Graham Baggaley Posted January 28 Author Report Share Posted January 28 On 1/25/2024 at 12:26 PM, stuart said: But do you have a block breather pipe? item 39 here https://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/engine/engines-components/external-engine-tr2-4a-1953-67.html That should vent the engine sufficiently though if you have an external oil feed up to the rockers then you may have too much oil getting up round the top of the engine anyway. Stuart. Stuart. I don’t have an external oil feed. But do have the original vent pipe in the block. Quote Link to post Share on other sites
Graham Baggaley Posted January 28 Author Report Share Posted January 28 Strange question but related to the engine rebuild. I noticed today that the old pistons from the car have a different design. I actually use the old pistons as desk raisers! The attached pictures show the old pistons which have cut outs in them which I can only imagine is to get more oil onto the liners? Plus slightly less moving weight. any of you guys with the knowledge able to add to this or give me any insight? Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 28 Report Share Posted January 28 First type is original style 4 ring piston as used by the factory. These are not what is described at an high performance type. Second view of 4 pistons look like aftermarket type with a 3 piece oil control ring. There looks what seems to be polishing on the piston surfaces on the gudgeon pin area, so not piston slap. Is the crank end float within limits? Otherwise they look like pistons that have done a few miles. Quote Link to post Share on other sites
Graham Baggaley Posted January 28 Author Report Share Posted January 28 6 hours ago, BlueTR3A-5EKT said: First type is original style 4 ring piston as used by the factory. These are not what is described at an high performance type. Second view of 4 pistons look like aftermarket type with a 3 piece oil control ring. There looks what seems to be polishing on the piston surfaces on the gudgeon pin area, so not piston slap. Is the crank end float within limits? Otherwise they look like pistons that have done a few miles. Great info and great eye. The pistons in the box had only done 1500miles. The wear is all related to the big end bearings dissolving I believe. Quote Link to post Share on other sites
iain Posted January 28 Report Share Posted January 28 I’m with Peter, the thrust on the crank must be suspect to have that wear on the pistons……… thrust washers in the wrong way round? Wouldn’t be the first time… Quote Link to post Share on other sites
Trumpy3 Posted January 28 Report Share Posted January 28 I may well be wrong but those pistons look to me like the wear is on the thrust/anti thrust side. The 'polishing' is the actual original machined surface. Hard to see well in the photos. Need a close up. If it is on the thrust side then it is an unusual pattern, especially after only 1500mls. I assume they were new when fitted. If all bearings are good except for failed rod bearing it is unlikely to be a thrust bearing issue. Not impossible, just unlikely. I've not seen any data here that would give the cause of the failure or the reported loss of oil pressure. If the cause Brian Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 29 Report Share Posted January 29 (edited) 19 hours ago, Trumpy3 said: I may well be wrong but those pistons look to me like the wear is on the thrust/anti thrust side. The 'polishing' is the actual original machined surface. Hard to see well in the photos. Need a close up. If it is on the thrust side then it is an unusual pattern, especially after only 1500mls. I assume they were new when fitted. If all bearings are good except for failed rod bearing it is unlikely to be a thrust bearing issue. Not impossible, just unlikely. I've not seen any data here that would give the cause of the failure or the reported loss of oil pressure. If the cause Brian Yes I have now viewed this photo on a bigger screen and the scuffing and score marks on the thrust anti thrust sides is evident. This is what an 87 mm PowerMax piston looks like after it part seized at 4500 rpm in overdrive top on the Witney bypass heading to the IWE some years ago. I drove it home 100 miles low on power. The left hand one is a new unused one. The slight scratching on the RH one that seized can be seen if you look closely. My MG owning friend said new set of rings and give it a going over with the wire brush then put it back. The liner was another issue….. Edited January 29 by BlueTR3A-5EKT Quote Link to post Share on other sites
iain Posted January 29 Report Share Posted January 29 Peter did you really re use that? :-) Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 30 Report Share Posted January 30 (edited) On 1/29/2024 at 6:22 PM, iain said: Peter did you really re use that? :-) NO, that is why it sits on the shelf in the garage as a reminder with its matching liner. Edited January 30 by BlueTR3A-5EKT Quote Link to post Share on other sites
Graham Baggaley Posted February 1 Author Report Share Posted February 1 I was also surprised when I removed the gudgeon pins that two of them had noticeable deep grooves. From a 1500mile engine with new bits this really was surprising. The crank and conrods are now at the machine shop for cleaning, checking and polishing Quote Link to post Share on other sites
Trumpy3 Posted February 1 Report Share Posted February 1 Certainly starting to look like a lubrication issue. Take a good close look at the filter head, all removed gaskets, particularly the filter head and oil pump/drive. Also all oil passages and cam bearings. You would be looking for incorrect fit or clearance, breakage or cracks, blockage, etc. It would be best to do all this prior to having the parts machined/repaired as that could destroy any evidence. I say this as a reminder as it is easy to 'get on with it' and loose the evidence. You may fix the problem but never know why. I don't know about you but that really annoys me. I'm not trying to tell you how to suck eggs, its just my background is aircraft and knowing the cause of failure is critical before repair. Quote Link to post Share on other sites
Graham Baggaley Posted February 2 Author Report Share Posted February 2 10 hours ago, Trumpy3 said: Certainly starting to look like a lubrication issue. Take a good close look at the filter head, all removed gaskets, particularly the filter head and oil pump/drive. Also all oil passages and cam bearings. You would be looking for incorrect fit or clearance, breakage or cracks, blockage, etc. It would be best to do all this prior to having the parts machined/repaired as that could destroy any evidence. I say this as a reminder as it is easy to 'get on with it' and loose the evidence. You may fix the problem but never know why. I don't know about you but that really annoys me. I'm not trying to tell you how to suck eggs, its just my background is aircraft and knowing the cause of failure is critical before repair. The cause is driving me mad! thanks for the talk. I appreciate everyone’s time on here. Quote Link to post Share on other sites
Trumpy3 Posted February 5 Report Share Posted February 5 Graham How you going with that engine? Brian Quote Link to post Share on other sites
Graham Baggaley Posted February 20 Author Report Share Posted February 20 On 2/5/2024 at 11:09 PM, Trumpy3 said: Graham How you going with that engine? Brian Well Brian; the engine is all apart. The liners had +0.020 on them and there tapering on sleeve 2. this would probably account for the crankcase pressure. the oil gallery plugs have been pulled. The block has been totally cleaned out and new plugs put back in. The block was also crack tested. I will start the rebuild soon but just licking my wounds from the costs at the moment! Quote Link to post Share on other sites
iain Posted February 20 Report Share Posted February 20 Did you get the Crank plugs removed for cleaning of the oil ways?………given the considerable damage in the engine I think it’s a false economy not too. Iain Quote Link to post Share on other sites
Trumpy3 Posted February 21 Report Share Posted February 21 I'm a fan of removing the crank gallery plugs. The one concerned with no1 rod should be checked at least. As there was no damage to the main bearings there is a good chance that the crank galleries are clean. Your decision. That is one of the major problems with not knowing what was the cause of the initial failure. The crank tends to act as a centrifuge and heavy (metal/dirt) particles end up pressed against the plugs. It is this that we clean by removing the plugs. If No1 rod bearing failed due to debris trapped during the first build in the crank ??????? Brian Quote Link to post Share on other sites
Graham Baggaley Posted February 21 Author Report Share Posted February 21 14 hours ago, iain said: Did you get the Crank plugs removed for cleaning of the oil ways?………given the considerable damage in the engine I think it’s a false economy not too. Iain Yes the crank plugs came out. They were full of ****. Here’s the crank pre grind. Quote Link to post Share on other sites
iain Posted February 21 Report Share Posted February 21 Good grief, that got hot. Quote Link to post Share on other sites
Trumpy3 Posted February 21 Report Share Posted February 21 That's not a very nice looking crank. What is all that discoloration? I thought that only No1 rod bearing failed? I would be reluctant to use that crank without some testing and certainly not the rod. With only that photo to go by, it looks like lack of oil was the cause of failure and No1 was the first to completely fail. Looking back over your previous input on the subject, did the rod bearing suffer from low oil pressure and finally fail after your attempt to rectify the low pressure? I'm not a big believer in coincidences. It looks to me with the information at hand that your issue started with the rebuild and ended with the rod bearing failure. Brian Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 21 Report Share Posted February 21 What was the outcome of the inspection of the oil pump rotors and the drive shaft for it? Grip the inner rotor in a vice and try to turn the spindle that is fitted in it with a bar in its drive slot. Quote Link to post Share on other sites
roy53 Posted February 22 Report Share Posted February 22 The same discolouration on the nose of he crank which dosen't have oil . perhaps the degreasing did this Roy Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 22 Report Share Posted February 22 (edited) Discolouration Did the machine shop put the whole crank in the furnace to help get the gallery plugs out ? Has the crank just been nitrided? the crank when first stripped. Image from start of thread. No discoloured journals Edited February 22 by BlueTR3A-5EKT Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 22 Report Share Posted February 22 (edited) 40 minutes ago, roy53 said: The same discolouration on the nose of he crank which dosen't have oil . perhaps the degreasing did this Roy Edited February 22 by BlueTR3A-5EKT Quote Link to post Share on other sites
Graham Baggaley Posted February 23 Author Report Share Posted February 23 Ok. A bit more of an update. Engineering shop gave me the report back on the liners and pistons. three of the liners had tapering on them. there was 4 thou gap on cylinder 4 and almost the same on another two. this wouldn’t explain the pressure drop when hot but it certainly would explain the oil leak from the crankcase breather via blow by. its all getting expensive but hopefully this build should last me 30 years. Quote Link to post Share on other sites
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.