Tech Support Forum banner
Status
Not open for further replies.
1 - 7 of 7 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Dear sir

I am facing the high blow by/oil spitting through internal breather in newly designed diesel engine.

for your information

1. The barrel size & piston sizes are ok
2. the engine vaccum is ok
3. There is no external leakages
4. Lub oil temp is around 135 deg centigrade

the other engine PDI parameters are ok.


Please help me to come out of this problem.



Regards

Sajjan M.B.
 

·
Moderator Automotive Center
Joined
·
2,755 Posts
Hi sajjan1969


Excessive blow-by is compression leaking through the rings or the piston to cylinder wall gap is passed tolerance. Do a leak down test on all cylinders find out which cylinder is leaking.


Question: Were the cylinders oversized and re-sleeved?


post back your findings.
 

·
Premium Member
Joined
·
2,172 Posts
I valve timing is not right, you can get excessive cylinder pressure, which can cause blowby.

If it's a fresh rebuild, you'll often get blowby for the first few hundred miles until the rings seat.
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #5 ·
Sir
We are manufacturing the single cylinder diesel engine.
Dimensional report are


1. The cylinder size is OK ,The problem facing on fresh component( fresh CYLINDER & piston measured one.
The clearnce between cylinder & piston is 0.080 mm&

The TOP Ring end gap is around 0.25 to 0.35 mm

The rejection is around 1% to 2 % engine in house.
Even though the ok engine sent form plant 0.2% of engine breather leak in field also( it converts in high lub oil consumption in field the oil is completely empty from oil sump).

Further guide line please

Regards

Sajjan M.B.



Hi sajjan1969


Excessive blow-by is compression leaking through the rings or the piston to cylinder wall gap is passed tolerance. Do a leak down test on all cylinders find out which cylinder is leaking.


Question: Were the cylinders oversized and re-sleeved?


post back your findings.
 

·
Registered
Joined
·
560 Posts
I have had were a new engine gets blow by cause the ring is not seating .... not good cross hatching ... what we use to do was mix up a mixture of water & comet or any other type that is gritty ... with the engine running we would pour it in a little at a time ... makes a hell of a smoke cloud but it help to like sand blast the cyl walls and get rid of any glazing on them, then take it for a ride and wind it up and down for a couple min


do you have the 2 compression rings so the gaps are 180 deg from each other

if you are 100% sure the rings are 100% good . then your exhaust valve has to opening to late ... first thing you need to do is like octaneman said ... DO a leak down test dont say oh the rings are this gap and that gap DO the test ... testing is the only way to discover the prob ... you ask for our help and a damn good tech told you what you needed to do
 

·
Registered
Joined
·
560 Posts
forgot about one other thing
crank case ventilation
Since diesel work on much higher compression its a lot easier to build up pressure in the engine oil bath system... you need to make sure that engine is breathing good enough to release pressure in it.If you dont have a PCV valve you will need to add one and you might need to add a breather filter to the valve cover
 
1 - 7 of 7 Posts
Status
Not open for further replies.
Top