Crank case pressure ?

[makeitfit]

Noticed tonight while "TESTING" the Black Pearl, that I have a bit of crank case pressure
Enough to blow oil out of the open oil blow by return pipe.
I've done a compression test on all 4 cylinders. 520 psi each near as damn it and hardly any change when oil added.
Anyone know what sort of figures are healthy ?
Assuming rings are OK , could the crank case be pressurising from worn valve seats, or stems ?

 

[solarman216]

Noticed tonight while "TESTING" the Black Pearl, that I have a bit of crank case pressure
Enough to blow oil out of the open oil blow by return pipe.
I've done a compression test on all 4 cylinders. 520 psi each near as damn it and hardly any change when oil added.
Anyone know what sort of figures are healthy ?
Assuming rings are OK , could the crank case be pressurising from worn valve seats, or stems ?

CC pressure can only come from piston by pass, do not worry about it, Rick

 

[rustic]

Check oil level, other than that you might need a catch can, return the oil to the crankcase.

See:-

http://oilcatchcan.com

 

[makeitfit]

I have a catch can already that takes rocker gases. I'll modify that to incorporate crank pressure too.
I've not returned it to the intake :sly so I can use both connections "inlets" and simply vent the can to atmospheric pressure.
That should let the old girl breath :thumb2

 

[rustic]

I have a catch can already that takes rocker gases. I'll modify that to incorporate crank pressure too.
I've not returned it to the intake :sly so I can use both connections "inlets" and simply vent the can to atmospheric pressure.
That should let the old girl breath :thumb2

The rocker box is connected to the crankcase within the engine anyway, That's how new oil or rocker oil gets to the sump. :thumb2

 

[macabethiel]

Crank pressure

CC pressure can only come from piston by pass, do not worry about it, Rick

I agree with Solarman216 don't worry about it. With the extra pressure that diesels run at they all seem to have some by-pass. You can always put a little 2T oil in your fuel he help reduce it if it bothers you.

 

[Monaro Pete]

I agree with Solarman216 don't worry about it. With the extra pressure that diesels run at they all seem to have some by-pass. You can always put a little 2T oil in your fuel he help reduce it if it bothers you.

With the lack of sulphur in diesel nowadays I used to put some 2 stroke in the tank of the Omega 2.2 DTi. The pump internals required the sulphur as a lubricant so this made a good substitute :thumb2

 

[makeitfit]

Ah ha yes I understand :thumbs
I already have an oil catch can but it's collected nothing yet from the rocker. However I did get a lot of oil squirting out the crank case.
So if I block the crank case tube will the rocker breather / vent be sufficient to relieve the whole engine's pressure ?

 

[solarman216]

Which crank case tube are you referring to? Rick

 

[Lazy-Ferret]

I thought the tube from crank case, on the Turbo side of the engine is actually an oil return from the control valve, the crankcase pressure relief is from the top of the engine via the rocker cover.

 

[makeitfit]

Ah sorry I forgot it's another mod on mod :lol
I no longer have the oil blow by trap thingy. The old pipe that was the return to sump from it is still in place though. It's through that the oil has been shot out of under some enthusiastic turbo testing :sly

 

[solarman216]

Ah well it will, that is precisely why most engines are allowed to breath via the rocker cover, your crankcase is full of oil mist and droplets, it settles down time it reaches the top end, Rick

 

[Terrano Steve]

Noticed tonight while "TESTING" the Black Pearl, that I have a bit of crank case pressure
Enough to blow oil out of the open oil blow by return pipe.
I've done a compression test on all 4 cylinders. 520 psi each near as damn it and hardly any change when oil added.
Anyone know what sort of figures are healthy ?
Assuming rings are OK , could the crank case be pressurising from worn valve seats, or stems ?

Not tried adding oil but as I am changing glow plugs just thought I would do a dry compression test.

 

[solarman216]

Thought Pete's numbers were high, just had a look at the manual, 427 psi is the good normal, 356 is minimum, both at 200 rpm so you need to get your gauge checked/calibrated Pete, regards Rick

 

[rustic]

Check all 4, if they are all close to each other, then take that as a sign of a good engine.
If one is well down, then you have a problem.

Here is a question..
Would using mineral engine oil in the sump, give better compression than synthetic for the same viscosity.
Equally, would a higher viscosity oil in general improve things?
Are there oil additives that could improve things too.

DIY meters could well show an error, what is important is repeatability, ie how close to each other are three readings say for the same cylinder.

Rustic

 

[makeitfit]

Thought Pete's numbers were high, just had a look at the manual, 427 psi is the good normal, 356 is minimum, both at 200 rpm so you need to get your gauge checked/calibrated Pete, regards Rick

Hmmm interesting ? I'll recheck tonight and see what's what ?

 

[makeitfit]

Update

HELP .
Revisiting this issue.
Today I have had great fun "testing" the boost and right foot action on the Pearl. All seemed well till I could smell OIL
Opened the bonnet to see that awful sight of an engine bay totally awash in spewed out oil
It turns out the engine had filled my oil catch can in about 30 miles. ( some of that was spent at full chat :naughty) , the resulting over spill being pressured enough to spray round the engine bay.
There was also some out the end of the dipstick tube. I'd recently PTFE taped that too.
Engine never got to half way on the temp gauge and no missfire once warm.
So tonight I've started the investigations with multiple comp tests while the engine was still warm.
It's a bugger to do accurately . I did the first round at as near one / two compressions as I could .
Figures were 200, 180, 200, 200
Then again at near enough 3/4 compressions
Figures were 270, 270, 250, 270
Then as a comparison, several seconds of cranking till the gauge maxed, resulting figures were 470, 500, 500, 500
No great difference repeating it self anywhere :nenau
Next I dropped in a bit of oil to each cylinder and repeated the 2/3 compression cycle and got the following figures 320, 320, 340, 350 ?

So with oil added there is an increment of a bit over 15% . is this a typical increment following oil test ?

No time tonight to get the rocker cover off for valve clearances but what do you guys reckon is going on ?
Have I killed the Pearl :bow

 

[solarman216]

Odd one this Pete, you are not overfilled with oil are you? this would cause this issue as would crankcase breather blockage, wait to hear, Rick

 

[Banshee]

HELP .
Revisiting this issue.
Today I have had great fun "testing" the boost and right foot action on the Pearl. All seemed well till I could smell OIL
Opened the bonnet to see that awful sight of an engine bay totally awash in spewed out oil
It turns out the engine had filled my oil catch can in about 30 miles. ( some of that was spent at full chat :naughty) , the resulting over spill being pressured enough to spray round the engine bay.
There was also some out the end of the dipstick tube. I'd recently PTFE taped that too.
Engine never got to half way on the temp gauge and no missfire once warm.
So tonight I've started the investigations with multiple comp tests while the engine was still warm.
It's a bugger to do accurately . I did the first round at as near one / two compressions as I could .
Figures were 200, 180, 200, 200
Then again at near enough 3/4 compressions
Figures were 270, 270, 250, 270
Then as a comparison, several seconds of cranking till the gauge maxed, resulting figures were 470, 500, 500, 500
No great difference repeating it self anywhere :nenau
Next I dropped in a bit of oil to each cylinder and repeated the 2/3 compression cycle and got the following figures 320, 320, 340, 350 ?

So with oil added there is an increment of a bit over 15% . is this a typical increment following oil test ?

No time tonight to get the rocker cover off for valve clearances but what do you guys reckon is going on ?
Have I killed the Pearl :bow

Ah Pete bad luck mate

That's two TD27's in a week

The ZD30 boys must be wetting themselves :doh

 

[macabethiel]

Crankcase pressure issue ?

Not sure where you are with this now but in the olden days there used to be steel mesh gauzes inside the top of some manufacturers rocker covers with a metal strip spot welded inside to act as a splash shield. You had to replace the whole rocker cover as a service item after around 60k miles as the gauze would bung up and stop the engine from venting.

Does your rocker contain such a thing ?