Volvo 850 T-5 Distributor & Rotor Arm Replacement

It's been a while since I used this blog and I'm afraid this post is slightly off topic, but relevant to Volvo maintenance.  My 'other' car is another 850; a T-5 estate.  After a recent trip to Wales (see http://www.chroniclerally.co.uk/rally---wales.html for details) I had started experiencing running problems.  A slight misfire/hesitation whilst under heavy load.  Initially blaming supermarket petrol and thinking I'd got some water in the system, I put a couple of bottles of Wynn's Dry Fuel through a couple of tanks of V-Power, but the issue remained.

Talking through the symptoms with a former mechanic friend, he suggested taking a look at the distributor cap & rotor arm, which I did and this is what I found:

Manky Cap

As you can see, the contacts are pretty poor and there are trace lines where the spark has been taking the scenic route instead of heading for the plugs.

And the rotor arm (below) didn't look much better, so I hit up German & Swedish, handed over £24 and went home with some new bits.

Rank Rotor

The next few paragraphs will be about the removal of the old components.  There's not much about fitting the new ones, but as the book of lies always says, "refitting is the reverse of removal."

That said, I will mention anything I caught which is worth noting, but there's no images of the refit process.

Although this post is based on the process for a T-5 engine, the instructions will work for non-turbo 5-bangers just as well.  You n/a owners will actually find the cap is more easily accessible due to the reduced amount of plumbing involved.

It's in there somewhere...

First things first, where is it?  You'll find it dangling off the 'back' of the inlet camshaft.  In English, that means it's the opposite end of the engine to all the pulleys (which are next to the V in Volvo in this image) and it's in the top corner of the engine, nearest the front of the car.  Handily, that means it's squished between the engine and the airbox (the bit that says 'TURBO' in the picture).  On a turbo model, that also means it's under that whacking great pipe running over the top of the motor.

Separation isn't so hard

The first thing to do to access the distributor is to remove the airbox.  That's a relatively easy task, so don't give up yet!

Before yanking it out, you'll want to do three things.  Firstly, you'll want to disconnect the air intake from the very front of the car where it disappears into the grille next to the radiator.  This is easily achieved by separating it along the seam between the ribbed/flexible part to the right of the image and the plate-like bezel around the front part.  This is probably more evident when you're looking at it in real life!

Pesky Pipe

Secondly, you'll want to disconnect a wee rubber hose from the intake pipe.  It's on the bottom of the pipe, just behind the jubilee clip holding the MAF sensor in place.  It has a blue band around it for accurate identification purposes.

This will then allow you to unclip the top of the airbox and fold it out of the way.  Be careful to check that nothing else is clipped to the box (like the main ignition lead from the coil, for instance!)

Clippy Clippy!

Unclip all of the retaining clips which hold the top half of the box in place - I think there are three on the front side, a further three on the back side and another one on the end where the actual distributor is (remember what we're trying to achieve?)

Once they're all unclipped, lift the top half off the box, but try to keep the air filter in the bottom half as you do so - it will want to come with you, but let it down gently.  I find the top of the box will hook neatly onto one of the suspension strut bolts where you can forget about it.

Now we're getting somewhere

This is probably a good opportunity to take a look at the condition of your air filter.  Mine could probably do with a change, but I just beat the dust out of it and will get around to replacing it another time.

The last of the three things then is to remove a sensor mount from the side of the bottom half of the airbox.  It's easier to get to with the top removed, which is why it's the last thing to do.

(Un)screw this!

I'm afraid this is about the clearest picture I could get, but you should be able to make out the two screws holding the greyish thing to the side of the airbox.  The screws are T-25 self tappers, so you'll need a T-25 Torx bit and it's probably easiest to loosen them with a ratchet spanner.

You also may benefit from disconnecting the sensor from the wiring loom by depressing the little clip on top of the connector and pulling it away (towards the front of the car).  You can let the sensor dangle, as the rubber hoses will keep it nearby.

Breathe Relieved

At this stage, you should simply be able to wrangle the airbox free.  It is held in place by two clips at the engine end and a rubber grommet in the inner wing.  Giving a decent upward tug at the engine end should liberate it from the clips and pushing the whole thing towards the engine should free it from the grommet.

This will completely free the airbox, but there's a slight caveat in that I actually have a slightly smaller battery than standard in my car.  That means you might have to either remove the battery or unclip the inlet pipe from the bottom of the airbox (from inside the box, under the filter) before you can actually set it free.  Please do let me know in the comments whether you had to do this and which method was easiest - I couldn't get the pipe unclipped when I tried, but I didn't try very hard!

With the airbox removed, you should have all the working space you need to actually remove & replace the dissy cap & rotor arm.

Space: The Ultimate Luxury

I am not a number!

I know I've already been teaching you to suck eggs, but one thing I think is rather important before you go any further is to label the ignition leads in order to make sure you put them back on in the correct layout for the firing order.  The firing order of the Volvo 5-cylinder modular engine is 1, 2, 4, 5, 3 and the lead for cylinder #1 is the one in the roughly ten o'clock position when you look at the cap end-on.  Again, looking end-on, the firing order is anticlockwise, so I just used the end of a screw to scratch the numbers into the rubber of the leads.  You may choose to use Tippex, a pen, or some chocolate.  You may also choose to label them something else.  A, B, C, D, E, for example.  Or maybe Roman numerals.  Or α, β, γ, δ, ε.  Or perhaps Klingon.  It really doesn't matter, as long as you make sure you put them back in the same order when you're done.

Bare Terminals

With the leads labelled, you can go ahead and pull them all off.  They will generally stay out of your way, so you probably won't need to tie them up, but there's no harm in it.

It's probably wise to keep the coil lead away from the battery, so you might want to tie that one up.

As you can hopefully see in the image, just three bolts stand between you and removal of the cap.  Due to the still marginal access, it's probably easiest to use a screwdriver to take them out.  The original Volvo ones are slotted for a flat blade driver.  The replacement item I bought also allow the use of posi-drive, which is nice.

Hello Roto!

The bolts don't come out all the way, so don't worry about dropping them, but do try to keep the cap level & supported until all three bolts are loose.  Simply pull the cap straight off (towards the void you created by removing the airbox) to expose the rotor arm.

The last time I replaced a dissy & rotor was on an Austin Metro, so I was pleasantly surprised to see a wee plastic cap inside the Volvo (Bosch) cap.  I presume this is to help prevent oil spraying all over the inside.  My engine could do with a few seals replacing, so there's oil everywhere, but the cap was reasonably clean inside.

Cap Doffed

You'll need to remove this inner cap to get the rotor arm off, but it's not actually fixed in place.  You just need to pull it away from the base and angle it over the rotor arm to expose the three bolts holding the arm in place.

In typical Swedish fashion, a third type of bolt (after the Torx self-tappers and the slot-cut bolts of the distributor cap) hold the rotor arm on.  This time, the bit I needed from the box was a 3mm allen bolt bit.  Oddly, the replacement part came with 4mm allen heads.

And you're done!  Well, everything's removed and I've run out of photos, but it's the same thing.  Fitting is the reverse of removal, but here's a couple of pointers:

• When tightening the bolts on the arm and the cap, put them in loosely to start with to make sure there's wiggle room in case one doesn't want to go in the hole.  Then, working clockwise, tighten them to thumb-tight.  Clockwise again, nip them up tight-ish.  Finally, clockwise again, go around and give it a bit of effort.
• The original distributor cap came with a plastic black cover.  If you want to reuse this, you will need to remove the three bolts from the cap by pulling them up against the inside of the cap and then unscrewing them.  You will also need to put the bolts for the new cap through the plastic cover first.  Be warned though, the plastic cover didn't fit my replacement cap, so it's probably only suitable for a genuine Volvo replacement part (which probably comes with a replacement cover as well!)
• Before trying to fit the new cap, wind the bolts into the three bolt-holes until they slide through.  It's just easier, trust me.
• The 'tallest tower' on the cap is for the ignition lead for cylinder #1 which is at roughly the ten o'clock position.  That should get you lined up close enough for the bolts to do the rest.
• When refitting the airbox, remember to reattach the sensor you removed earlier (press the clip to plug in the connector) before you put the top half back on, as access is limited.
• Also remember to reattach that wee rubber hose to the top half of the airbox after you've clipped it back on.

Please do let me know about any comments or corrections and I hope you've found this useful.