How to Keep bis air intake free from oil (crankcase pressure)

[andyzeetec]

The previous owner had disconnected the breather pipe (oil filler end) and let it dangle, which has made a bit of a mess around the engine bay. I have checked the oil filler cap spring washer which is fine and the dipstick hasnt poped out, so I think the crankcase pressure is fine, but guess I need to do a compression test to confirm. The intake on the airbox is oily, so I guess thats why they removed it.

Anyway I was thinking of one of these.. any thoughts?

Thanks.

http://www.ebay.co.uk/itm/Mini-Air-Oil-Crankcase-Vent-Breather-Filter-18mm-RED-/180675287331?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2a11161923#ht_1745wt_1190


REDUCE CRANKCASE PRESSURE AND KEEP INTAKE AIR FREE FROM OIL PARTICULATES

[Rusty's Uncle]

My 126 aircooled engine started to blow oil back to the air filter and make a bit of a mess as well as not running so well. I checked the tappet/valve clearances and only one had any clearance on the rocker. Set them properly and all is fine now 

[andyzeetec]

My 126 aircooled engine started to blow oil back to the air filter and make a bit of a mess as well as not running so well. I checked the tappet/valve clearances and only one had any clearance on the rocker. Set them properly and all is fine now 

Ok thanks, another job to add to the list.

[andyzeetec]

My 126 aircooled engine started to blow oil back to the air filter and make a bit of a mess as well as not running so well. I checked the tappet/valve clearances and only one had any clearance on the rocker. Set them properly and all is fine now     

Haven’t checked clearance's yet but have checked compression, 60psi on both cylinders    does that mean the headgasket is shot? I cannot see any mayo in oil filler or dipstick?

 

I have found out that the following can cause low compression readings.. a blown head gasket, valve not closing (probably exhaust), bad compression rings, severely cracked block or a hole in the piston and that a head gasket can fail between the cylinder and oil passages, cylinder and coolant passages, cylinder and outside of the block, or between the oil and coolant passages.

So I am guessing it could be leaking between cylinder and oil passages or maybe an exhaust valve not seating properly?   

Found these figures in one post..

126 BIS

Normal:
0,95 МРа
9,7 kg/cm2
9,5 bar (137psi)

Minimum:
0,7 МРа
7,15 kg/cm2
7 bar  (101psi)



any advice appreciated

[gammakeith]

That would be worryingly low on pretty much any engine.  However, it might be worth double checking your gauge on another engine first!  If the gauge is OK then recheck compression after having squirted some oil in the bores.  If the compression doesn't go up (and valve clearances are ok) then its not rings and you need to pull the head.  You'll only get mayo in oil if the gasket has failed near a water passage.  A compression leak (eg between cylinders) will just rob you of power.

Keith

[andyzeetec]

That would be worryingly low on pretty much any engine.  However, it might be worth double checking your gauge on another engine first!  If the gauge is OK then recheck compression after having squirted some oil in the bores.  If the compression doesn't go up (and valve clearances are ok) then its not rings and you need to pull the head.  You'll only get mayo in oil if the gasket has failed near a water passage.  A compression leak (eg between cylinders) will just rob you of power.

Keith

thanks Keith, I'll check the gauge on the other car.

[andyzeetec]

Right, ventured outside, feet are now like blocks of ice, but slowly thawing out.
Compression gauge is fine. Squirted some oil in cylinders, pressures did go up from 60psi, 60psi to 70psi and 75psi     
Drained oil, checked tappet clearances, rotating engine anticlockwise, not sure if makes difference. cylinder 1 (Rear of car), valve #1 at 0.1mm, #2 at 0.1mm, #3 at 0.05 to 0.1, #4 at 0.1mm. Used Petes rule of 5 method...which is measuring the gap when the other valve is fully compressed, although I can get a bigger gap if the other valve  isnt fully compressed  , so do I Rotate/rock the engine till I get the largest gap or fully compress the other valve then measure the gap which is bigger. I havent made any adjustments as of yet.

Any conclusions, doesnt look too good to me, would a leak pressure test confirm?

http://club126uk.co.uk/smf/index.php?topic=3229.



Thanks guys.

[Rusty's Uncle]

Not sure what the Bis clearances are but the air cooled is 0.2mm exhaust & 0.25 inlet so I would guess that yours are too tight. As for the odd one (no 3) you may well have a worn cam lobe as all of these engines are prone to camshaft wear. If you have access to a DTI you should be able to check the lift at each rocker arm. From the engines I have worked on about 1 in 3 camshafts have been scrap. The cfamshaft on my brand new 1989 Bis broke after 300 miles 

[andyzeetec]

Not sure what the Bis clearances are but the air cooled is 0.2mm exhaust & 0.25 inlet so I would guess that yours are too tight. As for the odd one (no 3) you may well have a worn cam lobe as all of these engines are prone to camshaft wear. If you have access to a DTI you should be able to check the lift at each rocker arm. From the engines I have worked on about 1 in 3 camshafts have been scrap. The cfamshaft on my brand new 1989 Bis broke after 300 miles  

Got hold of another comp tester which proved the new original tester was faulty, reading a third of what it should.At the time I did check the original on another car which showed ok although I used an adapter and extension piece so that was the cause of the faulty readings  .promptly returned for a refund from ebay supplier, get what you pay for!

185psi on gunson to 70psi on bergen

Adjusted tappets to spec as I had gone that far, 0.15mm  +/- 0.05mm.