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Chain gang: we renew timing chains in a SAAB 9-5 Aero engine
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Applies to SAAB 9000 (from 1993), NG900 , 9-3 (9400) up to 2002 & 9-5 (9600)

Chain chatter is bad news but the job is necessarily expensive at a dealer (typcally £1200+) because of the scale of the work. The good news is that the parts are quite affordable as a special SAAB kit that is a massive saving over buying the parts individually. Don't even think about changing just the chains and tensioners on their own because it will be a waste of money and time. This job demands patience, for it must not be rushed. Cleanliness is essential - 3 or 4 hours worth of cleaning of items like the sump and timing cover is quite normal.


Tools & materials required for changing timing chains on the 9-5 4 cylinder petrol engine

The SAAB kit contains just about everything required and is seriously good value

Method

Start by ensuring the engine is timed up or ‘zeroed’, as SAAB would say. To do this, check that the marks on the crankshaft pulley and timing case are in alignment and that the marks on the camshafts and camshaft bearing caps line up too (see below)

The engine MUST be timed up before starting the procedure

Fit the two new camshaft chain gears, noting that they are notched for precise location. Press the gears into position (on NO account tap them with a hammer, as the camshafts are brittle and can break!) locking the flats on the back of the camshafts with an 18mm open ended spanner to prevent them moving.  Nip the bolts tight before torquing the bolts down to 63 Nm.

Fit the new crankshaft bottom gear, then install the curved moving chain guide (1).  Now, fit the main chain, noting that the yellow alignment marks need to be in line with the tops of the camshaft sprockets. (see photo for clarification)

Next, install the static plastic chain guide (2) noting that both the main and balance chains act upon it.

Timing gear topology - see text for fitting details

Refit the 'u' shaped chain guard at the bottom of the block and then prepare to fit the main timing chain tensioner to the drilling at the back of the cylinder head. Be sure to use the new composite metal/neoprene sealing washer.  This is very important, as this seal can be a notorious source of oil leaks.

The SAAB kit does not include a new main chain tensioner. This is because the tensioner tends to wear far less than the chain itself. A new tensioner is SAAB part 7585086 (£90 + VAT) but pattern parts are available for around athird of this price. As a rule, they are not sufficiently worn to warrant their renewal. A new tensioner comes ready to fit but when re-using the old unit, give it a good clean and proceed as follows.

Turn the chain tensioner so that the serrated part of the plunger is visible, then press down the small latch and push the plunger inward as far as it will go. Ensure that the threaded drilling in the cylinder head is suitably clean. Tighten the tensioner body by hand to avoid any possibility of cross-threading, then achieve final tightness by using a 27mm deep socket on a torque wrench set to 63 Nm.

Now install the smaller tensioner plug with the pin and small spring. Don't forget the new 'o' ring seal in the kit! Tighten the plug by hand then nip with a socket before using a torque wrench to achieve a final tightness of 22 Nm. These actions set the tension because the spring depresses the plunger so it acts directly upon the chain. See photo below for clarification.

Always use the new seals provided in the kit when refitting the tensioner. Set the tensioner by depressing the latch and pushing the plunger as far as it will go.

At this stage, the main timing chain elements are in position.  Double check that the timing marks are all still in perfect alignment and that all fasteners are nipped tight.  We invariably rotate the engine 2 whole turns and check again that the timing marks are correct.  If you do this, don’t be concerned that the yellow painted marks do not line up where they were originally - this is inevitable.  When you are satisfied that the timing marks are correct, start with the torque wrench and suitable sockets to achieve the final tightness on each fastener in turn.

Plastic guides                                        10 Nm
Camshaft chain gears                            63 Nm
Chain tensioner (main chain)                63 Nm

With the main chain in position, make a start on the balance shaft chain by installing the new upper chain guide for the balancer shaft chain. This is a short plastic component secured by x2 bolts (component number 3 in the photograph above).

IMPORTANT: the balance shaft gears are handed and must not be mixed up.  Note that each is marked and should be fitted so that the gear (A) marked INL is fitted to the inlet (back) shaft while the other (C) which is stamped EXH is fitted to the front (exhaust) shaft. The new gears have yellow paint alignment marks to ensure the balancer shafts are in their correct positions. This is important because if the shafts are not set up correctly the engine will suffer from mysterious vibrations.

The balancer shaft chain tensioner (4) is fixed with x2 bolts but before fitting, note that the new tensioner in the kit is fitted with a pin, that must be removed when the chain is fitted correctly with all marks aligned. Fit the idler sprocket (item B) and note that timing up the balancer shaft chain is fiddly and it is so easy to end up with the set up just one tooth out. Fit the tensioner and moving chain guide (5). Take your time when carrying out this procedure. For the tensioner to work correctly, ensure that the fixing bolts are tightened to precisely 10 Nm. Now, remove the pin from the balancer shaft chain tensioner before rotating the engine one complete turn. This is to confirm that the balance shaft timing marks are aligned correctly. If for any reason the chain has to be removed after the pin has been taken out of the balance chain tensioner, reset by rotating the plunger half a turn (180°). Turn 90°, then press the plunger in and turn another 90°. This resets the position but replace the pin in the hole in the top of the tesnsioner body or use a paper clip, if the pin has mysteriously(!) vanished.

These photos show the final positions of the chains relarive to their alignment marks. The whole area needs to be as clean as possible, including the chain gallery. There are no prizes for rushing this job.

Now that the chains have been fitted, turn your attention next to cleaning traces of old flange sealant from the underside of the cylinder block on the mating face where the sump will be refitted.  Next, the sump should be washed out thoroughly and the strainer cleaned and fitted with the seal supplied in the SAAB chain kit.  (Cleaning the sump, baffle and strainer is an operation already covered as a separate article on this site)

Assembling the timing cover

Timing cover needs to be spotless inside and out. We always bin the oil pump and dismantle the oil pressure relief valve just for extra peace of mind.

The timing cover (5) needs cleaning thoroughly, too (inside and out). The following text refers to the photo above. Before doing anything else to the cover, it is essential to remove the oil pressure relief valve (6). In order to remove the oil pump, a pair of circlip pliers will be needed (1) that have an operating range of between 120-200mm.  There is a special SAAB tool number 82 93 086 for this (Facom 479 A.S.) but a good tool shop should stock something similar. The cap is in the base of the cover and it is notorious for pulling the thread out of the cover but this must be done, as the valve needs to be checks for scoring and signs of sticking. We always clean the oilway thoroughly with some solvent and compressed air, then polish the valve with fine metal polish like Brasso. All traces of the polish must be removed thoroughly before lightly oiling the valve, spring and cap. In a full overhaul, we always bin the valve and spring.

Remove the big circlip (3). The oil pump cover (2) should then lift out. Examine the cover carefully for signs of scoring, cracks or other damage and remove the outer oil seal. If no damage is found, the cover can be reused. With the cover removed, the two planetary gears (4) are exposed. These should be discarded! The gears may look perfectly usable but in service, the teeth wear uniformly and the full extent of the wear can only be seen when compared side by side with the new gears (available as a kit from SAAB as part number 88 22 702. The cost is modest enough to be considered a bargain at around £44 + VAT).

Note that the gears fit just one way and there are two alignment marks (7) that should be positioned opposite each other. Lightly oil the new gears with machine oil or proprietary engine assembly lube (as shown below). Be sure to use assembly lube sparingly - we find one container will be good for at least 10 engines. The oil pump cover seal is included within the timing chain kit and must be replaced. Use petroleum jelly (vaseline) to lubricate the seal lightly.

Use petroleum jelly to lubricate the new oil pump seal and assembly lube applied sparingly to the new gears

Refit the pump cover with its new seal by using the circlip but note that the circlip is tapered and fits just one way. Install the circlip so that the open end is at the bottom of the cover. Do NOT fit the new crankshaft pulley oil seal at this stage, as there is every likelihood that it will be damaged as the pulley will need to be removed again before the power unit is refitted. We only fit the new seal when the power unit is bolted back in the car - this is a very easy operation, as access is good.

Check the torque of all fasteners:
Plastic guides                                        10 Nm
Balance shaft chain gears                      25 Nm
Chain tensioner (balance chain)            10 Nm

After checking the torque settings, refit the timing cover carefully. It is at this stage that having the x2 locating dowels removed from the engine block plays its part for if this has not been done it will be nigh on impossible to refit the cover without damaging the cylinder head gasket. The problem with that is simple - oil is constantly washing around this joint and it will leak like fury if damaged in any way. Trust me - no amount of sealant will stop this.

Final assembly

Check the mating faces of the cylinder block and timing cover are suitably clean before applying a thin bead of Loctite 518 sealant (this red cement is included in the SAAB timing chain renovation kit). What you are aiming for is a continuous thin bead in the centre of one mating face. Also apply (important) a small quantity of sealant to the join between cylinder black and head. The objective is to avoid using sealant like 'stawberry jam' - a 1-2mm bead applied to the middle of one mating face is sufficient, as this will spread under compression but not so much that it will get inside the cover with the risk it might end up blocking the sump strainer. For this reason, NEVER use Hylomar or conventional silicone sealants on a SAAB B204, 234, 205 OR 235 engine. The sealants may well be good for other engines but not these, as little 'bobbles' form with disasterous results.

Locate all the timing cover bolts loosely in their locations before tightening each down progressively, then replace the two locating dowels, tapping into position with a ball pein hammer to centralise the cover before nipping the bolts down progressively. Use a torque wrench to achieve the final tightness of 22 Nm.

All that remains to complete the job is to refit the cambox cover but this needs a thorough clean. Attention should be paid to the metal breather pipes which should be blown though with compressed air. If this is not done, there is a chance of blockages that can impair the crankcase breathing (not good!) and this can sometimes manifest itself as blue smoke in the exhaust at startup.

Tighten the cambox bolts carefully, ensuring that the rubber gaskets ghave not moved before using a torque wrench to achieve a torque of 15Nm or 11Lbs/ft.

Fit the new rubber chain control slipper to the inside of the cambox. Removing the old black rubber slipper can be fun, as it tends to harden with age. Clean away all traces of the old cambox gaskets (new gaskets are supplied in the timing chain kit). Apply a very small amount of oil to the recess machined into the cover, then carefully press the new rubber gaskets into position. Take extra care not to get the outer gasket trapped. Check the position of the gasket all the way around before working the Torx type bolts down finger tight. Use a torque wrench set to 15 Nm (11 Lbs/ft) to finish tightening.

Finishing up involves refitting ancilliaries removed to access the timing case and whereas this is straightforward, so long as none of the bolts have become mixed up, the water pump can be fiddly to sort out. It is essential to ensure that the seating for the metal coolant pipe is clean enough to receive the new rubber seals (in the kit). Use fine emery paper if necessary and a smear of petroleum jelly. Also, renew the pair of larger thin seals either side of the alloy pump adaptor, again using petroeum jelly. You do not want a leak here and even if it involves waiting another day, bin the water pump if there is any play in the pulley shaft or signs of leakage from the gland.


What none of the manuals tell you...

Having spent a LOT of time cleaning components like the timing cover, sump, strainer, oil cooler, cambox cover (real fun!) and been driven mad by the balancer shaft chain timing marks (which always seem to be a tooth out!) I must warn you that when the time comes to start the engine, even though you will have taken out the spark plugs and cranked the engine (DI cartridge disconnected and allowing the starter a rest every so often) for a good 5+ minutes to fill the oil cooler, filter etc the engine WILL sound absolutely dreadful! What is more, the engine will need to be run for at least 25 minutes and possibly as much as 40 minutes for hydraulic lifters to run silently. Even a decade's expereience of rebuilding the engines scarcely prepares you for the unholy heart-stopping clattering cacophony that assails the ears but all will be well, so long as the oil light is out.

Finally, having read this procedure, some readers may like this cautionary tale...

It really is a false economy not to change the oil pump gears but it is a job that is often skipped. We wouldn't recommend changing components just for the hell of it and the procedures featured here have been carried out many times over during the last decade. This is the story of a B234 engine in a 1996 model year 9000 automatic, where the pump was not changed by a garage after quite an extensive overhaul. The net result was that worn teeth broke off the oil pump gears inside the cover, locking the engine solid. This not only trashed the timing cover but destroyed the bottom chain gear too.

Nver skimp on parts when rebuilding a SAAB B204/234/205 or 235 unit unless you enjoy making the acquaintance of the drivers of those big recovery trucks with the big lights on the top.

The author and his brother travelled some distance for the car in question, which was listed on eBay as a spares or repair project (6+ years ago!). Apparently, the car had driven onto the drive at the owner's drive but would not start the next day because the engine would not turn at all. A new battery had been considered until somebody had discovered that the engine had apparently seized up over night. The author had a gut feeling that an engine full of nice clean blue coolant and very clean oil just would not siezed up for no reason but loaded the car onto the trailer and drove several hundred miles home. On the following day, we removed the power unit and started stripping the engine, only to discover that it had been treated to quite substantial expenditure. Unfortunately, this had not extended to changing the oil pump, which was in a shocking state.

We fitted a full set of new chains and gears before sourcing a good timing cover and oil pump cover from the stores. This was fitted with a new relief valve and spring plus new pump gears. The sump was removed and the strainer was cleaned (9000 strainers can and do block too!) before the engine was replaced in the car. The repair was completed in less than 24 hours - just in time for the SAAB Owners Club National Rally.


Parts
Parts for this operation were supplied from stock within 24hrs by Euro SAAB Parts Direct at a discounted price that offered a huge saving over retail. Of course, we have sourced parts from many dealers and suppliers in the past but ESPD are consistently best.


Coming next...
A major series of new features walking readers through the various stages of reconditioning an engine:

  • rebuilding the cylinder head
  • changing balancer shaft bearings
  • overhauling the cylinder block: reboring the block and fitting oversize pistons
  • overhauling the crankshaft: regrinding or polishing the crankshaft and fitting new shells
  • overhauling the timing case: replacing the oil pump gears and oil pressure relief valve

The series will not necessarily be uploaded in the order above and the author hopes readers will understand that even the article above took far longer to write, check and find suitable photographs to support than the actual job itself.

ANY of these procedures constitutes a major repair but even if you have no intention of doing any of these jobs, the articles will help you understand the workings of your engine and the true cost of skimping on maintenance.

Page updated March 10th 2010


 

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