Smokin

[batespeed 0]

right, ive got a tu3s engine in my mini, the engine had been lying in my shed for three years, two of them with the head off.and oily rags stuffed down the bores. in my previous mini it wasnt noticibly burning oil

 

i ground in the valves and fitted new stem seals to a second hand tu3s head and fitted it when i fitted the engine in the mini two weeks ago, (the rush was on to get it ready for "la crofterra pandemonia"(google it, there was a 205 rallye on it as well) a two day classic car tour of the highlands) i only got it up and running the night before the event so didnt have any time for testing,

 

it was smoking slightly before the off, but i wasnt too worried about it, as the previous engine had deposited a heap of oil into the exhaust system, i thought it was just this, and would burn off

 

on the morning of the start it was pissing rain and was hard to see any smoke with the spray , but ive now been told by other competitors that the mini was smoking from the start. after about 100 (hard driven ) miles i blew off a top hose and gave it a good roasting, left it to cool for half an hour, fixed the hose filled up the cooling system, topped up the oil,(half a litre) and carried on, by now the rain had stopped and i could see that it was smoking a bit (i thought it was a result of the hose coming off, but like i said it was smoking all morning) i kept thrashing it, the temp stayed normal , but the smoke got worse to the extent i used 2 liters in 250 hard driven miles, i put the mini home on the sat night and continued in my 205

i started it today for the first time since and there was no visible smoke to start with , but within a couple of minutes it was back, smoking bad when you rev it

i know this points towards piston rings as opposed to valve seals (they have only done 250 miles remember, but it was smoking from the start, much worse now)

today i did a wet and dry compression test on it with a warm engine , all showed 185 to 190 psi dry and 200 to 210 psi with 3 squirts of oil down the bores,

i did exactly the same on my (iron block) 205 and the figures were as near as damn it exactly the same, but it doesnt smoke!

 

 

i took the rocker cover off and the valve seals are all still in place,

 

do you think its the oil control rings ??? the compressions seem good, so the bores and compression rings are probably ok

or am i missing something ??

 

i filled the bores with a mixture of diesel and redex, i will leave it over night and change the oil and filter again in the morning then give it a run, if its sticking oil control rings then this should free them off but im convinced it needs new rings (which seem to be unavailable just now)

 

any body got any pointers as to what i may have done wrong ? or what it might be? thanks in advance

 

there doesnt seem to be excessive pressure coming out of the breather or the oil cap and it still goes like shot off a shiffle but i feel like james bond !

Edited September 22, 2011 by batespeed

[DamirGTI 342]

the compressions seem good, so the bores and compression rings are probably ok

 

On the engine with busted rings/cylinder walls you'll get "good" compression reading , but must not let that fool you , the compression reading is "good" cos the oil is already present inside the cylinders when dry measuring and hence seals the rings and what you get is a fake good compression ...

 

Only leak down test will be precise diagnostic method in this case ..

 

Damir

[RossD 44]

Possible head gasket issue - especially with the top hose having blown? It shouldnt do this unless you're putting combustion gasses into the cooling system. Head gasket could have failed between oil and coolant passages, allowing oil into combustion chambers and combustion gases into coolant.

[trogboy 17]

I'm gonna say head gasket too. Did you get the 2nd hand head skimmed before fitting?

 

Ad

[batespeed 0]

changed the oil and filter today and did about 50 odd miles of mixed driving, still smoking like james bond unfortunatley, oil level went from max to half way in 50 miles..............seems to be smoking more under acceleration, but not all the time. sometimes it clears a bit, some times smokes worst at a steady cruise on a light throttle, it doesnt overheat or use coolant, and it doesnt appear to be pressurising the coolant.

i noticed something interesting though, when warmed up, at tick over there is a small puff of pressure out of the breather hose, but when you rev the engine it smokes out the exhaust, but the breather pressure seems to stop , or at least subside? surely if it was the rings the crank case pressure would increase when reved ? im begining to think head gasket myself, is it common or even possible for the gasket to blow between the oilfeed and a cylinder?

 

think ill take the head off when i get a chance and try and work out where the oil is getting in. see if the backs of the valves are oiled up and what the bores look like................................it will be interesting

[batespeed 0]

i took the head off yesterday afternoon, the gasket was ok, there was no oil on the back of the inlet valves and the bores looked ok, no visible ridge at the top and no scoring, but i dont have a micrometer to measure them

the bores seemed to be glazed though, so i gave them a quick hone (i know you cant do it properly with the pistons still in, but i was wanting to get it back together, and didnt have new rings and gaskets) i put on a new headgasket and stuck it back together , i only had time for a quick testdrive of about 15 miles, but it seems a lot better, although still smoking under load, i,m hoping its just the oil in the exhust burning off but i have my doubts

 

ive got a hang over today and dont want to risk driving, but will give it a longer run tomorrow to see if the smoke burns off, if not i will put the saxo short motor in sometime.................................

 

 

 

ps the top hose split because it was rubbing in the radiator fan housing (its got a mini radiator mounted in the front) it wasnt a pressure issue that caused it

 

Edited September 25, 2011 by batespeed

[omega 82]

seams to me that you are rushing the job without checking everything and hopeing,[not haveing a go] but might be a good idea to take a stepback and look/check every thing again.

[batespeed 0]

i know what your saying, but i didnt want to disable the car in the garage to investigate further yesterday , i only have space in the garage for one car at a time and use the garage most days for work (im a self employed mobile mechanic) so cant afford to have it blocked up all week waiting for parts for my own car, unfortunatly i have to earn a living as well...........................................thats why i dont just strip it down and order bits up, it may seem a stange way of doing things to most people but its the way i have to do it.......

[batespeed 0]

the smoke didnt burn off !!

so i swapped the cylinder head and everything attached to it onto my 205, and it works great, no smoking. so thats ruled the head out,

ive started swapping over the saxo bottom end and gearbox onto the mini, it will be interesting to see how the tu3s spec works with the slightly higher compression ratio of the flat top pistons ,

also the higher final drive of the 1.4 saxo box should make the cruising a bit more civilised in the mini, seeing as its got 12" wheels and 165/60 tyres.

 

it pulled like a bugger with the ax gt gearbox/diff but was pulling just under 17 mph per 1000 revs in 5th with the 12" wheels, it should be over 20 mph per 1000 rpm with the saxo box (22.3 mph with standard 13" wheels)

 

 

 

 

 

i just hope it stops the smoking !!!!!

Edited September 29, 2011 by batespeed

[batespeed 0]

ive put the saxo short motor and gearbox in, got it running this evening, but it wont tick over so i will have to strip and clean the carb tomorow, it started to get dark, and its friday night , time for a southern comfort , but on the plus side , it appears to have stopped smoking....................

Edited September 30, 2011 by batespeed

[batespeed 0]

its all sorted now, no more smoking, the saxo engine works well with the tu3s head and will rev to over 7000 revs, the saxo 1.4 box gives about 35 ,55 and 85mph in the first three gears even with the 12" wheels, it goes well...................................and ive still got two gears left which is a novelty in a mini ! . (click on picture for video)

 

 

Edited October 6, 2011 by batespeed