Thread: Td5 Blowby, Okay or too much?

quite a few kilometres left in that by the look, it's breathing but I've seen worse , agree to run it back through the catch can .
If you get someone to rev it while looking at the oil filler and it reduces the breathing while revs climbing then it'll more than likely be fine especially under load / boost as it will push the rings harder into the bores giving a better seal.
If it smokes worse with revs climbing then it could indicate excessively worn , broken or stuck rings or worn bore ( usually caused by dusting of engine )

maybe start looking for another to build up while still driving yours

Originally Posted by discorevy

quite a few kilometres left in that by the look, it's breathing but I've seen worse , agree to run it back through the catch can .
If you get someone to rev it while looking at the oil filler and it reduces the breathing while revs climbing then it'll more than likely be fine especially under load / boost as it will push the rings harder into the bores giving a better seal.
If it smokes worse with revs climbing then it could indicate excessively worn , broken or stuck rings or worn bore ( usually caused by dusting of engine )

maybe start looking for another to build up while still driving yours

Thanks for that, somewhat good news, I have a feeling I’ve checked it while revving it up and made no difference to smoke but I’ll double check it.
Good idea about building another engine while still driving it. As a student unfortunately I can’t quite afford to do everything at once.

Originally Posted by LeakinOil

It was up to operating temp as I’d just been for a drive, when it’s cold there’s no pressure at all coming from the crank - I had heard that is normal but not sure how that works as you’d think with the engine cold and everything not expanded there would be more but maybe someone could answer that.
It’s already got a flashlube catch can fitted which definitely catches a lot.
Thanks

When I was running a mineral oil (Valvoline Super Diesel 15w-40 Premium Mineral) my crankcase blow-by was measured at 58 L/Min at idle, 76 L/min cruising in top gear at 100kph with TC locked, and the oil collection in my flashlube catch can was averaging 20mm per 1000km**. I have since changed to a Full Synthetic Oil which by the way is the Land Rover specified oil for the TD5 engine, and I find that the oil collection in the catch can has halved - and is now at 10ml per 1000km which seems to reflect the fact that Full Synthetic Oil has way less volatile components than a Mineral Oil.
I intend to repeat the crank case blow-by test now that the full synthetic oil has been in for a while and will try to get to that over Easter and post the results here.

** i have retained all the oil collected by the Flashlube Catch Can since its installation 12000km ago for future oil analysis. Mineral and synthetic are each in separate containers. My ODO reading is currently 417999km.

Originally Posted by onebob

When I was running a mineral oil (Valvoline Super Diesel 15w-40 Premium Mineral) my crankcase blow-by was measured at 58 L/Min at idle, 76 L/min cruising in top gear at 100kph with TC locked, and the oil collection in my flashlube catch can was averaging 20mm per 1000km**. I have since changed to a Full Synthetic Oil which by the way is the Land Rover specified oil for the TD5 engine, and I find that the oil collection in the catch can has halved - and is now at 10ml per 1000km which seems to reflect the fact that Full Synthetic Oil has way less volatile components than a Mineral Oil.
I intend to repeat the crank case blow-by test now that the full synthetic oil has been in for a while and will try to get to that over Easter and post the results here.

** i have retained all the oil collected by the Flashlube Catch Can since its installation 12000km ago for future oil analysis. Mineral and synthetic are each in separate containers. My ODO reading is currently 417999km.

Oil consumed can also depend on the additive package.
Some blends are more suitable with certain ring materials and bore finishes and sometimes a simple change in oil brand can dramatically reduce oil consumption.

Full syn oils are less volatile, the number to look for on a spec sheet is the NOACK number. (Often not published unfortunately)
Anything under 10 is very good, the lower the number the better.

Ring seal is a funny one, I was always told that ester based oils are generally better in that regard and my own dyno testing back in the early 90's seemed to bear that out but I don't think that holds 100% true anymore.

So how much is too much? Well there is no published spec for Td5 crankcase pressure that I could discover, however absolute crankcase pressure is not difficult to measure with a homemade water manometer and for what it is worth my result may serve for comparison purposes for a +400,000km 10P Td5.

NB-Measuring blow-by L/min is more involved and requires an additional piece of metering apparatus and is derived by sampling absolute crankcase pressure. What you want to measure depends on what you want the data for.

Originally Posted by onebob

So how much is too much? Well there is no published spec for Td5 crankcase pressure that I could discover, however absolute crankcase pressure is not difficult to measure with a homemade water manometer and for what it is worth my result may serve for comparison purposes for a +400,000km 10P Td5.

NB-Measuring blow-by L/min is more involved and requires an additional piece of metering apparatus and is derived by sampling absolute crankcase pressure. What you want to measure depends on what you want the data for.

Great bit of information there, might make myself up a manometer and see what happens. At least at the moment there’s plenty of time to do these jobs!

Well good news in that when I rev the engine up it makes quite a significant difference, the smoke from the fill cap pretty much all but disappears

Originally Posted by LeakinOil

Well good news in that when I rev the engine up it makes quite a significant difference, the smoke from the fill cap pretty much all but disappears

.... indicating that your depression control valve is open