Don Cook Posted March 20, 2014 Share Posted March 20, 2014 I'm thinking about taking the head off my early 71 MK3 GT6 for a clean up. I had it modified a few years ago for unleaded and had a go at flowing as well (as per Kaz Kastner'd booklet). I'll replace the rockers as they are pitted and, fingers crossed, that should be it for the head.However, because I'm getting oil leaks (I'll check/divert the engine breather first) I was thinking about replacing the piston rings and while the sump is off, possibly the con rod shells. Now, is this a good idea, wondering if there is any ovality it might be best to leave them. Also what else can be replaced with just the sump off...crankshaft shims maybe?Am I likely to experience any probs doing this just by removing the sump? I'm not having a complete strip of the engine, just climbing around the top and underneath. Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 20, 2014 Share Posted March 20, 2014 I did this a long time ago. You have to undo the engine mounts and jack up the engine on one side to wiggle the sump out. I did it because I had massive end float and I did get those bearings in. Also changed the con road shells as they were in the kit but, as to the main bearings, I don't remember, not sure how I could have got them in. Also while you've got the sump off replace that horrible leak prone aluminium piece at the lower front of the block with a steel one. And did changing the bearings fix my engine? No it didn't! After six months end float as bad as before and oil turning to jelly. All due to elongated S shape wear it the bores caused by original massive end float. All fixed by my first re-bore and regrind. Quote Link to comment Share on other sites More sharing options...
CHRIS211083 Posted March 20, 2014 Share Posted March 20, 2014 Good story DougBGT6, this happens alot. You go to fix the immediate problem when really its just a symptom of other things going wrong. That coupled with the crap bearing metal we get these days is the reason I'm no longer using the triumph unit.Don let us know how you get on and what you decide to do.Chris. Quote Link to comment Share on other sites More sharing options...
ferny Posted March 20, 2014 Share Posted March 20, 2014 I've learnt not to fiddle with working things. If you're not using oil, your compression is good and the oil pressure correct I'd not touch it! Quote Link to comment Share on other sites More sharing options...
Velocita Rosso Posted March 20, 2014 Share Posted March 20, 2014 ferny wrote:I've learnt not to fiddle with working things. If you're not using oil, your compression is good and the oil pressure correct I'd not touch it!(clap) Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 20, 2014 Share Posted March 20, 2014 As above, if you've got decent oil pressure when hot, no nasty noises on cold starts, no excessive crank end-float and not using loads of oil, I'd be inclined to leave well alone.Doing the bearings from below on a GT6 or Vitesse is a miserable job though it is just about possible to change all the bearings (including mains). Changing rings means that the bores MUST be honed. While I suppose it is possible to do this with a flex-hone (or similar) in an electric drill, I don't see how you'd ever get things clean enough afterwards. It's not that hard to get the engine to do it properly if you really think it needs doing.CheersNick Quote Link to comment Share on other sites More sharing options...
thescrapman Posted March 20, 2014 Share Posted March 20, 2014 8009 wrote:I'm thinking about taking the head off my early 71 MK3 GT6 for a clean up. I had it modified a few years ago for unleaded and had a go at flowing as well (as per Kaz Kastner'd booklet). I'll replace the rockers as they are pitted and, fingers crossed, that should be it for the head.However, because I'm getting oil leaks (I'll check/divert the engine breather first) I was thinking about replacing the piston rings and while the sump is off, possibly the con rod shells. Now, is this a good idea, wondering if there is any ovality it might be best to leave them. Also what else can be replaced with just the sump off...crankshaft shims maybe?Am I likely to experience any probs doing this just by removing the sump? I'm not having a complete strip of the engine, just climbing around the top and underneath.DonIt's a Triumph, it leaks!If you still insist, do a proper job and take the engine out. I can borrow a crane for you if needed.CheersColin Quote Link to comment Share on other sites More sharing options...
piman Posted March 20, 2014 Share Posted March 20, 2014 Hello Doug, "Also while you've got the sump off replace that horrible leak prone aluminium piece at the lower front of the block with a steel one. "As long as the bridge strip is assembled correctly and the sump bolts that screw into it are not overtightned, stripping the threads then it is as good as steel. If I find a stripped thread I would simply helicoil it, I see little point in having to find a steel bridge?Alec Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 20, 2014 Share Posted March 20, 2014 Sorry Alec,But I've had it happen to me and I've heard about it too many times from others to think it's not a problem, the thing is weak link and frequently a major source of leakage. As to availability another club has it in their shop and I believe it's a best seller.Doug Quote Link to comment Share on other sites More sharing options...
piman Posted March 21, 2014 Share Posted March 21, 2014 Hello Doug, in what way is steel better in this application? I don't doubt that the shop you refer to sells plenty of them but that is not an indication of it's superiority.I can understand those with limited resources replacing a damaged bridge piece due to stripped threads which is fair enough.Alec Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 21, 2014 Share Posted March 21, 2014 Alex,Number 1 it doesn't leak.And number 2 it doesn't leak ;DI have repaired the aluminium one in the past as you describe. It lasts about 6 month and then....... it leaks. I think Duckhams sponsored Triumph to install the original to increase oil sales.Doug Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 21, 2014 Share Posted March 21, 2014 Sorry Alec, x is right next to c hence Alex :-/ Quote Link to comment Share on other sites More sharing options...
piman Posted March 21, 2014 Share Posted March 21, 2014 Hello Doug,not a problem, I often get called Alex.Sorry but we'll have to disagree on this subject.Alec Quote Link to comment Share on other sites More sharing options...
Bainzy Posted March 22, 2014 Share Posted March 22, 2014 A steel bridge also provides strength to the engine block, particularly in the 6 cylinder block which is longer than the 4, so that's an added extra to preventing stripping the threads.It's quite a common modification for those tuning the 6 cylinder, especially on overbores, to replace the alloy parts with a kit of steel pieces (bridging piece, rear oil seal and main caps) to provide torsional strength to the engine block. Don't know how beneficial that would be to the 4 cylinder blocks, but given that the bottom end weakness on the 4cyl is caused by oil film breakdown as a byproduct of crankshaft flexibility, I suppose every little thing that makes the block more stable would be of benefit. Quote Link to comment Share on other sites More sharing options...
esxefi Posted March 22, 2014 Share Posted March 22, 2014 how does it add strength? Quote Link to comment Share on other sites More sharing options...
rotoflex Posted March 22, 2014 Share Posted March 22, 2014 How bad are the oil leaks? From where does it leak? Quote Link to comment Share on other sites More sharing options...
Sheepy Posted March 22, 2014 Share Posted March 22, 2014 esxefi wrote:how does it add strength?I suppose it will add strength to the "flex" of the motor. Not had personnel experience with the 6 yet, but going by what rover did with the V8 for the same reasons, when they cross bolted their blocks! Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted March 22, 2014 Share Posted March 22, 2014 Here is a link to Canley’s spares catalogue for the engine. The item in question is 151134. http://www.canleyclassics.com/?xhtml=xhtml/diagram/gt6mkiiiengineunitcylinderblocklinersoilpressureswitch.html&xhtmlcatalogue=xhtml/catalogue/gt6mkiii.html&category=engine&xsl=diagram.xslNotice items 36234 which are wooden :-/ packing pieces.The leak is between 151134 and the sump. Two of the sump bolts screw into 151134. Steel bolts, aluminium thread. No matter how carefully you torque them up, do not over tighten, do not under tighten, eventually it leaks. Spillage for me was about an egg cup full a week, doesn’t sound like much but it used to drive my Dad insane! He was very proud of his garage floor! Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted March 22, 2014 Share Posted March 22, 2014 Neither of my cars leak from there. One is original 45 year Triumph build and one is a recent red monkey build. Blocks do sometimes need careful straightening before use due to previous over-tightening. The bolts really don't need to be very tight for everything to seal. Over tightening distorts things and causes leaks.Nick Quote Link to comment Share on other sites More sharing options...
Don Cook Posted March 23, 2014 Author Share Posted March 23, 2014 Anyway...Oil comes out in the usual places indicating crankcase pressure build up. Oil started spewing out on the 10CR (2011) along with a real problem keeping the carbs in tune (I had re-fitted original Strombergs for economy and they're still on), wasn't much better during the following La Carrera Caledonia, since then I haven't used it. Engine doesn't knock. I suppose the first thing to do is get her running, I'll put back the SUs and make sure engine ventilation is working as it should and then find out the oil pressure. Any recommends as what type oil pressure gauge to use and where to site it (I have a radio/CD so no room there). Combined water/oil gauge, can you still get these?Does anyone know the order/sequence of the internal gubbins of the Smith's emission control valve (toward the top left of picture), I might have re-assembled mine incorrectly (can't find exploded view on the web)?Don Quote Link to comment Share on other sites More sharing options...
don cook1 Posted May 27, 2014 Share Posted May 27, 2014 Well, a whole two months later all I have done is rebuild the Smiths engine breather valve, it was assembled wrongly. Plus, I have used a very, very old Redex compression tester. I didn't have enough hands and it was raining but I got readings as follows: 1 = 125, 2 = 125, 3 = 125, 4 = 60, 5 = 60, 6 = 125. These are approx as, in the time and rain, I could only measure while spinning the engine over.I assume that I have a head gasket go between cylinders 4 and 5, compression being lost between the two? Would this be a cause for crankcase pressure to build up or is compression just being lost between pots 4 and 5, what do you think? Not used this for two years...getting quite excited now. Quote Link to comment Share on other sites More sharing options...
rotoflex Posted May 27, 2014 Share Posted May 27, 2014 I don't know how you'll ascertain the sealing efficacy of the rings in the cylinders with identical low pressure.It may be more work, but you may just have to replace the head gasket & do a compression test again. Quote Link to comment Share on other sites More sharing options...
GT6 M Posted May 27, 2014 Share Posted May 27, 2014 Id say your aboot right there Donanother way of check,n is to have the plug oot on one, and turn over till other on fire strokeye should hear air whizzing oot of plug oleGet it off.M Quote Link to comment Share on other sites More sharing options...
don cook1 Posted May 27, 2014 Share Posted May 27, 2014 I was thinking that my initial concerns about crankcase pressure build up and the oil leaks might have been knackered piston rings but perhaps its just the head gasket gone between pots 4 and 5. Head off time methinks! Quote Link to comment Share on other sites More sharing options...
GT6 M Posted May 27, 2014 Share Posted May 27, 2014 seems like 2 pistons go together is a bit strangeBUTT, if waters been getting in, woe knows.generally crankcase wont pressurise unless the blow is toward the tappet chest, as this will let air into sump.nee water coming oot, so its gotta be between the cylsmoer than likely the fire ring has blown thrujust hope it aint ..flame cut.. into the block !!!get it offfffM Quote Link to comment Share on other sites More sharing options...
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