Mi16 Head Bolts

[kaich 6 1 Cars]

I'm going to remove the head from a xu9j4

I dismantled many TU engines, but this is my first XU engine (alloy scary me!), so the question is:

any advice about removing cylinder head bolts?

Haynes says :" working in reverse of tightening sequence, progressively slacken then ten bolts by half a turn at a time, until all the bolts can be unscrewed by a hand"

that sound pretty simple, just using a torx 55 and a lot of force , but there is any tips to do that e to prevent any damage?

thanks

Edited March 12, 2008 by kaich

[davemar 16]

Just make sure you're using a really long breaker bar for those first few nips as they are damn tight and you don't want to give yourself a hernia! I've never had a bolt seize or snap, but I suppose it could be possible, so if a bolt is still feeling really tight after more than the expected turn then it might be ready to break. But, this is pretty unlikely, and it should be all OK.

 

The head might also need a bit of persuasion to remove, as they can get a bit stuck. Don't forget there's dowels holding it in place.

[GLPoomobile 958]

Any idea how old the bolts are, and is the engine staying in the car? If they are old bolts (or unknown age) and you can't afford to take out the engine IF a bolt snaps, then I'd advise liberal doses of Plusgas to help free them up.

 

I've only removed 2 8v heads before, and the first one snapped a bolt (I was scrapping the car though and only wanted the head so didn't matter). Since I absolutely could not afford to have another bolt snap on me, the 2nd one I did I soaked in Plusgas for a few days, and used it in between every small turn of each bolt. Might have been overkill but I had the luxury of time and it worked a treat with each bolt coming out pretty easily.

[DamirGTI 327]

Yes it's not unusual for these bolts to snap/break as they can rust really badly inside the block and also if they've been reused in the past (they are stretch type bolts for one time use only..) ... anyway just go nice and easy in reverse order of the tightening sequence one bolt by one and do not undo them more then 1/8 turn (ignore the Haynes recommendation , do 1/8 turn maxi. , not half a turn !) , and make as much stages as you can until you release the pressure from the bolts so that they can be undone by hand - nice and easy take your time don't rush , if one of the bolts feels "springy" do not force him - torque down all the bolts except that one and then try again , with a little bit of hammering/pulling combo on the bolt it'll ease up on the end ..

 

Have fun !

Damir

[kaich 6 1 Cars]

uderstood ( I hope!)

 

the secret is either use a lot of svitol (it must be the italian version of plusgas!) and of course a very long rod ( iKnow how much harder can be a head bolt)!

stay tuned guys!

Cheers

[DrSarty 90 1 Cars]

I must confess I thought my head (the one on my shoulders) was gonna explode when I undid mine, twice now!

 

In hindsight these ^^ precautionary measures with a bit of patience would definately be advisable.

 

Good luck.

[DamirGTI 327]

Well you'll have little use of plusgas when removing the bolts (as the liquid wont reach the threads deep down , it's useful if the bolt breaks inside the block then you can freeze/soak him with the liquid )

From my experience the secret is just - go slowly , slow and with "feel" , the important thing is not to undo each bot too much at a time as i said half a turn is too much undo them 1/8 turn each in as much stages as you can/need to release the pressure so that they can be removed/turned by hand , because then the pressure will let loose slowly and evenly from each bolt in circle as you untight them from bolt No.10 to the bolt No.1 , if you go faster - undo them half a turn or more each , the pressure will rise up on the head of the next bolt in turn which will load the force on it and then he might snap/break ...

1/8 a turn please - thank you !

 

Rgs !

Damir

Edited March 12, 2008 by DamirGTI

[pug_ham 242 3 Cars]

They tend to seize solid causing them to snap due to dissimlar metal corrosion (Alloy & steel, same as Bendix caliper bleed nipples).

 

Not the best practice but if the engine is slightly warm when you initially try to loosen the bolts, you might be lucky & none will snap during the process of completely removing them.

 

Graham.

[kaich 6 1 Cars]

right, I'll take my time to do that!

and as Damir said, slowly and a 1/8 a turn

forgot to say, the engine in out of the car (at now is on the garage floor) and to warm the engine could be at good idea, this can help to slacken bolts, I'll consider this option

[pugman211 0]

if the engine is out, see if you can spray some WD-40 or similar up into the bottom of the headbolts, as that will be where they are likely to seize up from alloy - steel and air and muck.

[sorr 0]

I have also found that employing a friend to whack the top of your breaker bar knuckle with a large hammer as you put tension on the bolt a useful way of getting it out without breakage.

[Tom Fenton 1,526]

I take these out with a windy gun turned down, it therefore can't generate enough torque to snap the buggers off, but the impact action helps break any corrosion/seizing on the threads......

[kaich 6 1 Cars]

holy s##t

I've broken a head bolt

I've slacken 8 head bolts, one broken and one is still in original position

and now? what can I do?

[DamirGTI 327]

bugger

....

.....

well you don't have much choice now , remove this last bolt , remove the head and inspect the broken one - if you get lucky and you see him protrude above the block surface you can still remove him by welding one nut on top of it .. but if it has snapped beyond the block surface deep down inside the bolt hole then it'll be a bit difficult I've had this problem two times before .. one time it has snapped deep down inside the block and rusted really badly like it was welded to the block and i couldn't remove it out no matter what i tried ...

 

Damir

[kaich 6 1 Cars]

bugger

....

.....

well you don't have much choice now , remove this last bolt , remove the head and inspect the broken one - if you get lucky and you see him protrude above the block surface you can still remove him by welding one nut on top of it .. but if it has snapped beyond the block surface deep down inside the bolt hole then it'll be a bit difficult I've had this problem two times before .. one time it has snapped deep down inside the block and rusted really badly like it was welded to the block and i couldn't remove it out no matter what i tried ...

 

Damir

 

I removed the last bolt and I removed the head. I'm not lucky the broken bolt is inside about 1,5 cm in the block . so? I need a new block? any tips?

regards

Edited March 20, 2008 by kaich

[ifcho 0]

I have two bolts like that.

 

To remove them, get them on a column drill and drill them inside with a 3-6 mm drill bit. If the bolt doesn't come out during the drilling (if possible use a reverse drill bit) then you use an expensive bolt extractor bit, or a reverse tap. When drilled from the inside, it should be easy to go off..

 

Must say I am still to do this...

[woodsy 0]

i had 2 engines do this to me before.In the end i had to see a mate who owned an engine recon shop and was expert engineer.He drilled out bolt hole in block slightly bigger and put an insert in block above broke bolt then used a headbolt of a diesel as its shorter and sits on top of the broken one.Aint had any problems at all even when had to remove head again few years later.Was a really good job he did though.

[DamirGTI 327]

s***t ... well id say strip the block completely , or if you can lift it (get someone to help you out regarding transport ..)leave the crankshaft/pistons inside and take it to machine shop they will pull him out .. as it's really hard to drill the hole in the bolt for stud extractor by yourself if it's snapped deep down cos you'll struggle to drill the hole in the center of the broken bolt , and if you can't drill it in dead center it'll be of no (little) use .. it's best to take the block to some good machine shop and they will know what to do and they have a machines for this job fair better and accurate then ordinary hand drilling machine .. also they must have a "heli-coil"-s for repairing the threads if they'll be damaged afterwards they remove the bolt from the block ..

 

Anyway don't despair it can be done but as i said it's best to leave that to professionals rather then trying to remove/drill the bolt by yourself as you can just make the things worse and then it'll be much more harder to remove him afterwards ..

 

Is that 2.0 Mi16 engine or 1.9 Mi16 with wet liners ?

 

Best luck !

Damir

[kaich 6 1 Cars]

s***t ... well id say strip the block completely , or if you can lift it (get someone to help you out regarding transport ..)leave the crankshaft/pistons inside and take it to machine shop they will pull him out .. as it's really hard to drill the hole in the bolt for stud extractor by yourself if it's snapped deep down cos you'll struggle to drill the hole in the center of the broken bolt , and if you can't drill it in dead center it'll be of no (little) use .. it's best to take the block to some good machine shop and they will know what to do and they have a machines for this job fair better and accurate then ordinary hand drilling machine .. also they must have a "heli-coil"-s for repairing the threads if they'll be damaged afterwards they remove the bolt from the block ..

 

Anyway don't despair it can be done but as i said it's best to leave that to professionals rather then trying to remove/drill the bolt by yourself as you can just make the things worse and then it'll be much more harder to remove him afterwards ..

 

Is that 2.0 Mi16 engine or 1.9 Mi16 with wet liners ?

 

Best luck !

Damir

 

it's a 1.9 mi16 mate (with good wet liners ad class c pistons)

anyway now I'll strip the block as you said, and I strip also pistons and crankshaftm, because I think it's better go to the engine shop with only the block or is it a bad idea?

thanks for the help guys

Edited March 25, 2008 by kaich

[DamirGTI 327]

it's a 1.9 mi16 mate (with good wet liners ad class c pistons)

anyway now I'll strip the block as you said, and I strip also pistons and crankshaftm, because I think it's better go to the engine shop with only the block or is it a bad idea?

thanks for the help guys

 

 

No , it's a good idea cos it'll be easier for them to manoevre with the block on the lathe/drilling machines etc. , and it'll be much more easier for transport as fully striped block is in fact very light , you'll see

 

Let us now how did it go

 

Regards !

Damir

 

(but it'll be wise to replace the main bearings , the big end bearings , piston rings and re-seal the block afterwards when assembling the block back ..)