Thread: Can changing oil types cause oil consumption?

After an interesting experience today, I think it's my turbo. Looks like I won't be taking the rover on the Christmas and New Years jaunts.

Think slow 90 deg corner, accelerate out and notice a big cloud of black behind me. Lift off and the EGT gauge stays pinned at 750C with the boost gauge sitting on 3psi. Clutch in and engine sits at about 2500rpm sounding awful while feeding on it's own oil. Luckily it only last a few seconds, but felt like a lot longer.

It did exactly the same thing on a similar left hander 10km later. My theory is the turbo has worn bearings and seals which are bleeding oil into the intake piping, the left handers are dislodging it where it's running into the manifold and fumigating the road ways.

This turbo bearings and seals were dubious when I built and fitted it. One of those short term experiments that turned out to be a long term fitment. A rebuild is no problem, but it'll be well into the new year before I can get a T25 rebuild kit.

Bit of an update with no good news.

Over the past few weeks I have rebuilt the turbo at midnight, rebuilt the turbo a second time at a more reasonable hour remembering to install the compressor side seal ring. Remachined the turbo compressor housing (different tolerances on the new thrust bearings) and still no improvement in smoke or oil consumption. Turbo drains are all large and clear right through the engine block. I even tried a restrictor in the turbo oil feed. No change. Oil consumption hit an all time high of around 1 litre per 20km the other night. I was pushing it hard to test though.

Today I unbolted the turbo and went for a run. Underbonnet inspection afterwards shows the vent hose from the provent is spraying a decent quantity of oil around, the provent itself is flooded with oil. This explains the oil in the vent tube. Normally this vent tube is feeding the turbo intake, hence the suspicion of the turbo.

In summary, the turbo is an innocent victim. I'll wait to hear from Ben about the provent and possible mitigation there (i.e. bigger drain, possibly raise the drain to above oil level). I'll also start saving for genuine piston/liner/ring kits.

In the mean-time I'll just back off the power a lot so it can do the short range offroad work without chewing too much of it's own oil.

Solved. It was the provent and here is what I did to fix it.

http://www.aulro.com/afvb/showthread...56#post1622842

With the benefit of hindsight, the oil consumption started early december and that was when I fitted the provent. I noted in mid december that I had to add 2-3 litres of oil and the engine was very smokey. The original vent hose from the provent went uphill and thus gravity drained a lot of it back.

The oil consumption hit a peak when I re-routed that hose to be more level. At this point the vehicle was literally a smoke machine. It created banks of bad smelling fog.

As mentioned in the other thread, you must have serious amounts of blowby/oil.

The PV200 is ftted to engines up to 200 kW. Most heavy diesels are known for having high rates of blowby.

I once had some issues running Penrite Japan truck 25, which is significantly more viscous than Castrol RX Super that I normally run. The front main seal was on the way out, and slight increase in crankcase pressure was causing oil to push out past the front main seal. I pulled the provent element, which stopped the oil leak, allowing me to drive the ~2500 km home to replace the seal and change back to RX Super!

I don't have a way of easily measuring the exact amount of blowby, but it isn't extreme.
Last rebuild was approx 35,000km ago, ring gaps were IIRC 17 thou, which is on the high side of factory spec (10-18 thou), but still in spec.

This engine has always breathed a lot, but not excessively. The previous setup had a 12mm restriction which under sustained high load and rpm caused the crank case to pressurise and the rear crank seal to leak, but was okay if you weren't heavy towing or chasing sports cars up hills.
With the provent and 1" lines (down to 16mm OD barbs either end) the crankcase pressure is too low to register on a basic pressure gauge (i.e. not even 1psi).
It flowed well, there were just two problems. Not seperating oil and letting go of it in big gloops on certain inclinations. An engine running on it's own oil is a terrible sound.

The provent may have worked fine with the stock setup if it could be mounted half a metre higher to help it drain. But I can't do that.

Just another thought. The provent might be intended for up to 200kw diesels with internal oil seperators still fitted.
The 4BD1T has a factory external air/oil seperator which the provent has replaced. It's going to take more oil on this engine than any other of comparable output.

Originally Posted by Dougal

Just another thought. The provent might be intended for up to 200kw diesels with internal oil seperators still fitted.
The 4BD1T has a factory external air/oil seperator which the provent has replaced. It's going to take more oil on this engine than any other of comparable output.

No, it is intended/used as a stand-alone unit. Btw, the factory 4BD1T rocker covers (which I also have fitted) use inertial oil separation before the gas leaves the rocker cover.

Do you have a long hump or short hump rocker cover?
I couldn't get the screws undone on the breather cover between the inner rocker cover and the outer the acoustic cover. So I left it alone. I have the short hump cover (pre 1988) and I suspect whatever in there that was supposed to seperate oil, no longer works.

Under the inner rocker cover mine just picks up at the rear and travels along a bit to meet the tube.