Nissan Pathfinder VG30 Head Gasket Replacement

Nissan VG30 Head Gasket Replacement

After years of red line and forgetting to turn my Ford Taurus E-Fan on my Head Gasket was starting to go with a bit of oil showing up under the rad cap. Grabbing some new head gaskets off of RockAuto, as well as an assortment of other gaskets and seals that I may need along the way, including a timing belt I tore into the Pathmaker and got started.

If you don’t yet have it, head over to NicoClub.com to pick up the FSM – Factory Service Manual for your Nissan, it will answer a lot of troubleshooting questions you may have it also has all the bolt torque sequences and specs you’ll need for the job. Best of all, its totally free!

Click HERE or scroll to the bottom for a video on the whole project.

Setting Engine to Top Dead Center

Before you begin you’ll want to set your engine to Top Dead Center (TDC). If you have never done that before it can be a bit tricky, but its not a difficult procedure if you know the steps. TDC is making sure that Cylinder #1 is at the top of the COMPRESSION stroke which essentially zeros the motor so all your timing marks are correct.
To find TDC you need:

  • To pull spark plug #1, which is the closest to the front plug on the passenger side.
  • With the plug removed put a long zip-tie, piece of stiff wire, a chopstick or something similar down the hole. 
  • Using a 22mm socket on the crank bolt, turn the engine clockwise, watching the ziptie as you turn.
  • Make sure engine is on compression stroke, not exhaust stroke as it will be at the top on both strokes.
  • If you are on compression stroke you will feel air coming out the spark plug hole, the timing mark on the crank should be lined up and the rotor on your distributor should be pointing directly at cylinder #1 on the cap. (See photo below)

A lot of what I need to take of are parts that were just removed during my EFI swap, so thankfully the bolts arn’t seized and the hose clamps have all been recently loosened. Start by removing essentially the entire top end of the engine as you’ll have to get down to the block. The Pathmaker Rig is pretty stripped down these days, with zero emissions control or charcoal canisters so there are less hoses and vacuum lines to remove but the remaining fuel hoses, intake hose, spark plug wires and wiring harness can all be removed. You shouldn’t have to label much on your wiring harness as there are no two connectors alike under the hood so everything can only hook up where it needs to go!

Intake Plenum

The intake plenum is next on your list and be aware there are a few hoses and wires on the underside of the plenum that will still be attached when you try to lift it off. It will be awkward to reach under to unplug the IAC Valve and the Knock Sensor wiring. You can remove the lower intake manifold next.

Next on the list is the front end of the engine. Radiator, fan, alternator and power steering belts all need to be removed to take off the timing belt cover. There is an upper and lower cover, with a ton of tiny 8mm bolts. You will need a puller to remove the harmonic balancer off the end of the crank. It is cast and fragile so do not hit it with a hammer. Once the covers are removed you can double check all your timing marks to ensure you’re at TDC. There is a dot on either cam sprocket which you will need to line up the new timing belt with. Those dots should line up with a mark on the rear of the timing cover. Passenger side at approx 11 o’clock, Drivers side at approx 1 o’clock. There is also a mark on the crank sprocket at approx 5 o’clock.

Cam sprockets will come off next, making sure not to turn the motor when loosening them. They are marked L and R, which is always as if you are sitting in the drivers seat, meaning L is the drivers side.

Removing Cylinder Heads

The removal of the cylinder heads is quite an involved process and not the time to play cowboy! You need to unbolt the head bolts in order, as well as reinstall them in order with a correct torque sequence. To make my life easier I drew up the bolt order on a piece of cardboard, so I can pierce each bolt in its location as I go and not mix them up.

Another fun part of the cylinder head removal is you need a special tool, a 10mm allen cap socket that is approximately 3″ in length so it can fit past the rocker arms. Not having such a tool I had to sacrifice my 10mm allen wrench, cutting the short end off with an angle grinder and sliding the 10mm piece into a 10mm socket!

With that figured out I realized I also need to remove my headers, which also required me to unbolt my y-pipe so the headers could slide off the studs. With the head bolts fully removed I was able to take a look at the head for the first time.

There was no apparent place where my gasket was blown, VG30 are not known for blowing head gaskets, and mine had just barely gone so I didn’t see any blatant blow thru spots.

With my shop-vac running I got out my scraper and scraped as much of the old gasket away as possible, making sure not to scratch the surface of the block, but also knowing the block is steel and much less prone to being the issue.

Block scraped clean and it was time to turn my attention to the heads. They are aluminum and much softer, so more care is needed when cleaning the gaskets off. If you have a badly blown head gasket, or just arn’t a hackshow mechanic like I am, working on a trail rig, you’d be smart to get your heads looked at by a machine shop to make sure they’re still nice and flat, and they can deck the heads for you if need be. Throwing a straight edge on my heads they look good enough for my hunk of junk so once the gaskets were fully cleaned off it was time to start putting everything back together on top of the brand new head gaskets. They do not require any silicone, they’re designed to be a dry gasket.

Re-installation of Cylinder Heads

Hopefully you kept all your bolts organized because now is the time for one of the most tedious steps of the whole project, torquing down the heads. (You downloaded the FSM from Nicoclub.com right? it will help you bigtime) The wonderful steps go:

  • Torque bolts down in order to 22ftlb
  • Torque bolts down in order to 44ftlb
  • Loosen bolts off in reverse order
  • Torque bolts in order to 22ftlb
  • Torque bolts a final time to 47ftlb.

With the heads bolted back up it was time to reinstall the cam gears and set up the timing belt.

Timing Belt installation

The timing belt can be another tedious job but also crucially important. I highly recommend replacing your water pump at this time if your pump is old at all, the T-Belt needs to be off to replace it so its a great time to re and re. Also DO NOT reuse your timing belt, they’re not very expensive and if the old one breaks you can easily bend valves and cost thousands in repairs. Reinstall your cam sprockets, double checking the dot on the sprocket and the mark on the back of the timing cover.

Your new timing belt should have 3 marks on it, confusingly 40 teeth apart and 43 teeth apart.
You need to line up the marks so that you have 40 teeth between the R and L cam sprockets, and 43 teeth from the L/Drivers cam sprocket and the dot on the crank sprocket. If you were at TDC and the engine did not turn at all during the process your marks should line up perfectly.
The next confusing and tricky bit is how to get the tension right on the timing belt. The VG30 has a poor design, with the tensioner on the side, instead of between the two cam sprockets. What that means is the belt needs to be a lot looser than you would expect, as the belt tightens up when its running and if you have the belt too tight you can snap the cam on the drivers side.
I’m not going to lie, I struggled, I put it all back together too tight, flashed it up and heard the terrible sound of belt whine (sounds like a super charger). It required me pulling the whole front end apart again to try to figure out where I went wrong.
After hours of head scratching I figured out my issue, when the instructions say, install the tensioner pulley and turn to the right to tighten they mean, spin it far enough that the tensioner spring actually flips all the way around clockwise once and then rests on the tensioner stop. The first time I did not do that and the tension was way off. After I figured the spring out I set the belt to move up and down 1/2″ on the middle of the belt between the cam sprockets. The FSM has an extremely difficult to follow list of instructions involving feeler gauges and following their instructions made the belt much too loose. Which is where my warnings at the start of this article come in….follow my instructions at your own risk!

With the timing belt back together it was just a case of putting the timing light on it and setting the timing (in my case 22* advanced because of my cams). My rig seems to have a bit of an exhaust tick (I hope its exhaust!) and a vacuum leak but overall its running ok. After getting it timed the last thing on the list was doing an oil change, to get rid of any crap that I didn’t clean out very well during the head gasket scraping.

It may not be perfect, but its running!
Check out the full video here:

Time to get the Pathmaker back out on the trail!
If you have any questions, comments or suggestions feel free to let me know at the bottom of this post!


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