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Moses76

Looking for proven/good R51 mods

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I recently bought my second Pathfinder 2006 LE R51 and already have a blown head gasket. So while I have it taken apart, I would like to know what are some good things to mod, upgrade or change while I have it all in pieces? Thank you very much in advance for replying and helping me!

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If you haven't already, do the trans cooler bypass to prevent the strawberry milkshake of death. IIRC the 4.0 had some timing chain guide issues as well, so have a look at those while it's torn down.

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Agreed. If it blew a head gasket, it must have gotten hot? Therefore I would focus on cooling system maintenance.

 

Depending on mileage, you could also replace the water pump whilst you have the timing gear off as that requires removal of timing chain to do. Definitely completely replace all the timing gear.

 

I would also check or replace the thermostat, and remove the radiator and wash it out from the back side to remove debris from the fins, and give it a good internal flushing too.

 

While you're there, replace the entire belt drive system - all pulleys, belt and tensioner. Ensure the belt is the correct length as these vehicles are quite sensitive to the wrong length belt and/or a bad tensioner. Could also replace the viscous fan hub too while you're there.

 

Definitely bypass the in-radiator trans lines and fit an external cooler. Will help your vehicle run cooler on a hot day.

 

Could replace the cam sensors too if you're really keen as they're another failure point.

 

Ensure you have bled the system properly - surprisingly difficult due to the rear heater setup.

 

In terms of performance mods, I find the VQ40 to have quite acceptable performance in standard trim. You could replace the spark plugs too, as they require removing the intake manifold to do so may as well kill that bird since you've got it apart.

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20 hours ago, Slartibartfast said:

If you haven't already, do the trans cooler bypass to prevent the strawberry milkshake of death. IIRC the 4.0 had some timing chain guide issues as well, so have a look at those while it's torn down.

Thanks but I am aware of that from prior research and the radiator has already been changed. I am considering added a secondary cooler anyway just for longer life and added performance. I am also aware of the secondary timing chain guide issue, but thanks for replying.

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7 hours ago, KiwiTerrano said:

Agreed. If it blew a head gasket, it must have gotten hot? Therefore I would focus on cooling system maintenance.

 

Depending on mileage, you could also replace the water pump whilst you have the timing gear off as that requires removal of timing chain to do. Definitely completely replace all the timing gear.

 

I would also check or replace the thermostat, and remove the radiator and wash it out from the back side to remove debris from the fins, and give it a good internal flushing too.

 

While you're there, replace the entire belt drive system - all pulleys, belt and tensioner. Ensure the belt is the correct length as these vehicles are quite sensitive to the wrong length belt and/or a bad tensioner. Could also replace the viscous fan hub too while you're there.

 

Definitely bypass the in-radiator trans lines and fit an external cooler. Will help your vehicle run cooler on a hot day.

 

Could replace the cam sensors too if you're really keen as they're another failure point.

 

Ensure you have bled the system properly - surprisingly difficult due to the rear heater setup.

 

In terms of performance mods, I find the VQ40 to have quite acceptable performance in standard trim. You could replace the spark plugs too, as they require removing the intake manifold to do so may as well kill that bird since you've got it apart.

Thank you for all the details. The water pump was the issue and has already been replaced as well as the thermostat and housing. Also with complete flush of system, radiator and both heater cores that were both clogged. By pass for trany will be done. I will look up cam sensors tonight, thanks for that addition. Also reconsidering all the timing as you stated, kinda rather not but not a bad idea while there.

 

Any ideas on making it more fuel efficient? Or just anything else?

 

Thank you very much for the reply!

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