Engine overspeed, oil coming up from the oil pan etc...

[-=Alex=-]

2005 Terrano 2, engine 2.7

In addition to my previous post:
http://nissan4x4ownersclub.com/forum/showthread.php?t=22177

To cut the story short, oil started dripping about 1.5 month ago, not much – about teaspoon overnight. As mechanic suggested, removed rocker cover vent pipe – leak stopped, but reappeared a week after. When towing trailer was leaking a lot, but I still couldn’t figure out where from.
10 days ago put 2 bottles of Wynn's Stop Smoke Oil Treatment 325ml. First couple of days seemed to work quite well, engine became quieter, but then oil started leaking again…

4 days ago things started changing rapidly – started with minor smoke when starting smelling burnt motor oil, then turned to Huge clouds of smoke every time engine starts, even hot; then smoke while driving.; then smoke while driving.
And as a final – yesterday got engine overspeed – 6000 revs, clouds of smoke etc.. Lasted for only 1-2 seconts, but that was enough.
For the sake of interest decided to put oil pan vent pipe into bottle and see if any oil comes from there – and was shocked!
Oil was pumped from the sump like mad, not a surprise engine was running on motor oil:
14km empty car - 1 litre
10with empty trailer - 1 litre
3.5km with car in the trailer – 0.5l

I don’t know what happened to oil separator, but as oil comes from the sump up – I believe separator is kaput.
Also, open rocker cover vent pipe does not help to reduce engine pressure.
Interestingly, exhaust gases from crank case don’t have high pressure, probably less than from rocker cover.
Here is the video: View My Video

My understanding is rings are kaput, and oil additive has made things even worse (as it was very thick and potentially could thicken oil in rings)?
Also, dipstick behaves really strange, new level every time. Just curious, maybe I have overfilled oil pan?

On photos – brand new glowplugs after month of driving. Not wander they burn over if they get covered in burnt oil deposits.

 

[Lazy-Ferret]

If oil is coming out the oil pan pipe, assuming we are both talking about the same thing, then the car is overfull of oil.

If we are talking the same thing, there is a vent pipe of the top of the rocker cover which goes into the black oil separator on the top front of the engine, by the alternator. From there, 2 pipes leave, one goes into the large air pipe that connects to the turbo, and the 2nd, comes off the bottom, and allows any oil trapped by the separator to drain back into the sump. Basically, it is a down pipe, not up.

If oil is coming up that pipe, then it is being fed straight into the turbo, and you are sending it in with the air as fuel.

Is your dip stick blowing out? When I was having issues with mine, and trying to find where the oil was coming from, I blocked the vent pipe from the rocker cover, as I did not realise that was where it went at that point and the engine almost immediately blew the dip stick out about 4 inches.

 

[-=Alex=-]

Yes, that's the pipe you are talking about, down pipe. I didn't try to block both rocker cover and sump pipes, but my main suspicion now is dipstick and amount of oil in the pan.
Will try different stick tomorrow and drain all oil to see how much is there. If it's not the reason, then will block pipes.

 

[-=Alex=-]

Just curious, if I block both pipes and dipstick will be blown up - what will it mean? High pressure and issue with rings?

 

[rustic]

Just curious, if I block both pipes and dipstick will be blown up - what will it mean? High pressure and issue with rings?

Worn rings can allow blow back, ie some of the compressed exhaust gasses from the upper cylinder goes past the rings, increasing the pressure in the crankcase, this pressure has to go somewhere, dip stick is like a safety valve.

There will always be some leakage, but a compression test can show which cylinder, and how bad it is.

Hope I have understood the question...

best regards,

Rustic

 

[Lazy-Ferret]

Worn rings can allow blow back, ie some of the compressed exhaust gasses from the upper cylinder goes past the rings, increasing the pressure in the crankcase, this pressure has to go somewhere, dip stick is like a safety valve.

There will always be some leakage, but a compression test can show which cylinder, and how bad it is.

Hope I have understood the question...

best regards,

Rustic

Exactly as Rustic says.

There is always back pressure, I just meant it as a way to gauge how much you have. When we took the head off of mine, there is a bit of Scoring on number 2 or 3 piston (I forget which now), Rick says it probably over heated at some point in its life, but she still runs a dream, so I have ignored it for now, but I do at least know where my back pressure is coming from.

It turned out, I had 4 problems with my car, but they masqueraded as one, which was excessive oil consumption like you are experiencing, and engine runaway.

Mine were,
first I found the Oil Separator was knackered, and the one way valve was not working. After messing around blocking the feed pipe to the turbo, and fitting a mini filter to the rocker cover vent, which just resulted in a very oily engine bay, I ended up fitting a second oil catch tank after the separator, that also drains back into the sump, via a "T" piece in the return pipe. This helped a lot to start with, but did not actually cure my issues which were getting worse and worse as I used the car.

Next, I bit the bullet, and replaced the Turbo as even when the breather system was disconnected, I was still getting oil puddling in the bottom of the air intake hose going into the turbo. In my case, this was actually the worst part of the problem, and changing it cured nearly all of the oil issues. Oil was coming past the bearings and of course, towing made the turbo work a lot more, so towards the end, I was using 7 litres of oil to tow the caravan 280mile. It did save worrying about oil changes though:lol:augie

I had already purchased and arranged with Rick to change the valve stem seals so went ahead and did that as well just after the Turbo change. When we removed the old ones, some were hardened (Probably from when ever it over heated before I had it) and changing these stopped the last problem of smoke of start up.

Lastly, I also had a snapped glowplug, and decided to purchase a replacement head off of a car Rick was breaking, so I could have all 4 working again for the remainder of the Winter. While we we had the head off to sort that, we discovered a bit of light scoring in the Number 2 or 3 piston, and so I have put the last bit of oil use and higher back pressure down to that, but as now it only uses oil when towing hard, and even then it's only about 1/2 a litre over 300 miles, I can live with that.