Very very exessive oil burning

[firehor5e]

Hello all, I bought a 68 2 door minor just a few weeks ago,and very nice she is too,she answers to the name Ruby.She was stored for 13 years in a dry barn,just 2 years after being restored...Loads done to her,Marina servo,brakes,axle ,box..long branch manifold,stainless exhaust etc... Mk3 midget (rebuilt)1275,+.020,twin su.. After doing quite minimal repairs and re commisioning she flew through MOT with no advisorys..great..now the bad news..drinking fuel like its going out of fasion,carbs wont adjust (A N needles in AUD136 carbs) crank case vented to atmosphere via K+N filter,carb breather pipes ajoined to each other,so i fitted "T" piece and connected to crank breather.Job done,now to adjust carbs,recentered jet on front carb,fitted needles as they should be,as they were too low,to up dampers etc...Start Ruby up,no choke needed,reving too high,then she started burning oil,deffinately oil,thought i had over filled the dash pots and exess oil burning off.So let her run a while...smoke really bad now..neat engine oil dripping from exhaust(New decent 20/50 oil change done last week) ... Oh crap..."What have i done"i thought..Has that breather pipe conected to the carbs just sucked the contents of the sump up and dumped it into the inlet manifold?.NO,pipe is dry..hmm..no bottom end crank pressure either..Oil pressure arround 75psi .compression test,with all plugs removed,160 to 165 ..no signs of oil/water mixing,or coolant pressurising,no external oil or water head gasket leaks... P.S....she did smoke a lot when i changed the oil,for a short while..suspect valve stem seals.... Removed the head..oil every where,cylinders,inlet and exhaust ports in head. cylinder bores good and pistons fit nicely. block stamped .020 as are the dished piston crowns....Help....Advice urgently needed....Please!!

[bmcecosse]

The oil rings may be stuck with lying so long. Twin carbs are hopeless - a large single will be MUCH better, and easier to set up - but first you obviously need to fix the oil problem. May be that the rocker shaft is excessively worn - dumping a lot of oil over the valves - and if the valve guides are worn - and perhaps the seals.... It would be the first things to check - and also pop the pistons out to look at the rings.

[firehor5e]

Oil rings was what i thought..will pull the pistons out tomo..Valve guides are good,very little play,stem seals seem good too,8 fitted-exhaut ones have the springs removed.i will replace them anyways as i will regrind valves etc..will check for rocker wear tomo too.. When i bought her,the previous owner said she was a little smokey last time she ran(12+ years ago) she had only done about 500 miles since rebuild then though,so i put the smoke issue down to running too rich..Thanks for your quick reply..

[bmcecosse]

Normally there would be no seals on the exhaust valves.

[firehor5e]

Valve seals....now theres another discussion! pros and cons... Will go for the 4 option me thinks...

[kennatt]

can,t see it being rings /pistons with 160 pressure ,not just simply overfilled with oil when you did oil change.

[bmcecosse]

The oil rings may be wrongly assembled/upside down/broken - none of which would affect the compression readings.

[busguy]

Incorrect dipstick for 1275 engine?

can,t see it being rings /pistons with 160 pressure ,not just simply overfilled with oil when you did oil change.

[firehor5e]

Thanks for all your replys....Engine was rebuilt and has done very little milage(aprox 500)but has been unused 13 years!..Pulled the pistons out this morning, all appear to be good,however,on number 2.3 and 4 the oil scraper rings had their gaps pretty much adjasent to eachother,so it could be as simple as that??.i also removed one compression ring and slid it into its cylinder and measured its gap,its about a tho"seems a tad to big?(+020 stamped on block and pistons) cylinder bores all good.Pistons have 3 compression rings,oil scraper at bottom..Engine not over filled(took aprox 3 liters of oil) Im tempted to realign the scraper rings and reassemble the engine.. awaiting gaskets,valve grinding paste etc...wish i could afford to have hardened valve seats done while head is off..but... On another subject,bypass hose is blanked off..i should really reinstate that i think. Thanks for all of your input.

[bmcecosse]

No - leave the bypass blanked - that's one less thing to go wrong. And faster warm up, and better heater - but always leave the heater valve open. No need for hard seats - just use 15 thou exhaust valve gap and all will be well, I very much doubt it's an oil ring 'gap alignment' problem.. When the engine was 'rebuilt' - do you know what was actually done? Some 'rebuilds' are better than others...

[firehor5e]

Hi BMC.thanks for heater/bypass and exhaust valve tip.Dont know who rebuilt engine,just a mention of it being done.From an MG Midget Mk3.Lightened and balanced,upgraded cam shaft and a ported cylinder head.Supplied by Minor Motive of Northants.(they also did the restoration circa 1996 to 2000.Found a recipt from Abingdon car restorations December 2001 that reads-running problems=cylinder head leaking,no3 plug gets wet,smoke-oil burning..(they replaced the points and condencer!)no other mention of engin parts or work in Rubys history.....So you dont recon ring alignment then?maybe wrong size ring set fitted,as a 1.00 thou ring gap seems quite big to me?Maybe just the head gasket?? was burning LOADS of oil though--would have emptied her sump if i had let her...oil pi---g out of exhaust...HO hum.the saga continues

[firehor5e]

Also the coolant was "rusty" so perhaps no antifreeze? Hope the head or block has not frozen up and cracked!!!! is that likely on cast iron? Dread the thought! Upon closer inspection of the old head gasket,it is showing possable signs of oil transferance between oil gallery AND No 2 and 3 cylinders..Tempted to put it all back together and see what happens...Drill a small hole in exhaust silencer to drain out the oil!?

[bmcecosse]

I'm not getting your 1 thou ring gap = do you mean 100 thou? ie 1/10 of an inch - in which case that is far too much. Usual is somewhere between 15 and 25 thou. Unlikely the block would crack - it usually just pushes out the core plugs. Oil gallery to cylinders 2 and 3 ? The only near oil passage is at #1 cylinder where it passes oil up to the rocker shaft.

[firehor5e]

My misstake BMC..I must have had a "blond moment"or too many G+Tonics! I used my METRIC feelers!so 1mm gap!Head gasket oil residue etc between 2+3 and nearest hole in gasket,i just assumed(incorrectly)it was an oil gallery..Big appologyto you all..Any hoo,popped the pistons back in,sump etc.cleaned all the gasket surfaces.Not much else i can do till grinding paste arrives.Will keep ya all posted. Thanks

[bmcecosse]

Well -1mm gap is 40 thou - still a bit big... Is it a one piece oil ring - or two thin rings with a corrugated spacer to hold them apart?

[firehor5e]

1mm gap on comp ring,and i only took one of them out of piston to measure it in its cylinder as i was afraid of breaking one of them!.oil rings are 3 piece.

[firehor5e]

Hi all,bottom end of engine is now put back together. Valves lapped in,all except #3 exhaust as valve a bit burnt..awaiting delivery of new valve..also new rocker shaft as it appeared worn.(thanks BMC...good advice as usual).

[kennatt]

I'm not really sure what you gained by stripping the bottom end and rebuilding it using the. same bore,pistons and rings .apart from your satisfaction that the rings are fitted correctly .If the oil burning is as excessive as you say,then there must be serious wear in the engine somewhere,bottom end or top , so unless you find out why and where,then its unlikely that the problem will have gone away. Unless I have missed something in the posts.

[bmcecosse]

The oil rings may be assembled incorrectly - I can't now remember - but the thin rings are tapered and must be assembled so they sweep the oil down the bore - if wrong way round - they may sweep it upwards.

[firehor5e]

Quick update....we(my 12 year old son and i)checked the piston rings etc again,all seems good,correctly fitted etc.We changed all the valve guides,worn rocker shaft,burnt valve etc.Un siezed carb jet/choke.. Have done 100 miles in Ruby over the last few days now...All good..(took a white to burn off the oil in the exhaust system!).plugs all a nice biscuit colour.Compression all at 170 now.oil pressure at 50 at ide,175 while driving,no botton end crank pressure,no oil or water issues..Happy days !!... thank you all for your input..