VG30 Head Gasket Replacement: WD21 Nissan Pathfinder Step-by-Step Guide

VG30 Head Gasket Replacement: WD21 Nissan Pathfinder Step-by-Step Guide

If you are finding oil in your coolant, chocolate milk under the radiator cap, or suspect a blown head gasket on your WD21 Nissan Pathfinder or D21 Hardbody, this article walks through the process I used to replace the head gaskets on my VG30E.

This was done on my Pathmaker trail rig after years of full throttle launches, redline abuse, and general automotive stupidity. The engine was still running, but oil was starting to show up in the coolant and the radiator cap was starting to look like chocolate milk.

The VG30E is a tough engine, but once the head gaskets start to go, it is time to tear into it.

This guide covers the teardown, setting the engine to top dead center, removing the intake, timing belt, cylinder heads, cleaning the block and heads, reinstalling the heads, setting up the timing belt, and getting the engine running again.

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Quick Answer

• The WD21 Nissan Pathfinder and D21 Hardbody VG30E head gaskets can be replaced at home, but it is a fairly involved job.
• The engine should be set to top dead center before teardown so the timing marks are easier to keep track of.
• The upper intake, lower intake, front accessories, timing belt, cam sprockets, exhaust manifolds or headers, and cylinder heads all need to come off.
• You need the factory service manual for the correct head bolt removal order, torque sequence, and timing belt setup.
• This is a good time to replace the timing belt, water pump, thermostat, spark plugs, plug wires, distributor cap, and rotor.
• The VG30E timing belt tensioner setup can be confusing, so take your time and double check belt tension before final assembly.

Symptoms of a Blown VG30E Head Gasket

In my case, the main symptom was oil in the coolant.

When I removed the radiator cap, the coolant was starting to look like chocolate milk. That is never a good sign. The engine had lived a hard life with years of full throttle launches, rock crawling, and plenty of time near redline, so I was not exactly shocked.

Common VG30E head gasket symptoms can include:

• Oil in the coolant
• Coolant that looks milky or chocolate brown
• Coolant loss
• Overheating
• Bubbles in the radiator
• White smoke from the exhaust
• Poor running or low compression

I did not pressure test the engine before tearing it apart. On a VG30E, compression testing is annoying because the spark plugs are not especially fun to reach. The smart move is to test and confirm the problem before taking the engine apart, but in my case I knew what I was dealing with and decided to get the job done.

Download the Factory Service Manual First

Before starting this job, download the factory service manual for your Nissan.

You can find free Nissan factory service manuals through NicoClub.com.

The FSM is important because it includes the correct:

• Head bolt removal order
• Head bolt torque sequence
• Timing belt marks
• Torque specs
• Engine diagrams

This article shows the process I used, but you should still have the FSM open while doing the job.

Parts and Tools Used

Since you have to tear down so much of the engine to replace the head gaskets, this is a good time to replace other parts while everything is apart.

Parts I replaced or recommend replacing during the job:

• VG30E head gasket set
• Timing belt
• Water pump
• Thermostat
• Spark plugs
• Spark plug wires
• Distributor cap
• Distributor rotor
• Coolant
• Engine oil and filter

Tools that are useful for the job:

• Torque wrench
• 22mm socket for the crank bolt
• Harmonic balancer puller
• 10mm Allen socket or modified 10mm Allen key
• Basic metric socket set
• Scraper or gasket removal tools
• Shop vacuum
• Timing light
• Zip tie, wire, chopstick, or similar tool for finding top dead center

VG30E head gasket, timing belt and seal kit

VG30E Water pump

VG30E Spark Plug Wires

VG30E Spark Plugs

V30E Distributor Cap and Rotor

Harmonic balancer puller

Torque wrench

Timing Light

Browse the tools and equipment I personally use:
https://www.amazon.com/shop/pathmakerpr03

Some of the links above may be Amazon affiliate links. If you buy through them, I may earn a small commission at no extra cost to you. It helps support the videos, fabrication projects, and tech articles on this site.

Step 1: Set the VG30E to Top Dead Center

Before tearing the engine apart, set it to top dead center.

Top dead center means cylinder number one is at the top of the compression stroke. This helps zero the engine so the timing marks make sense when you remove and reinstall the timing belt.

To find TDC on the VG30E:

1. Remove spark plug number one. This is the front spark plug on the passenger side.
2. Put a long zip tie, piece of stiff wire, chopstick, or similar object carefully into the spark plug hole.
3. Use a 22mm socket on the crank bolt to turn the engine clockwise.
4. Watch the zip tie move up as the piston comes toward the top of the cylinder.
5. Make sure you are on the compression stroke, not the exhaust stroke.
6. You should feel air coming out of the spark plug hole as the piston comes up on compression.
7. The crank timing mark should line up and the distributor rotor should point toward cylinder number one on the cap.

The engine will be at the top on both compression and exhaust strokes, so do not skip checking that you’re on compression stroke.

Step 2: Remove the Upper Engine Components

Once the engine is set to TDC, start removing the upper engine components so you can access the cylinder heads.

On my rig, a lot of these parts had already been removed during my EFI swap, so I had fewer vacuum lines, emissions parts, and old seized hose clamps to deal with.

On a stock WD21 Pathfinder or D21 Hardbody, expect more hoses, wiring, and emissions parts than I had.

Start by removing:

• Intake tube
• Fuel hoses
• Spark plug wires
• Wiring harness connections
• Vacuum lines
• Anything attached to the upper intake plenum

The VG30E wiring harness is not too bad. Most connectors only fit where they are supposed to go, but taking photos before unplugging everything is still a good idea.

Step 3: Remove the Intake Plenum and Lower Intake

The intake plenum needs to come off next.

Be aware that there are hoses and wiring connections underneath the plenum. Do not just yank it off once the visible bolts are removed.

You may need to reach underneath to unplug or disconnect:

• IAC valve wiring
• Knock sensor wiring
• Vacuum hoses
• Coolant hoses

Once the upper plenum is out of the way, remove the lower intake manifold.

This is a good time to slow down and keep your bolts organized. There are enough parts coming off the engine that throwing everything into one coffee can is a good way to hate your life later.

Step 4: Remove the Front Accessories and Timing Covers

Next, move to the front of the engine.

To access the timing belt, remove:

• Radiator
• Fan
• Accessory belts
• Alternator belt
• Power steering belt
• Upper timing belt cover
• Lower timing belt cover

The timing covers are held on with a pile of small 8mm bolts.

You will also need to remove the harmonic balancer from the end of the crank. Use a puller. Do not beat on it with a hammer. The harmonic balancer is cast and can be damaged.

Once the timing covers are removed, double check all your timing marks before removing the belt.

On the VG30E:

• The passenger side cam sprocket mark is roughly around 11 o’clock.
• The driver side cam sprocket mark is roughly around 1 o’clock.
• The crank sprocket mark is roughly around 5 o’clock.

The cam sprockets are marked L and R. Left and right are based on sitting in the driver seat, so L is the driver side.

Step 5: Remove the Timing Belt and Cam Sprockets

With the engine at TDC and the timing marks confirmed, remove the timing belt.

If you are doing head gaskets, do not reuse the old timing belt. The belt is already off, and a failed timing belt can bend valves and turn this job into a much more expensive repair.

I replaced the timing belt while I was in there, and I recommend replacing the water pump at the same time if it has any age on it. The timing belt has to be removed to access the water pump, so this is the time to do it.

Before removing the cam sprockets, make sure the engine does not rotate while loosening them.

Step 6: Remove the Cylinder Heads

Removing the cylinder heads is where this job becomes more serious.

This is not the time to play cowboy. The head bolts need to be removed in the correct order, and they need to be reinstalled using the correct torque sequence.

Use the factory service manual.

To keep everything organized, I drew the head bolt layout on a piece of cardboard and pushed each bolt through the cardboard in its correct location as I removed it. That way each bolt stayed in order and I was not guessing during reassembly.

Step 7: Make or Buy the Long 10mm Allen Socket

One annoying part of removing the VG30E heads is the head bolts.

You need a long 10mm Allen socket that can reach down past the rocker arms.

I did not have the right tool, so I sacrificed a 10mm Allen key by cutting off the short end with an angle grinder and sliding that piece into a 10mm socket.

It worked, but buying the proper long 10mm Allen socket is obviously the cleaner way to do it.

Long 10mm Allen socket

Step 8: Remove the Exhaust Manifolds or Headers

Before the heads can come off, the exhaust manifolds or headers need to be dealt with.

In my case, I had headers, so I had to unbolt the Y-pipe and slide the headers off the studs before the heads could be removed.

If your truck still has factory exhaust manifolds, your process may be slightly different, but the goal is the same: the cylinder heads need to be free from the exhaust system before they can come off the engine.

Step 9: Remove the Heads and Inspect the Gaskets

With the intake, timing belt, cam sprockets, head bolts, and exhaust out of the way, the cylinder heads can finally come off.

In my case, there was no huge obvious blown-out section in the gasket. The VG30E is not especially known for blowing head gaskets, and mine had only started to fail.

The symptoms were there, but the gasket did not have a massive missing section or dramatic failure point.

That is worth knowing. Sometimes a head gasket problem is obvious when you take it apart. Sometimes it is not.

Step 10: Clean the Block Surface

Once the heads were off, I cleaned the block surface.

I used a scraper and kept the shop vacuum running while I worked to catch as much gasket material as possible.

The block is cast iron, so it is less delicate than the aluminum heads, but that does not mean you should gouge it up. Take your time and clean the surface without scratching or damaging it.

Do not let chunks of old gasket material fall into oil or coolant passages if you can avoid it.

Step 11: Clean and Inspect the Cylinder Heads

The cylinder heads are aluminum, so they need more care than the block.

Clean the old gasket material off carefully and avoid scratching the sealing surface.

The smart move is to take the heads to a machine shop and have them checked for flatness. If they need to be decked, the machine shop can handle it properly.

I checked mine with a straight edge and decided they were good enough for my trail rig.

That is not the textbook answer, but this is also a rock crawler that has spent years getting abused in the woods. Use your judgment. If this is a daily driver or you overheated the engine badly, get the heads checked.

The new head gaskets go on dry. Do not smear silicone all over them.

Step 12: Reinstall the Cylinder Heads

With the block and heads cleaned, install the new head gaskets and set the heads back in place.

Now comes one of the most tedious parts of the job: torquing the heads.

Use the factory service manual for the proper bolt order. The sequence matters.

The torque process I used was:

1. Torque the head bolts in order to 22 ft-lb.
2. Torque the head bolts in order to 44 ft-lb.
3. Loosen the head bolts in reverse order.
4. Torque the head bolts in order to 22 ft-lb.
5. Torque the head bolts in order to 47 ft-lb.

Take your time here. Make sure your torque wrench is set correctly and follow the sequence.

Step 13: Reinstall the Cam Sprockets and Timing Belt

With the heads installed, reinstall the cam sprockets and set up the timing belt.

This is one of the most important parts of the whole job.

The new timing belt should have three marks on it. The spacing is confusing because there are 40 teeth between the cam sprocket marks and 43 teeth between the driver side cam sprocket and the crank sprocket mark.

Line up the belt marks with:

• Right cam sprocket mark
• Left cam sprocket mark
• Crank sprocket mark

If the engine was set to TDC and nothing moved during disassembly, the timing marks should line up properly.

Do not rush this step. If the timing belt is wrong, the engine will not run correctly, and you can damage parts.

Step 14: Set the VG30E Timing Belt Tension

The VG30E timing belt tensioner setup is one of the more confusing parts of this job.

The tensioner is on the side, not between the two cam sprockets, which means the belt can seem looser than expected. The belt tightens as the engine runs, and if you set it too tight, bad things can happen.

I learned this the annoying way.

The first time I put everything back together, the belt was too tight. When I fired the engine up, it had a terrible belt whine that sounded almost like a supercharger. That meant pulling the whole front of the engine apart again.

The issue was the tensioner spring.

When the instructions say to install the tensioner pulley and turn it to the right to tighten, they mean rotate it far enough that the tensioner spring flips clockwise and rests on the tensioner stop.

The first time I did not do that correctly, and the belt tension was way off.

After sorting that out, I set the belt so it could move about 1/2″ up and down in the middle of the belt between the cam sprockets.

The FSM procedure can be difficult to follow, and following it literally gave me a belt that seemed much too loose. This is one of those steps where you need to understand what the tensioner is actually doing, not just blindly slap the belt on and hope.

Step 15: Reassemble the Engine

Once the head gaskets are installed and the timing belt is correctly set, reassemble the engine in reverse order.

Reinstall:

• Timing covers
• Harmonic balancer
• Accessory belts
• Radiator
• Lower intake manifold
• Upper intake plenum
• Fuel lines
• Vacuum lines
• Wiring connections
• Spark plugs
• Plug wires
• Distributor cap and rotor

This is where all the photos you took during teardown become useful.

If you are working on a more complete stock truck than mine, take your time with the vacuum lines and emissions equipment.

Step 16: Set Ignition Timing and Change the Oil

After everything was reassembled, I set the ignition timing with a timing light.

In my case, I run mine at 22 degrees advanced because of the cams in my engine. Your setup may be different, so use the correct timing spec for your engine and build.

After the engine was running, I changed the oil.

That is worth doing after a head gasket job because there is always a chance some coolant, gasket material, or other debris made its way into the oil during the repair.

Results After the Repair

The engine fired up and ran after the repair.

It was not perfect. I still had what sounded like an exhaust tick and possibly a vacuum leak, but the head gasket job itself solved the coolant contamination issue.

More importantly, the engine has survived a lot of abuse since then. This was not a repair that lasted two weeks and failed again. The Pathmaker has had hundreds of hard hours on it after this job, including plenty more redline and trail abuse.

For a trail rig, that is good enough proof for me.

Should You Machine the Heads?

The proper answer is yes: if you have the heads off, especially after a blown head gasket or overheating, you should have a machine shop check them.

Aluminum heads can warp, and a head gasket job can fail if the surface is not flat.

On my rig, I checked the heads with a straight edge, decided they were good enough, and put it back together. That worked for me, but that does not mean it is the best answer for every truck.

If this is your daily driver, tow rig, or something you depend on, get the heads checked.

If it is a trail rig and you are comfortable making that call, that is up to you.

Should You Replace the Timing Belt During a VG30 Head Gasket Job?

Yes.

If the timing belt is coming off, replace it.

The VG30E is an interference engine, which means a failed timing belt can bend valves. A new belt is cheap compared to the amount of labor required to get back in there later.

This is also a good time to replace the water pump, thermostat, front seals, and other wear items while the front of the engine is apart.

Common Questions

Can oil in coolant be caused by a blown VG30E head gasket?

Yes. Oil in the coolant, milky coolant, or chocolate milk under the radiator cap can be signs of a head gasket problem. Other failures can also cause fluid contamination, but on my VG30E the head gaskets were the issue.

Does this apply to both WD21 Pathfinder and D21 Hardbody?

Yes. This article is focused on the VG30E used in the WD21 Nissan Pathfinder and D21 Hardbody. The exact details may vary slightly depending on year and emissions equipment, but the basic engine work is the same.

Do I need the factory service manual?

Yes. You should have the FSM available for torque specs, bolt sequences, timing belt setup, and diagrams. NicoClub has free Nissan factory service manuals available online.

Do the VG30E head gaskets need silicone?

No. The head gaskets are installed dry. Do not coat them in silicone.

Can I do this job at home?

Yes, but it is not a small job. You need enough mechanical ability to remove the intake, timing belt, heads, exhaust, and front engine accessories, then put everything back together correctly. If you are not comfortable with engine timing, this job can get expensive fast.

Final Thoughts

Replacing the head gaskets on a VG30E WD21 Pathfinder or D21 Hardbody is not technically complicated, but it is a lot of work.

The job is mostly about organization, timing marks, cleaning surfaces properly, and not rushing the reassembly.

For me, the repair was worth doing. The engine went back together, the coolant contamination issue was fixed, and the Pathmaker got back out on the trail.

If you are dealing with oil in the coolant, chocolate milk under the radiator cap, or a suspected blown head gasket on a VG30E Nissan Pathfinder or Hardbody, hopefully this gives you a clearer idea of what is involved before you tear into it.

More Nissan Pathfinder and VG30E Tech Articles

• WD21 Pathfinder EFI Swap
• Ford Taurus Electric Fan Swap
• Nissan Pathfinder Tech Articles
• Pathmaker Productions on YouTube

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