changing out head gasket, need advice.

[poopypants720]

So just pulled the head and it's just as the compression test showed... Blown between 1&2...(used the screwdriver, in place of the wedge for the timing chain, LoL)

 

 

 

But I'm cleaning up the head now and I'm concerned that it may need to be resurfaced? Only ran a couple applications of gasket remover sprays(with 10 min soaks n using a plastic scraper to clean) but I can see that the crosshatching of the metal inlays in the old gasket pitted the surface of the head...

 

 

 

 

 

 

Will cleaning it good, applying a copper coat gasket sealant to the head gasket and torquing down in steps be good enough, or does it really have to be baby butt smooth with a mirror finish?

 

Not asking for advice on the copper spray itself, I understand there's two sides to the fence and considering I just blew a dry application head gasket with proper upkeep on the specified re-torque intervals post rebuild and they were still torqued to spec when I pulled the head, I'm going to have a go this time around with the spray treatment to the gasket.

 

The engine never overheated, just started clacking/popping cause of the loss of compression between cylinders, not even 1/4 mile from my house, so I'm not concerned with it being warped, some may remember, it was just rebuilt in 2012 and has barley any miles on it at all... Mostly just grocery/gym/weekend off road runs. Fluids were well maintained and it has both a lower temp thermostat(live in the desert) and an oversized radiator.... No stress fracture in the block or head either....So just need to know if they need to smooth polish this surface pitting from the metal pattern in the old gasket...

[Rick-rat]

 

 

 

Surfaces just need to be completely clean and the check to see if it is warped with a straight edge. I use a wire wheel on a drill motor to clean the head surface

 

Make sure to run a bottom tap down your head bolts to clean the threads up

[MicroMachinery]

Like Rick said, run a straight edge across it and if there is no warpage, just make sure it's clean. You don't need a mirror finish unless you're putting a high dollar Cometic headgasket or something of that nature. Just make sure all the debris is off. I've done plenty of head jobs that looked similar to that. Cleanliness is key. A little staining on the aluminum isn't a big deal. I personally wouldn't use a wire wheel for fear of gouging up the head, but that's just me. I've always used scotch brite pads with good results.

[datsunaholic]

Scotchbrite or a BRASS wire wheel.  Not steel, that WILL tear up the head.

[banzai510(hainz)]

hopefull the Timming wedge is deep enough to push the tensioner in otherwise if pop out your gonna be fucked!!!!!!

 

just by looking at it i dont think thast handle is that long to push the tensioner in. Now if you pull that handle out NOW your really fucked.

good luck.

 

If you changed the head before then you know what your doing. Key is you using a nissan gasket or a Felpro.  I dont like Felpro that much anymore. I will use a Graphite gasket if possible. If head never over heated I would just swap a gasket myself.

[datzenmike]

If it blew it was likely slightly warped or you used copper coat instead of checking when built years ago. Clean it then straight edge. If you can fit a 0.002" feeler gauge under at any place get resurfaced. Look really close between 1 and 2 for erosion caused by gasses see-sawing back and forth between cylinders. Maybe it blew here before? If just in doubt get resurfaced. If milled flat you won't need any coatings. That's made for GM owners' engines where the parts don't fit tight. Nissan, in fact no one, uses that shit when assembling. Do it right and trust your own work.

 

 

edit: 0.002" is allowable. .004"is the maximum amount allowable. To be safe spend the $30 and have it fly cut now rather than doing again later when it blows.

[scooter]

Mikes got it right.

[Draker]

3M Yellow Roloc Disc will safely clean aluminum.

 

 

 

 

People say to use a straight edge to check the head. That is correct.. however, you need a precision straight edge. Something with a verified flatness of under .001 across the entire length, Ideally even flatter. These are at least $50.. to well over $100.

 

 

 

These are NOT what you should use. We are talking about a measurement of .002"!!!

 

[poopypants720]

Well if I just pull the cam and rockers, leave the valves and springs, the local shop I had it rebuilt at will resurface for $45....Cheaper than a precision straight edge... Think I may just go that route for some cheap insurance...

[poopypants720]

hopefull the Timming wedge is deep enough to push the tensioner in otherwise if pop out your gonna be fucked!!!!!!

 

just by looking at it i dont think thast handle is that long to push the tensioner in. Now if you pull that handle out NOW your really fucked.

good luck.

 

If you changed the head before then you know what your doing. Key is you using a nissan gasket or a Felpro. I dont like Felpro that much anymore. I will use a Graphite gasket if possible. If head never over heated I would just swap a gasket myself.

I'm certainly hoping it will hold too! LoL

 

But really, I got it in there pretty good before even pulling the cam sprocket and it hasn't budged since. I just laid the slack over the top and carefully avoided bumping it while removing that head (heavier than I remembered)...

[Draker]

Well if I just pull the cam and rockers, leave the valves and springs, the local shop I had it rebuilt at will resurface for $45....Cheaper than a precision straight edge... Think I may just go that route for some cheap insurance...

 

You could have them measure it first. But if they aren't an honest shop they will probably just say it needs it regardless of if it actually does or not. Might ask to be there when it's being measured.

[poopypants720]

No, he said to bring it by first and have them look at it... They are a really good shop... Even dipped/deep cleaned my IM for free when I had my engine rebuilt by them. And did my u joints in my axle for $40, parts included.

 

Don't really stay in biz 35 years around here being shady, too many other options.

[KoHeartsGPA]

The bottom line here...there's a reason a new head gasket blew, you MUST find it BEFORE you put it back together....or risk losing another head gasket....oh and that timing chain cover will have to come off....tensioner has popped out.

[MicroMachinery]

oh and that timing chain cover will have to come off....tensioner has popped out.

 

I do not completely agree with this. If the tension from the chain on the tensioner is held by the wedged in screwdriver, then the spring will stay compressed and the tensioner may very well be in place. If tension is released, however.. then yes, the tensioner will pop out. 

[KoHeartsGPA]

Better safe than sorry, it doesn't look right in that pic :(

[Draker]

No, he said to bring it by first and have them look at it... They are a really good shop... Even dipped/deep cleaned my IM for free when I had my engine rebuilt by them. And did my u joints in my axle for $40, parts included.

 

Don't really stay in biz 35 years around here being shady, too many other options.

 

You'd be surprised :) 

 

But that's good to know they have a good reputation. 

[KoHeartsGPA]

What's the old saying....."Good work ain't cheap, cheap work ain't good" you get what you pay for.....

[datzenmike]

I edited my first post. I was at work and going by memory.

 

 

What's the old saying....."Good work ain't cheap, cheap work ain't good" you get what you pay for.....

 

 

Also: FAST, CHEAP, GOOD. Pick any two you won't get the third.

[poopypants720]

I'm certainly hoping it will hold too! LoL

But really, I got it in there pretty good before even pulling the cam sprocket and it hasn't budged since. I just laid the slack over the top and carefully avoided bumping it while removing that head (heavier than I remembered)...

  

The bottom line here...there's a reason a new head gasket blew, you MUST find it BEFORE you put it back together....or risk losing another head gasket....oh and that timing chain cover will have to come off....tensioner has popped out.

I think you may have missed the post above yours.

 

The screwdriver wss set in place, wedged in there plenty well and has not moved since. I took pictures and check it often for possible movement each time I work around that area.

 

It's good.

 

I agree, finding the reason why is important, but these heads blow between cylinders regularly and both surfaces were trued up by the shop last time it was off(when it was rebuilt) and gaskets went on dry, no copper coat application. Nothing was skipped. I even followed the instructions in the haynes manual for intervals of retorquing the head bolts and used the method as described in the fsm doing one bolt at a time.

 

The fact is, the motors have a weak spot. It's a engineering issue. What I'm worried about is what this metal gasket may have done and even though I only drove 1/4 mile back to my house after it popped, if there had been any erosion between the cylinders.

[datzenmike]

Won't erode unless driven for a long time by an owner that doesn't know any better or got it in that condition. Then it can be TIGed to fill the gap and surface milled to fix.

 

You said a metal gasket? Use a cheap NAPA composite gasket. Metal gaskets can use Copper Kote because they don't compress to seal. Composite gaskets do compress to seal thus not needing any coatings.

[KoHeartsGPA]

I edited my first post. I was at work and going by memory.

 

 

 

 

 

Also: FAST, CHEAP, GOOD. Pick any two you won't get the third.

CHEAP and GOOD won't be FAST.

FAST and GOOD won't be CHEAP.

CHEAP and FAST won't be GOOD.

 

Something like that....

[poopypants720]

Won't erode unless driven for a long time by an owner that doesn't know any better or got it in that condition. Then it can be TIGed to fill the gap and surface milled to fix.

 

You said a metal gasket? Use a cheap NAPA composite gasket. Metal gaskets can use Copper Kote because they don't compress to seal. Composite gaskets do compress to seal thus not needing any coatings.

Not a full metal gasket, just the metal that's inlaid in the stupid felpro gaskets made marks on the head... Look at the pics at the top, you can see the blown gasket I'm referencing laying on the block and then see the underside of the head where it left little marks on the aluminum heads surface, they are not just discoloration, I can run my hand over it and they are tactile pock marks from the gasket and can even see it well in person.

 

That gasket was the one used in my rebuild and no additional coating was used. I have a similar looking gasket in the head gasket kit I picked up from rockauto, but I made sure not to grab a felpro this time...

[scooter]

Those little marks wont really do much, if you can skim it for 45 bucks just do it.

 

If your bolts wernt oiled they can misstorque, couldof been a flawed gasket, ive done headgaskets where ive just sanded the head and theyve been fine. So who knows. If you blow another one then somethings amiss.

[poopypants720]

If it blows again in the same spot, I'll be pretty pissed... I took extensive measures to ensure I'd never overheat... So if the heads out of spec, it's cause they screwed up on the rebuild...

 

I am assuming that it's the gasket itself though considering all the other negative reports on felpro head gaskets...

 

 

The bolts still had assembly grease on them though, so they should be fine on the torque.

[Charlie69]

I have run Felpro head gaskets for years on many Datsun/Nissan, Chevy, Ford, Dodge, Honda, Toyota, even a Yugo.  Never had a problem.

 

I always chase my threads in the block and the heads where necessary and I wire brush and chase the threads on all my bolts, I even chase the nut threads.  I lubricate all bolts and screws before assembly  I always run Head bolts in by hand before installing the head to be sure I did not miss a threaded hole.  This all takes lots of time but it takes more time and money to re do a head gasket because of skipping a step.