706 replies to this topic

[MartinS]

As oil consumption by the Saab engine seems to be/have been a problem, can people post up what they've done in the style below (list like) and results so far, then hopefully we can find a common way to resolve this.

 

Martin S

Saab 2.0, stage 2 cams, Siemens 630 injectors, exhaust ports opened up, uprated fuel pump etc

 

Oil breather pipe fed into the intake for the supercharger (when detached from the intake pipe with a catch tank, around 50ml caught over a 200 mile period)

Oil used              Mobil one 0-40 fully synthetic

Dipstick used     (Saab original) kept at 2nd notch from bottom.

Oil consumption 1 litre per 100 miles (160 km) average.

PCV valve open between inlets 2 +3 open to the inlet manifolds vacuum.

 

Where is it going? I am told my car smelt of fuel at full throttle (though the Dutch software says its all good), Could it be being washed out?

 

Martin S

 

 

 

 

 

 

Edited by MartinS, 30 September 2015 - 06:16 AM.

[fezzasus]

when detached from the intake pipe with a catch tank, around 50ml caught over a 200 mile period)

 

 

 

 

 

 

 

 

There's your problem.

 

The oil doesn't recirculate when attached into the supercharger throttle. It is simply burnt off. The danger with having this much oil pulled through the PCV is you'll generate a lot of deposits in the combustion zone.

 

I would fit an oil separator which feeds the collected oil back into the sump. Such as this https://www.mann-hum...ent_en_2013.pdf The turbo return valve would be ideal for this. 

[MartinS]

When  it wasn't fed into the sc it still went through a litre every 70-100 miles, so that's not my problem.

 

Martin s

 

[fezzasus]

How do you get to that conclusion? The pipe is still venting oil and blow by gasses from the engine.

 

Your problem is that the cam breather, regardless of how it is connected, is venting oil. You can either have it venting to atmosphere, where you will lose the oil, or have it venting to the air intake, where the engine burns the oil. Neither situation returns the oil to the engine in a usable state.

 

I'm suggesting fitting that type of oil separator as it collects oil and returns it to the sump, which allows it to be used and so will prevent oil loss.

 

The other routes for oil loss are:

 

1. Leak - obvious to detect, with the amount of oil you're putting in, you'll be able to identify that easily.

2. Stuck piston rings - unlikely with a new engine, detectable with blue smoke

3. leaking past valve stem seals - again unlikely with a new engine, detectable with blue smoke.

 

Bore wash would return the oil, and a lot of fuel, to the sump, so your oil volume will increase. It's also unlikely in a new engine as it's related to piston ring sticking.

Edited by fezzasus, 30 September 2015 - 08:58 AM.

[fiveoclock]

How do you get to that conclusion? The pipe is still venting oil and blow by gasses from the engine.

 

Your problem is that the cam breather, regardless of how it is connected, is venting oil. You can either have it venting to atmosphere, where you will lose the oil, or have it venting to the air intake, where the engine burns the oil. Neither situation returns the oil to the engine in a usable state.

 

But a litre every 70 to 100 miles being lost in that fashion??

[fezzasus]

 

How do you get to that conclusion? The pipe is still venting oil and blow by gasses from the engine.

 

Your problem is that the cam breather, regardless of how it is connected, is venting oil. You can either have it venting to atmosphere, where you will lose the oil, or have it venting to the air intake, where the engine burns the oil. Neither situation returns the oil to the engine in a usable state.

 

But a litre every 70 to 100 miles being lost in that fashion??

 

 

As I said, every other route has an obvious loss mechanism. Either blue smoke or a puddle of oil. The only place you can experience a loss without a detectable route is if it's being burnt in the engine. 

 

Look at it another way. Oil is approx 98 % combustible hydrocarbons, truck companies often add used oil to the diesel tanks as a way of disposing of the oil (free fuel, plus no disposal cost). It burns just as well. given that a VX burns about 20 L of fuel in 100 miles, adding another 1 L of oil isn't going to make much of a difference in terms of fuel delivery.

[Zoobeef]

Does the crank breather go straight into the inlet on the saab engine too. Martin does have some smoke as seen on the video when mbes2 was following him.

[fezzasus]

Does the crank breather go straight into the inlet on the saab engine too. Martin does have some smoke as seen on the video when mbes2 was following him.

 

Just watched the video. You'll also get smoke from burning oil entering the combustion zone from the PCV, if it's plumbed into the inlet. The fact that Chris' car does do this adds further weight to controlling and recovering the oil going out of the breather into the inlet manifold.

[mbes2]

Does the crank breather go straight into the inlet on the saab engine too. Martin does have some smoke as seen on the video when mbes2 was following him.

 

What video is that, time stamp ?

 

I vent mine externally, I sometimes see white vapour and a very thin layer of oil near the filter ontop of the catch tank  

Edited by mbes2, 30 September 2015 - 10:02 AM.

[Sutol]

So Tom, if 50ml of oil was collected with an open breather after 200miles, the rest is being burnt in the engine, at 975ml every 100 miles, is that right? Martin's getting this on normal road driving not on track ie low boost levels, surely the pcv system isn't working properly??

[fezzasus]

So Tom, if 50ml of oil was collected with an open breather after 200miles, the rest is being burnt in the engine, at 975ml every 100 miles, is that right? Martin's getting this on normal road driving not on track ie low boost levels, surely the pcv system isn't working properly??

 

It's a bit more complicated than that.

 

The PCV works when there's a vacuum in the inlet manifold. This draws air from the crankcase breather at the top, down across the sump and out into the inlet manifold where it combines with the inlet air and vapors are burnt during combustion. In the original configuration, the crankcase breather is attached to the inlet after the air filter to ensure that filtered air is drawn into the engine.

 

so that's fresh air into the crankcase breather in the cam cover, across engine, out of inlet manifold and into combustion zone.

 

When this vacuum doesn't exist, the PCV valve closes to prevent boosted air from reversing the flow, entering the crankcase and forcing air and vapours out of the crank breather into the air inlet after the air filter. This process isn't perfect, as the engine will also generate blow by gasses which pressurise the crankcase, these cause the PCV system to reverse and forces the gasses out of the crankcase breather.

 

So under boost, the PCV valve in the inlet manifold closes, forces the gas flow to reverse and carries gas out of the crankcase breather in the cam cover. This ejects the gas after the air filter in normal configuration, or out of the pipe if disconnected. As the system is designed to mostly flow the other way, oil is ejected with the gas when the flow reverses.

 

To conclude, it's not just track, it's any change in transient throttle (meaning any acceleration) as this will generate boost and close the PCV valve, forcing reversal of the system and oil ejection with the crankcase gasses. 

[Sutol]

How can you tell if the PCV valve is working properly?

 

I have noticed that when the cam cover breather is connected to the intake ie conventional setup, and the oil cap removed with the engine idling, there is a definite suction at the filler hole. If however the breather is left free ie not connected to the intake then there is air/gases blown out of the oil cap hole. Is this an indication that the valve is working?

[fezzasus]

I don't think that means much. By opening the oil filler you are creating a path of less resistance verses the normal PCV route (in through the crankcase breather, out through the inlet manifold), the suction when the breather is connected will be due to the oil filler cap being a lower resistance path than the breather (because it's pulling through the air filter, and because the area after the air filter is a low pressure zone = more resistance to pull air from it) whereas the resistance when the breather is disconnected is about the same as the oil filler cap, so no suction.

 

Best way to check if the PCV valve is working is to pull a vacuum through it both ways, one way will allow air to pass, the other way won't.

[MartinS]

So when I had a catch tank (which on the day was a water bottle gaffer taped onto the breather pipe with a hole cut in its upper side to vent air) somehow vented over 2.5 litres of oil in gas form in an afternoon?

My engine bay and interior boot lid are clean as is the back of the car and I have no oil leaks

Please don't think I'm arguing I don't have knowledge in this area at all, just trying to get my head around a new engine that behaves worse than mine old one did after 73000 mikles and a third of a piston missing!

 

Martin S

 

ps Why are no other saab engines listing there solutions? 

Is 0-40 oil too thin?

 

[CHILL Gone DUTCH]

I would say no Martin to the oil But I would ask fezz that as he more experience with oils Did you get a compression test done ? So we can see how good these Pistons/rings are Or how well they have bedded in

[smiley]

ps Why are no other saab engines listing there solutions? 

 

 

They are not that much different then your config.

 

Something is wrong with your´s, but can´t wrap my head around on what it could be.

 

[fezzasus]

So when I had a catch tank (which on the day was a water bottle gaffer taped onto the breather pipe with a hole cut in its upper side to vent air) somehow vented over 2.5 litres of oil in gas form in an afternoon?

My engine bay and interior boot lid are clean as is the back of the car and I have no oil leaks

Please don't think I'm arguing I don't have knowledge in this area at all, just trying to get my head around a new engine that behaves worse than mine old one did after 73000 mikles and a third of a piston missing!

 

Martin S

 

ps Why are no other saab engines listing there solutions? 

Is 0-40 oil too thin?

 

 

Most oil will be a vapour, so unless you condense the gasses with a chiller unit, you won't catch the oil. This is why the aftermarket oil catch tanks are useless, they don't have enough surface area for the oil to condense on to. The proper ones, like the one I linked to, has a paper filter to provide the catch tank with a very high surface area which allows the oil to cool and condense.

 

Lots of oil oxidation testing has trouble collecting oil vapour for the same reason.

 

0W-40 should be fine. This isn't something you can solve by changing the oil type.

[fezzasus]

 

ps Why are no other saab engines listing there solutions? 

 

 

They are not that much different then your config.

 

Something is wrong with your´s, but can´t wrap my head around on what it could be.

 

 

 

If the PCV valve isn't working, it would use much more oil than others.

[smiley]

 

If the PCV valve isn't working, it would use much more oil than others.

 

 

Yeah, but I´ve not seen Z22SE with blocked PCV´s being reported to consume oil so bad like martin is currently doing.

   

[fezzasus]

A blocked PCV is different to a failed one, one that has failed might be in the open position rather than closed. Meaning the boost from the supercharger could pressurise the crankcase and cause much greater loss of oil than normal.