71 replies to this topic

[cal844]

No image, host it on a photo sharing site and use the bb code

[sam138]

 36392828-2E76-441F-A47A-547A1118DEEB.jpeg   164.7K   11 downloads

[sam138]

Can someone advise the best item to purchase so I can measure the crank pressure? With the low pressure compression readings are we possibly saying I need a rebuild ?

Edited by sam138, 16 July 2021 - 08:16 PM.

[cal844]

Can someone advise the best item to purchase so I can measure the crank pressure? With the low pressure compression readings are we possibly saying I need a rebuild ?

I have limited experience in turbo/ charged motors but on an N/A engine those figures are low enough for a partial strip...

However with the above said I strongly recommend a leak down test on all 4 cylinders to confirm if its valves or piston ring related.

I will let another member advise further but the above is what I would be doing before pulling the motor

Edited by cal844, 16 July 2021 - 10:18 PM.

[sam138]

Thanks for the reply, is it possible that anything other than pistons and valve can be leaking during a compression test ? I didn’t isolate the fuel pump could this bore wash the cylinders as your cranking ?

How about my 1.5 rockers with 12 thou of clearance ? Should this be 15 thou ?

Also my boost gauge ( Tim’s turbo one) when you rev it stays in the minus figure all the time and doesn’t go positive to show the boost running.

Just trying to rule everything out like air leaks somewhere etc, I’m getting a leak down test kit ordered.

Edited by sam138, 17 July 2021 - 09:05 PM.

[Dusky]

Compression test numbers say next to nothing. Just make sure they're within 10% of each other. Too many variables; battery, starter motor health, throttle opening,...

But, being almost all identical, AND the results didn't go up a lot with oil in the bore, it seems like it ll be a healthy engine.

[sam138]

Would something like this work to measure crankcase pressure? Looks to have a bung fitting that I can put in the dipstick hole.

https://www.amazon.c...e/dp/B075TYJ4WZ

[nicklouse]

Would something like this work to measure crankcase pressure? Looks to have a bung fitting that I can put in the dipstick hole.

https://www.amazon.c...e/dp/B075TYJ4WZ

I would not waste the cash. Sounds like you have more issues. 
 

where is the pressure sensor fitted?

 

you don’t mention what the cam is? Why did you set the clearance to 12 thou?

[sam138]

I’ve got a boost take off fitted into the inlet manifold but don’t have a pressure sensor. clearance for tappets set at 12 thou after looking in Haynes manual but looking online it seems people with 1.5 rockers are setting at 15 thou ?

Cam is standard that comes with the Mini Cooper 1275 carb engine, the engine was running fine in NA form.

Surely as others have said I need to check crankcase pressure due to oil leak in clutch case ?

Edited by sam138, 18 July 2021 - 10:22 AM.

[Dusky]

I’ve got a boost take off fitted into the inlet manifold but don’t have a pressure sensor. clearance for tappets set at 12 thou after looking in Haynes manual but looking online it seems people with 1.5 rockers are setting at 15 thou ?

Cam is standard that comes with the Mini Cooper 1275 carb engine, the engine was running fine in NA form.

Surely as others have said I need to check crankcase pressure due to oil leak in clutch case ?

Your compression test results don't point to a worn engine anyway. So that's good.

[Magneto]

Were your compression test results after installing the decompression plate? If so I wouldn't worry about them. If not then they're really low to me.

[sam138]

Thanks for the reply’s, I’ve fitted a 6cc decompression plate which after calculating with an additional head gasket gets me down to 8.1 ish on compression, this was all fitted before the compression test was carried out.

So should I still proceed with a leak down test / crankcase test ? Or just simply pull the flywheel and inspect the leaking clutch seal.

Edited by sam138, 18 July 2021 - 10:04 PM.

[sam138]

Just a bit of an update, I adjusted the 1.5 rockers to 15 thou clearance and redone the compression test ( dry ) on a cold engine and the psi increased !

Cylinder 1 - 125psi
Cylinder 2 - 125 psi
Cylinder 3 - 137 psi
Cylinder 4 - 130 psi

Looking online a fellow person who supercharged their mini had an issue with increased oil pressure and pushing oil out the clutch seal as per below. He fitted an oil catch can with an additional rocker breather all linked to the catch can. Does this sound like a better option than feeding pressure back to the carb from clutch case and an open filter on the mechanical fuel pump ?

https://www.diyauto....grahamxx/page/3

Edited by sam138, 20 July 2021 - 08:30 PM.

[Icey]

You’re not putting boost pressure into the breather system, are you?

Edit: It looks like this question was asked before but I’m not seeing a clear response. Your breather system should only ever see vacuum.

Edited by Icey, 20 July 2021 - 08:57 PM.

[sam138]

You’re not putting boost pressure into the breather system, are you?

Edit: It looks like this question was asked before but I’m not seeing a clear response. Your breather system should only ever see vacuum.

I’ve got the crankcase breather connected to the hif44 carb and a DSN filter on the mechanical fuel pump with a stand alone filter, neither of these would cause boost pressure in the breather system would they ?

Edited by sam138, 20 July 2021 - 09:22 PM.