Richard Farrant Posted August 4, 2011 Share Posted August 4, 2011 I would not take too much notice of a rebuild plate on an engine as old as this, because it is possible that in private ownership, it has been rebuilt again ( seen this many times). Sure fire way is to measure bores and crank on inspection. Just as an aside, I recently stripped an engine, from an ex-Portugese army vehicle dating from WW2, no rebuild plate and two sizes of cylinders, three were +020 and other three were +040 !! Must have had a shortage of pistons. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 4, 2011 Author Share Posted August 4, 2011 (edited) yes NOS I have cleaned tops of pistons no numbers ! I have a set of +20 pistons and they do not fit in the cylinders by miles, so I recon the cylinders are std. < EDITED > But fitting the new std rings gives a gap of under 0.015 it is a tight squeeze to get a 0.015 feeler in the gap this is the same for all cylinders in the working areas, so with a limit of 0.009 to 0.014, I might have to live with it !!!! On the flip side I have measured all the rings which have come out and this is quite a shock, ring end gaps of them are LARGE most over 0.045 ( a BIG gap ) so suspect due to this it was allowing the pistons to float about in the cylinders possibly giving a knocking sound. Edited August 6, 2011 by R Cubed Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 4, 2011 Share Posted August 4, 2011 (edited) That's a very good point Richard. In the case of my GMC I knew it was rebuilt and straight into French storage and then out to preservation and then to me, so I could be confident about the Ergma plate. If it has been bored + 10 thou this would add (10 x 3.142) thou to the circumference, so if ring gap is 30 odd thou greater than you were expecting R3, this would indicate + 10 oversize. 60 thou greater and it is bored + 20 thou. Edited August 4, 2011 by N.O.S. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 4, 2011 Share Posted August 4, 2011 (edited) The new rings we just put in after a very light cylinder hone were 15 gap You can get rings which are not gapped - you have to grind a little of to gap them correctly. This could be a way of taking up any wear, but would not have thought it was worth the trouble. Just out of interest (I'm not qualified to comment further :-D), what is your biggest gap in the working area of the cylinder? Edited August 4, 2011 by N.O.S. Quote Link to comment Share on other sites More sharing options...
marmon Posted August 5, 2011 Share Posted August 5, 2011 Maybe I can help, If the pistons aren't marked they should be standard but it is vital that you measure the cylinder bores, the large ring gap would indicate to me worn bores and your original noise could well have been piston slap, is there a wear ridge (step) on top of the bores? either way this will need to be removed with a ridge cutter before honing or it will more than likely contact the new rings causing a new knock, also you should measure the crank they don't wear evenly and it would be difficult to tell with plastigauge. I think it best to take accurate measurements of everything and compare it to the manufactures specs and wear limits, all should be in the proper workshop manual, it would be very disappointing to reassemble and find it still knocks due to a worn piston or bore. For a quick guide check the ring gap in various places in the bores (push in with piston) including the very top 10mm. But I highly recommend you strip the whole engine take accurate measurements of everything and if any thing is even close to max tolerances you re-bore or regrind as necessary and fit new pistons and bearings, cam & followers, valve guides, oil pump etc,. This may seem a bit much but it is better to do it right once. Also check very carefully the small end clearances, am I right that you have not found a definitive answer for the knock? I don't believe pitted bearings would be the cause they would need to be pretty badly worn. If your not certain I would suggest you keep stripping and checking until you are 100% satisfied you have found the cause. A quick note on noises, although it's hard to tell without hearing it, anything cam or valve gear related will be continuous, the knocking under load you describe must be piston or big end related, if it went with #4 lead off I would lean towards piston, Big ends unless something obvious like bearings spinning in rod or cap coming loose generally all wear pretty evenly, more so furthest from the oil supply. Single knock to me leans towards piston or little end particularly if you didn't find anything out of the ordinary on #4 bearing. Pitting on bearing shells is caused by long periods of standing with used oil in the engine, partly acidic and partly electrolysis. Anyway I hope this is of some help. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 6, 2011 Author Share Posted August 6, 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..... ah ha found the plate has columns numbered 1 to 6 ( left to right ) next row down dia Cylindre all are 96.01 !!!!! row below that is : Coussinets de bielle reading 5872 for all !!!!!! and the last row is : ###ssinets de palier reading 6818, 6897, 6976, 7054, last two columns blank. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 6, 2011 Author Share Posted August 6, 2011 For a quick guide check the ring gap in various places in the bores (push in with piston) including the very top 10mm. But I highly recommend you strip the whole engine take accurate measurements of everything and if any thing is even close to max tolerances you re-bore or regrind as necessary and fit new pistons and bearings, cam & followers, valve guides, oil pump etc,. This may seem a bit much but it is better to do it right once. See edited post No77 on page 8 Also check very carefully the small end clearances, am I right that you have not found a definitive answer for the knock? I don't believe pitted bearings would be the cause they would need to be pretty badly worn. If your not certain I would suggest you keep stripping and checking until you are 100% satisfied you have found the cause. How can you check the small end clearances ? I have washed all oil off all surfaces and I am unable to detect any play by trying to move the conrods in relation to the pistons and gudgeon pins. Apart from the pitted big end shells I have not discovered any major problems apart from the old worn rings ! A quick note on noises, although it's hard to tell without hearing it, anything cam or valve gear related will be continuous, the knocking under load you describe must be piston or big end related, if it went with #4 lead off I would lean towards piston, Big ends unless something obvious like bearings spinning in rod or cap coming loose generally all wear pretty evenly, more so furthest from the oil supply. Single knock to me leans towards piston or little end particularly if you didn't find anything out of the ordinary on #4 bearing. Pitting on bearing shells is caused by long periods of standing with used oil in the engine, partly acidic and partly electrolysis. Anyway I hope this is of some help. I suspect the noise is piston slap due to worn rings with them having an end gap of over 0.045" they must be very worn and with the new rings in the cylinders only having an end gap of just under 0.015" suspect the rings have worn more than the cylinders. You are right nothing obvious that shouts knocking ! Quote Link to comment Share on other sites More sharing options...
marmon Posted August 6, 2011 Share Posted August 6, 2011 Worn rings won't cause a knock, they don't support the piston they float freely in the groves and the piston thrusts to the side of the bore and the ring retracts flush on one side on power and the other on compression, were any rings seized? Little ends should be OK if you have no play, but when hot? It is still best to pull and measure the gudgeon pins and bearings, (elongation) clean the oil hole and good visual for any wear in pistons, I'm not sure what method your particular engine uses some float in the piston others need to be pressed (cool pin or heat piston) and should only move in the little end bearing, other still are clamped into the rod I think you are missing something, is this a knock like one knuckle on a wooden table or all knuckles together loud? If it is heavy knock have a good look at the crank shaft it could be broken, look for a small crack, Is there any sign of scoring on the thrust faces of the pistons, did it get hot? any metal particulars in the oil? when did it start? did you buy it like that? any sign the engine has been apart recently? It really can be a bit of a Sherlock job sometimes try not to miss any clues. Cheap but well up to the job Chinese bore gauges and large micrometers are available and if you don't have already someone on here must have a proper workshop manual, it will have all the dimensions, crank journal minimum and out of round tolerances, bore and piston minimums, max taper etc,. Also maximum overbore and crank grind spec's. Usually there is no advantage to re-sleeving back to standard. My best advice would be to keep looking, striping and measuring until you find something conclusive then decide how far you want to go with the re-build, It depends how much you are going to use it and how close to home, it is a low compression low revving engine and you can get away with a bit of wear here and there but not as much as a lot of people think. However it will take something pretty major before they actually start knocking. Your worn rings might have caused some heavy crankcase breathing or oil consumption but you would see excessive blow-by on the pistons. Good luck and I hope you find something. Quote Link to comment Share on other sites More sharing options...
HWade Posted August 7, 2011 Share Posted August 7, 2011 Hi R.Cubed If you really get stuck I have a good take out engine French rebuild, good oil pressure ect,just transfer all your ancillarys. Howard Quote Link to comment Share on other sites More sharing options...
rosie Posted August 7, 2011 Share Posted August 7, 2011 Hi R.Cubed If you really get stuck I have a good take out engine French rebuild, good oil pressure ect,just transfer all your ancillarys. Howard Cheers Howard I will let him know. He is currently looking over the family car as its due its MOT, there's always something to get in the way hey!!! Quote Link to comment Share on other sites More sharing options...
marmon Posted August 7, 2011 Share Posted August 7, 2011 I'm trying to upload three scans of all the engine specs you need in case you don't have but they are rather small and one seems to be missing... If you don't already have these maybe PM me with an email and I will send them. Quote Link to comment Share on other sites More sharing options...
deadline Posted August 7, 2011 Share Posted August 7, 2011 Its not the rings (oil or compression) simply because 1. you had OK compression and 2. you were not burning oil. So either some of the tests were not done properly, or the gauges were read improperly, or you are not explaining what exactly is going on. My jeep engine makes all sorts or horrible noises... It still does. But compression, pressures, temp and mileage is still good so its just gonna make noise. Quote Link to comment Share on other sites More sharing options...
rosie Posted August 13, 2011 Share Posted August 13, 2011 Just a quick update The cubed one is making good progress. All the rings are now back on the pistons and pistons hopefully will be put back in this afternoon (weather permitting) The cubed one has been off line cos I have decided to move the rooms about here and this has meant he has been evicted from the office!!!!! Quote Link to comment Share on other sites More sharing options...
deadline Posted August 13, 2011 Share Posted August 13, 2011 Have you checked the valve guide wear? I tore into my jeep this weekend and 4 of the 8 valve guides are shot. I could see oil in the intake ports. If you have a dial indicator you can easily check the guide wear... also measure the valve stem wear. I don't think you had a 'knock' (aka detonation) but since all the other diagnostic tests passed look at the valves/guides. They can make very horrible noises (the valve would slap against the side of the seat instead of being guided directly onto them. A quick check would be to see if the valve face is concave or worn unevenly. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 14, 2011 Author Share Posted August 14, 2011 (edited) Hi Deadline thanks for all the input, I have been through all valve train from camshaft to valves, all the cam followers are nice and tight with no dishing on the cam lobe contact surface, they all lift up and down smoothly too, all push rods nice and straight, no play in the rocker arms, all valve guides are in very good condition most of the valves / guides have no or only just detectable lateral play so all is good there. Re seated all valves replaced two exhaust valves due to heads being slightly bent and faces being badly pitted, these were on cylinders No 3 and 4, the middle two and theses were the cylinders with lower compression pressures before the strip down. So just the tappets to sort out once the rocker shaft is back on. Had a good day today head is on and torqued down to correct setting, push rods fitted and block waterways flushed through with clean water. Edited November 23, 2011 by R Cubed Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 14, 2011 Author Share Posted August 14, 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..... aha.......... like this :cool2: Can you translate !! Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 14, 2011 Share Posted August 14, 2011 Your mate Ergma, he say - Cylinder dia. 1 to 6 = 96.01mm (= 3 25/32 = std size) Crank Conn. rod journal dia. 1 to 6 = 58.72mm (= 2.311" = std size) Crank Main bearings 1 to 4 (see manual for engine spec. - all 4 are different from new) Quote Link to comment Share on other sites More sharing options...
deadline Posted August 15, 2011 Share Posted August 15, 2011 Worn guides are about lateral motion, not vertical. New or worn valve guides are going to go in/out just fine. But any play side to side means that the valve is slamming into the seat crooked, not parallel to the face. I just completed my valve work on the jeep (new guides, valves, springs, lap the seats) and I cannot tell its running (I have to check the oil pressure gauge to see if its still running). And before it sounded like I had pebbles in the cylinders. My CCKW motor puts out a blueish smoke screen... so I'll dive into the valves on that first (compression was good over 100PSI on all tubes). Its not a noisy motor at all... just burns oil. Please post if you find the root cause of your noise. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted August 21, 2011 Author Share Posted August 21, 2011 Well here is an update to the on going engine rebuild. So I have got it all back together but wanted to build oil pressure before starting the engine so came up with this sneaky tool... Got some steel bar about foot long and 10mm in dia, on one end ground 2 flats opposite each other, like a screwdriver put this bar in a drill and the tip then fits in place of the distributor and engages with the oil pump drive, so turn drill this spins the oil pump and hey presto you get oil pressure without running the engine, he he he Will be carrying out road tests over the next few days. Quote Link to comment Share on other sites More sharing options...
HWade Posted August 22, 2011 Share Posted August 22, 2011 Hi R.Cubed Good to here you have the engine all back together,I hope all goes well with the road tests, let us know how you get on. Howard Quote Link to comment Share on other sites More sharing options...
deadline Posted August 23, 2011 Share Posted August 23, 2011 So what work was done? I read a lot.. but can't recall what work was accomplished? Did you just change rings and hone the cylinders? Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted September 10, 2011 Share Posted September 10, 2011 How did it go R3? Have you managed to cure the knock? No oil leaks from the sump? Quote Link to comment Share on other sites More sharing options...
rosie Posted September 10, 2011 Share Posted September 10, 2011 Hiya NOS , We took the truck over to IOW and sadley she still knocks! Not only that we have developed a squeak to!!!! The cubed one I think is going for a completestrip down (of the truck not himself!!!!!!!) during the cold wet months! Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted September 10, 2011 Share Posted September 10, 2011 Oh no, how annoying. If only the squeak had been loud enough to hide the knocking :cool2: These things can be so frustrating to resolve. I ended up with a few different noises (the run to Hardwick was the first proper 'test run') - all totally unconnected with the work we'd done, must be the truck's way of talking to us :-D. Quote Link to comment Share on other sites More sharing options...
HWade Posted September 10, 2011 Share Posted September 10, 2011 Hello Rosie Thats bad luck on the truck and now a squeak, well thats your winter project sorted out then,all the best and I hope it all goes well. Howard Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.