Right then, finally got the head off [:D][:D][:D], and looking at the gasket, it's all in one piece [:0], dry at the front of the block, caked in oil accross the rear of the whole gasket[^].
Without my manual to hand, I'll try and explain what I've also found..
I have some pictures, but they won't be ready until Wednesday, and I won't post them anyway unless someone really wants me to [:D]
1) The inlet / exhaust area of the head was liberally covered in oil, some of which had aparently cooked on.
2) The cylinder area of the head was completely black, with evidence of heavy carbon deposits around the pre-chamber ( all of which appear at first glance to be intact ).
3) The inlet and exhaust valves of all cylinders had a funny 'growth' on them, as if someone had flicked copper grease on the valves.
4) The pistons themselves show the same deposits, but in one place ( ie. not obviously directly in-line with the valves.
5) The two outer pistons are at full stroke, so I can't see these at the moment, but the two inner ones are very black, so they've not been steam cleaned !
6) The funny triangular holes in the head and block that are between the cylinders eg.. O:O:O:O are presumably coolant channels [?] Anyway, these had almost covered over with a thin layer of what appears to be rust !!!
So, bearing in mind the car had been standing for a month without turning a piston, can someone identify the funny 'growth' I found ?
I've cleaned the head, it's the block's turn tomorrow ( top surface only ). Is it worth me trying to clean the piston tops, the whole cylinder, or both ?
Cheers for any thoughts.
Mat.
Cylinder head off - funny 'growth'
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Dave Burns
- Posts: 1915
- Joined: 14 May 2001, 05:30
- x 2
Heavy black carbon all over the shop is normal, this being a diesel engine with a few miles under its belt.
The funny growth on the valves could be rust formed by condensation on the valves.
Stuff rag into the camshaft oil supply gallery in the head and in the block, any dirt getting in here can eventualy find its way to the bearings and lock up the camshaft, very bad news.
Clean everything thouroughly, get the outer piston's at tdc and smear grease round the edge of the crowns to prevent debris getting down the sides of the pistons, clean the crowns and those area's of the block and then scrape the grease away, have rag stuffed tightly into the other bores while doing so. Then do the others.
Be carefull not to go and gouge the soft alloy of the head while cleaning it.
The holes in the gasket that correspond with the triangular ones in the block are usualy much smaller, which is why they tend to grow over a bit with rust.
Dave
The funny growth on the valves could be rust formed by condensation on the valves.
Stuff rag into the camshaft oil supply gallery in the head and in the block, any dirt getting in here can eventualy find its way to the bearings and lock up the camshaft, very bad news.
Clean everything thouroughly, get the outer piston's at tdc and smear grease round the edge of the crowns to prevent debris getting down the sides of the pistons, clean the crowns and those area's of the block and then scrape the grease away, have rag stuffed tightly into the other bores while doing so. Then do the others.
Be carefull not to go and gouge the soft alloy of the head while cleaning it.
The holes in the gasket that correspond with the triangular ones in the block are usualy much smaller, which is why they tend to grow over a bit with rust.
Dave
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mbunting
- Posts: 712
- Joined: 21 Dec 2001, 15:19
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jeremy
- Posts: 3959
- Joined: 20 Oct 2002, 16:00
- x 2
Glad to hear you've got the head off and that what you've found is normal.
Before you start scraping everything off have a very good look at your scrapers and make sure the edges are smooth without any nicks where they were used for opening paint tins etc. If there are any nicks - remove them before you start putting scratches in machined aluminium surfaces.
The most important bits to get clean are the mating surfaces. Piston crowns are not particularily important although major deposits should be cleaned off, there is no need to get them as clean as the gasket faces. You should resist any temptation to gouge down the side of the piston and the is a school of thought that the carbon at the edge of the crown should be left undisturbed to prevent an increase in oil consumption. I have always found this impossible! and any increase in oil consumption should be temporary.
While you are cleaning you should look carefully at the bolt holes to make sure that the top thread has not pulled up slightly and could interfere with sealing. I don't know if the threads are cut to the top of the holes on these engines - they may start a small way down in which case this will not happen. If it has happened carefully remove the raised bit with something like a carpenters oil stone.
Make sure no crud goes down the bolt holes as it is possible that this could cause the bolts to bottom in the holes and prevent a proper torque measurement on tightening. These holes can be cleaned with a largeish hand held twist drill - simply put it in, twist it and pull it out and wipe the muck off the end!
While you've got the head off its worth doing any rectification work to manifold fastenings etc. Its also worth checking the valve clearances and re-shimming before you re-fit the thing. (I think these engines are prone to the clearances closing up) You should also have a look at the valve seats which should be smooth and even with no visible pits. These engines don't seem prone to valve failure judgeing from the posts on here and therefore everything should be ok. If its not I doubt if you will be able to grind the valves satisfactorily due to the extremely hard materials used.
Its always nice to reach the half way stage in a job where you hope the difficult bit has been done and there should be no more nasty surprises! - even nicer when its all done and you can enjoy your drive in it. I'm such a pessimist that after major work I drive round a well established route first time so that I won't have to walk more than about 10 minutes to get home! I then have a good look, smell and listen before going further!
Enjoy your bank holiday week-end
Jeremy
Before you start scraping everything off have a very good look at your scrapers and make sure the edges are smooth without any nicks where they were used for opening paint tins etc. If there are any nicks - remove them before you start putting scratches in machined aluminium surfaces.
The most important bits to get clean are the mating surfaces. Piston crowns are not particularily important although major deposits should be cleaned off, there is no need to get them as clean as the gasket faces. You should resist any temptation to gouge down the side of the piston and the is a school of thought that the carbon at the edge of the crown should be left undisturbed to prevent an increase in oil consumption. I have always found this impossible! and any increase in oil consumption should be temporary.
While you are cleaning you should look carefully at the bolt holes to make sure that the top thread has not pulled up slightly and could interfere with sealing. I don't know if the threads are cut to the top of the holes on these engines - they may start a small way down in which case this will not happen. If it has happened carefully remove the raised bit with something like a carpenters oil stone.
Make sure no crud goes down the bolt holes as it is possible that this could cause the bolts to bottom in the holes and prevent a proper torque measurement on tightening. These holes can be cleaned with a largeish hand held twist drill - simply put it in, twist it and pull it out and wipe the muck off the end!
While you've got the head off its worth doing any rectification work to manifold fastenings etc. Its also worth checking the valve clearances and re-shimming before you re-fit the thing. (I think these engines are prone to the clearances closing up) You should also have a look at the valve seats which should be smooth and even with no visible pits. These engines don't seem prone to valve failure judgeing from the posts on here and therefore everything should be ok. If its not I doubt if you will be able to grind the valves satisfactorily due to the extremely hard materials used.
Its always nice to reach the half way stage in a job where you hope the difficult bit has been done and there should be no more nasty surprises! - even nicer when its all done and you can enjoy your drive in it. I'm such a pessimist that after major work I drive round a well established route first time so that I won't have to walk more than about 10 minutes to get home! I then have a good look, smell and listen before going further!
Enjoy your bank holiday week-end
Jeremy
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mbunting
- Posts: 712
- Joined: 21 Dec 2001, 15:19
Jeremy,
I'm using a soft toothbrush, with some fine wet and dry for the edges ( to get the old gasket bits off, and some engine de-greaser which is left to soak for 30 seconds.
The head came up about 90% nice and clean with only 15 minutes work.
Regarding the testing, I advise the other half of my route, take my mobile and full tool-kit in the boot ( trolley jack, ramps etc. ), AA Card, and do a gentle lap, increasing the 'thrash factor' until about lap 3 - 5, when, if it's still in one piece, I'm happy ! Adds about 30 - 50 miles for nothing, but it's worth it !
Did this after sphere and LHM change, cycling height all the time, a few emergency stops to check for air etc. etc..
Sad isn't it !!!
I'm using a soft toothbrush, with some fine wet and dry for the edges ( to get the old gasket bits off, and some engine de-greaser which is left to soak for 30 seconds.
The head came up about 90% nice and clean with only 15 minutes work.
Regarding the testing, I advise the other half of my route, take my mobile and full tool-kit in the boot ( trolley jack, ramps etc. ), AA Card, and do a gentle lap, increasing the 'thrash factor' until about lap 3 - 5, when, if it's still in one piece, I'm happy ! Adds about 30 - 50 miles for nothing, but it's worth it !
Did this after sphere and LHM change, cycling height all the time, a few emergency stops to check for air etc. etc..
Sad isn't it !!!
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jeremy
- Posts: 3959
- Joined: 20 Oct 2002, 16:00
- x 2
It reminds me of the dim dark past when before mobile phones were invented I re-engined a LandRover for my brother with a BMC 2.2 diesel. This was not easy and of course there were loads of modifications to be done to get it fitted and working. After a false start when it turned out the replacement engine was knackered the my nerves were very frayed with this thing and my problem was that in the country it wasn't easy to find a circuit that didn't involve a very fast main road or was extremely remote. Fortunately the thing went like a dream (albeit very slowly LOL).
Happy days!
Jeremy
Happy days!
Jeremy
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AndersDK
- Posts: 6060
- Joined: 21 Feb 2003, 04:56
- x 1
In general - there should be NO need to re-shim valve clearance on a head off-on job, since the head to block mating does not interfere with this setting (like on the old type pushrod engines).
This is of course especially true if the valve lifters are hydraulic - like on the BX16v and other high end XM/Xantia engines.
Another general rule is, that the valve clearance allways tends to INCREASE, since any carbon deposit build up on valves & seats would increase valve lifter/cam clearance. Also general wear in these components adds to this. THIS - however - MAY be the onset of a reshim job.
This is of course especially true if the valve lifters are hydraulic - like on the BX16v and other high end XM/Xantia engines.
Another general rule is, that the valve clearance allways tends to INCREASE, since any carbon deposit build up on valves & seats would increase valve lifter/cam clearance. Also general wear in these components adds to this. THIS - however - MAY be the onset of a reshim job.
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jeremy
- Posts: 3959
- Joined: 20 Oct 2002, 16:00
- x 2
Anders - I'm going to take issue with you here.
I entirely agree that the removal of the head will not affect the valve clearances on these engines. I have however seen many postings and articles concerning the tendancy of the valves on diesels to sink slightly after prolonged use. I have seen it suggested that this is confined to 1.7's but I have also seen it suggested as a cause of bad starting on any diesel. Apparently the symptoms are misfiring on starting which clears as the engine warms and the aluminium expands.
I therefore stick to my suggestion that Mat checks these clearances while the head is on the bench.
jeremy
I entirely agree that the removal of the head will not affect the valve clearances on these engines. I have however seen many postings and articles concerning the tendancy of the valves on diesels to sink slightly after prolonged use. I have seen it suggested that this is confined to 1.7's but I have also seen it suggested as a cause of bad starting on any diesel. Apparently the symptoms are misfiring on starting which clears as the engine warms and the aluminium expands.
I therefore stick to my suggestion that Mat checks these clearances while the head is on the bench.
jeremy
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AndersDK
- Posts: 6060
- Joined: 21 Feb 2003, 04:56
- x 1
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mbunting
- Posts: 712
- Joined: 21 Dec 2001, 15:19
Again, haven't read the book of fiction today ( taking a day off ! ), buy by valve clearance, are we talking about whether the valve is a nice snug fit into the hole in the head ?
I presume if the gap is wider than the mersey, the compression would be rubbish, and therefore there would be problems, and by cleaning up the surfaces, I am potentially removing some of the carbon build-up, and opening a gap caused by wear which is currently 'plugged' by carbon ?
Regards
Mat.
I presume if the gap is wider than the mersey, the compression would be rubbish, and therefore there would be problems, and by cleaning up the surfaces, I am potentially removing some of the carbon build-up, and opening a gap caused by wear which is currently 'plugged' by carbon ?
Regards
Mat.
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algieuk
- Posts: 127
- Joined: 07 Apr 2003, 14:56
Valve seat recession causes valve clearances to close. I've known several poor starting diesels to be diagnosed as terminal because of this, including mine. Ground the valve stems down a little while it was on the bench to cure it (reshimming would be a MUCH better way) 
Best starting diesel in town after that.
It was a very big problem on early petrol cars running on unleaded too.
Best starting diesel in town after that.It was a very big problem on early petrol cars running on unleaded too.
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AndersDK
- Posts: 6060
- Joined: 21 Feb 2003, 04:56
- x 1
Ok - seems you guys have experienced the valves can wear down in their seats ? This surely makes sense, and will of course give TOO close clearance problems, eventually causing the valve to burn, since there is a risc they can still be partially open in the closed cycle, also giving compression loss.
Tx - think I understand now [:D]
Tx - think I understand now [:D]
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jeremy
- Posts: 3959
- Joined: 20 Oct 2002, 16:00
- x 2
Mat - we seem to have forgotten about you in thisfascinating discussion of advanced reasons for engine failure.
The clearance we are talking about is the clearance between the cam and the next bit (the tappett). To check mount the head so you can turn the camshaft without the valves touching anything when open - ie on its side or on a couple of supports, and measure the clearance between the BACK of the cam and the tappet using a feeler gauge. The clearance should be 0.15 mm for inlets and 0.30mm for the exhaust with a tolerance of plus or minus 0.05 mm for both.
The object is simply to make sure the valve shuts properly. If the clearance needs adjusting you have to take the cam off, pull out the tappet, find the shim (flat hard metal disc) and get one of the appropriate size and re-fit. Its in Haynes if you need further instructions.
It is essential that the cam lobe is pointing away form the tappet as modern engines use complicated cam profiles for quietness and the gap will close soon after the cam rotates from this position.
With luck all will be OK and should you have problems later then you will know that this is not the cause!
jeremy
The clearance we are talking about is the clearance between the cam and the next bit (the tappett). To check mount the head so you can turn the camshaft without the valves touching anything when open - ie on its side or on a couple of supports, and measure the clearance between the BACK of the cam and the tappet using a feeler gauge. The clearance should be 0.15 mm for inlets and 0.30mm for the exhaust with a tolerance of plus or minus 0.05 mm for both.
The object is simply to make sure the valve shuts properly. If the clearance needs adjusting you have to take the cam off, pull out the tappet, find the shim (flat hard metal disc) and get one of the appropriate size and re-fit. Its in Haynes if you need further instructions.
It is essential that the cam lobe is pointing away form the tappet as modern engines use complicated cam profiles for quietness and the gap will close soon after the cam rotates from this position.
With luck all will be OK and should you have problems later then you will know that this is not the cause!
jeremy
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algieuk
- Posts: 127
- Joined: 07 Apr 2003, 14:56
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mbunting
- Posts: 712
- Joined: 21 Dec 2001, 15:19
Right then, time for a quick update.
Got everything back together today, new Head Gasket ( no skim required ! ), new manifold gasket, new oil / fuel / air filter.
To recap on the original problem, I noticed a lack of power, white smoke coming out of the exhaust under load ( ok if idle or on overrun ) for approx 1/2 mile behind car, and bubbles and fumes coming out of the coolant tank under pressure.
The head has been off, didn't need skimming, thick gasket put on, head back on, new manifold gasket, new glowplugs, new cam belt ( timed OK. ) NOTHING DONE WITH THE VALVES.
The car now starts, the coolant is fine, but I'm leaking oil down the underside of the middle section, and still emitting more smoke that a forest fire.
I've tried taking the Intercooler - manifold pipe off, breating unfiltered air - still smokes while under load ( clutch slip / handbrake ). No oily deposits on the rag from the intercooler.
I've tried taking off the fuel pump turbo pressure pipe, to try and eliminate fuelling.
So, I need to find out..
a) where this oil leak is coming from ( I'll check the upper turbo oil feeder ).
b) Where oil is getting into the system ( eg. could it be the turbo seals, and the oil is leaking into the output side of the exhaust - so not combusting in the engine, but smoking ? ).
For point B above, I would mention that there is no smoke at idle, and there is still smoke when cold and under load.
Any ideas folks, I'm so near, yet so far. As soon as this is fixed, I'll tow the AX to the scrappy ( nah, I'll have it up on ramps !! )
Cheers for any input.
Mat.
Got everything back together today, new Head Gasket ( no skim required ! ), new manifold gasket, new oil / fuel / air filter.
To recap on the original problem, I noticed a lack of power, white smoke coming out of the exhaust under load ( ok if idle or on overrun ) for approx 1/2 mile behind car, and bubbles and fumes coming out of the coolant tank under pressure.
The head has been off, didn't need skimming, thick gasket put on, head back on, new manifold gasket, new glowplugs, new cam belt ( timed OK. ) NOTHING DONE WITH THE VALVES.
The car now starts, the coolant is fine, but I'm leaking oil down the underside of the middle section, and still emitting more smoke that a forest fire.
I've tried taking the Intercooler - manifold pipe off, breating unfiltered air - still smokes while under load ( clutch slip / handbrake ). No oily deposits on the rag from the intercooler.
I've tried taking off the fuel pump turbo pressure pipe, to try and eliminate fuelling.
So, I need to find out..
a) where this oil leak is coming from ( I'll check the upper turbo oil feeder ).
b) Where oil is getting into the system ( eg. could it be the turbo seals, and the oil is leaking into the output side of the exhaust - so not combusting in the engine, but smoking ? ).
For point B above, I would mention that there is no smoke at idle, and there is still smoke when cold and under load.
Any ideas folks, I'm so near, yet so far. As soon as this is fixed, I'll tow the AX to the scrappy ( nah, I'll have it up on ramps !! )
Cheers for any input.
Mat.