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Changing Cambelt, Water Pump and Coolant


Phil S1

Changing Cambelt, Water Pump and Coolant...with photos Here's a bit of an account on what's involved when doing a cambelt change. Other items were also changed at this point because it's an ideal opportunity while the cambelt's off. This work was done on my 1999 S1 Elise with the standard (non-V.V.C.) 118bhp K series engine and an automatic cambelt tensioner. This is the second time the belt has been changed on my car. Part of the reason of me buying the car in the first place was to have a go at some of the more challenging aspects of car maintenance as prior to this I had only done the more basic stuff like minor services and changing brake pads etc… I will state right here at the start though that changing the cambelt was and still is something I don't have the confidence to do on my own. If you decide to have a go for yourself then good on you but please beware that getting something wrong could result in a rather costly engine rebuild or serious injury! If in doubt, let someone who knows what they're doing do the job for you.

 

Okay then, like I said I took the opportunity to also change the cambelt tensioner, alternator belt, water pump and coolant. The belts, pump and tensioner were all sourced from www.eliseparts.com The coolant and de-ionised water were from my local motor factor. The first photo shows these laid out on the bench. The object to pay particular attention too in this photo though is the 'tool' on the right and the cut-down socket. The lack of this tool the first time round was one of the reason's I gave up! It is required to undo the crankshaft pulley bolt which has a 22mm hex head. The cut-down socket is used on a torque wrench to tighten it back up again. For reference, the socket was cut down to 33mm in length and the 'tool' measures 600mm long by 38mm total thickness, including the welded on socket. Also in the photo, is the blue anodised camshaft gear locking tool…

 

Coolant1.jpg

 

First job was to get the back end of the car jacked up, the higher the better, but making sure it was well supported and the front wheels chocked. You are lying underneath it and putting a lot of force on that aforementioned torque wrench! I removed the undertray and supported the back end of the car with axle stands on the ends of the chassis rails as shown below. (You could also support it under the steel rear sub-frame which, in hindsight, may have been the better option for this job). I then removed the driver's side rear wheel. The wheel arch liner is retained at 5 points, 2 at the rear into rawlnuts (these and their associated screws may need replacing if badly corroded) 2 plastic fasteners at the front and the screw you can see next to the damper in the photo…

 

Coolant2.jpg

 

Once the wheel arch liner was removed I could access the upper timing belt cover. (The procedure from here on in is pretty well covered in the Elise service manual so refer to that above all else. The only problem with the manual is that it is working on an engine on a bench, not one that is shoe-horned into the back of an Elise). Photo below shows the upper cover and some of the fasteners. (The rusty looking 18mm hex head bolt is one of two on the engine mount that needed to be undone later in order to remove the belt)…

 

Coolant3.jpg

 

Once the upper cover was removed I was able to see the cambelt and camshaft pulleys. Using the 'tool' and referring to the service manual, I rotated the crankshaft to align the camshaft gear timing marks 90 degrees BTDC. You'll see in the photo below at the 3 o'clock and 9 o'clock positions we put some tipex on the pulleys. The method we use is to then mark the belt at these same 2 positions and a 3rd position relative to the crankshaft pulley. (Once the belt is removed we then transfer these marks from the old belt onto the new one as a back up to make sure we don't end up being a tooth out on the timing. Ignore the marks you can see on the belt in this photo though, as they are the ones from when it was fitted the last time round!)…

 

Coolant4.jpg

 

With the upper cover removed you can also see the cambelt tensioner and below it, the water pump. At the bottom of this photo you'll also notice a coolant stain coming from the pump, so it's probably just as well I'd decided to replace it anyway!

 

Coolant5.jpg

 

The next step was to undo the dreaded crankshaft pulley bolt. Here is a photo from underneath that gives you some, but not much of an idea of how close the crankshaft pulley is to the chassis side rail. (Unfortunately you can't see the bolt itself but you can see the alternator belt that has to come off so may as well be changed for a new one while you're there)…

 

Coolant6.jpg

 

In order to wield the tool in the first photo I had to jack the car a bit higher so the tool could hang vertically down from the pulley. Doing this enabled about 60 degrees of swing. The following photo shows the bigger axle stands and the sort of height I raised the car to…

 

Coolant7.jpg

 

To undo the crankshaft pulley bolt you need to be able to react against something, or else you'll just be turning the engine over. It is not physically possible to use the flywheel locking tool (Part No 18G 1571) referred to in the Elise service manual so you have to improvise. The first time we did this on my car we used the method of putting the car in gear and someone carefully getting in the car and pressing the brake pedal as hard as possible. It worked but there is a lot of wind-up of the gear-train, which is probably not a good thing, plus it all seemed a bit too dangerous to be honest. The best way is to try and lock the starter ring. There are some people who do this by removing the starter motor to gain access to the starter ring and then locking it with a suitably sized screwdriver and others who do it like 'we' did by again, locking it with a screwdriver through a suitable opening like the one shown below, near the inboard end of the driver's side driveshaft…

 

Coolant8.jpg

 

I used the term 'we' just now because it is at this point that I once again handed over to Brian (Elise+Imp). Brian has been a very good friend for some years now and in my opinion his engineering know-how is unsurpassed. From a farming background and with a Degree in Mech Eng I have yet to see anything that he can't turn his hand to. You've only got to see his Hillman Imp to see what he's capable of! He has done no end of cambelt changes, a good half a dozen on S1 Elises. With the added benefit of his four-post lift he reckons on about 4 hours from start to finish to change just the cambelt. If you decide you lack the confidence to tackle this job yourself, don't want to pay dealership prices and are not bothered about a stamp in your logbook then I can't recommend him highly enough. So, plug over, Brian locked the starter ring with a screwdriver and undid the crankshaft pulley bolt with the 'tool'. This released the pulley, the alternator belt and allowed access to be able to remove the lower timing belt cover. We then put the camshaft gear locking tool into place ensuring everything was still aligned correctly…

 

Coolant9.jpg

 

In order to remove the belt you have to first remove the two hex head bolts from the engine mount because the mount itself is within the loop of the belt. Before doing this we supported the engine with a trolley jack under the sump, protecting the sump with a piece of wood. You can see the 2 bolts in this photo…

 

Coolant10.jpg

 

After undoing the bolts a little and carefully lowering the jack you can see the joint starting to separate in this photo…

 

Coolant11.jpg

 

Once the joint was fully separated and the tensioner slackened off, we removed the old cambelt through the newly opened joint. Here's a photo of the new belt ready with the tipex markings transferred over from the old belt…

 

Coolant12.jpg

 

Whilst Brian had been transferring the timing marks I removed the water pump. Not sure why but when you look at the service manual it tells you to remove the thermostat housing before removing the water pump, which is not necessary. Repeating an earlier photo below, you'll see there are 4 conventional bolts, a pillar bolt in the bottom right hand corner and not so obvious, a bolt fitted from the back, in the top left hand corner. It is also dowelled at 2 positions, one of which you can also see in the top left hand corner…

 

Coolant13.jpg

 

I removed the pump and caught most of the coolant. Was going to be changing it any way but if you can avoid creating a slick all over the garage floor it's a bonus!

 

Here's a photo comparing the old and new pumps. I have to say, although it had obviously started weeping a little and needed changing, I much prefer the look of the nice stainless impeller to the cast affair on the new one…

 

Coolant14.jpg

 

Here's another of the old pump showing the leak…

 

Coolant15.jpg

 

Here's what you see in the engine when the pump is removed, all looks nice and shiny. You also get a better picture of the 2 dowels…

 

Coolant16.jpg

 

I secured the o-ring in the new pump with some RTV sealant as per the service manual and fitted the assembly back onto the engine. Might have overdone the sealant as it oozed out a bit!

 

Coolant17.jpg

 

We then fitted the new tensioner and the new belt ensuring that the tipex marks on the belt aligned with those on the pulleys. We then applied threadlock to the 2 engine mount bolts and torqued them back up. Here's a photo of the new tensioner fitted but yet to be tensioned…

 

Coolant18.jpg

 

Barely visible in the above photo is the pointer (just behind the teeth of the belt and about 2 teeth below that, the index wire with which it has to be aligned to set the tension).

 

We refitted the lower timing belt cover, cleaned up the threads of the crankshaft pulley bolt, applied some threadlock to it and then refitted the crankshaft pulley. This requires a torque wrench capable of 205Nm, the 22mm socket that has been cut down in length makes life a whole lot easier too! Once more, the starter ring was locked using the screwdriver method. (Make sure you've removed the camshaft gear locking tool before torque tightening!)

 

We set the tension and rotated the engine a couple of times, as per the manual, to make sure the setting didn't alter and that no valves and pistons were crashing together! Once we were happy with everything and I'd temporarily replenished the coolant, we fired it up again.

 

After all that, it was just a matter of refitting the upper timing belt cover, wheel arch liner, wheel and ordinarily, the undertray, but I was going to change the coolant whilst I was at it so I'll go onto that now…

 

To drain the coolant the car needs to be level, or slightly nose up, but high enough off the ground that you can get under it. Jacking the car up with some large blocks of wood under each wheel is one method of achieving this. As with the cambelt, please refer to the Elise service manual for further detailed information on the drain and refill procedure. I first undid the expansion bottle cap and then got underneath to undo the relevant jubilee clips from the hoses. There are two jubilee clips that need to be undone. One smaller one on the driver's side where the metal pipe emerges from the sill…

 

Coolant19.jpg

 

and the other larger one on the passenger side, coming out at right angles to the sill…

 

Coolant20.jpg

 

Here's the driver's side disconnected and draining…

 

Coolant21.jpg

 

And here's the passenger side disconnected and drained, pretty much like I was at this point!

 

Coolant22.jpg

 

Unless you plan on removing the heater matrix you will not be able to drain out the full 8 litres from the system, reckon on about 6 litres. After another hopeless attempt at catching the coolant and once I'd again mopped up the slick from the garage floor, I reconnected the hoses. Something to be aware of is there are compatibility problems between different types of antifreeze, so it's important to either use the same type or flush the system completely with clean water prior to putting the new anti-freeze in. (I was using the same OAT based antifreeze as previously so didn't need to flush it all out). I then removed the engine bay bleed screw, visible as the shiny hex-head screw next to the HT lead in the photo below…

 

Coolant23.jpg

 

I then refilled with a 50/50 mix of antifreeze and de-ionised water. Although the service manual suggests pressurising the system I have had no trouble in relying on gravity to do the job for me. Once the coolant started flowing out of the bleed point (another slick on the garage floor!) I re-fitted the bleed screw. Next step was to open the radiator outlet bleed screw. You find this one more by feel than looking. If you turn the steering to full RH lock and bend the front of the LH wheel arch liner back, then shine a torch in, you should be able to just make out the brass bleed screw. Took a few attempts but just about managed a photo of this one too. You can see the protrusion coming up from the hose and then on top of that is the brass knurled top of the bleed screw…

 

Coolant24.jpg

 

I opened this one and waited for the hissing to stop and the coolant to start flowing out before tightening again.

 

After that, I ran the engine up as per the service manual instructions, re-bleeding at the radiator as necessary, re-fitting the expansion bottle cap and waiting for the rad fan to cut in and out.

 

Once it had all cooled down again I topped up the expansion bottle to the min mark and that was it.

 

Job done!

 

All in all, it took around 9 hours to do all of the above. I guess to have had this all done at a Dealership you'd be looking at a bill approaching a grand whereas this has cost me around £130 in parts and materials plus a huge thank you to Brian of course!


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Great article Phil!

Just a few comments from me...

 

First, where you have jacked up the car, shown in pictures 2 and 7, is not a recommended jacking point. I did this at first, and although it doesn't seem to bend, it could crumple there and drop the car. I didn't put the full back-end weight on the stand when I did it......

 

In order to get the old belt off and the new one on, the other method of loosening both engine mount bolts enough to lower the engine, then removing one bolt, getting the belt halfway, replacing that bolt and removing the other, so threading the belt past the bolts in turn, works very well. I was a bit nervous about holding the engine up on the jack with both bolts out...

 

Finally, it's worth a reminder to look up all the torque figures in the service manual and use a torque wrench! I couldn't believe how many bolts and screws were way too tight when I did mine.

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