I'm stumped

[strada-caster]

Strada-caster:
The best way to check 'the rings' theory is to measure the gas flow coming from the vent hose The pressure test is useless when it comes to the issue like this; there is enough liquid in the pistons to seal the gaps. Ideally you need a rotameter and the numbers to compare the readinds with. I am not sure about your engine but the numbers for a 4M40 are as follows; anything under 20 L/min is excellent, 20-40 L/min is fair and readings above 50 L/min will tell you that the piston rings are not working properly. One of rotameter examples is a household gas flow meter. There are some tecniques you can use without a rotameter; the picture below is showing the idea. Collect the vent gas into a plastic bag for 1 minute and push it into the measuring tank. On the second picture you can see how to use a household gas flow metering device. There might be some other ways of doing it in your home garage but don't rely on a pressure test.

how does gas from the crankcase breather tell you the rings are bad? correct me if i'm wrong but isn't that gas coming from blow-by past the valve seals?

[Profister]

I have to tell the story 'how a combustion engine works' to answer your question in details. I hope this brief excerpt from Wiki helps:

'Internal combustion inevitably involves a small but continual amount of blow-by, which occurs when some of the gases from the combustion leak past the piston rings (that is, blow by them) to end up inside the crankcase.'

I also hope this does not start another off-topic discussion.

[Morganizer]

Have you checked for a dragging brake? After driving, feel each brake. The one that's (ow!) hot needs servicing.

If both rear brakes are warm, lube/adjust your emergency brake cable.

(I know it makes the mystery less exciting if it turns out to be this, but at least it's easily fixed.)

[strada-caster]

I have to tell the story 'how a combustion engine works' to answer your question in details. I hope this brief excerpt from Wiki helps:

'Internal combustion inevitably involves a small but continual amount of blow-by, which occurs when some of the gases from the combustion leak past the piston rings (that is, blow by them) to end up inside the crankcase.'

I also hope this does not start another off-topic discussion.

this blow by is DOWN into the crankcase. there must be a route from the bottom end to the top end (camshaft area) since oil is found up there. do the blow by gases follow a similar route to exit at the top of the engine?

[Profister]

Correct. I hope this simple picture helps but I assume that everybody has this basic knowledge.

[strada-caster]

looking back at my last question I don't even know why I asked that, I knew that already....

unfortunately, it's looking like the oil rings on my engine have/are going bad... or maybe the valve stem diameter is worn (new seals would still allow oil to pass), or the shop didn't lubrcate the valve seals for install and new ones quickly became old ones.
-new valve seals didn't make any difference(possible install screw up?)
-engine starts the exact same way if I remove the piping from turbo to intake, turbo/pcv is not the culprit
-a leak-down test won't tell me anything useful, at this point in time I don't care if valve isn't seating correctly, it's not the oil problem and won't fix my problem.

I'm burning oil upon start-up and the only way to accomplish that is from the internals at this point. I've eliminated everything else.

So, how bad is it to run an engine with bad oil rings?? compression rings seem to be ok (from my compression test results)
this is our second vehicle for the winter, I'll only be using it when necesary(4x4 since other vehicle doesn't have it) and for sledding(probably only on weekends)
it will see some -30° Celsius temps...

[thedjjack]

Burning oil at start up generally is the valve seals. As the oil leaks into the cylinder and at start up there is lots of oil.

Running a diesel that is burning oil is not bad since diesel is oil.

I wonder if you have a cracked head or head gasket problem. As it heats up the leak could increase and it could leak oil shutting off warm and oil gets into the cylinder. Head/Gaskets do not always mix oil/coolant or leak compression depends where the failure is occurring.

A good diesel mechanic should be able to diagnose for you. If you compression reading was on a cold motor the failure might not be showing up.

good luck....

[legionnair]

Simple to test rings, use your compression tester test the holes the add a small squirt of engine oil to the cylinder, if the compression improves after the addition of oil then that hole has worn rings. If the cylinder does not improve after the addition of oil then its burned valve or cracked head and the you want to use compressed air to see if you can isolate the leak.
If you are losing 700 ml of oil per 3500 km and your halve moon gasket is leaking then that is the problem. Looking for something more is a waste of your time. The small puff of blue on start up ignore it, unless it is a steady stream of blue smoke while driving.

[Strada 92]

700ml of oil for 3500km is perfectly normal.
Oil consumption can be as high as 1L/1000km max. under severe driving condition and 1L/1500km max. under normal driving condition, following the specification
from the lubrication chart coming from Mitsubishi shop manual.And 5w-30 is not the best oil for 4d56.

Here is a copy of that.

[MardyDelica]

maybe you have small blow by
what oil do you used synthetic all the time
if synthetic you will have this problem.
very thin layer of oil 5w/40 is ok
but 0W/40 is not good for this engine
Cheers;

[strada-caster]

it is not a little puff of blue in the morning. it is constant for 5 mins or so with a miss in the engine, then it will smooth out and act normal. I have nothing while driving that i can see.

i'm not worrying about the half moon seal, it's fixed now anyhow.

the oil weight makes no difference for this problem. i was running 15w40 conventional before and 0w40 syn for the winter in thunder bay(-40 can be common). it has the same symptoms with either oil.

[MardyDelica]

ow-40 is so thin on this engine.
try 5w40 maybe it lessen the smoke as the thin layer of synthetic oil will just by pass the piston ring
cheer;s
Mardy

[strada-caster]

ow-40 is so thin on this engine.
try 5w40 maybe it lessen the smoke as the thin layer of synthetic oil will just by pass the piston ring
cheer;s
Mardy

correct. I will not be using 0w40 syn again.
as soon as the ambient temp gets to around -5°C, the low oil pressure switch stays on for the first few seconds of an engine start. -10°C and below this did not happen.

[redmond]

One of the posts in this thread asked about pcv valve - is there one on the L300? I haven't looked inside the valve cover yet (don't imagine there's much room in there); I don't see one from a quick outside look at the engine. Can anyone answer this?

[legionnair]

Nope