Should I still be burning oil?

A couple of months ago I developed a knocking noise which turned out to be piston slap from a cracked (and breaking up) piston.

I have since replaced all 4 pistons and rings and had the head skimmed and the valves re-ground. I didn't have it re-bored but the cylinders were honed.

I have now done about 350 miles since the rebuild and I still get a LOT of blue smoke on start up, especially 1st thing on a morning. Is this right?

Daz

SuperDaz said:

A couple of months ago I developed a knocking noise which turned out to be piston slap from a cracked (and breaking up) piston.

I have since replaced all 4 pistons and rings and had the head skimmed and the valves re-ground. I didn't have it re-bored but the cylinders were honed.

I have now done about 350 miles since the rebuild and I still get a LOT of blue smoke on start up, especially 1st thing on a morning. Is this right?

Daz

Click to expand...

Did you put new valve seals on when you did the valves?

What engine do you have? It could be down to a whole number of things. To put things into perspective, the worst case scenario is broken / stuck rings, and it can't be anything worse than that if it wasn't doing it before the rebuild. My first guess would be that the rings haven't bedded in yet. When you say the bores were honed, do you mean the glaze was broken using a glaze busting tool that you stick in a drill? It is crucial that you use a very cheap 100% mineral oil for the first thousand or so miles after fitting new rings, just to ensure that there is enough lubrication to prevent the piston rings from over heating, expanding and ceasing, but enough friction to allow the rings to bed into the bores (which will undoubtedly be slightly oval depending on how many miles it's done).

It could also be something as simple as the head gasket not sealing properly. If for example when you cleaned the surface of the block and the head, there was a slight high spot, or perhaps even an oily patch, it will allow oil to seep from the oil channels / push rod slots into the bores which will then be burned. You did fit the gasket totally dry didn't you? There should be absolutely no gasket goo used on a head gasket what so ever (as I learned the hard way!)

Then again, it could just be a build up of oil in the exhaust manifold or if you are luck enough to have a turbo diesel, the turbo seals could be on their way out.

Also, do bear in mind that an older "fits where it touches" kind of engine like the N/A TD 200 and 300 tdi's will burn oil until they're bedded back in, which could even take a thousand miles or so.

The possibilities are endless!
-Pos

Sorry boys, I should have given more detail. The engine is a 2.5D N/A with 178K on the clock.

I was made redundant in March and this was a fix-it-on-the-drive jobby just to get me mobile again as cheaply as possible (but using quality parts).

iannotts said:

Did you put new valve seals on when you did the valves?

Click to expand...

I don't know is the answer. The head was skimmed, the rockers re-faced and the valves re-ground by a friend who has his own engine business. It was all done F.O.C. so I can't complain if they weren't. It did burn oil before, but not this much.

pos said:

My first guess would be that the rings haven't bedded in yet. When you say the bores were honed, do you mean the glaze was broken using a glaze busting tool that you stick in a drill? It is crucial that you use a very cheap 100% mineral oil for the first thousand or so miles after fitting new rings, just to ensure that there is enough lubrication to prevent the piston rings from over heating, expanding and ceasing, but enough friction to allow the rings to bed into the bores (which will undoubtedly be slightly oval depending on how many miles it's done).

Click to expand...

Yes and yes

pos said:

It could also be something as simple as the head gasket not sealing properly. You did fit the gasket totally dry didn't you?

Click to expand...

Yes and all torqued up in the correct sequence.

pos said:

Also, do bear in mind that an older "fits where it touches" kind of engine like the N/A TD 200 and 300 tdi's will burn oil until they're bedded back in, which could even take a thousand miles or so.

The possibilities are endless!
-Pos

Click to expand...

Maybe at 350 miles I'm worrying for nothing then?

Thanks boys.

If the smoke is on start up and it clears after a little while it'll probably be caused by oil seeping through the valve guides while the engine is not running. When you start it it burns off and causes the smoke. It's pretty normal on most LR diesel engines. If the smoke persists while you're driving then the above posts have probably got it covered.

The N/A! My old favorite

First thing to do is remove the short piece of breather pipe between the oil filler cap and the intake manifold. This little bugger can lead to all sorts of problems, BUT it also prevents problems which I'll explain in a moment. With the pipe removed. Start the engine and allow it to tick over / rev it up to temperature and then perform the following test:

1) Remove the oil dipstick from the dipstick tube and press your thumb firmly over the hole.

2) Observe the breather outlet on the oil filler cap. The oily mist ('blow-by') that you see gushing out of the hole should increase slightly.

3) Next, fully block the breather outlet on the oil filler cap and also press your thumb firmly over the dipstick tube and hold both hands in place for 5 seconds.

4) After 5 seconds, uncover the dipstick tube. Does it produce a loud hiss, and / or spray any oil out at you?

If this is the case, you need not worry. With time these engines become tired, and even following a rebuild there will still be intolerances due to the ovality of the bores which are worn into an elongated shape over the years of hard work. THIS ISN'T THE END OF YOUR ENGINE THOUGH! No, not by any means! It s generally accepted that the N/A is one of Land Rovers most solid and reliable engines and it genuinely will last for ever providing it's well serviced.

If you did notice a lot of blow by from the test above, then the oil that you are burning is undoubtedly being fed to the engine via the breather pipe that you removed earlier. Basically any combustion that seeps past worn oil seal rings or piston rings that don't quite fit blows oily fumes straight down that pipe and back into the air intake, where the oil is then obviously drawn into the cylinders and burned as fuel, hence the blue smoke.

You do not however, want to remove the breather pipe completely. It prevents your engine from developing oil leaks due to the build up of pressure. The whole idea of the breather being that the downward stroke creates a vacuum which draws the escaped combustion pressure into the cylinders. You should fit an oil catch tank which will keep the breather in place, but prevent any oil from getting into the engine.

Eventually if you hadn't have done anything, the engine would have run on its own oil where it effectively sucks so much oil into the cylinders that it revs higher and higher and the only way to stop it is by whacking it into fifth and braking as hard as you can. If that fails BOOM!!!

-Pos

If it disappears after a short while from starting then don't worry about it. Are you using a lot of oil?

Every morning when I put my foot down after the first take off, I get a puff of blue smoke which is the oil that has leaked down the valve stem. On tickover it doesn't pull much cold oil into the cylinder to be burnt, but as soon as I give it a little go pedal it pulls it in, burns it and thats it. It looks worse from the cold engine.

I need to top up my oil by about a mugful every 1000miles ish (I also have a leak from the sump) now that isn't bad.