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!
I figure your a busy man but I’m hoping you have time to answer this. If not no worries, I understand. I live out in Arkansas and bought my 13 year old son a 94 D21 4X4 project truck. Same motor (VG30E). The motor was completely rebuilt but that’s about it. We stripped it down and painted the engine bay and we have been replacing all the old worn out sensors. Power steering pressure switch, coolant temp to the ECM (this was like missing half of it when I got it???), deleted the EGR, replaced the drivers side manifold, rotor and cap, all 6 injectors with Hitachi, injector/fuel rail seal kit, all vacuum and vent lines, deleted charcoal canister, completely rebuilt the wire harness (this took forever), ECM, plugs and wires, fuel filter, and knock sensor. I cleaned the tested the AIC.
It was hard to start and high idling at first but as it turns out I’m a complete dumb ass and had the distributor 180 out. It fires up with ease and idles fine now. But the damn this is blowing out this white? grey? stinking ass smoke. IDK??? 🤬🤯😤 The head gaskets were just done but maybe they weren’t done right? I pulled the lower intake and replaced those gaskets for shits and giggles but its doing the same thing. Ive tore this thing down 4 times now.
I got this to bond with my oldest. I was in the oil fields for 10 years of his life maybe home 14 days a year. And I’ve done 3 combat deployments, 2 since his little ass rocked our world. He showed my your Youtube channel during my last deployment and we have been watching it since. (which is why I got him this truck) And I’ve hit a wall with it. Any input would be great weather it works or not. Just to give me a direction to go.
BTW, I do know the driver side head is leaking a bit because the smoke or whatever came from it as well. I stripped a stud and will have to tap it later this week. But I didn’t think it’s cause this. Also, it didn’t do this initially. (before EGR delete and everything else)
If you get time to reply to this awesome! If not I understand. My family doesn’t jeep must but we do love our big jacked up side by sides! Mudding and crawling, camping, and hunting through the Magazine Mountains! Happy wheelin brother!
Hey Matt, Thanks for the message! Cool story and sounds like you put a lot of work into it! That definitely doesn’t sound right, a few questions, does the smoke smell sweet? (Burning coolant smells kinda like cotton candy) If you pop your rad cap is the coolant still nice and green or has it turned into a sort of milky coffee color? (If its green its most likely not your HG, if its got any brown in it thats a bad sign). Its definitely not good to run it 180 out (but also super common) so it doesn’t bend the rods like that. You might have a stuck lifter but you’ll typically get a clatter if you have one.
If you leave it running for 15min does the smoke go away? It could just be burning all the moisture out of the exhaust if it sat for a long time. Its honestly pretty uncommon to wreck Head Gaskets in VG30’s because they’re stupidly over built and have a crazy number of head studs. Did you get your heads decked? Put a straight edge on them? If they’re warped a bit from heat you’ll never get a good seal no matter how many times you have them off. Its typically part of the process but I’m cheap and lazy (and mine were nice and flat) so I didn’t bother.
Last thing, its SUPER common to snap exhaust manifold bolts on VGs, the steel manifold and the aluminum head like to heat/cool at different temps so they are known for snapping the studs (I had 7 of 13 snapped in mine back in the day) that will cause exhaust leaks and stink under the hood.
Let me know and we’ll get you figured out!
Cheers!
So I got the sucker running great now. It turns out it was running rich as hell. So like a typical non mechanic I starting throwing parts at it. Literally replaced everything that controls idle and fuel. IACV, TPS, distributor, plugs, wires, fuel sending unit with pump, coil, thing behind the coil (I forgot the name), fuel pressure regulator, filter, re-coated the tank, ECM. Nothing made it stop running rich. So, I did TONS of research one night and read where the coolant temp sensor that runs to the ECM can be messed up and it can make your rig think its cold, making the ECM call for more fuel. So I replaced the sensor and thermostat…But it didn’t fix it. So I tested the sensor and found it to be good so I pulled the new thermostat to put it in a pot of boiling water to see if it reacts… it did. So I’m frustrated and about to put it together again when I noticed the thermostat housing inlet was corroded all the way around where it seals off the thermostat. I didn’t think it was the issue but ordered one anyways. It was like 7 bucks. I slapped it back together and BAM! Fixed. I did have to reset the ignition timing because I set it when the coolant temp wasn’t reading right. But now it runs perfect. It was a dumb issue to have but I learned for it.
No if I can get the coolant temp gauge in the truck and speedo to read we will get to start the “make it look cool” stuff. 😂
Thanks for replying! I was surprised. Sorry I didn’t reply sooner. I figured I’d get an email or something if you did. Ill be looking this time. Thanks man and keep making videos for dumb a**es like me!
Awesome! I’m stoked to hear you got it figured out! Sometimes tracking down things like that can be a nightmare (I currently have a bad internal clunk I can’t figure out…..its going to reveal itself in an expensive way I assume.) Sucks you had to go thru that much headache to figure it out, its usually just something “simple” like that. On the bright side, you’ve got some new parts that you can rely on now!
Cheers!