Sudden big end noise?
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types26/36 wrote:Mr.Gale wrote:Drop a valve? Mr.GNIGELAN wrote: Pulled each plug lead in turn, no change in noise.and same drop in revs so assume that all cylinders are firing .
Unlikely to be a dropped valve if all cylinders are firing equally.
Yes, you are right. I wrote my comment before I realized there was a second page.
I dropped a valve in my Lotus Cortina once and what happen is the piston came up and bent the valve and pushed it up in the combustion chamber. The other bad new is it was a intake valve so it was firing out the carburetor and started a fire in the air box. The good news is it only put a mark on the piston and combustion chamber.
Mr.G
- Mr.Gale
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I have the SE fabricated headers and back in the 70s when I drove my Elan everyday in the summer, I came home from the office one day sure I had a failed big end from the noise it made. A little investigative work that evening had eliminated the noise by tightening the header bolts.
Turns out that there was enough flex in the headers that when #4 loosened slightly, it would blow the header off the head slightly and then slam it back to the head when the pressure was released. This was a single cylinder sound that was very scary.
Roger
Turns out that there was enough flex in the headers that when #4 loosened slightly, it would blow the header off the head slightly and then slam it back to the head when the pressure was released. This was a single cylinder sound that was very scary.
Roger
'67 Elan S3 SS DHC
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
- Elan45
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Embarrassed and need to apologise for leading you all astray.
I was certain it was firing on all four, but it wasn't!
No compression on no.1, spark plug has no gap, boroscope shows damage and possible chunk of metal in cylinder.
Did not look any further, depressed and also got flu now.
Will report back when engine stripped and taken to expert to determine what may be salvaged.
Thank you all, sorry to have misled.
I was certain it was firing on all four, but it wasn't!
No compression on no.1, spark plug has no gap, boroscope shows damage and possible chunk of metal in cylinder.
Did not look any further, depressed and also got flu now.
Will report back when engine stripped and taken to expert to determine what may be salvaged.
Thank you all, sorry to have misled.
Elan S4 DHC 1970
Elan +2S 130/5 1973
Excel SA 1987
Elan +2S 130/5 1973
Excel SA 1987
- NIGELAN
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Thats bad luck but it may not be terminal, check the valve clearances on that cylinder, you may have a collet adrift.
Fingers crossed!
Its random unstressed failures like this (might be) that put a whole new perspective on the discussion about using a Zetec engine.
Fingers crossed!
Its random unstressed failures like this (might be) that put a whole new perspective on the discussion about using a Zetec engine.
- Chancer
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Thanks Chancer, I spent time and money removing a zetec and replacing it with the original TC in my S4 (which is now a brilliant drve). It would be sad to have to put a zetec into the +2!
I will not give in without a fight. If nothing else it is all a learning experience
I will not give in without a fight. If nothing else it is all a learning experience
Elan S4 DHC 1970
Elan +2S 130/5 1973
Excel SA 1987
Elan +2S 130/5 1973
Excel SA 1987
- NIGELAN
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NIGELAN wrote:No compression on no.1, spark plug has no gap, boroscope shows damage and possible chunk of metal in cylinder.
sorry to read that... You may want to fiddle and look into that cylinder a bit more to check what kind of lose piece would be there (moving around a piece of copper wire to see what moves...)
Then if not in a rush and depending on engine condition before the problem, you may opt to remove the head first, in case it is a broken valve (I'm assuming there is no way something could have been swallowed by the carb...) then decide from what you uncover.
Good luck !
S4SE 36/8198
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nmauduit - Coveted Fifth Gear
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Having just looked at Miles Wilkins book page 102, he has a picture of part of a valve seat sitting in the cylinder. My piece of metal looks to be identical!
Miles captions this picture as .........."valve seat fell out making this cylinder head scrap".......
Mind you, what does he know about Lotus TCs.......
Miles captions this picture as .........."valve seat fell out making this cylinder head scrap".......
Mind you, what does he know about Lotus TCs.......
Elan S4 DHC 1970
Elan +2S 130/5 1973
Excel SA 1987
Elan +2S 130/5 1973
Excel SA 1987
- NIGELAN
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NIGELAN wrote:Having just looked at Miles Wilkins book page 102, he has a picture of part of a valve seat sitting in the cylinder. My piece of metal looks to be identical!
Miles captions this picture as .........."valve seat fell out making this cylinder head scrap".......
nowadays TIG welding to fill up a combustion chamber damage offers more options than back in the days... a careful assessment of the damage (and of the probable cause: if fallen seat was because of inadequate tolerance during a previous rebuild, you may want to change all seats... ) will lead you to a repair cost estimate as a basis for decision.
S4SE 36/8198
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nmauduit - Coveted Fifth Gear
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A failed crank isn't going to maintain oil pressure. Even a spun bearing won't maintain oil pressure. If you have oil pressure, unless it's a flywheel bolt failure it's unlikely to be a crank problem.
Crank failures rap twice as fast as top-end or jackshaft failures. Even at idle it's a pretty fast rap. rap-rap-rap-rap-rap instead of rap -- rap -- rap.
Very unlikely a big-end failure lets the engine run at idle, particularly if it's sudden. Too much friction. Failed bearings are the exception, but they come on slowly and always show low oil pressure.
With the cost of a Weber head, not sure which I'd rather have.
Are all of your airbox and carb-related bolts accounted for? Swallowing one of those can be the worst of both worlds. And makes a crank-speed noise if it gets past the valve.
Crank failures rap twice as fast as top-end or jackshaft failures. Even at idle it's a pretty fast rap. rap-rap-rap-rap-rap instead of rap -- rap -- rap.
Very unlikely a big-end failure lets the engine run at idle, particularly if it's sudden. Too much friction. Failed bearings are the exception, but they come on slowly and always show low oil pressure.
With the cost of a Weber head, not sure which I'd rather have.
Are all of your airbox and carb-related bolts accounted for? Swallowing one of those can be the worst of both worlds. And makes a crank-speed noise if it gets past the valve.
- denicholls2
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If the problem is a Valve Seat i would only change the problem Seat. If the other Seats haven't moved leave them alone.
I hope the damage is not too bad.
Alan
I hope the damage is not too bad.
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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This afternoon I removed the head.
Top of no.1 piston now pebbledashed with a couple of deeper gouges
Head combustion chamber now missing an exhaust seat and is extensively pebbledashed as well.
Bore has lost its honing marks when compared to the other cylinders but no scoring or gouge marks.
Have not checked big end yet for damage.
Will post some photos when I learn how.
Nothing more depressing than seeing an engine in bits
Top of no.1 piston now pebbledashed with a couple of deeper gouges
Head combustion chamber now missing an exhaust seat and is extensively pebbledashed as well.
Bore has lost its honing marks when compared to the other cylinders but no scoring or gouge marks.
Have not checked big end yet for damage.
Will post some photos when I learn how.
Nothing more depressing than seeing an engine in bits
Elan S4 DHC 1970
Elan +2S 130/5 1973
Excel SA 1987
Elan +2S 130/5 1973
Excel SA 1987
- NIGELAN
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- Joined: 02 Aug 2012
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