VQ35DE (Nissan) Engine Oil Cooler Leak Repair

     This is the repair procedure for stopping a common leak in the engine V6 3.5L VQ35DE that comes in several Nissan vehicles.


    The oil cooler part number in the vehicle I'm repairing is: #21304JA11A and below are the applicable vehicles--this a generalized list meaning that some car years may come with a slightly different cooler but at the end is certainly the same procedure; you can check with the part number to see if it specifically applies to your car in Google:

• 2002 - 2006 Nissan 350Z 
• 2002 - 2015 Nissan Altima
• 2002 - 2014 Nissan Murano
• 2013 Nissan Pathfinder
• 2004 - 2015 Nissan Quest

   The tools you will need for this job are:

• Oil filter wrench.
• Ratchet 1/2" or 3/8" drive with a 7/8" or 22mm deep socket (Note: I own a set of Stanley 1/2 drive sockets where the 7/8" socket is perfect--more on this below).
• 10, 12, 13, 14mm sockets
• Oil receiver pan
• Jack and Lug nut wrench
• Razor knife
• Electrician or other suitable pliers
• Flat screwdrivers
• 1 foot of 1/2" heater hose--just in case.
• Torque wrench
• Coolant
• Oil cooler seal: Felpro: #72493 or Victor Reinz: #B32450
• 5w30 oil 

     Start by lifting the vehicle and remove the front passenger wheel in order to have access to the oil filter. You will need to remove the side cover; the car I'm doing the job did not came with that cover but usually those covers are bolted to the body with 10mm head bolts. After removing those, place your pan below the oil filter and unloosen it with your filter wrench; let it drain for a while before removing it. 

    

Pinch Type Clamps

     Next, remove or loose the clams holding the In and Out cooling hoses from the oil cooler. This vehicle had pinch type clamps in one hose and regular clamps in the other.

Regular Clamps

After loosing the clamps, you need the remove the 7/8" or 22mm bolt. If you own Stanley 1/2" regular drive sockets, the 7/8 or 22mm socket is actually deep enough to clear the oil filter bolting side so you can save buying a deep socket for it which is actually not expensive. Autozone or other auto part stores have them for around $5




   



      After removing the bolt, it is time for pulling the cooler out of the hoses. In my vehicle was a PITA because they were hard and old--pretty much toasted--so I had to cut them lengthwise to release the pressure and run the auto parts store and buy a 1 foot 1/2" heater hose. You will have some coolant lose when you remove the cooler; place a clean receiver in order to catch it for reuse.

When you remove the gasket, you will see a film of burned oil that needs to be removed in order to have a perfect seal with the new gasket. If you fail to clean this, there is more changes that it will leak in a year if you have luck. You can remove it with a flat screwdriver at a 90 degree angle by doing gently strokes in one direction.







 

At the right, you can see how I let the surface; be careful when cleaning with the screwdriver in order to not gouge the surface. Clean the engine gasket surface as well since it has been accumulating a film also.

Oil cooler surface (engine side)

Finally, when installing the cooler, replace the hoses first and the cooler without placing the bolt yet. After putting oil cooler with hoses, you can pull the oil cooler gently and slide the seal between the cooler and engine surface; then, insert bolt and hand tighten. I did it this way because is easier in my opinion; however, if your are not sure in doing it this way, place the cooler first with the gasket and then install the coolant hoses--this is laborious specially when installing the hose going behind the oil pan.  When installing the gasket, coated with a little of new engine oil.

Tighten the oil cooler bolt at 31-40 ft lbs. Do not tighten in one step. I usually torque in either two step or three step in order to avoid damage to the castings. If the torque force would be between 5 to 25 ft lbs, you usually don't have problems torquing in one step. In this case, I did an initial torque of 20 ft lbs. The second step was 31 ft lbs, and the last one I did 40 ft lbs.

Ensure that you tight your clamps very well in order to avoid coolant loss. If your car is a few weeks to its next oil change, it won't hurt to make it at this time. If not, refill as necessary. Also, you need to refill your coolant loss; it will be approximately 4 to 5 quarts. The oil refill will be approximately from 1/3 to 2/3 of oil. If changing the oil, you will need 4.5 quarts of oil.

That's all in this article and do not hesitate in leaving comments or questions

Thanks!