Thread: Oil Leaks in 300TDi

You could always do a leak down test to check blow-by.

I always used 5% (5 psi leakage @ 100psi cylinder pressure) for my limit on my old race engines, but you'd be mad to use that tight a figure as your condemnation limit on a road going engine.

Originally Posted by isuzurover

20-50 mBar should be the max for all engines, as the maximum crankcase pressure is limited by the oil seals, which don't change much from engine to engine.



Really??? You don't say???

Sorry old mate.... didn't mean to step on you post count or your toes, we're not all mechanics. I'm simply sharing my knowledge with those who aren't sure ( that clearly isn't you.)

excessive back pressure can cause oil leaks. I asked this question as I'd like to know if my non real TDi300 is within specs in the worn engine department as its new to me. this would be nice to know before I spend money on the rest of the Landie. I also thought this info might be useful for Landy110.

Don't worry Gav,your not the only one with a non real diesel,I have two myself. Pat

Originally Posted by langy

In order of what's probably happening:

Separator - if the o-ring of the cyclone separator gets a bit iffy, blow by exits and does what it does - ends up everywhere ( assisted by the fan)
P/N LLO 100000 (?) Try and use the LR part as I've tried standard metric and imperial o-rings and they didn't work too well.

Injectors - the spill line(s) (those things that run between the injectors and thence back to the tank) can get loose. Dirt and diesel can look a little like oil - small cable ties on the ends can fix it or new spill line from a Mercedes Diesel mechanic. The whole line is MJN 100910, and I've seen a reference online $18 for a 350mm chunk ( DIY)

Gasket - the rubber can get hard and fail and since the bolts are depth limited, it doesn't seal. Thence blow by escapes. Replacements are reasonably easy to find. P/N ERR2409

Give the engine a tub with CT14 - you'll be able to see what's happening.

So the seperator is part of the oil filter assy? I have not pulled this apart so know nothing of it. So if you could give a bit more info I would appreciate it.

I didn't think I would get oil leaking around the injectors but was worried it might indicate a head gasket failure. I will try to better identify the fluid. ( I understand exactly what you are saying )

The gasket on the rocker cover is new and still leaks, I have put a gasket on it with a non-hardenning gasket sealer in the past and it still leaks.

I washed the engine down recently and have been watching it as close as I can hence these specific questions.

But read on as I theorise about something in a few posts from here!

Thanks
Steve

if it's any consolation,
my 95 300 tdi leaks oil overnight, seems to be from the vac pump and the rear main seal, which i had replaced when i got the auto done recently, didn't seem to change the amount on the floor at all.

it annoys me, but i live with it.

Originally Posted by isuzurover

Oil cannot leak out around the injectors - only diesel, but by then you would have exhaust gas coming out as well.

If you have trouble keeping the tappet cover gasket (and elsewhere) leak free you may have too much blowby. Disconnect the breather hose from the tappet cover and see what the blowby is like.

So if I take the hose off the tappet cover with the engine running there should not be much air movement from the tappet cover, I am assuming "blowby" relates to combustion gasses passing the valves and ending up in the rocker chamber, is this correct ?

Originally Posted by PAT303

Don't worry Gav,your not the only one with a non real diesel,I have two myself. Pat

A certain filter manufacturer I work with - who made some of the OEM TD5 filters, referred to ALL the engines in the Provent field test as "schnickschanckmotoren". (the test included Tdi / TD5 / 3.9(T)Di). I will let you translate that.

So we are all in the same boat.

Originally Posted by Landy110

So if I take the hose off the tappet cover with the engine running there should not be much air movement from the tappet cover, I am assuming "blowby" relates to combustion gasses passing the valves and ending up in the rocker chamber, is this correct ?

Yes, correct. At idle/off boost there should be almost no measurable flow/mist coming out the breather.

Originally Posted by harry

if it's any consolation,
my 95 300 tdi leaks oil overnight, seems to be from the vac pump and the rear main seal, which i had replaced when i got the auto done recently, didn't seem to change the amount on the floor at all.

it annoys me, but i live with it.

Check in "the good oil" there is a very simple fix to your leaky vac pump