Smoking engine, leakdown test
Turbo Mini Forums

Hi!

I havent been on this forum for a long time, but now I need your help!

My engine is smoking a bit to much. It has goten worse by time so I need to do something about it.
In my search for whats wrong I have rebuilt the head with new valves and guides. I have change the turbo to a new one (although it had been on the shelf for a couple of years).
I dont think its the turbo because it smokes even if I disconnect the pipe between the turbo and carb (and there is no oil inside the pipe). If its the turbo its got to be leaking oil on the exhaust side but I dont think this is the case!?
So, the next thing I thought about are the cylinders and pistons. I bought a leakdown tester to find out if the bores are worn.
Does anybody have any experience with leakdown tests!?
The leakdown tester measures leakage at a give pressure, this is the result I got:

Cyl1 1bar:64% 1,5bar:47% 2,5bar:10% 0%leakage@2,75bar

Cyl2 1bar:64% 1,5bar:47% 2,5bar:10% 0%leakage@2,8bar

Cyl3 1bar:64% 1,5bar:46% 2,5bar:7% 0%leakage@2,7bar

Cyl4 1bar:67% 1,5bar:49% 2,5bar:15% 0%leakage@2,9bar

From this I can see that Cyl 4 has a bit more leak than the others, but is this difference enough to say the no 4 cyl is worn?
How do I know if all cylinders are worn!?

If somebody has experience with leakdown tests or know of another way to tell if the cylinders are worn, all help is appreciated!!

Have a nice day!
/Jonas

according to your test the rings or bores are goosed!

but...........................
in my humble opinion
usuall the A series engine does not suffer from oil burning to the degree you state and especially the A+ metro engines dont suffer too much either even with this much wear with oil controll problems

even on starship milages

my bet is
you have fitted a turbo of unknown origin and wear again ...................of the shelf! on to your motor

this will be the problem!

source a "good" secondhand one if it was me and go from there

my sun tester says minimum leak down test mester feed pressure pressure 70psi minimum max 200 psi , but threres a regulator on the machine as well and what it regulates it down to i dont know ,,and you really need to know this to know what youtr measurements mean ,,leakdown measurement wize .. anything over 15% is iffy ,7 %is ok 3% or lower excellent .

regards robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I always do a leak down test at the compressor output pressure at least 100 psi for meaning full figures. 2.8 bar (42psi forget it!!!)
You need to set your tester to 100% or zero leakage before connecting it for each cylinder. On a competition engine anything more than 12% is rebuild time!

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

Im suspectiong that I dont use the leakdown tester the right way.

Scruffy, what do you mean by "set your tester to 100% or zero leakage "?
I have more than 100PSI pressure from the compressor. The tester has a regulator, pressure gauge and a leak gauge. I have adjusted the regulator to the above settings (1, 1,5 and 2,5 bar) on the pressure gauge and read the leak gauge.
Scruffy, at what pressure (on the pressure gauge on the leakdown tester) do you meassure the leak (max 12%)??

/Jonas

my mini was using a litre a day of oil on a 14 mile trip, smoking loads. Ive just managed to get anohter 1500 miles out of my engine though by taking it steady just from using wynn's stopsmoke from halfords.

Its given me chance to get the new engine ready. Looking forward to stripping it down and seeing what was making it smoke!

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

Any more than 15% or so leakage (difference between before connection and after) = rebuild/attention required

Leakage/loss should be the same all cylinders
Reset gauge to 0% for each cylinder before connecting.

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

Looks like your rings might be as slack as Norra Batty's stockings.

Thanks, I will give it another try this weekend.
This is the one I have, but I gues it works the same way as yours:

Attachments:

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I have done a new test, the right way this time
I set the gauge to zero and then connected the airline from the cylinder.

I did the tests a coulpe of times and got some different results but the overall leakage is as I understand it to much (even if the gauge says "Low leakage" between 10-40%).
Could this be the cause for the smoke!?
Does these numbers tell me its time for a rebore?

Cyl: Test1 Test2 Test3 Test4 Test5 Test6
1 10% 8% 9% 23% 24% 24%

2 15% 23% 23% 23% 24% 24%

3 21% 23% 22% 24% 21% 34%

4 27% 15% 15% 29% 30% 30%

Attachments:

183.37kb

211.92kb

if thats liek the leack down tester i have you need to ajus the regulator to get the left gauge to show 100psi, then note the reading on the right gauge.

do this with the cylidner at TDC on teh compression/firing stroke, with the car in gear and the hand brake firmly on.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

If I adjust the left gauge to read 100PSI, the right gauge will go past 0%(-xx%)!

When you did the test where did the air leak to?
(There is something wrong with it judging by the figures)
But depending on where it was hissing will tell you where the problem is.

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

I can hear (and feel) the air coming from the oil dipstick hole if I lift the dipstick.
The measure varies a bit if I turn the engine just a little bit. Its like the ring seal is different depending on where the piston is.

Thats what I suspected
It´s time to take the engine apart and have it rebored. I think I´ll buy MiniSpares Metro Turbo Mega 9.4cr +40 pistons as it seems like many thinks this is a good choice.