MD11 Cylinder head - removal and refitting advice please

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Airscrew

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Hi all, a few of you may have seen my question last week about steam in the exhaust.

http://www.ybw.com/forums/showthread.php?506414-Can-you-diagnose-this-engine-symptom

The conclusion is that it is steam and a partial head problem.
So its time to take the heads off and investigate. Last time I did this was on a mini (Cooper for rallying), but that was a while ago.... :)

I have previously removed and replaced the exhaust manifold, and admitting the need to be a masochistic contortionist again, that is straightforward.
I have studied the workshop diagrams, which are helpful.
I read the manual, which is not so helpful 'remove cylinder head!!'.
I have found a couple of useful videos on YouTube.

But I still have a few specific questions:

Release and bend (carefully) the rocker oil feed. OK.
Does this remain attached to the block, and each head is drawn over the pipe, leaving it proud, free standing, and protruding from the block?

Is there a risk of it becoming detached from its fitting lower in the block?

If the pipe splits during unbending / rebending, what is the remedy?

Presumably, you would remove and carefully store the push rods (and check for straightness on the workbench)?

Leaving the cylinder head bolts in place, would you defo replace new nuts? Does anyone know the size?

At that point, I will see an indication of wether it is only the gasket, or wether there is any sort of crack or groove.

I plan that if the block is grooved but fixable, I dont want a major project and so will leave in place and use JBWeld or similar. Any advice on the best proprietary solution for this?

If it is only the head which is grooved, I plan to take to a workshop and have it welded and machined. Any ideas on wether this is the right approach, and the anticipated cost of this?

And what is the head material? Cast iron or steel??

So, assuming it is fixable:

I already have a full head kit from KeyPart

Once on the workbench,

should I be able to see with a straight edge wether there is any warping of the head?
Can an MD11 head warp, as it is only roughly 150mm square?

Can I remove (and refit) the valve springs without a spring compressor? The (Irish) guy I saw on YouTube did it by hand (on a 2010)?

The engine had a full top-end done in c.2010, so I dont anticipate changing the value guides, but how do check the valve guide wear, with only basis workbench tools.?

I dont believe there is a compression problem, but is it worth cleaning and re-lapping these valves, or should I NOT do that because of what appears to be a critical ground angle on the valves?


Any other thoughts or comments would be appreciated.

Many Thanks.!!
 
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The oil feed pipes are actually screwed to nipples ( ??) on the top face of the crank case . Be careful with them or you will have to remove the cylinder block(s) to rectify any damage

Make sure the push rods are returned to their original positions ( You know that from past engine work). Check that they are straight. They will be.

The heads are on long studs that also secure the blocks. Try not to disturb the blocks. Make sure the the studs are still tight before re-assembling. The manual says use new nuts but at £10 a time no way unless damaged.
If you use JB weld for any remedial work ( there wont be any needed) look at the specs and consider the high temperature one.

"Special" cast iron according to the manual.I would not have thought they would warp ( not like Richards flimsy landRover heads !)

Pretty sure you will need a spring compressor. A bigger one than the one you used on the Mini!

Check the fit of the valve stems in the guides ( IIRC there is something about it in the manual)

You can lap the valves if necessary ( it wont be) but take note of the measurements if you have to re-cut the seats

If you can do a Minicooper this one is a piece of cake. Read the manual. All you need to know is in there
 
You may not need to take both heads off. It is likely that only one is leaking. Try turning the engine over slowly with one of the decompression levers up, and see how easy it is ore whether you can here any hiss. Then try with the other cylinder. It might tell you which head is leaking.

I found getting the head of without disturbing the block beneath was very difficult (i could not do it) and re-tightening the head has to be down after you have the exhaust manifold made up.
 
Pyro,
good advice re first checking which is the offending head.
Re tightening the head, from what you say, does that mean:
check the studs are tight, head(s) back on, loosley tighten, re-attach manifold (plus new gasket(s), and yes thats awkward to say the least), and THEN tighten the head per the sequence in manual?

Vic,
I can now picture the oil feed attachment with the head off now.
Other useful points well noted.

Tam,
yes, pictures are always useful, that would be appreciated.

Thanks to each of you.
I will buy some more penetrating oil (!!), and probably start this weekend.


Any additional thoughts or comments from others out there would also be appreciated.
 
The oil pipe does not usually split due to bending and straightening but only straighten just enough to remove the head and no more. As Vic says the other end of the pipe is secure and to remove it you need a crowfoot.
The studs can stretch if abused and the nuts can lose the seals and as they have a serrated bottom can allow oil drips down the studs which are enclosed in the rocker covers . When tightening take the torque up in stages and if a stud has been stretched then you will observe this by its behavior as tightening and how much further you may have to move the spanner Change any suspect studs. I had some at day 1.

Valve seat to valve angles are critical for long life I found some time ago that rather than play around with the volvo angle I adopted as I think Viv is saying Mini BMC angles for which there is a Pickavant seat cutter and I cut the seats on the valve to the necessary 1/2 deg difference . You need just a 1mm seal line around the valve and excessive seat to seat grinding might exceed this seat width and a shorter life.

If you get away from the waters edge where prices are lower you might find a motor workshop that will do the valves seats and guides at a sensible cost.

If your head is cut then please do not try epoxy products here as you might finish up doing a second fix mid channel. I adopt a cold repair process which has worked on head and block on older engines. Your engine has a steel liner so maybe not cut. If cut you have a choice of repair process depending on resources however the taper pin dodge must be done with care if used .


I lightly centre bunch the centre of the cut about half way across the land. I obtain a small taper pin a little less than 1.5 mm at small end . drill a hole at the centre point into the centre of the cut. The cut should be smaller than this. The hole should be about 10 mm deep. Shorten the taper pin at the small end till it only just enters the hole and then tap it lightly till it becomes a tight fit.

Cut the taper pin leaving it slightly proud of the head using a razor saw or small hacksaw and then file starting with very fine file and finishing with an oil stone. I have one such repair which is good after ten years.

While you have the head gasket surface exposed make sure you check the water cooling port in the gasket surface on the exhaust side is clear. It would be good practice to flush the head and block when out to remove sand and scale. The block can be flushed via the drain cock port as well as the hole mentioned above

The manual covers measurements for Valve Guides if you intend to replace them.

The blocks should lift of easily but may give a fight. There are compression shims between the blocks and crankcase. Don t mix up. If the bores appear unworn but a smooth finish they may benefit from a de glazing and restoring the herring boned finish. This is not difficult if you can get a drill powered honing tool. It isn't the first time I have done a Volvo block on the pontoon and it does make a difference.

If you fit new rings then of course check the gaps.

When refitting the blocks it helps if the pistons are not flopping around. A good trick is to position the piston about mid stroke height the place a batten about 40 mm / 20 mm and about 130 mm long across the crankcase forard and aft of the con rod and then wind the piston down so it is firmly sitting on the wood. Position the rings after oiling and with a well oiled bore lower the block. The wood can be removed once the piston is in place within the bore.

There are instructions in the manual for adjusting compression but if lucky it will be in limits.

I would recommend using the correct nuts . The head should not be warped as is is a stiff casting. However if there is an uneven discolouring of the surface of the gasket seal around the bore then it could be that remedial work needs to be done on the block or head. This should not be the case and MD 2 etc were more prone to this. They had long curved water passages between head and block and I believe your engine may have drilled holes which were introduced to cure this problem at some time also you have steel liners forming the compression joint with a unform surface.

The heads and blocks are similar materials and believe it is cast iron.

Hope this is of some use and just ask questions if unsure.



Manual.
https://www.maritimepropulsion.com/files/pdf/1001252
 
The manifold needs to tightened up to align the two heads bore you tightened the head bolts. Once the head bolts are tight, the manifold will not seat correctly unless the head are perectely aligned with it.

Seat the manifold and tightened but don’t torque up. Make up the head bolts, but don’t torque. Torque up the manifold, then the head.
 
pyrojames said:
The manifold needs to tightened up to align the two heads before you tightened the head bolts. Once the head bolts are tight, the manifold will not seat correctly unless the heads are perfectly aligned with it.

Seat the manifold and tightened but don’t torque up. Make up the head bolts, but don’t torque. Torque up the manifold, then the head.
Click to expand...
That is a good point which I overlooked . I just do the torquing the other way round but doubt it makes a difference . Certainly need the heads untorqued to engage the manifold bolts easily so that the heads can be aligned to the manifold.
 
pyrojames said:
The manifold needs to tightened up to align the two heads bore you tightened the head bolts. Once the head bolts are tight, the manifold will not seat correctly unless the head are perectely aligned with it.

Seat the manifold and tightened but don’t torque up. Make up the head bolts, but don’t torque. Torque up the manifold, then the head.
Click to expand...

That makes sense and is clear.
Thanks Pyro.
 
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