R Cubed Posted July 7, 2011 Author Share Posted July 7, 2011 I did think this as all other pistons have tight gudgeon pins and the little ends on the conrods are nice and free. the one which has a loose pin the little end is a bit tight. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 10, 2011 Author Share Posted July 10, 2011 Been at it as much as I can trying to get the engine striped down so I can decide what needs to be replaced. Well all the cylinders are nice and clean but also very shiny !! the pistons are in good shape not tapered towards the skirt and no picking up on the sides, the only down side is two of the pistons, 4 and 5 have slightly loose gudgeon pins however a local American engine builder says this is not an issue as they all float when the engine is hot! Big end shells are all pretty much shot to bits though, some material missing and heavy wear this is the result of excess wear and then the shells hitting the big end bearing surfaces on the crank. Had head apart today, Oh forgot to say when checking the engine before strip down I did check the valve clearances after the engine had had a run and all were the correct gap, all valves are out and looks like the head has had hardened valve seats fitted as there are inserts in there, not just cut into the head.These are all fine and in very good condition no erosion to them at all. Going back to the compression tests I noted 3 and 4 were lower than the others this is due to both the exhaust valves having erosion on the seat faces so allowing blow by, strange that it is only these two valves which have a problem. These will be re cut then lapped in. All the others valves are cleaned and lapped in a treat, ready to refit. Quote Link to comment Share on other sites More sharing options...
rbrtcrowther Posted July 11, 2011 Share Posted July 11, 2011 Small cracks and craters in the white metal bearings are normaly caused by overloading and the oil film being squeezed out alowing contact between the surfaces. Overloading is is caused by "lugging" the engine at low revs in a high gear. When i stripped my meadows down there were signs of this damage on the big ends. Never try to hold a gear cos your nearly over the hill your always better to rev hard in a lower gear. With Mine being a big square stroke diesel i would rather sit on the govener in 5th for two mins than lug it in top. Got to watch it with a petrol engine cos you dont have a govener but the drivers handbook should tell you the safe maximum engine speed. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted July 11, 2011 Share Posted July 11, 2011 Small cracks and craters in the white metal bearings are normaly caused by overloading and the oil film being squeezed out alowing contact between the surfaces. . The fact that ignition was well advanced would not have helped either. Quote Link to comment Share on other sites More sharing options...
rbrtcrowther Posted July 11, 2011 Share Posted July 11, 2011 Are your shells as bad as my main bearings. And you know what.......there was not a single rumble or knock just very low oil pressure Never thought about the advanced timing but your right it won't help at all....Unless it was going to run about 10,000 rpm then it might help.... Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 12, 2011 Author Share Posted July 12, 2011 (edited) yes, we have been chatting about the ignition timing, l have no idea why the ignition timing was that advanced, I can't remember the last time I checked it, ( note to check regularly in case of slippage ) I should have set it right when I fitted the new dizzy, presume as it was so far advanced the fuel air mix was igniting as the piston was still coming up to T.D.C. on the compression stroke! so trying to push the piston back down the cylinder. Edited July 30, 2011 by R Cubed wrong words used in wrong places !!!! Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted July 12, 2011 Share Posted July 12, 2011 yes, we have been chatting about the ignition timing, l have no idea why the ignition timing was that advanced, I can't remember the last time I checked it. presume as it was so far advanced the fuel air mix was igniting as the cylinder was still coming up to the T.D.C. so trying to push the cylinder back down. You get a pronounced "knock" with ignition too far advanced, and it will not do the bearings a lot of good either. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 29, 2011 Author Share Posted July 29, 2011 Are your shells as bad as my main bearings. And you know what.......there was not a single rumble or knock just very low oil pressure[ATTACH=CONFIG]47931[/ATTACH] Never thought about the advanced timing but your right it won't help at all....Unless it was going to run about 10,000 rpm then it might help.... No not that bad will get some pics of the big end shells when I get a chance, this weekend will be a fit new parts and re assembly session hopefully if all goes well. Quote Link to comment Share on other sites More sharing options...
deadline Posted July 30, 2011 Share Posted July 30, 2011 A quick plastigauge of the main bearing would tell you all you needed. They may look horrible, but its all about the clearance for oil. If you didn't note low oil pressure, then they would work fine as long as they gauged .003 or less. My jeep main bearings looked new, except that I couldn't muster more than 30 psi on the oil gauge at speed and they gauged at .005. New main bearings and I hold 50psi, 10 at idle. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted July 30, 2011 Author Share Posted July 30, 2011 Before I assemble the big ends I will give them a measure with some plastigauge to check clearances, on the subject of oil pressure what are other CCKW users getting on their gauges on the dash ( I am aware these will vary due to age and quality just to get some idea ) before I stripped down my engine I got 45psi cold at any rpm and once hot it only dropped a little at idle to 40psi. Quote Link to comment Share on other sites More sharing options...
deadline Posted July 30, 2011 Share Posted July 30, 2011 If you have the crank out it might be a good idea to take it to a machine shop to have it mic'd and polished. My jeep crank only needed a polish but they told me the correct size of bearings to get. I really didn't want to rely on the painted on number on the crank. Cost about $60 US last year. The painted number was right, but the bearing shells were not marked, well, other than the script 'F' on each one. When you put the connecting rods back in, measure the side clearance. Your noise could be from a sloppy lateral fit. Quote Link to comment Share on other sites More sharing options...
David Robertson Posted August 1, 2011 Share Posted August 1, 2011 Before I assemble the big ends I will give them a measure with some plastigauge to check clearances, on the subject of oil pressure what are other CCKW users getting on their gauges on the dash ( I am aware these will vary due to age and quality just to get some idea ) before I stripped down my engine I got 45psi cold at any rpm and once hot it only dropped a little at idle to 40psi. Starting from cold i get 50 psi at idle but when hot only 30 psi. As the rev's rise the psi goes back to 45/50. Hope this helps, good luck with the rebuild, regards David. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 1, 2011 Author Share Posted August 1, 2011 Thanks for the oil pressure readings, will have to see what I get once the engine is done. Got the new bits what I could do with knowing is the piston ring end gap tolerances for the new rings in the cylinders I know it cant be less than 0.003" I think its between 0.009" and 0.014" can any one confirm ? Also edge ring clearance in piston groves ? Thanks Quote Link to comment Share on other sites More sharing options...
Chrisg Posted August 1, 2011 Share Posted August 1, 2011 Compression ring gaps I think is .003 per inch of bore and land clearance .0015 memorys not that good these days Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 1, 2011 Author Share Posted August 1, 2011 (edited) Got some pics of the strip down. Here is a pic of the combustion chambers and valves, the bigger of the two are the inlets ! all 6 much the same as this. Top of piston No1 just after removing head. Top of piston No6 just after removing head. mmmm nice box of rings :laugh: The individual packets for the rings. Edited August 1, 2011 by R Cubed Quote Link to comment Share on other sites More sharing options...
Chrisg Posted August 1, 2011 Share Posted August 1, 2011 If you want to borrow it I have a piston ring fitting tool Quote Link to comment Share on other sites More sharing options...
Big ray Posted August 1, 2011 Share Posted August 1, 2011 Small cracks and craters in the white metal bearings are normaly caused by overloading and the oil film being squeezed out alowing contact between the surfaces. Overloading is is caused by "lugging" the engine at low revs in a high gear. When i stripped my meadows down there were signs of this damage on the big ends. Never try to hold a gear cos your nearly over the hill your always better to rev hard in a lower gear. With Mine being a big square stroke diesel i would rather sit on the govener in 5th for two mins than lug it in top. Got to watch it with a petrol engine cos you dont have a govener but the drivers handbook should tell you the safe maximum engine speed. I started driving trucks (on the road) in 1954, most of the trucks in those days were fitted with petrol engines, we had a technique when lugging up hills, as the engine revs began to die we eased back on the throttle, this reduced the ammount of air/fuel mixture going in, and didnt choke the engine, it also had the effect of reducing the "overloading" of the engine and she would keep pulling without undue stresses on the motor...... not to mention better fuel ecconomy. This technique would only be applied on reasonable gradients, anything particularly step was a different matter. We got very good with practice. Quote Link to comment Share on other sites More sharing options...
deadline Posted August 2, 2011 Share Posted August 2, 2011 Your best source of specs is the older TM10 series. They actually had rebuild information as they were before the shift to the echelon system of maintenance that was introduced mid-war (43 or so). From the TM-10-1563 Jan 43 Compression ring: Gap .008 - .015 Ring and groove clearance .0015 - .0025 Oil ring: Gap .008 - .015 Ring and Groove clearance .002 - .0025 As for oil pressure the book number is 35-40 PSI at 1000RPM So about 50-60 at 2000 20-30 at idle. Higher if oil is cold. But should not be significantly lower. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 3, 2011 Author Share Posted August 3, 2011 If you want to borrow it I have a piston ring fitting tool Got one too, thanks for the thought though... Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 3, 2011 Author Share Posted August 3, 2011 Got some Plastigauge from the manufacturers today to check the big end clearances, fitted new shells cleaned all oil off surfaces torqued up big end bolts to spec and striped down, checked spread of Plastigauge and found all 6 bearings giving a reading of very close to 0.003" so all looks to be spot on. Have checked the mains too, all smooth no damaged or scoring. Used some micrometer blue on the valve seats to find out if they all had a gas tight seals, three valves needed some more lapping in but once this was done and re blued all is good so have now started fitting the valves back in the head. Quote Link to comment Share on other sites More sharing options...
rosie Posted August 3, 2011 Share Posted August 3, 2011 can anyone tell me the std size for cylinder diameter as might have an issue with new ring end to end gap being too big :-( Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted August 3, 2011 Share Posted August 3, 2011 . [ATTACH=CONFIG]49202[/ATTACH] Your Standard bore size is on the ring packet, it says STD on the box. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 3, 2011 Share Posted August 3, 2011 Oooh. It has not gone unnoticed that the R3 has got himself a set of standard rings. But is there a plate on the engine (maybe left hand side of block towards rear end?) which gives actual cylinder sizes? Might be in metric so you will need to convert. In all probability you have an engine that's been bored out - the plate should show by how much. I blame that ERGMA bloke..... Quote Link to comment Share on other sites More sharing options...
deadline Posted August 4, 2011 Share Posted August 4, 2011 Sleeve the cylinders back to standard is an option. In the US that about $30-80 per hole... including the sleeve. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 4, 2011 Share Posted August 4, 2011 (edited) So you did clean the piston tops and check piston size stamped on top face - didn't you? It would still be worth checking for rebuid plate just in case someone usd std pistons in a bored out block (you'd probably get away with +10 ). Just out of interest and to show what you can get away with: We had a 200hp engine rebuild by a John Deere main dealer. They had ground crank - 40, but put -20 shells in! It was worked very hard but sounded beautifully quiet until after 4 months a con rod cap bolt snapped and we discovered the error on strip down to investigate knocking. Not a mark on crank! set of correct shells and was fine. Edited August 4, 2011 by N.O.S. Quote Link to comment Share on other sites More sharing options...
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