the fan by hand. It should be hard to turn. If you can turn it easily, that tells you the clutch is bad and letting the fan slip too much, so it isn't pulling enough air. 

 

I feel like if the thermostat wasn't opening I'd have much bigger overheating issues? I could try running without the thermostat to see what that yields.

 

I'll try the fan clutch tomorrow. If That's good and the compression test passes then perhaps I'm looking potentially at the pump then.

 

Nobody touched on the video I linked too.. seems normal?

 

Also... how does everyone else's hoses feel at running temp? Mine's are really solid.. feels like too much pressure.

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21 hours ago, onespiritbrain said:

You deleted both your most recent posts.

 

My coolant hoses are all pretty tight at running temperature.

 

Thermostat and radiator are two that’ll cause your woes but you’ve replaced them both. Chances that you’d get a part with the exact same failure mode are slim but not impossible.

 

Did you notice any chalky looking buildup on the radiator cap?

 

Do you notice any bubbling in the coolant reservoir after the engine is shut off?

 

The steady stream of bubbles in the radiator filler neck is no bueno. Not enough to call it a head gasket though.

 

You’re no longer loosing coolant. Before using the sealant, did you notice any light misfiring when starting the engine after sitting for a while?

 

You might want to read this thread:

http://www.nissanpathfinders.net/forum/topic/43908-blownseeping-head-gasket/?tab=comments#comment-795883

 

No chalk on the rad cap.

 

No bubbling in coolant res after shut off

 

No misfiring of engine ever since I have owned it.

 

I'm going to check fan clutch and get a combustion gas test done.

 

Will keep note on the pump.. also isn't there a 2nd thermostat behind the engine? Could this be causing the problem?

 

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Update;

 

Checked my fan clutch and it's tight enough. Only 1/4 or 1/2 spin after engine warmed up.

 

Showed my video in OP to the mechanic and he said that's not head gasket as it would be more pronounced bubbling or fuzzing and since I've had the problem for a year it would have gotten worse by now if this was the result of a very minor failure in the gasket.

 

On the pump he reckons this car has metal fins and so the pump would either fail or work properly, so if it was the pump id have more serious overheating due to pump failing to circulate coolant properly.

 

He reckons not to bother with combustion test (doesnt reckon itll show up) and just live with it if I've tried all else.. easier said than done!

 

Might just get the test done for peace of mind..  

 

 

 

 

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I can vouch for water wetter. That stuff does work and if turning on the heater is all the nudge you need to be in range then it might just work for you.

You might also consider an electric fan. My engine would try to overheat with the AC on at idle on a hot day. Now the electric fan keeps the temps below 210 no matter what, AC on up a mountain at nearly 100 degrees outside.

I hope you find a solution where you don’t have to worry about it anymore.. I truly loath worrying about major vehicle failures.

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Try using the high pressure wash at a car wash to clean out the fins of the a/c condenser, it could be dirty and restricting airflow. 

 

With the fan, it shouldn't really spin at all by hand with the engine hot. It should have a pretty heavy drag and stop moving the moment you let go. With the engine cold, it should turn pretty easily, but still have a light drag. 

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I assume you would need to be careful to spray the radiator squarely and a bit back to not fold over any fins?

I've been thinking about this problem. If it was me I'd hook an OBD reader up to it and drive around to verify it wasn't an out of calibration gauge. If that shows it is still too hot, I'd probably test the coolant temp sensor. There is a procedure in the service manual I think by dipping it in boiling water and checking the resistance.

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