Hello, hope I could get some help with fixing our 09 lf45 with 6.7 paccar engine. It has recently started to have lots of crankcase pressure and blows oil out of the breather. I thought it bay have bust the compressor so I removed it and made a blanking plate up so I could run the motor. This made no difference to the situation. The engine starts and runs fine and does not seem to have lost any power. I am getting very concerned that it may be serious. any suggestions would be appreciated.
Stand back boys,shees ready to BLOW !
Only thing that can really cause the symptoms you describe is piston ring blow by.Sounds like the cylinders have glazed up and only cure is get the cylinders honed and a new set of rings.
Can be caused by an engine running cold for long periods eg bad thermostats,or long tick over periods.Diesel “wash” polishes the cylinders.
You will have a melted piston and scored bore ,sorry to be the bearer of bad news .Also if there is any holes in the trunking from the airfilter housing to the turbo then you may have dusted the engine,again not good…
Thanks for the replys, This motor has only done 60000 miles which is why we got it. very bad news is this. What would be the route cause of this disaster? Bad injector? Also what is the repair method, ie liners or in situ rebore or engine out?
Broncobillyboy:
Thanks for the replys, This motor has only done 60000 miles which is why we got it. very bad news is this. What would be the route cause of this disaster? Bad injector? Also what is the repair method, ie liners or in situ rebore or engine out?
If its only done 60 k just pull the pistons and get a good rough honing tool,or if you dont mind a good 2 or 3 hours graft some course emery paper and score the cylinder walls and a new set of rings.
Just make sure you wrap the crank journals with insulating tape to stop grit getting into the oil galleries then when you finished give the block a good wash out.A steam out is best.
Lazy way of doing it is put the truck outside stripped down,grease the crank journals and let the cylinders rust for a week or 2.Thats what they do with dry liner blocks at engine production plants.
Gives the liners a “key” to retain an oil film to lubricate the rings.
There is some history missing here, to start with how long have you owned this vehicle? what servicing has been done during this 60,000 miles etc? Is this a genuine 60,000 or just an interpretation of the tacho reading? Extended oil drain periods only apply to vehicles which cover a significant annual mileage. For it to have melted a piston there must have been an abnormal amount of heat involved and you haven’t mentioned any previous incidents, nor have you mentioned any other of the symptoms one would normally expect to result from this.
You have been given reasons for what appears to be happening and also what is frequently found to be the failing for this particular type of engine. Whatever the problem is you do need to stop using the vehicle and investigate fully.
As always one must rule out the simple causes of any trouble. While it is very unlikely to be what has happened on this occasion, and would require symptoms that you haven’t mentioned, it will take little more than a few minutes to confirm that what you are seeing as crankcase pressure is in fact that, and not steam exiting the breather and depositing oil/water on the ground. Just the smell should help you to confirm what the vapour is.
ringfur:
Stand back boys,shees ready to BLOW !
in your dreams 
I have done a few LFs with breathing issues…Generally ,though not always it is the injector that causes the issue ,you either end up with a melted piston or a cracked piston crown. It is usually just the 1 cylinder that suffers ,number in the 4 cylinder &6 in the 6 cylinder …A good engineering shop will be able to machine out the bore if it is damaged and fit a sleeve to bring it back to standard…I think the company we use charge about £500ish…Or you can over size all the cylinders…If the valves are badly adjusted the valve can overheat and embed itself in the head and piston,Your best to strip the cylinder head off, and then just take it from there .There is no need to remove the engine …The hardest part of the job is the cleaning after the bore has been replaced…Even after you have cleaned to what looks spotless,because it is nearly always the rearmost cylinder machining debri gets in to the timing gear ,so after running for a couple of mins ,it is wise to drain the oil and remove the sump to get the debri out that has now been washed in to the sump
cav551:
There is some history missing here, to start with how long have you owned this vehicle? what servicing has been done during this 60,000 miles etc? Is this a genuine 60,000 or just an interpretation of the tacho reading? Extended oil drain periods only apply to vehicles which cover a significant annual mileage. For it to have melted a piston there must have been an abnormal amount of heat involved and you haven’t mentioned any previous incidents, nor have you mentioned any other of the symptoms one would normally expect to result from this.You have been given reasons for what appears to be happening and also what is frequently found to be the failing for this particular type of engine. Whatever the problem is you do need to stop using the vehicle and investigate fully.
As always one must rule out the simple causes of any trouble. While it is very unlikely to be what has happened on this occasion, and would require symptoms that you haven’t mentioned, it will take little more than a few minutes to confirm that what you are seeing as crankcase pressure is in fact that, and not steam exiting the breather and depositing oil/water on the ground. Just the smell should help you to confirm what the vapour is.[/quote
If he removes the filler cap on the rocker ,if he has back pressure it will look like a steam train with the fumes
Thanks again for all the help. The motor is a genuine 60000 miler as we purchased it off someone we know. It is a skip/bin loader and does spend a lot of time at idle. If the motor is running and you block the breather pipe with your finger, you would only be able to keep your finger on the pipe for about 6 seconds before the pressure blows it off. If the oil filler cap is removed then the pressure comes out of the filler hole and stops at the breather, so rulling out a blockage in the pipework. Will just have to bite the bullet as suggested and strip it down.I just thought it would run rough with these symptoms but its sweet. Guess it can carry a half working cylinder easy enough.
If everything at first glance looks ok check for dusting ,with it being a skip motor if it has been in dusty areas with poor maintainance ,then dusting is a possibility.I have seen it,and always with non OE airfilters fitted.You will see what looks like small geains of dirt on he cylinder walls …and the turbo vanes will be worn
Cheers Norb, will post up the findings. Wont be till next week now. busy putting back together a jcb thats had pistons/liners.
With it being a skip wagon I wonder if it ended up with its nose in the air at daft angle that upset it.
Would suspect other symptoms but is the dipstick innacurate and it over-filled with oil.
Be interested to see what way this goes with such a young engine when you do get the head off.
Own Account Driver:
With it being a skip wagon I wonder if it ended up with its nose in the air at daft angle that upset it.Would suspect other symptoms but is the dipstick innacurate and it over-filled with oil.
Be interested to see what way this goes with such a young engine when you do get the head off.
The dipstick on the LF is a waste of time…it never gives an accurate reading due to condensation build up in the tube …It is so bad even when you refill an engine ,you still can’t tell if there is any oil in it 
I’ll go for melted /cracked piston crown …
norb:
I have done a few LFs with breathing issues…Generally ,though not always it is the injector that causes the issue ,you either end up with a melted piston or a cracked piston crown. It is usually just the 1 cylinder that suffers ,number in the 4 cylinder &6 in the 6 cylinder …A good engineering shop will be able to machine out the bore if it is damaged and fit a sleeve to bring it back to standard…I think the company we use charge about £500ish…Or you can over size all the cylinders…If the valves are badly adjusted the valve can overheat and embed itself in the head and piston,Your best to strip the cylinder head off, and then just take it from there .There is no need to remove the engine …The hardest part of the job is the cleaning after the bore has been replaced…Even after you have cleaned to what looks spotless,because it is nearly always the rearmost cylinder machining debri gets in to the timing gear ,so after running for a couple of mins ,it is wise to drain the oil and remove the sump to get the debri out that has now been washed in to the sump
We used to do this if the customer wanted it when the Gardners picked up a couple of pistons and one liner would clean up but the other wouldn’t. Even with a vacuum cleaner running while the boring and honing was going on and masking off as much of the crankcase as possible, it took forever to clean all the ledges. Happy days 
Lets keep up to speed on this one…has it gone bang yet ?
If it’s running ok then the most likely cause is liner wear, as has been suggested. I wouldn’t bother tearing it apart until it needed it and a bit of blow by isn’t reason enough to do that in my opinion.
First thing I would do is get an oil sample done, check for high levels of oxidation to confirm that it is worn cylinder kits and monitor oil consumption from there, using that to make the decision of when to put new pistons and liners in it.
If the oil sample comes back full of wear metals and extremely high levels if fuel dilution then it’s time to take it apart now.
cav551:
There is some history missing here, to start with how long have you owned this vehicle? what servicing has been done during this 60,000 miles etc? Is this a genuine 60,000 or just an interpretation of the tacho reading? Extended oil drain periods only apply to vehicles which cover a significant annual mileage. For it to have melted a piston there must have been an abnormal amount of heat involved and you haven’t mentioned any previous incidents, nor have you mentioned any other of the symptoms one would normally expect to result from this.You have been given reasons for what appears to be happening and also what is frequently found to be the failing for this particular type of engine. Whatever the problem is you do need to stop using the vehicle and investigate fully.
As always one must rule out the simple causes of any trouble. While it is very unlikely to be what has happened on this occasion, and would require symptoms that you haven’t mentioned, it will take little more than a few minutes to confirm that what you are seeing as crankcase pressure is in fact that, and not steam exiting the breather and depositing oil/water on the ground. Just the smell should help you to confirm what the vapour is.
Sounds like a monologue from Paul Whitehouse!
Unfortunately I was very drunk at the time.