Little Trucks, Big World

Blown head gasket.... WHICH gasket to buy as replacement?

Well, after 32 years on the original engine, the head gasket blew between cylinders 3 and 4 causing loud knocking under load.  I nursed it home using high rpm/low torque to not put any stress on the engine, which worked well.

You know, this truck has NEVER, not one single time, left me stranded in all those years.  This was no exception.  It got me home.

Anyway, time to finally change the gasket.  This engine was NEVER overheated or ran hot.  So it's probably fine.  Yes, I may have been remiss on re-tightening the head bolts lately. 

I did look but can't find the discussion on what head gasket to get for my Z24.  I "think" it was mentioned to only use Nissan original but I wanted to float the question again regardless.

Also..... while I have a wedge in there and the head off, would it make any sense to put in head studs instead?  And does anyone make them?


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Also check your cat,mine got clogged up,came apart and blocked the flow,causing it to blow between 3 and 4 cylinder,it was making a loud noise too,my 3 and 4 plugs were wasted too,I had new exhaust manifold studs put in,he used Fel-pro head gasket,Jack did the job,the same guy that installed my Jasper engine,he cut the cat off and ran a straight pipe,we have no smog test here.He sent the head to a machine shop,the valves were adjusted and the head checked for warpness,the machine shop was 195 bucks.He also put a new pipe coming from the exhaust manifold on.He also put a 160 degree thermostat in so it will run cooler,my temperature gauge shows only a third of the way up.Don't need much heater here,it don't get cold.O'Reilly's has Fel-pro head gaskets,they are 21.99 each here,may be more in Cali,it is showing them in stock here.He also put new head bolts in.

Your stock one lasted 30 years why gamble with a different brand on someone's opinion? As long as the head is off have checked for straightness. The only job that sucks more than a headgasket is doing a second headgasket shortly afterwards. Stock components=reliability. Good luck and don't slack the chain or you will blow a personal gasket!
Oh, I know about slacking the chain!

Well, I thought as much about the head gasket. But sometimes things actually improve after 30 years, so thought asking wouldn't hurt.

As far as stock parts = reliability.... YOU BET! Lesson learned a looong time ago.
Fastest way to junk your vehicle, aftermarket parts.

Go with Fel-pro Marc,it's better than stock.Stock isn't always better,like you said things get better in time,also send head to a head shop to get valves looked at and adjusted,it is 32 years old.And make sure it's not warped,my head blew cause of the cat and Jack put felpro on it,plus when he put new Jasper motor in,he used Fel-pro,no one uses old Nissan parts like that,you can go right to the Auto parts place and get it then,no waiting. Some people are behind times.I have parts on my Nissan that's never been changed,that doesn't mean I over pay at the Nissan place.I've had my 85 Nissan since 92 and I am proud to say I use after market parts and it will last till They put me 6 feet under.Just got new tires put on and they are after market BF Goodrich,the last one's last 61,000 miles,got them in 2009.I just washed it an I'm going to show ya'll what a 85 look's like with after market parts,lol.Got new lug nuts,they are after market too.

Hey Marc, sorry to hear about your baby. I used fel pros in a couple chevy small blocks and a 66 mustang straight 6 and never had issues. But honestly I can't remember what I have in the Nissan, I just told the guy not to pinch pennies and use what he thought was best because he specialized on imports (Didn't feel like doing that one myself at the time). But yeah, like Channing says, if the O.G. Lasted that long then why question it. Definitely stick with the Nissan lug nuts and tires though, not like they outsource them to companies that actually make lug nuts and tires. I'm gonna have to second tommy on the cat, keep an eye on it, once mine got all the moisture in it after my gasket popped it got clogged bad and fast, probably rusted from the inside out.

Good luck!

Hi Joe,

Long time...

Yep, between the stock and fel pro.

Cat's fine, totally clean.  NO coolant leaks, ever.  It just finally got through the fire ring between 3 and 4. 

Since the stock gasket is not in "stock" (heh), I may just go with plan B and get a fel pro.

If your head gasket is going to blow because of whatever issue,it will blow all head gaskets.Some people's vehicle will go longer without blowing but history states that 720's will blow them.Also if it  is not done  right it will blow it again real quick,have the head sent to a machine shop,our trucks are old as dirt,I would never attempt to try to save money doing it myself..It's not cheap having a real pro doing it but it will be right.My engine never ran hot when cat got clogged up.But you need to find out what caused the head to blow,be ashamed to put new head gasket on and a few days later it blew again.You have to also watch who you have doing it cause they may say they sent it out to a machine shop to make money off of you and the head can be warped and they will shim it,and it will blow again.

These trucks are simple to work on. If you have the tools and time pretty much any repair can be done at home. Most folks on here are looking for a little knowledge from others on what to expect on difficulty and tips for different repairs. Loosening of the timing chain and tensioner popping out is the big one for the headgasket. The head can even be checked at home with a glass table and a feeler guage if you really need to save pennies. The few specialty tools such as torque wrench can be gotten for free from the autoparts store that have a tool loaner program.

So it's a year later and I still have not fixed the 720.  I did get an OEM gasket set, but living in glorious Kalifornia, I have not been motivated all this time because they'll probably fail it for smog anyway.

Seems they are desperate to get rid of every old vehicle in Los Angeles in particular, as it's STAR Smog only.

But.... I miss my truck....  I'll have to fix it, even if I just store it to move out of Cali.

The weather is nice, but it's turned into a shit state to live. 

There are moments when I question if I should even bother to own a vehicle any longer.  Let someone else go nuts driving my ass where I need to go for a few bucks a trip.  Hmm....  Just google the 405 freeway...  the bane of my existence.

Damn, I'm getting old.

I'm in the middle of putting a earlier L head on my Z24 engine. A straight edge showed 0.015" gap where less than 1/3 of that is allowed. I have a sheet of glass form a stereo cabinet and glued 80 grit sand paper onto it. Pushed and pulled the head back and forth.

First 6 passes

20 more  After another 50 or so only low between 2 & 3

Now it takes a long time as you have to grind away the entire head to get rid of the middle.

Eventually success...

Cost about $5 for the sand paper. Could not get a 0.002" feeler gauge under the straight edge after. Anyway just showing you that a warped head is cheap to fix.

I have seen other people use the glass and sandpaper method before. 

But is it also warped where the camshaft sits?  I had a head that could not be resurfaced because it would bind the cam.  Or so the machine shop claimed.

If the head is warped top to bottom then the cam is already binding. Can't see shaving it causing a bind.Just remove the rockers and spin the cam. (don't do this on the engine) If it turns easily by hand then cam towers are not involved.

Warp (in this case) may not be the best word. High spot may be better. As you can see it was all centered between 2 and 3 and may have been caused by a bad over heating. The aluminum contracted when it cooled, causing a pucker. Avoid severely over heating an aluminum head.

This L20B head I must have reclaimed off of something but not mine, I don't know the history on it. It might even have had a blown gasket before I got it. It's a U67 so '75-'77 only on the 610/710/S-10 and 620. Anyway Z series heads are similar to fix.

Trying to avoid the Z24's propensity for blowing the head gaskets by switching to studs. The holes and threads vary in depth in the Z24 block and  studs can be turned down to the bottom in all of them and don't need to be torqued like bolts. The nuts do all the camping. An L head raises the compression into the 9s.


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