oldtuckunder

Hey that's my bush your talking about!

If the pump is picking up air or froth for a second or so, my assumption (could be a bad one) is that it isn't a very well designed air pump and that instead of pumping air/froth pass the pressure relief valve and then through the filter and then up to the gallery, that in effect the oil just stops flowing. Oil Pressure in the gallery will drop but oil will still drain away from the gallery to the mains, and as nature abhores a vacuum air will fill that space. The oil flow comes back and a massive slug of oil gets fed up to the gallery where it compresses the air and forces the air out of every available orifice, and as air is way thinner than oil its going to love speeding down the biggest passages it can find, like the main bearing oilways and on to the BE's, where in fact it could be the bearing with the most clearance that suffers the worst as thats where the air would want to go. So why #5 & #6 BE I havent a clue other than maybe it the rear of the gallery where the biggest slug of air collects? On bearing clearances, I was thinking of going up to .002 this time. On Oil I was using a 5w50 motorsport in 2014, but after that failure I was persuaded by the argument that these old engines don't like thin modern oils and that that was one of the possible causes, so switched to a 20W40, which of course has has the same or even worse result. So I'm now inclined to think the actual oil wasn't a problem. As to temperature I was very aware that under temperature oil does not perform, and as you say on a Sprint or Hillclimb the oil doesn't get much chance to get hot on a short 1-2 min burst. I had removed the oil cooler for this reason and always tried to make sure that the engine was up to temperature before each run. I had been about to fit an oil temp guage to keep an eye on it when the engine went bang. Its going to be fitted this rebuild! And if I ever see a sign that its getting Hot then the oil cooler (with a thermostat this time) will go back on. I could be wrong but gut hunch says to me it wasn't an oil temp problem, the engine temp with the electric fan regardless of how hard it was pushed never wavered more than a couple of degrees around 80-85. Alan

Here's the MK1 bush. Whopping big 1/4" holes right through! I'm beinging to think they found a problem so changed to the waisted shape and much smaller hole(s) but just kept quiet about it. Interesting that it still remained as a fitment in the GT6 though! I think I'm just going to order one of the waisted ones it can't be any smaller in OD than this one, and if it needs turning down a bit to press into the block then thats easy. With a bit of luck it will be the same OD anyway. Alan

Oil Ways all appear good! Can slide a 7/16" 11mm rod right the way through the main gallery from end to end with no restrictions, and as at that size its the same size at all the 1/2" pipework on oil cooler circuits etc, then if the gallery needs drilling out then everyones oil cooler circuits need to be scrapped & resized as well. Drillings from gallery to Mains also appear good I could feed a 4mm dia piece of plastic strimmer wire right through all of them around the angle where the drillings meet and back out through the gallery into clean air. I also measured the depth of all the drillings and they are identical. So my conclusion is that if a 4mm dia wire will feed around the angled drilled junction then the drillings have met well and deep enough. So my thoughts are now returning to either the crank drilling misalignment, the distributor drive bushing, or the theory that it could be cavitation or oil aeration and for some reason that hits 5 & 6 BE the worst. Alan

Can't find any information anywhere about crank sludge traps or where they might be fitted. As far as I can tell the drilling is direct from BE journal to Main Journal so I'm not sure where a sludge trap would go? Your correct if it was starvation to #3 Main then one would expect #4 BE and #3 Main also to show signs of distress. The only common factor between the two cranks with the problem #5 BE is that the drilling from the BE to The MAin doesn't exit centrally on the MB groove. However as on the older crank #2 & #3 BE drillings to #2 Main were also way out and they didn't seem to have suffered has me wondering of this is a red herring. Alan

Interesting just done a bit of checking on this bush and the 137978 non waisted bush was used in the Vitesse MK1 and the GT6 MK1, MK2 and early MK3. So for some reason they switched to the waisted bush for the MK2 Vitesse (and all the other 6's) but the GT6 kept the non waisted bush right into the MK3 series. Just an idle thought I wonder if GT6 engines suffered oiling problems from this until by chance the bush got changed? As I said just an idle thought? Alan

Thanks for the size. 3/4" UNF thread IIRC. I have a length of cut-down bolt in mine. All the engines I've extracted the distributor bush from from have had waisted bushes though I tend to agree that even without this the gallery is larger there than the drilling. Been looking at the distributor drive bush and all the sixes except the MK1 2ltr use the waisted bush 149776, however as the MK1 uses the same distributor drive gear and shaft as all the later 6's, unless the block is machined to a different size for the waisted bush then I think I could use the later waisted bush. If anyone has one lying around could they measure the OD of the bush please? My assumption is that Triumph found a need to modify the bush otherwise its a wasted extra machining cost, maybe flow to the front of the oil gallery. However looking at my non waisted bush I'm a bit perplexed. The bush has two 1/4" holes drilled in it to feed oil to the distributor drive shaft, this means that the distributor drive shaft that is rotating at half the speed of the crank and is vertically mounted with virtually no load on it has a bigger oil feed than #3 Main + #4 & #5 BE put together! and given that the shaft also has a spiral groove machined in it to act like a small oil pump, right at the point where the feed to #3 main is there is this distributor drive scavaging oil for all its worth from the gallery and returning it to the crank case. When they waisted the bush did they also reduce either the size or number of holes? Anyone got one they could check please. Alan

just to clarify, my 2.5 big end shells do not have a groove in, they are plain and as such the exit position into the big end journal is largely irrelevant? Are two litre engine shells different? Hi Alec No they are the same, the area of discussion is the Main Bearing shells and where the drilling from the BE's terminate on the Main Bearing Journal under the groove. Alan

Next job, finished extracting all the gallery grun screws today, and extracting the the distributor bush, so bolok in for a good prod tomorrow. I know from the clean last year that the drilling do actually meet as I was blasting cleaning solution through one end and could see it squirting out the other bit of course I don't know if that's a tiny intersection or a full one. NB. Given that the holes intersect at an angle (hidden deep in the casting) how the hell do you tell if the have completely intersected rather than having just met and made a through connection? The fact that #4 BE and Main #3 don't seem hit at all makes me think that the block drilling is OK, but who knows. If I got the holes chamfered do that before the grind or after ? Having pulled the distributor bush again, I realise that I have the old MK 1.5 bush i.e.its a straight bush with no step in the oil gallery area, I'm wondering if its worth machining one. Looking at the size of the chamber around the bush it looks way bigger in area than the oil gallery anyway, so I'm not sure what's to gain, and again that if anything would only help the bearings forward of that point, not #3 main. This time I did drill out the alloy bung on the feed from the oil filter to the oil gallery, a bit of effort but I got it out clean without damaging the the thread in the block. Anyone know that that thread is? PS. what sort of alloy did they use for that plug? its dam hard stuff! Alan

Hi Chris In 2014 I was using Comma 5w50 motosport and in 2015 I was using Castrol Magnatec 10x40 with some extra ZDDP, why did I switch? beacuse I was looking for something to blame. Guess I'll try something else after this rebuild :-) Anyway I have dug out the old crank (pictures below) and I/m even more confused. If anything its worse than the new crank I didn't even have to put it in the block you can see how far out of line the drilling on the MB journals are 2n3 are really bad on it. So its either a complete red herring and it doesn't matter a toss where the BE drillings are on the MB journal and if they are in-line withe the oil groove in the shells, or these cranks are all over the shop and its a lottery if you get a good crank or not. Anyone else got a crank lying around they could look at? Maybe I need to find somebody who makes cranks and ask them? Alan OLD CRANK 2 and 3 visibly way out of line 4 & 5 also way out NEW CRANK (maybe soon to bel old crank also?) 2 & 3 actually just about in line 4 & 5 A bit out of line with 5 being the one that didn't line up with the oil groove (see earlier pictures)

Yes but you need to take the head off first

Hi Nick I think you have nicely summarised my conundrum. 1) I'm going to dig last years scrap crank out at the weekend and see what the oilway drillings were like on that, if they are different then it may consign my oilway drilling theory to the scrap bin. 2) I read a few build recommendations that said .0007 per inch of diameter was a good target, so on the Triumph crank .0014, so I thought targeting .0015 seemed reasonable. I think this time I will shoot for .002 and use a slightly higher multigrade oil. 3) I think is also a good possible, the venue is possibly a red hearing, or maybe the straw that breaks the camels back. The major damage could of course have been done at a previous event i.e. a Sprint where longer faster corners are encountered and thus oil surge away from the oil pick up more likely. Shelsley may just finish it off as although there aren't any fast long bends, its a fairly long steep climb (so oil should be towards back of sump nicely anyway) but I'm pulling just about max RPM for what seems an agonising amount of time before the lower esses (but there isn't time to change up and then down again), So it may be at that point that a previously stressed bearing says "I give up". So in the absense of any any definate cause I think all I can assume is that it could be any or all of the posibilities and just hit them all. Probably overkill and if one had the time and money I'd do the mods one at a time to isolate the problem, but I can't afford to destroy that many engines. Alan

As Nick highlights below, I could find lots of references to people having problems with 1&2 etc, and lots of potential solutions for that, but the world seemed to be quiet on 5&6 failures, so I'm glad to find I'm not alone. Many thanks for the pointer to the Comp Oiler Article, which I think re-enforces some of my planned work this rebuild. Alan

Thanks for the welcome Nick, its kind of like dropping into a bar in a strange town and find a few people you already know :-) Yes thought I'd bring the issue somewhere serious? hoping that someone has either seen something similar or has some new thoughts on possible cause(s). Alan

Hi Folks Please excuse a long posting by a long-time lurker, but new member to Sideways. Just a quick thank you for the wealth of knowledge that I have gleamed from this site over the past few years. Haven't worked out how to edit my profile yet, so just as a background I have been playing with Triumphs since the early 70's (so the hair is now very grey) and the grey cells have started forgetting faster than they are learning. I just wrote about a page of introduction info to me and the car but have just deleted, as I realise you guys want the meat and potatoes, not the icing! hope I have left enough for you to get a reasonable picture, in fact re-reading now before I post I realise that it has probably grown way too long again for anyone to get through! Anyway reason for post, I am of course looking for input on a problem that has been haunting me for a couple of years. Background to engine. Its what I call a MK1.5 2 ltr i.e. its the MK1 2Ltr Head on a MK2 big journal Block, a hybrid that Triumph produced for the last production years of the MK1 Vitesse & 2000 before the MK2 engine was launched (when they decided that using a head that weighs 13lbs extra was a good idea!) In early 80's fully rebuilt engine using good quality components and was fully balanced, did about 800 miles before it got put in the garage (another tale). So since 1986 it has been carefully wrapped up, moved from storage to storage but not turned a wheel. In late 2012 sanity prevailed, I woke up and realised that if I didn't get this car out and back on the track it would never happen. By chance I had purchased a MK1 head that (rather like the car) had had a radical amount of work done on it in the early 90's for a project that got canned and had sat in store waiting for someone to rediscover it, which was fortunately me. Up to this point given that I knew the bottom end had only done 800 miles and was fully balanced I had thought I'd get away with just changing the crank seals, and fitting an appropriate cam for the new head. Which is what I nearly did, but as I decided I wanted a lightened flywheel it meant that I was going to have to have the bottom end rebalanced so started pulling the crank, only to find that #5 BE was badly marked, and a bit of marking on #6. Oh well 800 miles but no great hassle got the crank reground, agonised over bearings and decided to go for King Tri-Metal Competition ones. Anyway long story short, everything rebuilt, engine as sweat as a nut, get to do a couple of hill climbs late in 2013 (have incredible fun getting the fuelling right) but with a pair of Bosch AFR sensors and an Innovate LM2 data logger and dozens of hours testing we get there, the engine would spin up to 6.5K plus in the blinking of an eye and pulled like a train. Alan was one happy bunny. We start the 2014 hill climb season and get half a dozen events in when after a Shelsley event I notice a rumble from the bottom end. OK too busy, give up for the season and set my self a winter task of an engine rebuild. It was actually very late winter before I found the time and pulled the engine, every single bearing apart from #5 BE looked like new (which at about 1000 miles they were) but #5 BE was a mess, through the babbit? and ripped torn copper? and the crank journal was heavily scored, and #5 Rod had gone oval. OK lots of reading, Classic signs of oil starvation. NOS crank obtained, taken to a good rep machine shop and checked and reground, Mains just needed a polish, BE's need a .010 grind. Bearings were all set with a target .0015 clearance and plastiguaged all between .0014 and .0017. New forged rods, everything rebalanced, NOS VP2 Mains and new AEM VP2 (copy) BE's, new blueprinted oil pump, extra baffling in the sump and the block completely stripped and every single oilway cleaned within an inch of its life. Also had the bores honed and fitted new rings Oh and had new bronze guides made and fitted. Also fitted a new Pressure Relief Valve and Spring. Engine was carefully run in according to current advice re making it work hard but not too fast. And it was sweet again. PS also fitted a rev limiter this time, set at 6200 soft 6500 hard as I thought the problem may have just been caused by over cooking it as it just spins up so quickly. 5 events into the 2015 season at Shelsley again, massive rumble again from bottom end, throw car in garage, buy a TR7 and complete the season. I have just stripped the engine. #5 BE completely shot, this time it had obviously grabbed the journal and spun the shells in the rod, the bearing surface of the shell although badly marked wasn't very worn but the back of the shells had worn about half through and it had been stretched and squeezed out of the cap and folded over the sides of the rod! Oh and the journal on the rod had also worn a bit which isn't surprising given that the rod end is now a nice dark shade of blue indicating the massive amount of heat generated. #6 BE also has some marking but every other bearing looks like new apart from #5. I must admit before I stripped it I had expected the problem this time to be one of the lower numbered bearings and had been looking at various oilers and spider/octopus to solve it as everyone else seemed to have stories about the low number bearings being the ones that always had problems. But no its #5 again very bad plus #6 was obviously stressed. Ok I have a rebuild strategy that will repeat the last one, plus ensure every oilway gets drilled to ensure they really are good, bigger sump more capacity even better baffling, going to get the block Mains line bore checked and corrected if necessary, but everything is telling me that in July at Shelsley its going to go bad again. So the conundrum, if its oil starvation to #5 & 6 why isn't Main 3 or BE 4 also hit? They are both on the same feed in the block! and if it was starvation due to a sump surge I would have expected the bearings forward of #3 main to be hit worst. So I'm looking for a cause. Anyway there I am looking at the crank sat in the block idly spinning it when I notice that the oil drilling in the crank for MB #3 that feeds BE #5 was way out of line with the oil feed groove in the MB shell! and that the feed to #4 BE was also out of line but nowhere near as much, a quick look at the other MB journals and the same thing! Duh stupid me I had removed the thrust washers to stop then dropping out when I had take the MB caps off. Anyway pop the thrust washers back in and recheck (NB I have an end float of .007 which is about perfect) bugger me #5 is still way out of line about 1/3rd + of the oil feed drilling to #5 BE is covered by the shell bearing surface whilst #4 hole is sat nicely over the groove in the shell. A quick check of all the others showed them to be fairly central although not as good as I might have expected, #6 was a tad to the edge, as was #1, interestingly in opposite directions so if the crank was moved forward #6 would improve but #1 worsen, and vice versa if the crank was moved back. Does anyone ever check the alignment of the drillings in the crank with the oil groove in the MB shells? The only reason I spotted it was that I hadn't yet lifted the crank out and removed the bottom half of the shells in the block, and I had a flood light on over the engine and could just see the edge of the shells next to the crank as I rotated it! I'm going to try and attach a picture that shows the alignment of the BE oil drillings. Ok here is a picture of all 6 crank BE drillings where they exit on the MB journal showing the alignment with the oil groove in the MB Shells, and it really frightens me so I hope someone will come back and say my fears are groundless. However if you look at #5 which is the one that I have the constant problem with you can see how much of the hole would normally be closed off by the MB shell. The yellow lines show the extremities of the oil groove in the MB shell and the pink lines the extremities of the hole. I have never read anywhere about checking this alignment, so its either irrelevant, or a hidden secret that nobody talks about. Looking at the crank the feeds from the MB to the BE have to be drilled from the BE end to the MB end, so I'm wondering if its a bit hit or miss where the MB end of the hole ends up. I imagine that they must have had multiple work stations set up in the factory drilling these things, so I can imagine that some cranks might be spot on, some off on some journals, and some off on others. Could this be an explanation why some people have cranks that consistently seem to have a problem with a particular BE whilst others have a problem with a different BE, and some lucky bastards just have a good one. Someone tell me this is a rubbish train of thought, and that I'm just clutching at straws to find the cause of my problem. Regards Alan