Ian Mackenzie Posted February 12, 2015 Share Posted February 12, 2015 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 togther 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 Blatchat 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 hights for pistons No1 and No4, No4 sitting lower.CheersIan Link to comment Share on other sites More sharing options...
elie boone Posted February 12, 2015 Share Posted February 12, 2015 Shorter conrod ? 1.5 mm is quite a big bent Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted February 12, 2015 Author Share Posted February 12, 2015 I've just done a quick measurment with a dial gauge and I'm getting a difference of 1.4mm between 1 and 4!! Link to comment Share on other sites More sharing options...
Hanns Per Posted February 12, 2015 Share Posted February 12, 2015 If its really bent I would assume that the conrod bearings are are also gone. If the piston does not reach the top at all then the conrod might be shorter? Otherwise the crank might be offset, I mean 1 and 4 not in the same position. Or the piston is shorter? Link to comment Share on other sites More sharing options...
ECR Posted February 12, 2015 Share Posted February 12, 2015 I'd vote for the piston as the culprit ... Link to comment Share on other sites More sharing options...
OliverSedlacek Posted February 12, 2015 Share Posted February 12, 2015 I doubt the conrod is that bent! If it's a production crank, the throws will also match so my money is on an odd conrod or an odd piston. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted February 12, 2015 Share Posted February 12, 2015 A rod would usually bend in a side load which would cockle the piston to one side, odd length rod is a very long shot as is and odd crank stroke.I'd go for a big end bearing shell, every wet sumped engine I've taken down has at least kissed a shell or two. If you do need a piston or rod I've a couple of set you can have for free, or you could always go for an upgrade to steel. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted February 12, 2015 Share Posted February 12, 2015 If it's a shell gone you will feel a dead spot / soft clonk where theres no piston movement on No4 around BDC when rocking the crank back and forth whilst No1 is stll moving Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted February 12, 2015 Author Share Posted February 12, 2015 Thanks for all the posts.....looks like 7 Wonders is on the ball.I've just checked again in the garage and the pistons are all in a perfect line and I agree it would be unlikely for a rod to bend and not rotate a piston.And.......yes there is a dead spot on 4 while 1 is still moving.....and I can get a clonk......I'll update you tomorrow with some pictures, just a little concerned on the condition of the crank.CheersIan Link to comment Share on other sites More sharing options...
7 wonders of the world Posted February 12, 2015 Share Posted February 12, 2015 Cranks are very good, yet to have to grind one when the shells have gone, have had to replace the odd rod though due to localised overheating, Link to comment Share on other sites More sharing options...
Bricol Posted February 13, 2015 Share Posted February 13, 2015 I have bent a con-rod which dropped the piston by more than 1.5mm, so don't rule it out. Tried to start a Lancia engine the day after the head gasket failed - which proved oil and water don't compress much. It have a very noticeable bend in it - I think it's still hanging up in my mum's garage. Bri Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 13, 2015 Share Posted February 13, 2015 if it turns out to be the bearing shell, check the rod and cap very carefully for blueing due to overheating. If you have any doubts at all, change it or it will let you down in a big way by waving to you through a hole in the block! Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted February 13, 2015 Author Share Posted February 13, 2015 Here is what I've found.......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!!The end cap looks OK and I couldn't see any sign of blueing / overheating......and now onto the crank......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 (side to side) 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....CheersIanP.S. I did borrow the shells from No3 and put them into No4, No4 whith good bearings now reaches the top of the cylinder head with no flatspot.... Link to comment Share on other sites More sharing options...
Pendennis Posted February 13, 2015 Share Posted February 13, 2015 Yep crank looks scrap. However you could get it reground and fit oversize shells but it's probably more economical to get another crank and use standard new shells.Swindon were selling brand new unused standard cranks early last year, give them a ring you may get a pleasant surprise!Did you not notice any unusual engine noise or experience abnormal oil pressure? Link to comment Share on other sites More sharing options...
Ian Mackenzie Posted February 13, 2015 Author Share Posted February 13, 2015 Hi thereI've not had the engine running in the car, it's been in the my garage the last year waiting to go in the 7 to replace the K-series and this was part of the final refresh before going in the 7. I will give Swindon a call!CheersIan Link to comment Share on other sites More sharing options...
Pendennis Posted February 13, 2015 Share Posted February 13, 2015 Oh blimey, thats bad luck Link to comment Share on other sites More sharing options...
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