home about us tech tips faq employment what's new contact
  Home > Tech Tips

 

Tech Tips


Use this comprehensive information library whenever you need helpful hints from car repair professionals. Whether you are a professional or a DIY mechanic, you’re sure to find the tips you need to insure a job well done. Click here to go back to the previous page any time during your search.

 

Saab

Saab Head Gasket Replacement

 

Saab has long been acknowledged as a leading manufacturer of car engines. The automaker’s objective has always been to design compact, lightweight powerplants, with high power-to-weight and power-to-bulk ratios. Four valves per cylinder, with a hemispherical design, ensure smooth gas flow and efficient combustion.

While Saab engines are very efficient, durable and reliable, there are some inherent intricacies that could make repairs, such as replacing a head gasket, a difficult task if the servicing technician misses certain details.

In this article, I will provide suggestions for replacing the head gasket and point out certain faults that some technicians, who are not familiar with these extraordinary engines, can get caught up in.

When the head gasket fails, the servicing technician should determine why it failed before the completing the repair. Common problem areas include a plugged radiator, a non-functioning cooling fan, water pump failure, thermostat stuck in the closed position, or the serpentine belts are loose or not secure. Try to obtain some information about the vehicle from the customer to determine what type of service/maintenance was performed over the years. You might find this information to be useful in preventing costly comebacks.

Just a few weeks ago, I had a customer bring in his Saab 900 to our repair shop so we could find out why the engine was making strange tapping noises after the head gasket had just been replaced. We discovered that the other repair shop used a 2.0 head gasket as a replacement on the 2.1 L engine, which was causing havoc. The pistons were actually hitting the head gasket. (The 2.3 L 9000 engine shares the same 2.0 gasket because of stroking the crank and pistons for more displacement.) If you are in doubt about which gasket to use, note that when the head is removed, the gaskets are marked at the flywheel side (See Photo 1).

REPLACEMENT PROCEDURES
The first step is to try to drain out all of the coolant from the engine. When this step is overlooked, the result will be a huge mess, plus the crankcase and the tops of the pistons will be filled with coolant. There is a large threaded plug located below the A/C compressor on the 9000 or behind the power steering pump on the 900. In most cases, after removing the plug, you must poke a screwdriver or some sharp, straight object to loosen the corrosion so the coolant will drain at a faster rate.

Remove the cam cover and turn the engine TDC by using a ratchet and socket on the harmonic balancer. Make sure that the cam marks are lined up with the cam caps (See Photo 2). Locate the sprocket markings and use paint or whiteout to mark the timing chain-to-sprocket location. This is a much faster way to ensure precise timing mark location. And, it eliminates the chance of making a mistake and having to try to figure out the correct timing on a stretched chain (See Photo 3).

As a rule, there are seven full links between the camshaft sprocket markings. Remove the chain tensioner with a 1-1/16 socket. Don’t worry about the 12mm bolt head in the center of the tensioner at this time. Remove the 14mm sprocket bolts and let the chain drop below the cylinder head surface. To ease removal of the sprocket bolts, without moving the camshafts too much, place a drift pin or a strong screwdriver through the sprocket and rest it on the head (See Photo 4).

Next, remove the A/C compressor on both the 900 and 9000. It is not necessary to discharge the system. Remove the exhaust, hoses and intake manifold. On the 9000 Series, the intake manifold could give you some trouble, as the mounting bolts are difficult to reach. Try to remove the fuel rail with the injectors attached. Remove the two bolts located under the head on the timing chain cover. Then, remove all 10 head bolts using a Torx 16.

When a resurface is needed, you must remove the camshafts as well as the hydraulic tappets. Place the camshaft bearing caps in order for correct assembly, as they are marked from the factory in an obscure way. The ignition distributor mounting must also be removed. You’ll find that the 40 Torx screws, which are tamperproof, are very tough to remove (they are applied with Loctite from the factory so that they won’t back out). The dowel bushings could also give you trouble, but I found that if you screw in the bolts a few turns and use pliers, they will come out undamaged (See Photo 5).

If the cylinder head needs to be resurfaced, it should not exceed .016 in. The valves and springs do not have to be removed, as they are not going to interfere with the resurfacing procedure. A quick tip is to remove the coolant temperature sender located in front of the cylinder head, since there is the possibility of it being damaged while handling. Clean the engine block with 80 grit or use a jitterbug to smooth sand the surface, then wash it down with a suitable solvent. Try to stay away from those high-speed, scuff-pad gasket removers.

If the engine has more than 100,000 miles on it, you should consider replacing the timing chain at this time. Saab has developed a special split timing chain and a specific tool kit to aid in the replacement process.

The head gasket should be installed dry. No type of sealant is to be used, except on two certain areas — the timing cover to block and end plate to block (See Photo 6). The Saab-recommended sealant is Loctite 518. The sealant is incredible — it hardens only when oil (which speeds the curing process) is present.

Next, install the camshafts with lifters and make certain that the cam bearing cap bolts are in the correct location for oil transfer to the hydraulic lifters (See Photo 7). Tighten bolts to 12 ft. lbs., align the camshafts on TDC and ensure that the crankshaft is on TDC. Install the cylinder head and tighten bolts to an initial torque of 44 ft. lbs., then tighten to 59 ft. lbs.

Finally, tighten each bolt an additional 90 degrees. Use the diagram at right to aid in the correct tightening sequence. Install the two timing-cover-to-cylinder head bolts, timing chain and camshaft sprockets. Torque the sprockets to 48 ft. lbs.

Remove the center bolt off the chain tensioner, which is a spring-loaded, ratchet-type configuration (note the spring and plastic plunger). Pull down the spring-loaded ratchet and slide in the pressure lever. Install the tensioner with a new seal, then install the spring assembly in the tensioner.

There is a chain guide mounted in the cam cover (See Photo 8). Replace it if it seems hard and brittle. I’ve found that when installing the two-part cam cover gasket, it’s a good idea to use some kind of a glue substance, such as a general trim spray adhesive.

It is also a good practice to replace the thermostat at this time to avoid the possibility of failure (plus it is easy to install).

While head gasket replacement may seem to be a complicated procedure to some technicians, there are large profits to be gained in this type of repair. And with each completed job, the replacement process becomes an easier task.

 

SAAB ENGINE EVOLUTION

In the early years of the Saab, especially in the ‘70s, the automaker took steps to improve its durable four-cylinder engines in a special kind of way. The British 1700 & 1850 engine had its share of problems. The main complaints were head gasket leaks, water pump leaks and timing chain failure, with the possibility of overheating and cracking the cylinder head.

Replacing that particular head gasket was a nightmare. The upper head studs were positioned in such an angle that they had to be extracted before the cylinder head was removed. The studs seized in the head, making it almost impossible to remove them. Saab developed a tool to make replacement easier, but it did not work very well. Most of the time, I ran the engines to operating temperature and removed the studs at that point.

In 1972, the company merged with Scania. The new larger company had increased financial capability to produce a whole new powerplant, the 2.0 L H engine. It had the same old-style water pumps that caused similar problems, but the cylinder head was a snap to remove. It had a special type of double roller timing chain, but the tensioner was a weak unit.

Saab had trouble with the cylinder head. For example, it would crack and develop small tiny pinholes. This problem was prompted by the coolant eating away at the casting, when the antifreeze was not serviced on a regular basis. It had a strong block-to-head configuration that lasted until 1980.

When the B-201 8-valve engine was launched, it was a huge success. The water pump was an external unit and easy to service, while the cylinder head was redesigned for increased strength around the exhaust seats and a more solid design in the camshaft tower area. The head gaskets were more difficult to replace in the turbocharged versions because of all the plumbing and different configurations.

Some technicians blamed the turbocharger for leaking engine oil into the combustion chamber when, in reality, it was the head gasket leaking into the timing chain area or the oil feed to the cylinder head leaking into number one cylinder. It was very easy to diagnose — just by pulling all of the plugs out and doing a visual inspection.

The 16-valve engine made its debut in 1985 in the 900 turbo only. It was an excellent, redesigned engine with an all-new fuel system. The cylinder head was a double overhead cam style with hydraulic tappets. Replacing the head gasket was a very similar task to that required for the earlier 8-valve engine.

When the 9000 Series was introduced in 1986, the above-mentioned 16-valve powerplant could also be found under the hood. The head gasket replacement procedure is almost exactly the same as that of the 900 turbo.

MORE THAN MEETS THE EYE
In the 1991 model year, the Saab 900 was equipped with a 2.1 L engine. It had a different head gasket than earlier models because of a larger displacement in boring out the 2.0 L block, larger intake runners and different flow rate injectors. The engines look very similar, right down to the black valve cover. If you’re not too sure of the engine size, just look at the left fender tag (See Photo 9). The 2.0 L head gasket will fit, and the engine will run, but it will produce a small knocking noise (see main article for additional details and replacement procedures).

Go back