Saab NINES Articles

4 Cylinder Engines: 9-3 and 9-5

Little did any of us consider that we would be talking about the longevity of Saab engines when we attended the Saab Jubilee Celebration in Trollhatten in 1997. Eric Johnson and I had just completed the Northern Lights Rally prior to attending the Jubilee Celebration and many if not all of the North Americans were treated to an introductory launch presentation of the 9/5’s. We test drove and scrutinized the engine and chassis cutaways. We were sold on the design and construction of the then “new cars.” Eight years later both Eric and I drive 9/5 wagons and have some concerns about our beloved 4-cylinder engines.

I wrote in a previous NINES about the sludging issue of these engines and now, (see press release), Saab has recognized the problem and is taking appropriate action. It is disappointing to have read in a Swedish newspaper clipping that Saab had some knowledge of the problem from almost the beginning of production. At any rate, Saab will help those who have had engine failures related to sludging problems. Some people who have already paid to have their blown engines repaired may be eligible for refunds if they can meet all the requirements that Saab has outlined. We have seen many sludged engines that have failed and we have flushed and cleaned many engines that were partially sludged and have not had any of these fail yet. They may!! I think there may be a related issue to the sludging--that is the integrity of the oil pump. Another related issue is the doubt raised by what Mike Davis of TheCarConnection wrote about in the following report. It is causing quite a stir! This information can be found all over the internet.

A team of chemists and mathematicians at the University of Western Ontario deduced that most oil additives are complicated compounds containing zinc and phosphate. They then used computer simulations to find out what happens “at a molecular level when a film of oil containing additives is compressed between two hot, hard surfaces” like engine parts. They concluded that as the pressure rises, the molecules of zinc and phosphate form cross-links with each other, according to a science report in The Washington Post. In engines of steel alloys, this process helps minimize wear. But not so in aluminum engines, where the cross-linked molecular hash become harder than the metal and abrades the aluminum surfaces. In other words, if these guys are right, additives are good for engines with steel parts but potentially harmful if used in engines with major aluminum parts, especially on wear surfaces. Experts at the American Petroleum Institute told TheCarConnection they were not familiar with the Ontario Study.

We will first look at the oil pumps and then three examples of engine failures. As you can see in the pictures, the NG900 and 9000 use a different style of gears in the pump. The housing in all of these engines is aluminum. The oil pump in 9000 and NG900 using the straight-tooth gears and an arc divider seem to never be a problem. Engine oil is sucked from the oil pan through the oil pickup screen. The screen is about like a window screen and it only strains out the chunks. The oil and all the rest of the grit it carries moves on into the oil pump, through the gears and out the pressure side of the pump. If the oil pressure is too high the relief valve allows the oil to by-pass to the intake side of the oil pump. The oil then travels through the engine block to the oil filter where it is relieved of sediment and then goes to the oil cooler before moving back to lubricate the engine. Oil pressure can only be produced by the pump if there is sufficient resistance from proper bearing clearance. Normal bearing clearances produce normal oil pressure. Loose bearings allow oil to leak so pressure is lost. Think about putting your thumb over the end of a garden hose. When you restrict the water with your thumb you develop pressure in the hose. Without your thumb on the hose, virtually no pressure is generated. Back to the oil flow: anything that goes through the oil screen can wear and tear at the steel oil pump gears and the aluminum housing. If the housing, the drive gear in the housing or the gears themselves wear there is loss of pressure. Less oil pressure means less lubrication and more heat and wear throughout the engine.

(click an image to enlarge)

9000 Ng900 oil pump on the left and 9-5, 9-3 on the rt. Notice that the NG900 has square cut teeth and an arc divider between the gears. The oil pump covers are aluminum for both pumps.	Notice the lack of divider and shape of the teeth. The round opening at the bottom is the passage to the oil pick up screen. The oil comes into the pump at that opening and is picked up and carried in the gap of the gears and as the center gear turns clockwise by the crankshaft the oil is carried around till it is compressed by the gear and goes out the opening on the right. The pressure relief is located there. Any wear in the housing or gears could cause low oil pressure!	Oil pump housing. The center gear is turning in the housing driven by the crankshaft. Center upper rt you can see the notch to allow oil to the bearing surface of the gear. Wear in the center area will be accelerated by excess clearance in the crankshaft main bearings.

So this may be a story about what comes first: the chicken or the egg-- the pump pressure is low because of other engine wear, or if the other engine wear is caused by low pressure from the pump. Remember the older engines used the same-looking housing but a different style of gears and it did just fine! What could it be about the newer style? I do know that Saab is on its third part number for the aluminum housings for the 9/3 and 9/5 cars. I would have to think that means something needed to be changed.

We have had quite a number of 9/3, and 9/5 engine failures this spring. But I will relate just three failures to give you an understanding why I think the pump could be a problem.

Case #1: 1999 9/5 We started servicing this car at 90,000 miles for its 3rd owner. The 9/5 ran well with no noise, like timing chain noise that shows up many times before other failures. There was no Saab history of sludging. At 92,365 miles the oil light flickered a couple of times and the engine developed a severe knock. Upon disassembly we did not find sludging or a plugged oil screen but we did find spun rod bearings. The oil pan could have been removed previously and cleaned prior to our servicing the car. Nonetheless, we had a ruined engine. It had scored pistons and a bad crankshaft. Fortunately, the owner had a service contract that paid virtually the whole bill.

Case #2: 1999 9/5 One-owner, off-lease car that we sold to a local customer at 45,179 miles. Our shop did the oil changes every 3,000 miles till the car had a new owner at 63,908 miles. We also serviced the 9/5 for this owner regularly. The oil changes were done at slightly higher miles but well within the one-year or 10,000 mile Saab recommended interval. (We realize there are conditions to be met to do 10,000-mile oil changes that probably no one can meet and we highly discourage the practice!). At the time of failure, this owner was driving down the interstate with the cruise control set at 75 mph. Either the oil light did not come on or else he didn’t see it, but the large end of a connecting rod went clear through the engine block breaking the idler shaft. He came to a sudden stop! This engine upon disassembly had no sludge in the oil pan but it sure had a big hole in the block!

Case #3: 99 9/5 One-owner, off lease car with 63,000 miles that we sold to a local customer. He drove it to 73,000 miles and traded it in on a newer 9/5. The next owner (#3) commutes about 100 miles per day. Saab records show no history of sludging. We serviced this car through the second and third owners who were meticulous about oil changes. By the way, our shop uses Mobil 10w30, Saab semi-synthetic and Mobil 1 oil depending upon customer preference. At just over 100,000 miles the owner called because he had a flickering oil light at idle. We scheduled the car in immediately and put an oil pressure gauge on the engine. When cold, the oil pressure was fine and as it warmed up the oil pressure gradually went down until the light would flicker. The engine had no noises or other issues. This was a first!! With an oil light we usually would be dealing with serious engine noises. We pulled the pan and found no sludge. We removed the bearing caps and measured the bearing clearances with Plastigage. All the bearings were at the maximum limit if not just over. The customer allowed us to remove the engine and replace the crankshaft and bearings. We disassembled the oil pump and couldn’t find any measurable reason to sell the customer a new one. We did replace the pressure relief valve just to be sure. The engine was re-installed and driven. Same result! Low oil pressure when the engine was hot. We removed the engine and installed it on an engine stand again so we could turn it to different positions. We removed the oil pan and applied pressurized oil to the system. This would allow us to see if there were some bad bearings or an internal leak in the engine. We found the idler shaft bearings were leaking badly. We installed new bearings and re-installed the engine. However, the test drive proved that we still didn’t have the answer! This was the very first non-sludged engine that we had fixed in a 9/5. It became apparent that there was something in the oil pump or housing that was causing the problem--the only parts left. We removed the engine one more time and replaced both the pump and the housing. Presto! Just like that! We had oil pressure! The parts, including both the pump and the housing, are just under $300 so it is not something we would have just put in on a whim! But, we do now. There has been about 20,000 put on this engine since and it is doing fine!

So was the oil pump the culprit from the beginning? Did poor oil pressure over a long period cause the bearings to wear? Lest you think that these engine failures are not important think about the fact that if you can find a low mileage used engine it will run $3000 to $5000 plus labor to install it. A short block from Saab is $6500 just for that part. With labor the cost of these engine repairs can easily exceed the value of a high mileage 99 9/5!

I’m going to check the oil pressure on my own personal car at regular intervals to track changes in the pressure. I’m using Mobil 1 oil and changing it every 4,000 miles. So far, at 71,000 miles on the odometer, it is doing fine! I would recommend to all of you to: change oil, change oil, change oil and check the oil pressure to be sure your engine is in good condition. Even though Saab has extended the engine warranty to 8 years and unlimited miles I would like to have some warning before I heard a bang and was greeted by a hole in the engine block! Maybe the oil additives are a part of the problem, who knows? As always, we’ll keep you posted as things develop!

(click an image to enlarge)

This is a 9-5 piston from a sludged engine. Damage is caused lack of lubrication and heat!	You may be able to see the hole in the side of the block, broken balance shaft, and large end of the connecting rod protruding.