mackei23b
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| posted on 12/2/15 at 07:18 PM |
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Bent Conrod?? Now with concluding pics
OK so this may not be the best day in the garage.....I dropped the head off to be skimmed after doing some porting to match to the inlet and exhaust
manifolds... I went to clean up the top of the block in anticipation of putting the engine back together tomorrow afternoon.
When cleaning I noticed that the No4 piston was circa 1.5mm from reaching the top of the bore, while all the others reached the top of the bore, and
when measured again, No4 piston also was about 1.5mm lower at the bottom end of the stroke... So I'll now be stripping the bottom end tomorrow,
but my initial conclusion is the conrod in No4 is about 1.5mm shorter than the rest....and therefore bent....
So over to the power of the Locostbuilders wisdom....what are your thoughts....and if the conrod is bent does anyone have some standard 2l Duratec
conrods left over after an upgrade? Here is a pic and you can just make out the difference in the crown heights for pistons No1 and No4, No4 sitting
lower.
 
Duratec
Cheers
Ian
[Edited on 13/2/15 by mackei23b]
[Edited on 13/2/15 by mackei23b]
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coozer
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| posted on 12/2/15 at 07:24 PM |
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Does look like a rod issue unless the crank journal and bottom end of the rod are smaller than the others... (Unlikely)
Should be able to tell by dropping the sump and seeing bif you can tell from there.
1972 V8 Jago
1980 Z750
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MikeRJ
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| posted on 12/2/15 at 07:44 PM |
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Could also be caused by a very knackered big end bearing I suppose, but the piston wouldn't go down further than the rest unless you pushed it.
More likely it's sucked up water some time in it's life.
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owelly
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| posted on 12/2/15 at 07:58 PM |
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What's the history of the engine? Could it be a rogue rod or piston? Perhaps assembled with the wrong bits?
http://www.ppcmag.co.uk
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mackei23b
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| posted on 12/2/15 at 08:46 PM |
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I can't remember the exact history, but I think it had about 30K mileage before it was parked at speed into a hedge!
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mackei23b
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| posted on 12/2/15 at 09:55 PM |
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I've done some more investigation and it's looking toward a big end as there is a dead spot in the piston travel around TDC and I can get
a clonk form the crank around this spot, tomorrow will tell when I take it out!
Thanks for all the suggestions.
Ian
[Edited on 12/2/15 by mackei23b]
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perksy
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| posted on 12/2/15 at 10:06 PM |
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Heard of an XE engine once that had been reground on two crank journals only and had resized shells fitted 
Think I'd take all the big end caps off and give it all a good check, You only want to be doing it the once...
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MikeRJ
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| posted on 13/2/15 at 08:07 AM |
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quote:
Originally posted by perksy
Heard of an XE engine once that had been reground on two crank journals only and had resized shells fitted
Having the crank reground doesn't change anything unless it's been offset ground to increase or reduce the stroke.
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perksy
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| posted on 13/2/15 at 08:17 AM |
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Problem was not only had it been reground incorrectly the new shells
We're also the wrong size.
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Jenko
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| posted on 13/2/15 at 08:57 AM |
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Could it just be that someone has installed the incorrect piston or con rod....May be out of an 1800.
MY BLOG - http://westfieldv8.blogspot.co.uk/
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mackei23b
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| posted on 13/2/15 at 01:14 PM |
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Here is what I found today.......
 
Shells
The above shows what a state the shell was in on No4, the good shell is pulled from No3 as a comparison. When I first took the cap of I had to look
twice to see the shell as it looked like it had disappeared!!
 
Bearing cap
The end cap looks OK and I couldn't see any sign of blueing / overheating......and now onto the crank......
 
Big end
While it is marked the journal I think is OK and it is still smooth. My real concern with the crank is that the shells have been squeezed between the
side of the bearing cap and the side of crank and there is more axial play on the rod, I've just measured with a feeler gauge, the tollerance is
0.36mm according to the build manual and I'm getting just under 0.5mm so it's looking like the crank is scrap!
Just deciding on the best options and way forward.... rather gutted!
Cheers Ian
P.S. I did borrow the shells from No3 and put them into No4, No4 with good bearings now reaches the top of the cylinder head with no flatspot....
I've not checked the rod, but I'm pretty sure it was all due to the bearing!
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mark chandler
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| posted on 13/2/15 at 02:01 PM |
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Time for a re grind then or another engine, hope it did not cost you much.
At least you know now, not post gaskets, rebuild and install to find its knackered.
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Nickp
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| posted on 13/2/15 at 06:04 PM |
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Wasn't it knocking??
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mackei23b
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| posted on 13/2/15 at 06:25 PM |
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Never got to the point of fitting it, this was the final prep before installing 
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Nickp
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| posted on 13/2/15 at 06:34 PM |
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quote:
Originally posted by mackei23b
Never got to the point of fitting it, this was the final prep before installing
Ahhh I see, it would've knocked like an old diesel I reckon I wonder if it was starved of oil in the crash? Maybe left running / revving at a
jaunty angle ie upside down?
[Edited on 13/2/15 by Nickp]
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mackei23b
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| posted on 13/2/15 at 09:22 PM |
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Yes, I managed to get quite a knock turning it over by hand, when the fault was narrowed down.....the shell has taken one hell of a hammering,
it's not blue and there was still oil in it when I took it apart, so my current conclusion that it was driven for while by some mechanically
unsympathetic moron!
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atm92484
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| posted on 14/2/15 at 02:45 AM |
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Did you buy the engine from a business? If so, any chance there is a warranty?
-Andrew
Build Log
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mackei23b
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| posted on 14/2/15 at 07:15 PM |
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It was a private sale and it's been sitting in my garage for a year...and to be fair to the seller he had not run the engine either so he had
bought and sold the engine in good faith that all was OK. He was going to use the engine, but a change in plan meant that he sold the engine...
I've now pulled the rod and piston out and it looks OK and I think I've sources a replacement crank so moving forwards again....
Cheers
Ian
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