Cylinder Head removal problem

[Timmy99]

Hi All,
Sorry to join the forum just to ask a question, but hopefully somebody can help with this one.
I've been trying to remove the cylinder head from my K11 so as to replace a blown head gasket - this is something I did a few years ago on a Sunny so I had some hope of success, sadly I've got a bit stuck.
I followed the Haynes manual as far as disengaging the upper timing chain from the camshafts, and then removing the idler sprocket retaining bolt and washer. Then the manual says something about prising a shaft off with a screwdriver, and then removing the upper chain - that's where I am stuck.
On removing the bolt, I find the sprocket - actually there are two sprockets, one engaged with each chain, which seem to form a solid piece of metal - is pulled down a mm or two by the tension in the lower chain. It is forced down against a small ridge of metal extruded from the head, the upper chain is held between this bit of the head and the sprocket. That means I can't get the upper chain off the sprocket, it also means I don't see how the head is ever going to come off, not without mangling that chain and sprocket at any rate.
Also, like I say the whole sprocket assembly has been pulled down a bit, this means I now cannot get its bolt to screw back in, so even if I could get the head off how can I reassemble things?
As far as the 'screwdriver prising' business goes - the sprocket is loose on a shaft, it won't come all the way off though, I don't see anything that can be prised.
So, have I got something wrong here, am I missing something? As it stands the only way forward I can see here is to remove the lower chain cover, then the lower tensioner(s), that should allow the idler sprocket to move up enough to disengage the upper chain. But I don't see any way of accessing the bolts holding the lower cover on with the engine in car, and removing the engine is beyond me I'm afraid.
So, any suggestions - if not the thing is off to the scrap yard...
Cheers,
Tim

 

[frank]

the head just lifts off the 2 chains and idler tim, but if you need to change the upper chain with the head on, you have to cut the little stump off (or remove the chain cover)

 

[Stani1029]

Like frank says the top chain doesnt need to come out, leave it sitting on the sprocket. I hope youve not missed the 5x10mm bolts. 2 inside the cover, 1 at the back LH corner of the head, and 1 either corner at the front of the head. Also the water pipe that runs around the back of engine to the thermostat housing has a bolt there too thats a bit hidden. AND theres a bracket on the underside of the inlet manifold that has to be removed. Good luck

 

[pollyp]

always note/photo the locations of the coloured chain links vs dots on cam spocket & idler spocket before removal.

to loosen the upper chain, remove the upper chain tensioner first to slackin it, then unbolt the cam spockets. slide the cam spockets off making sure not to drop em

leave the upper chain hanging off the idler

the timing chain idle spocket that links the lower & upper chain rides on a shaft that has an offset locating hole. this hole is hanging on a locating dowel pin on the head and the lower chain has barely enough slack to allow reinsertion.

after unbolting the idler spocket, simply pull the spocket & shaft out a little to unhook it off the locating dowel pin and let it rest

undo bolts mentioned previously, undo headbolts. check everythings unplugged from head and pull head off.

##################

after reinstalling head, rotate the idler spocket shaft till the locating holes pointing up

now reinserting the idler shaft back into the dowel pin usually involves some brute force jiggering and swearing.

the lower chain is under constant spring tension and the idler shaft dowel hole can barely reach the pin, tis a tight fit.

so what you do is keep the locating hole pointing up and the spocket shaft fully inserted into the idler spocket. then pull the idler spocket up hard fighting against the lower chain tensioner till the locating hole eventually slips onto the locating dowel pin. bolt it up. install cams.

refit upper chain then cam spockets in same location as noted/photoed beforehand

take the upper chain tensioner out of its body and reset the internal spring ratchet by turning it all the way clockwise. gently reinsert tensioner back into the body but don't force it all the way otherwise you'll trigger the ratchet to release and start all over.

install upper tensioner onto the head, turning the inlet cam c-clockwise abit may help loosen the chain. then fully push & release the tensioner to engage and allow it to tension the upper chain.

turn the crank afew times to settle the tensioner and make sure nothings colliding with each other before refitting everything back

 

[Timmy99]

Thanks for the quick responses! In particular for explaining how the shaft locating dowel works, and confirming that brute force is needed there - I didn't want to be pulling too hard on the thing, not actually knowing whether that was necessary or not. I do see what looks like a small hollow pin embedded in the shaft, I guess that is the other side of the dowel - in which case knowing it needs to be at the top is probably half the battle
Anyway, camshafts are off (and the sprockets marked), sounds as though I still have a chance, looks like all that still needs doing is the head bolts inc. the 5 10mm ones, will let you know how it goes.

One more thing - obviously I have to disconnect the exhaust at some point, however the two 'special bolts' with attached springs the manual suggests undoing really do not want to turn. Instead I have managed to undo the four bolts on the top of the primary catalytic converter, which looks like it'll come apart at that point. But maybe it won't, or it isn't a good idea to do that?

Cheers again,
Tim

 

[pollyp]

no point attempting to undo the spring loaded cat-downpipe bolt cos they're guaranteed to be fused onto the cat from yrs of heat n road corrosion and are more likely to snap at the weaker thin section of the bolt = grind, drill & retap new holes & new nut/bolt

i'd suggest either unbolting the manifold off the head & 1st cat if not seized, cat & downpipe will drop down, or the unbolt downpipe from the 2nd cat then undo the manifold so that you could move it forwards clear of the manifold studs then drop it down.

 

[Stani1029]

You only need to unbolt the manifold from the head. The exhaust should be flexible enough to get the head off as ive done it with a full engine!

 

[Timmy99]

Thanks again... will let you know how I get on, won't be 'til next weekend as the car is at a friend's house.
As I recall the exhaust manifold was behind a heat shield, and the two bolts holding that on were rusted in place, still I will see what I can do there.

 

[frank]

Thanks again... will let you know how I get on, won't be 'til next weekend as the car is at a friend's house.
As I recall the exhaust manifold was behind a heat shield, and the two bolts holding that on were rusted in place, still I will see what I can do there.

thats very common tim, you can usually bladder a 9mm socket on them :grinning:

 

[Antony]

naah, tin snips FTW! cut the beggar off.

for future reference that little dowel on the oil pump cover needs cutting off..... its a pain in the backside doing anything with it still on. (had the cylinder head off my car 6 times in a weekend)

 

[Timmy99]

Thought I'd let you guys know, finally got around to doing this today, and the head did come off - more or less. Still no joy with the exhaust, but I got the inlet manifold off and was then able to lift the head, exhaust still attached, just high enough to change the gasket. A bit of the old one had completely disappeared between cylinders 1 and 2...
Now I am at the 'refit the idler sprocket' stage. I see what you mean about brute force... no luck as yet, I'm trying to lever the sprocket up with a big screwdriver but it won't quite go high enough. Maybe tomorrow I can find something a bit longer to lever it with.

 

[Timmy99]

Hah... got it. Silly me, I was assuming that the small hole on the side of the sprocket you can see, matched the position of the hole on the side you can't. They are of course 180 degrees apart.
Slightly concerning, the paint marks I put on the sprocket and the upper chain are now several links apart. Guess my screwdriver levering shifted the chain a bit... hopefully putting the same distance between the marks for the camshaft sprockets will be right, that is for tomorrow though. Will let you know if it starts

 

[Antony]

these little engines are gold dude. even with the sprockets miles out. it will still start, but will run like a bag of spanners... its all about trial and error with as much attention as possible paid to the possition of the crank in conjunction with the inlet and exhaust cams. the chain possition doesnt matter as long as the cams are in the right place at the right time..... (Y)

 

[tlo]

I have just done the top chain on my sons micra and its a big thanks to this site that i felt confidant enough to do it.Thanks guys next the gearbox(Y)