PicoScope 7 Automotive
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SAAB 9-3 petrol
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
SAAB 9-3 petrol
I'll try and keep this short and sweet. Customer asked me to look at this car as it was difficult to start engine and when it ran, it ran poorly and serious smoke emitted from the exhaust, blueish white. The engine when running smells of burning oil. The turbo was seized and I wondered if that was permitting oil into the exhaust system!
The spark plugs were removed and the plugs/cylinders had oil within. The turbo was rebuilt and refitted and the exhaust still produces the same smoke and oil smell.
I decided to do cylinder tests with the WPS500x and have waveforms to show the results of each cylinder. I'd be interested in views about the waveforms as each cylinder looks the same to me, but I definitely know something is wrong in cylinder 2 because when I removed the WPS500x from that cylinder, smoke appeared from the spark plug hole like the smoke from the exhaust system, quite a lot of it.
An approximate guide of the inlet depression readings shows cyl 1 at 20 inHg, cyl 2 at 19 inHg, cyl 3 at 19 inHg and cyl 4 at 20 inHg.
I've no doubt that the cylinder head gasket here will be rotted and permitting oil into the cylinder(s), but I'm not seeing it from the WPS500x readings?
The spark plugs were removed and the plugs/cylinders had oil within. The turbo was rebuilt and refitted and the exhaust still produces the same smoke and oil smell.
I decided to do cylinder tests with the WPS500x and have waveforms to show the results of each cylinder. I'd be interested in views about the waveforms as each cylinder looks the same to me, but I definitely know something is wrong in cylinder 2 because when I removed the WPS500x from that cylinder, smoke appeared from the spark plug hole like the smoke from the exhaust system, quite a lot of it.
An approximate guide of the inlet depression readings shows cyl 1 at 20 inHg, cyl 2 at 19 inHg, cyl 3 at 19 inHg and cyl 4 at 20 inHg.
I've no doubt that the cylinder head gasket here will be rotted and permitting oil into the cylinder(s), but I'm not seeing it from the WPS500x readings?
- Attachments
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- SAAB 9-3 cyl 4.psdata
- (19.67 MiB) Downloaded 374 times
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- SAAB 9-3 cyl 3.psdata
- (18.92 MiB) Downloaded 347 times
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- SAAB 9-3 cyl 2.psdata
- (14.76 MiB) Downloaded 359 times
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- SAAB 9-3 cyl 1.psdata
- (13.31 MiB) Downloaded 349 times
Re: SAAB 9-3 petrol
If the exhaust pipes are full of oil, I can imagine it will not burn out too soon. After such an event, the exhaust system is usually to be replaced.
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
Re: SAAB 9-3 petrol
Thanks for the reply. The exhaust system is a fairly new one and when I had it removed the visual inspection showed no traces of oil had entered the system. The oil contamination was confined to the turbo itself. Based on the evidence I've seen I reasonably convinced that the cylinder head gasket is leaking allowing the ingress of oil, but I'm not sure I'm seeing that through the use of the WPS500x?
Re: SAAB 9-3 petrol
Where’s oil there’s no rust, and I can’t figure how a test with wps would show oil leak to cylinders.
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
Re: SAAB 9-3 petrol
It's not so much showing the oil itself using WPS, its in the examination of the waveforms looking at symmetrical shapes of the towers for loss of pressure, or the turbulent flow where differential pressure takes place. I've read different view points regarding the waveform when examining the differential pressure section. Some authors believe that ripples are normal and some are saying they indicate a problem. Looking back at the waveforms the ripples are pronounced but are typically the same on all four cylinders. I have significant white smoke emitted from the spark plug orifice of cylinder 2, yet the waveform appears no different to the other three cylinders. Assuming for the time being that these ripples are a normal part of the operation of the waveform, then I must conclude at this time these ripples are created by the actions of the valves opening and closing. What I'm trying to evaluate and understand is what effect induced oil into a running cylinder would have on the readings of the pressure cycle, if any, and why a leaking head gasket does not seem to appear to be showing a fault?
I know PS7 is new and because of unfamiliarity at this time I used the guided tests, which appears that the settings should have been altered for this engine, so with this in mind before the bad weather kicks in later this week I'll try and do some more testing using different settings and see if I can see anything different.
I know PS7 is new and because of unfamiliarity at this time I used the guided tests, which appears that the settings should have been altered for this engine, so with this in mind before the bad weather kicks in later this week I'll try and do some more testing using different settings and see if I can see anything different.
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
Re: SAAB 9-3 petrol (Updated to FIXED)
For the readers that have followed the thread, I had concerns with whitish smoke from cylinder 2 when the spark plug was removed. I had major amounts of whitish/blue smoke from the exhaust tail pipe at engine idle, which never cleared during running. I did a couple of engine cylinder tests using the WPS and could not see any relevant data to suggest the engine had an internal cylinder fault, however, smoke (lots of it) gave me serious doubt that a fault in cylinder 2 was present.
When I was first asked to look at this car my gut feeling was that the engine was suffering from an internal blockage, which was creating some internal back pressure. Initially I thought about the engine breather purely because I'd seen this on a Volvo some time back which caused serious whistling when the engine was hot.
Initially the turbo was almost seized completely which was removed and reconditioned. The oil feed pipe and return hose was also cleaned and flow tested. Turbo people would always advise to replace these parts but on this car they simply were not available in this country and the costs to buy in from over seas was not justified.
Having refitted the turbo a second time after stripping and cleaning and all the pipes with it, the engine still smoked heavily. For a time I just lost interest in it, but since CV-19 came round and I had time on my hands, I decided I should take another look at it. I knew something somewhere must be restricted, which based on the design of this engine could only leave the cylinder block. I removed the turbo oil return pipe and checked the drain back into the sump. What I found was a blockage caused by build up of carbon. After removal and cleanup and refitting the turbo return pipe I ran the engine and now the smoke reduced until the exhaust system ran clear. Its a very long time since I have experienced a crankcase blockage for a breather system, which looking at the diameter of the turbo return hose I'd not of thought the cylinder block would have had such a serious restriction present.
The customer told me that the engine had always had regular services carried out, so I questioned why then would the turbo become some seriously soiled in carbon. I looked to the oil and based on what has been published in the trade press over time about low ash oil not being used in DPF equipped vehicles, I asked was it then possible that the trade have simply put a none recommended 5W-30 oil in this engine?
Some research into oils and not all 5W-30 oils are the same, and if an oil is used with the incorrect temperature rating than recommended, it seems problems will occur over time.
When I was first asked to look at this car my gut feeling was that the engine was suffering from an internal blockage, which was creating some internal back pressure. Initially I thought about the engine breather purely because I'd seen this on a Volvo some time back which caused serious whistling when the engine was hot.
Initially the turbo was almost seized completely which was removed and reconditioned. The oil feed pipe and return hose was also cleaned and flow tested. Turbo people would always advise to replace these parts but on this car they simply were not available in this country and the costs to buy in from over seas was not justified.
Having refitted the turbo a second time after stripping and cleaning and all the pipes with it, the engine still smoked heavily. For a time I just lost interest in it, but since CV-19 came round and I had time on my hands, I decided I should take another look at it. I knew something somewhere must be restricted, which based on the design of this engine could only leave the cylinder block. I removed the turbo oil return pipe and checked the drain back into the sump. What I found was a blockage caused by build up of carbon. After removal and cleanup and refitting the turbo return pipe I ran the engine and now the smoke reduced until the exhaust system ran clear. Its a very long time since I have experienced a crankcase blockage for a breather system, which looking at the diameter of the turbo return hose I'd not of thought the cylinder block would have had such a serious restriction present.
The customer told me that the engine had always had regular services carried out, so I questioned why then would the turbo become some seriously soiled in carbon. I looked to the oil and based on what has been published in the trade press over time about low ash oil not being used in DPF equipped vehicles, I asked was it then possible that the trade have simply put a none recommended 5W-30 oil in this engine?
Some research into oils and not all 5W-30 oils are the same, and if an oil is used with the incorrect temperature rating than recommended, it seems problems will occur over time.
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Steverider
- Newbie
- Posts: 5
- Joined: Mon Sep 23, 2019 2:04 pm
Re: SAAB 9-3 petrol
Just wondering if you ever got to the root cause of the problem?
I know that SAAB changed the specification for oil on these engines from semi-synthetic (as recommended in the owner handbook) to fully-synthetic because of this problem. There is a TSB in SAAB WIS to this effect. On the SAAB 95, there is a modified crankcase breather too which helps to allieviate this problem.
I know that SAAB changed the specification for oil on these engines from semi-synthetic (as recommended in the owner handbook) to fully-synthetic because of this problem. There is a TSB in SAAB WIS to this effect. On the SAAB 95, there is a modified crankcase breather too which helps to allieviate this problem.
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
Re: SAAB 9-3 petrol
Hi Steve,
Yes the crankcase on this SAAB was blocked and causing a back pressure of oil to build up in the turbo and then bypassing the seals into the exhaust system and intake. All sorted now and running very well.
Yes the crankcase on this SAAB was blocked and causing a back pressure of oil to build up in the turbo and then bypassing the seals into the exhaust system and intake. All sorted now and running very well.
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Steverider
- Newbie
- Posts: 5
- Joined: Mon Sep 23, 2019 2:04 pm
Re: SAAB 9-3 petrol
Great stuff. Did you ever get to the bottom of the smoking number two cylinder?
Now that is interesting!
Now that is interesting!
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Technician
- TwoWaves
- Posts: 707
- Joined: Thu Apr 24, 2014 8:32 pm
Re: SAAB 9-3 petrol
Yes I did get to the bottom of the cylinder 2 smoking. After seeing it smoking significantly out of the spark plug port I thought initially as the engineers did that the cylinder head gasket was leaking. I was unsure because a test using the WPS500x indicated that all cylinders were running the same. I needed to see evidence of something inside the cylinder before the head was lifted, and because no evidence was observed I concentrated on other areas. Turned out that the oil pressure backing up through the turbo was being induced into the cylinders, hence I'd already noticed oil in the cylinders previously and decided to concentrate my efforts there. All turned out to be a blockage in the lower crankcase port.