Removing cylinder block head... myth or not?

acidrain

acidrain

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OK, so this has been a confusing topic for me for quite some time as different people have different ideas of what you have to do if you want to remove your cylinder head and replace it. Some people say, it's just as easy as putting it back on, while others say you will have to send it in to have it machined ( why i don't know but thats what they say ).

Can we clear this up?
 
Depends if it's alluminium and why you removed it in the first place.

Alluminium heads are more susceptical to warping. Typically you would check what your vehicles tolerances are for warpage and if it is out, only then machine it.
 
exactly. generally they are either removed after a overheating problem or to redo pistons etc. If the engine has seized and/or overheated you will most likely have to have the head machined if it is not cracked or warped too badly.

If it is just removed to replace pistons etc it will probably still be ok but you will have to put a straight edge across and check for gaps according to specs.q
 
as far as i know if you remove the head or replace it, you must replace head gasket, thats about it
 
DOOMIE61 said:
as far as i know if you remove the head or replace it, you must replace head gasket, thats about it
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Hogwash, this is mostly applicable to 1937 Vaaljapie tractors and lawnmowers.
For all other occasions, psc and Freshy-ZN have given the correct answers already. :D:p
 
Depending on the mileage, I usually send the head in for refurbishment or get a factory exchange.
The refurb and factory exchange always fit new valves and valve guides when needed, plus valve stem seals, and in most modern engines service the hydraulic valve lifters.
They also normally lightly skim the head even if it's not warped just to be sure and it makes for a good surface for the new cylinder head gasket.

The cylinder head gasket cannot be re-used.
 
True, a gasket cannot be re-used. Also depends on what car. If it's a Citi or a Tazz, backyard job. A Merc, BMW, Audi, etc etc, you're talking about major labour. Recently had to replace my cylinder head (BMW 323i), and that was a bit more than a full day's job for the mechanic. A whole lot more has to come off the engine than you think.
 
Stokstert said:
Hogwash, this is mostly applicable to 1937 Vaaljapie tractors and lawnmowers.
For all other occasions, psc and Freshy-ZN have given the correct answers already. :D:p
Click to expand...

and what about if you taking your head off for other purpose's only like porting and flowing, then you just re-place the head gasket with a new one.. i would now as i have had it done to my car.. you don't just remove a head if it's cracked blown there are other reasons to..
 
DOOMIE61 said:
and what about if you taking your head off for other purpose's only like porting and flowing, then you just re-place the head gasket with a new one.. i would now as i have had it done to my car.. you don't just remove a head if it's cracked blown there are other reasons to..
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Even then you measure it for warping and straightness and if necessary re-machine or polish it and don't just fit a new gasket.
 
2 questions.

Is it the cyclinder block or the Head ?

Cyclinder block is the part just above the Sub assembly and the head is the top most part just under the tappid cover.

Head - Needs to be machined
Cyclinder block - Why on earth would you need to remove that ? Unless your Piston seized in the block.
 
acidrain said:
OK, so this has been a confusing topic for me for quite some time as different people have different ideas of what you have to do if you want to remove your cylinder head and replace it. Some people say, it's just as easy as putting it back on, while others say you will have to send it in to have it machined ( why i don't know but thats what they say ).

Can we clear this up?
Click to expand...

No acidrain. We can't quite fully do that... See here why:
http://mybroadband.co.za/vb/showthread.php?t=164504

In short though...IT IS an expensive exercise as you've already learned and it has to be done by someone who knows what is involved AND has the necesary information on how to do it right.

Did you guys know that on most new cars one HAS to replace the Head Bolts every time they are removed for whatever reason?
Most (ok some:p) mechanics don't have any idea why...
 
TestMate said:
No acidrain. We can't quite fully do that... See here why:
http://mybroadband.co.za/vb/showthread.php?t=164504
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1 - Include the vehicle details ( BMW 328i)
2 - Try to describe the 'problem' as fully as you can. ( Heavy amounts of oil on spark plug in one chamber, hence im assuming the head needs to come off to replace the gasket or so i recently found a common fault is the failure of the valve-cover gasket )
3 - Give pre-history to the 'problem' ( Car is heavyily under-powered, clearly not firing on all 6 cylinders, went the foot is put down the car jerks a bit and smokes )
4 - Give Feedback so we all know how it went. ( Feedback, well like i said, im leaving it for a pro)
 
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acidrain said:
1 - Include the vehicle details ( BMW 328i)
2 - Try to describe the 'problem' as fully as you can. ( Heavy amounts of oil on spark plug in one chamber, hence im assuming the head needs to come off to replace the gasket or so i recently found a common fault is the failure of the valve-cover gasket )
3 - Give pre-history to the 'problem' ( Car is heavyily under-powered, clearly not firing on all 6 cylinders, went the foot is put down the car jerks a bit and smokes )
4 - Give Feedback so we all know how it went. ( Feedback, well like i said, im leaving it for a pro)
Click to expand...

Judging from other technical posts by TestMate, I'd predict that you're going to get some useful information from him on your problem which you could use even if you're taking to someone else to repair, and he's certainly an expert on BM's.

You assumed the cylinder head to be the cause of oily spark plugs - this could most likely be a problem with the piston and rings, but lets wait for TestMate's response.

What year is your BM and the mileage?
 
Frankie said:
Judging from other technical posts by TestMate, I'd predict that you're going to get some useful information from him on your problem which you could use even if you're taking to someone else to repair, and he's certainly an expert on BM's.

You assumed the cylinder head to be the cause of oily spark plugs - this could most likely be a problem with the piston and rings, but lets wait for TestMate's response.

What year is your BM and the mileage?
Click to expand...

Thanks for the confidence guys.:D
Very busy today...will reply fully tonight...
 
Oil on a Spark plug = Rings not Headgasket.

Headgasket = Water in the oil or oil in the water or both.

You have a ring problem on that said cyclinder. Send it in mate ;)
 
Pitbull said:
Oil on a Spark plug = Rings not Headgasket.

Headgasket = Water in the oil or oil in the water or both.

You have a ring problem on that said cyclinder. Send it in mate ;)
Click to expand...

Oil on the thread of the plug. Head can cause this.
 
Slootvreter said:
Oil on the thread of the plug. Head can cause this.
Click to expand...

It's kinda hard depending on the head maybe. (No idea what the BM head looks like). As the Spark plug usually goes through the head into the cyclinder chamber directly. The thread is part of the actual head but not part of the water and oil ports.

But again, I have never seen a BM head :o
 
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