overfilled oil contributing to ZD failure?

had a bit of a chance to think while parked behind the wheel for 4000km. We all know diesels, esspecially tubo ones, dont like being overfilled with oil, the question i pose is, can the stupid dipstick design cause people to inadvertently overfill their engines thus causing dramas? ive had several people, mostly mechanics (including a nissan mechanic), argue black and blue with me that my engine was underfilled with oil because of its position in the centre of the dipstick. any thoughts?

Does this mean that if the oil is level with the top of the noch on the dipstick that it is over full.?

overfilled oil contributing to ZD failure?

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yes it can.

a lot of mechanics do over fill the hell out of them, simply because they don't allow them to sit long enough before checking the oil level. these motors blow a fair bit of oil out the breather at the best of times. when over filled it really throws a lot out. often you see it as a big oily mess all over the turbo/intake tubes.

problem is, apart from adding to the black goo in the intake, if enough is ingested at once it can cause over fueling of that cylinder. also because its ingested with the air it can ignite on the compression stroke well before the main fuel is injected causing it to knock. also because the compressed air is now even hotter than normal the main fuel can burn way to rapidly causing even more knocking. this all can lead to EGT damage and excessive stress
on the pistons.

fit a decent catch can and then you can over fill it without a problem.

So where on the dipstick should the oil level be when the vehicle is level & the engine has not been run for 1/2 an hour.?

not to sure with 1/2 hour. i prefer overnight.
as long as its just on full or just under it should be fine.

however it still needs a catch can regardless.

according to the good ol handbook, half way up the 'window' after engine has been run and oil is hot then allowed to sit for a few mins.

Catch can ordered today, taking your advise . Thanks Tweak'e. Recently I did an 8000 k trip through QLD/NT & WA. A few weeks before doing this trip I had my Navara checked out by a mechanic & a major service done belt, wheel bearings, drive train oils etc( I usually do my own services). As well as the usual running around I had to do a run from Ormeau to Lismore & back towing a 2 ton trailer, no prob's, but just before leaving to go on the big trip I decided to do an oil & fillter change as I had allready clocked up about 1800ks. What I found was 9 1/2 litre's of oil in the sump. Although I didn't notice any difference Like blowing smoke or any thing else. Could it have done any damage that I'm not aware of?. It never missed a beat on the big run, but I'm bloody glad I did that oil change.

Hootie said:

Catch can ordered today, taking your advise . Thanks Tweak'e. Recently I did an 8000 k trip through QLD/NT & WA. A few weeks before doing this trip I had my Navara checked out by a mechanic & a major service done belt, wheel bearings, drive train oils etc( I usually do my own services). As well as the usual running around I had to do a run from Ormeau to Lismore & back towing a 2 ton trailer, no prob's, but just before leaving to go on the big trip I decided to do an oil & fillter change as I had allready clocked up about 1800ks. What I found was 9 1/2 litre's of oil in the sump. Although I didn't notice any difference Like blowing smoke or any thing else. Could it have done any damage that I'm not aware of?. It never missed a beat on the big run, but I'm bloody glad I did that oil change.

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That's almost 3l over the recommended amount of 6.7l. It is amazing it didn't grenade itself when it was overfull. The oil presure would have been extremely high. I would say you are very lucky it was sorted before you towed your 2t trailer for long periods.

surprised you haven't got oil all over the turbo and inlet. it would have been fair blowing it out. a good indicator is take off the turbo - air filter hose and look in the turbo. theres often a puddle of oil sitting just before the turbo.

well hooties story is an exact example of the point i was trying to make, could this be a underlying factor in many zd failures? how many people (no offense meant here) out there take their vehicles to mechanic for service and actually double check oil level after couple days? this goes on for 80,000km, just think of all the extra oil the motor has ingested on top of what it normally does, the higher oil pressure pushing seals and piston rings to their limits, the extra carbon building up, the extra gunk and crap all thro intake, surely this can not be great for the longevity of these engines. everyone is down on these motors, but the people that i know that do their own services and are anal about it, havnt had a problem, like a 04' ZD that has towed a 25ft van around aus all its life, just clocked over the 400,000 without drama and unloaded it still does same km/100 as mine! this is not proof of course but is somewhat of a argument, cos surely if these motors are 'just bad' wouldnt there be much higher percentage of them failing and much lower numbers on the 2nd hand market?

the problem with overfilling is with the oil return line on the turbo. if the oil isn't able to drain out easily you can possibly blow the turbo's seals. the manual makes it clear not to overfill it.

personally i don't see much problem with a deisel engine injesting some oil vapor from the breather (other then gunking up the intake but i think it needs the egr for this as well) as long as you oil level is correct. nor do i believe extra oil increase the oil pressure

also the other problem you get is the oil can get aerated which is not to good for the bearings.
the extra oil won't increase oil pressure, but if there is way to much it can increase crankcase pressure, which can blow seals.

a small amount of oil into the intake won't hurt but these blow more than enough oil into the intake normally let alone when its over filed.

I will be taking off all the hoses this weekend & having a good look over them as well as giving them a good clean out when I fit the catch can & some new hoses.

The engine bay was & still is spotless, no oil spraying or leaking, no smoke,no unusual noises, I didn't notice any thing wasn't right until I changed the oil.

I will be doing the oil changes myself from now on. I will just have the mechanic do the things I can't do.

I recommend everyone should check the dip stick after they have had someone else service the vehicle, just to make sure an honest mistake hasn't been made.

Hootie.

sorry people, i had a bit of a moment in my last post, i was quickly typing that post already late for work and by increase in oil pressure i meant crankcase, put it down to a blonde moment lol. the reason brought the topic up was ive noticed myself, if the oil level is really accurate, the turbo only gets a tiny amount of oil around the housing, whereas when i first bought it and mech did fisrt 2 services and the first 4 or so i did on it, the oil used to cover the housing, run down the block drip from turbo onto the diff and start running down the side of it. just a observation i thought might have more to it and would try and share with fellow navarians.

yep, that sounds typical overfill.
hence fit a catch can and don't worry to much unless its grossly overfilled.

Hi Guys

When I had my navara last serviced at Nissan they put 8 litres of in the engine.Iask the question why so much oil when the manual said to put only 6.7 litres.All they said was that Nissan techincal department(Melbourne???) have told all dealer to put that amount of oil in all zd30 engines for navara's and patrol's.

Shane

that sounds like the dip stick mod nissan did to the patrols. i'm not sure if they did it to the navaras.

great post ! on this- I overfilled mine this week by just under 2lt, no big deal I thought ! well I drove it for 450ks towing a camper- egt's where high up to and sat on 500 falling to 350 or so. got home popped the bonnet and the blow-by hose I have re routed into the air box had popped off ! I'll be watching it closely now for sure ! It will be interesting to see the temps now I've dropped the oil level ! i'll keep you posted- I've been slack I'll take some photos of my set up and post them on my garage soon ..marry x-mass all
oh also I have a uni filter in the standard air box - I don't oil the inner foam just the outer and will be lightly oiling that in the future ! ohh the zd woes !
danm thirsty too- haven't fitted new turbo and intercooler yet as the intercooler from cross country came damaged, missing parts that should be welded on, missing the bonnet insulation frame work also- $1600 not f'n happy I tell you !

I have always had a concern with this filling problem. When the car was serviced by Nissan or any other garage the oil was always about 1/4 inch over the top mark on the stick so I presume they were filling with 6.7ltrs. When I started servicing myself this would always happen if I put the 6.7ltrs in. I now fill with 6ltrs and run the car then wait a few hours and check. It is usually at the top mark. I'm always wondering if I have it right, as the book says 1/2 way between the marks on the stick.

Mines sits dead on the top mark when sat over night- once run and stoped for 10 or so minutes it is sitting just over half full !