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Post by paulfrance on Dec 10, 2016 18:01:29 GMT
Whilst driving engine seized up-on declutching could turn engine back 3/4 turn and vice-versa.Removed rocker box found broken valve spring-colletts-valve guide-collet holder-no valve?With torch could`nt see valve but bore full of water assume whats left of valve is submerged! I can only think that the spring broke and collapsed leaving collets free to fall out and so on!!
Has anyone else had a similar problem.
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Post by Penguin45 on Dec 10, 2016 19:06:34 GMT
Hi Paul, welcome aboard. If the bore is full of water, this is perhaps more head gasket related? Water into bore, engine locks hydraulically, catastrophic consequences for valve gear. Really, you need to get the head off and have a proper look. It's only an hour or so's work. Mind you, I'm the welder - you'll probably get better mechanical advice from other members later!  Chris. |
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Post by paulfrance on Dec 10, 2016 19:31:29 GMT
Hi Chris thanks for your useful comments I did not think along those lines-I put the problem of bore full of water as to damage done by perhaps the valve stem jammed at full tilt into the head thus causing a crack into the water jacket or even worse damage to the side of the bore!! another idea was that the valve hit the underside of the head so hard that it strained the bolts holding the head down thus causing the head gasket to leak?? I will whip the head of next week and see what I find and will post as to my findings,though at this point in time I still tend to err towards the spring itself-when you think about it-its age-and how many operations it has done in that time!!perhaps among the forum readers there is a metallurgist who could throw some light upon this- perhaps a metal age fatigue problem?
Paul.
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Post by dave1800 on Dec 11, 2016 0:50:45 GMT
Do you have a Mk11 or Mk111 car. The former had dual valve springs so I would have thought it would be unusual for both to fail as the primary cause. As Chris suggested the most likely cause would seem to be a hydraulic lock caused by the water which seem most likely from head gasket or maybe head failure. Not sure what bottom end, con rod / piston damage you may find. Hope it's not too awful.
regards
David
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Post by Penguin45 on Dec 11, 2016 1:04:23 GMT
Hi Chris thanks for your useful comments I did not think along those lines-I put the problem of bore full of water as to damage done by perhaps the valve stem jammed at full tilt into the head thus causing a crack into the water jacket or even worse damage to the side of the bore!! another idea was that the valve hit the underside of the head so hard that it strained the bolts holding the head down thus causing the head gasket to leak?? I will whip the head of next week and see what I find and will post as to my findings,though at this point in time I still tend to err towards the spring itself-when you think about it-its age-and how many operations it has done in that time!!perhaps among the forum readers there is a metallurgist who could throw some light upon this- perhaps a metal age fatigue problem? Paul. I suppose that it's entirely possible that the valve has dropped and been thrown back into the head itself - it does seem rather unlikely to my mind. Get some pics when you get the head off. Being a forum, a picture can literally say a thousand words. Fingers crossed. P45. |
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Post by snoopy11 on Dec 11, 2016 16:08:35 GMT
Whatever has happened sounds pretty serious. If it was caused by a head gasket I would have thought there would have been other tell tales first like water in oil or vice versa.
If it will only now move quarter turn my guess is that there is something amiss further in.
As penguin has mentioned earlier you need to get the head off and look at the internal damage and put a few pictures on. We may be able to advise better then.
I have only once seen an engine smash up valves and springs and that was in a car that would do a 14 second quarter mile. The 1800 engine seems pretty bullet proof.
Is it possible for the timing to go amiss and the piston collide with an opened valve.
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Post by dave1800 on Dec 12, 2016 1:39:50 GMT
Unless the engine has been seriously modified the piston and valve should not collide even if the timing chain broke. I seem to recall there may have been an issue with collet (in)compatability that could cause the valve to drop but so far I can't find it. Anyone know of this? David Is it possible for the timing to go amiss and the piston collide with an opened valve. |
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Post by dave1800 on Dec 13, 2016 7:13:28 GMT
As far as the valves, springs, collets cups and collars are concerned, all I have been able to find is that there were some valve cups sold by a famous MG parts supplier made of an alloy that were prone to fracture which could allow valve drop. There may well also be an issue if there is a mix and match of collets, valves, cups and collars from later cars (single valve spring) with those of the earlier ones wth double valve spring spec.
Worth inspecting the dropped valve and its components with others on the head.
Good luck!
David
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wolseley1800
Member
Posts: 127
Attribute: The Voice of Doom!
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Post by wolseley1800 on Dec 13, 2016 22:47:07 GMT
If it was an hydraulic lock the damage depends on the engine speed. At high speed the worst is cracked head and/or block, bent conrods, stretched head bolts, etc. - total write off. Probably not valve damage At lower speeds not so bad. A hyd lock will be instantaneous. What you got sounds like a dropped valve that has caused something to penetrate the water jacket, probably the valve stem. As there is still water in the cylinder the piston is in one piece. The 270° turning also point to an obstruction in the cylinder - your valve. Afraid this sounds as it is gonna be expensive - maybe new engine. Wish you all the best luck, Your friendly harbinger of doom.  |
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Post by Penguin45 on Dec 14, 2016 0:13:45 GMT
So, really, we need PaulF to tell and show us a bit more. Head off and pics please, Paul. Don't see how we can proceed without as it's all conjecture so far.
Chris.
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Post by dave1800 on Dec 14, 2016 3:01:21 GMT
Sadly, I have to agree with Wolseley 1800's assessment but as Chris says please do post pictures so you can get advice from the members here and try to establish the cause. This is not a known failing with the B series engines even when they get (very) old.
David
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Post by paulfrance on Dec 14, 2016 13:16:58 GMT
Hello everyone for all comments-have now removed head and found a very bent valve sitting on top of the piston.I still think that this all started with the spring breaking into two parts!there- fore releasing the collets and the valve. So OK we now have the valve falling down into the bore,its fallen enough to be free of its guide-piston brings it back up towards the guide but slightly off centre-valve stem catches edge of its guide and ejects up into the rocker box where I found it-piston now coming up again and valve still sitting on top up into the inlet tract this time again not central and the end of the valve stems crashes right through the top of the inlet tract and into the water jacket-where there is now a very neat but unoriginal hole!Wet stuff now finds access to the inside of the engine,flows into the inlet manifold and fins its way into all cylinders QED ? I have taken photos but as yet not found a way to add them to this (too old to be computer literate) so if they appear all well and good if not can somebody explain how to do it! Looks like I got it right there are a couple more photos but I have reached the limit-one show light scoring of bores to deep to hone out.Will now settle down to remove unit so can strip all down and check rods etc Many thanks to all-look forward to your latest comments Paul.    |
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Post by peppib on Dec 14, 2016 16:16:12 GMT
Sorry to see that damage Paul.
The head looks like a write off to me. As for the block, depends how keen you are to do a rebuild and relining of the cylinders, assuming there is no serious distortion of the crank.
At least usable engines are still available out there.
Tech guys will no doubt be along soon with a more informed opinion.
Good luck
Dave
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Post by Penguin45 on Dec 14, 2016 16:35:43 GMT
Ouch.... Head's definitely finished. If you're lucky you might get away with a hone on the bore, so fingers crossed. The 18V cylinder head from the MGB pops up regularly and is a drop on fit. Twin valve springs when it comes back together...... Popped your pics into my Photobucket account and posted them back up. This is a free forum and we don't have a huge amount of storage space before they start menacing us for money. Chris. |
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Post by snoopy11 on Dec 14, 2016 21:16:01 GMT
I would agree with penguin.
That head looks like it's a new garage door stop.
If if it was me I would be looking for a complete strip and rebuild. The sudden lock up may have done damage further in and there is a possibility of bore damage.
In real terms I suppose how far you go will depend on skills, confidence and finances. A full rebuild can be costly depending on how much engineering you have done and if you fancy tweeking cams / capacity etc.
Most standard parts are available through moss.
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