300 tdi smoking and excess crankcase pressure assistance sought

Hi all, after some pointers to my g/f's Disco problems.

I've changed the head gasket twice, first time using a metal sandwich gasket, then removed the head again gave it a poor man's skim (glass plate and 600 grit wet and dry) to remove any high spots and used the normal gasket type as this seemed better for a less than perfect head/block interface.

On reassembly all seemed OK, started up OK but on driving seem to be ejecting oil from somewhere accompanied by hissing sound.

I'm guessing this could still be a head issue, but what else could cause this, we were due to go away in it next week but looks like the Skoda will be called upon!

If anyone's local and fancies a look please let me know. (Burntwood or Swadlincote area depending on where's best!)

Any other input appreciated.

Cheers

Glenn

grogers said:

Hi all, after some pointers to my g/f's Disco problems.

I've changed the head gasket twice, first time using a metal sandwich gasket, then removed the head again gave it a poor man's skim (glass plate and 600 grit wet and dry) to remove any high spots and used the normal gasket type as this seemed better for a less than perfect head/block interface.

On reassembly all seemed OK, started up OK but on driving seem to be ejecting oil from somewhere accompanied by hissing sound.

I'm guessing this could still be a head issue, but what else could cause this, we were due to go away in it next week but looks like the Skoda will be called upon!

If anyone's local and fancies a look please let me know. (Burntwood or Swadlincote area depending on where's best!)

Any other input appreciated.

Cheers

Glenn

Click to expand...

did you have it pressured tested?.Could have a crack in it somewhere.

Hi, no didn't have it pressure tested as the original reason for removing the head was to fix/replace a leaky core plug at back of engine block (now temporarily bodged until the return of warmer weather and use of a unit to remove engine permit!) there wasn't an issue with the head that i was aware of but i guess it's possible.

Replaced valve stem seals and lapped in valves while head was off, i've yet to recheck tappet clearances though since run, but doubt this would cause issues?

Only plus side to this is the underneath now seems to be getting a nice coating of engine oil so at least it'll slow down any chassis rot!

Hoping to have another look today while it's light see if i can locate the leak, and see what colour the smoke is..........

Update:

Found where the oil is coming from it's coming from the sump at the rear, nearest the bellhousing between the two larger spaced bolts, also found I'd neglected to reconnect the vacuum advance from turbo to fuel pump doh!

Smoking only occurred after acceleration but not tried again since reconnecting above hose, as the oil is being ejected at a fair rate of speed!

gemsdad said:

did you have it pressured tested?.Could have a crack in it somewhere.

Click to expand...

LOL he didn't even have it skimmed properly what makes you think he would spend the money having it pressure tested.

Yep couldn't be bothered to set it up on the mill and skim it, no distortion to bother the dti much so just flatted it off.

Guess pressure testing may have shown any faults up but as head was ok before it came off (No hgf just the leaking block core plug) i rather thought things would be tickety boo on reassembly that and the rather tight timescale rather hampered things lol

Only difference from before and after is reground valve seats and a new gasket, so things may have not been all that well before hand it'll have to wait till after the holiday now, you watch it flood it the lake district now i'm going in the Skoda!

Just to update this old thread and for anyone else that may suffer a similar problem. The cause of excess pressure was ......

wait for it you'll laugh when you find out ...

it was ...

The naffin cyclone breather was defective, the hole that was supposed to be under the spring loaded diaphragm hadn't been punched out, so the pressure was just building and not being vented, never thought to check it as it was a new part!! Next time i buy one i'll try blowing into it make sure the chuffin thing is working!!

That's sorta typical of replacement parts

Rich.