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PCV & Crankcase Breather or Tappet Chest Advice MK21970 MCS
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Author:  XC9000 [ Sun Feb 14, 2021 2:00 pm ]
Post subject:  PCV & Crankcase Breather or Tappet Chest Advice MK21970 MCS
Seeking advice: A fully reconditioned 9FXEY engine when started (hard to start BTW, yet HS2s cleaned and working well) resulted in a fog level of apparent steam being emitted from the exhaust. Oily plugs. Further inspection revealed oil emitting from tappet chest and onto extractors. Discussion with knowledgeable friends led to crankcase pressure forcing oil upwards past oil rings into chamber and being burnt off. Third start exhaust emission now more bluish. The block and head were crack-tested (APM) no problems. No oil in water, no water in oil. Neither the PCV or crankcase oil separator on the tappet chest have been 'serviced' - ever. I seemingly cannot buy a new tappet chest/oil separator. What I need to know is; 1. Can I 'service' (clean) the tappet chest oil separator (or is that necessary; 2. Can I simply replace the diaphragm in the PCV, or should I bite the bullet and replace the entire PCV? 3. Am I entirely on the wrong track? Most grateful for your advice - pleeeeze! Wayne
Author:  Stibbsy [ Sun Feb 14, 2021 2:21 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Careful when purchasing a diaphragm for the PCV. Quality is lacking from some suppliers. Mine lasted all of 30 minutes on initial start of my rebuilt Mk2 engine. Luckily the old diaphragm that was 30 years old was on the bench. It has a much thicker texture. Still in the PCV, that was two years ago.
Author:  ausdino [ Sun Feb 14, 2021 2:40 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
When you say " A fully reconditioned 9FXEY engine " , is it run in and the rings bedded ?
Author:  drmini in aust [ Sun Feb 14, 2021 4:28 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Re the 'oil separator' you can pull the mesh out the bottom and replace with a SS pot scourer.
I cut the bottom off mine to do this but others have hooked it out through the tube.

Edit
Blowby caused by rings broken on assembly?
Author:  Bill B [ Sun Feb 14, 2021 6:26 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Head gasket issue letting water into a cylinder?
Are you running water or coolant for start-up. A school of thought suggests using plain tap water to start up and initial running-in. I don't know why.
Excessive ring gaps on assembly?
Excessive crankcase pressure can also push oil past the clutch oil seal and you will see drips on the splitpin under the transfer cover.

PM sent too.
Author:  Hinesy1275 [ Sun Feb 14, 2021 9:13 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
A possible symptom is if you're also having excess oil within the rocker cover, is incorrectly installed front cam bearing. There is a 'slot' and a 'hole' within the front cam bearing, the latter needs to be towards the top of the block.

If the 'slot' has been inserted toward the top, the cutout groove on the cam's front journal will force a 'blip' of oil every rotation up the gallery towards the rocker pedestal.

Remove rocker cover and observe if excess oil is evident under idle.
Author:  1071 S [ Mon Feb 15, 2021 1:04 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Hi Wayne, "....Discussion with knowledgeable friends led to crankcase pressure forcing oil upwards past oil rings into chamber and being burnt off..."

I'd be really interested in having you knowledgeable friends explain where the crankcase pressure is coming from.

IME crankcase pressure results from exhaust/compressed gasses escaping - downwards - past the rings due to inadequate sealing.

BTDT...

Thankfully by the third rebuild I had a third party have a look and they identified the real problem.... bad cylinder machining. The original (and second) builder turned out to be totally reputable and accepted the error when pointed out to him. I got a refund on the second build and a third rebuild that included the new pistons that proved necessary. (Bring wine and I can expand .. :)

Its not too hard to differentiate between steam (not unusual and harmless) and oily smoke. Steam will billow about and dissipate quickly whereas smoke sort of just thins out and hangs around (unless there's a wind to blow it way). Your nose will also help with an ID.

Cheers, Ian

PS Your malady is not that unusual if the rings are not bedded in properly..
Author:  XC9000 [ Mon Feb 15, 2021 5:39 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Stibbsy wrote:
Careful when purchasing a diaphragm for the PCV. Quality is lacking from some suppliers. Mine lasted all of 30 minutes on initial start of my rebuilt Mk2 engine. Luckily the old diaphragm that was 30 years old was on the bench. It has a much thicker texture. Still in the PCV, that was two years ago.

Thanks Stibbsy. I appreciate the knowledge. Wayne
Author:  XC9000 [ Mon Feb 15, 2021 5:44 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
ausdino wrote:
When you say " A fully reconditioned 9FXEY engine " , is it run in and the rings bedded ?

Thanks Ausdino. The engine has been run 1 minute, then two, then three, then driven for no more than another three. So no, I dont expect 9 minutes at low revs is enough to bed them in. Also, I used XLD 20W-50 for start up as not to be too thin. Appreciate your thought. Wayne
Author:  XC9000 [ Mon Feb 15, 2021 5:50 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
drmini in aust wrote:
Re the 'oil separator' you can pull the mesh out the bottom and replace with a SS pot scourer.
I cut the bottom off mine to do this but others have hooked it out through the tube.
Edit
Blowby caused by rings broken on assembly?


I always respect your opinion. Thank you. I hope there are no broken rings and will probably only know if I have to rebuild (again).
With the Oil Separator I'll give hooking out the mesh as go and replace it with stainless if I get it out. Given you have cut the bottom of it in the past tells me you were serious about cleaning the damn thing. Its a wonder Mowog didnt fit a screw cap on it in the first place and allow cartridge styled replacements??? Wayne
Author:  XC9000 [ Mon Feb 15, 2021 5:58 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Bill B wrote:
Head gasket issue letting water into a cylinder?
Are you running water or coolant for start-up. A school of thought suggests using plain tap water to start up and initial running-in. I don't know why.
Excessive ring gaps on assembly?
Excessive crankcase pressure can also push oil past the clutch oil seal and you will see drips on the splitpin under the transfer cover.

PM sent too.

Thanks for the PM Bill. I've responded.
We did use only water to start off with intending to drain and fill the moment we knew the engine wasnt being removed. Rightly or wrongly - just our own logic.
Dr Mini (whom we respect) also mentioned rings. On rings, I didnt post originally - before starting the compression readings were around 175, later when the mass emissions occurred we re-tested and got 210-225psi - amazing so, we had two test gauges and got the same results with both gauges. But that doesnt set aside the oil rings issues...
I had not known to consider the oil leaking through the clutch seal - I hope not - but I will take it on board and watch out for that tell-tale. Thanks again Bill.
Wayne
Author:  XC9000 [ Mon Feb 15, 2021 6:00 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
Hinesy1275 wrote:
A possible symptom is if you're also having excess oil within the rocker cover, is incorrectly installed front cam bearing. There is a 'slot' and a 'hole' within the front cam bearing, the latter needs to be towards the top of the block.

If the 'slot' has been inserted toward the top, the cutout groove on the cam's front journal will force a 'blip' of oil every rotation up the gallery towards the rocker pedestal.

Remove rocker cover and observe if excess oil is evident under idle.

I'll check it out in due course Hinesy. Thanks
Author:  XC9000 [ Mon Feb 15, 2021 6:03 pm ]
Post subject:  Re: PCV & Crankcase Breather or Tappet Chest Advice MK21970
1071 S wrote:
Hi Wayne, "....Discussion with knowledgeable friends led to crankcase pressure forcing oil upwards past oil rings into chamber and being burnt off..."

I'd be really interested in having you knowledgeable friends explain where the crankcase pressure is coming from.

IME crankcase pressure results from exhaust/compressed gasses escaping - downwards - past the rings due to inadequate sealing.

BTDT...

Thankfully by the third rebuild I had a third party have a look and they identified the real problem.... bad cylinder machining. The original (and second) builder turned out to be totally reputable and accepted the error when pointed out to him. I got a refund on the second build and a third rebuild that included the new pistons that proved necessary. (Bring wine and I can expand .. :)

Its not too hard to differentiate between steam (not unusual and harmless) and oily smoke. Steam will billow about and dissipate quickly whereas smoke sort of just thins out and hangs around (unless there's a wind to blow it way). Your nose will also help with an ID.

Cheers, Ian

PS Your malady is not that unusual if the rings are not bedded in properly..


Hey mate
We probably should have had you involved in this. Red wine and all. I'll take it on board and maybe give you a call.
Its probably worthy of me coming over for the meeting Wednesday just to chat this matter out.
I'll SMS you or call.
Cheers, Wayne
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