Bringing a 740 back to life

[Laird Scooby]

Originally Posted by Challo

As my Mini is in the garage I have been using the Volvo for the last month and been going well. I got the alignment done by the local garage using their Hunter system, and they picked up a slight issue with the front left wheel.

According to the machine they could get the alignment right as the camber is out. Now from what I remember you the camber is fixed on these, is that correct?

Any idea what might be causing the camber to be slightly out? Issue with the strut?

Camber is adjustable but they haven't even set the alignment correctly, it should be 0deg 18' +/- 8' toe-in which is 0.3deg +/- 0.13deg in decimal. This will show as - 0.3deg +/- 0.13 total toe-in on their system.

Camber is -0deg12' to +0deg48' or -0.2 - +0.8deg in decimal and i suspect the difference in camber values between the sides (note the rear left has a higher negative value than the rear right, similar to the front) could be down to weak springs on one side. A tape measure will tell you if my suspicion is correct - measure from the centre of each wheel vertically upwards to the wheel arch - this is known as the trim height. Compare the front side to side and the rear side to side, that will almost certainly give a clue to the camber.

They appear to have set it to be toeing out which isn't good, this may also have an influence on the camber.

Have a look at your suspension towers on the front, you may have a spare set of holes for camber adjustment, if so, get some pics as that might give another clue.

[Challo]

Originally Posted by Laird Scooby

Camber is adjustable but they haven't even set the alignment correctly, it should be 0deg 18' +/- 8' toe-in which is 0.3deg +/- 0.13deg in decimal. This will show as - 0.3deg +/- 0.13 total toe-in on their system.

Camber is -0deg12' to +0deg48' or -0.2 - +0.8deg in decimal and i suspect the difference in camber values between the sides (note the rear left has a higher negative value than the rear right, similar to the front) could be down to weak springs on one side. A tape measure will tell you if my suspicion is correct - measure from the centre of each wheel vertically upwards to the wheel arch - this is known as the trim height. Compare the front side to side and the rear side to side, that will almost certainly give a clue to the camber.

They appear to have set it to be toeing out which isn't good, this may also have an influence on the camber.

Have a look at your suspension towers on the front, you may have a spare set of holes for camber adjustment, if so, get some pics as that might give another clue.

Cheers Dave. I’ll check tomorrow and report back. I do get a warranty with them so I can go back and get them to change it based on your numbers.

[Laird Scooby]

Originally Posted by Challo

Cheers Dave. I’ll check tomorrow and report back. I do get a warranty with them so I can go back and get them to change it based on your numbers.

You're welcome Chris, let me know how you get on!

[Challo]

Just completed the measurements and nothing stands out.

Front Left 35cm
Front Right 35cm

Rear Left 32cm
Rear Right 32.5cm

I have taken the pictures of the strut towers as well.

On a side note I remember that you advise to remove the pipe tubing which goes to the bottom of the air box as it puts hot air into the air box and potentially making it run rich.

Just thinking why would Volvo add that metal tubing if potentially makes the car run poorly?

Cheers

[Laird Scooby]

Originally Posted by Challo

Just completed the measurements and nothing stands out.

Front Left 35cm
Front Right 35cm

Rear Left 32cm
Rear Right 32.5cm

I have taken the pictures of the strut towers as well.

On a side note I remember that you advise to remove the pipe tubing which goes to the bottom of the air box as it puts hot air into the air box and potentially making it run rich.

Just thinking why would Volvo add that metal tubing if potentially makes the car run poorly?

Cheers

Something else that can potentially throw the castor out for certain and also maybe the camber angle are the space ship bushes. These are between the lower control arm and trailing arm/tie-rod to the chassis.

As for the corrugated aluminium tube feeding the airbox, yes it can cause running problems if the air it feeds is too hot.

What's meant to happen is it feeds a thermostatic flap at the main intake to the air filter box. This flap is meant to maintain a constant temperature and open completely to cold air under hard acceleration/high load to get colder, denser air into the combustion chambers.

However the wax-stat that moves the flap often fails, especially when older/higher mileage causing the flap to stay in the hot air intake position. In winter, it helps preheat the intake air which results in better fuel atomisation and hence better running. If it's stuck in the hot position it can cause problems, especially in the summer with rich running.

They can be renewed but they tend to be expensive, i belive Skandix still stock them. I prefer to just remove the corrugated hose and the air filter stays cleaner for longer as well! Mine were going black after a matter of months, mixture of oil (slightly leaky rocker cover gaskets) and road dust was clogging the air filters and costing me an arm and a leg in new filters prematurely. The one in there now has been in about 3-4 years and is still like brand new!

[Challo]

Originally Posted by Laird Scooby

Something else that can potentially throw the castor out for certain and also maybe the camber angle are the space ship bushes. These are between the lower control arm and trailing arm/tie-rod to the chassis.

As for the corrugated aluminium tube feeding the airbox, yes it can cause running problems if the air it feeds is too hot.

What's meant to happen is it feeds a thermostatic flap at the main intake to the air filter box. This flap is meant to maintain a constant temperature and open completely to cold air under hard acceleration/high load to get colder, denser air into the combustion chambers.

However the wax-stat that moves the flap often fails, especially when older/higher mileage causing the flap to stay in the hot air intake position. In winter, it helps preheat the intake air which results in better fuel atomisation and hence better running. If it's stuck in the hot position it can cause problems, especially in the summer with rich running.

They can be renewed but they tend to be expensive, i belive Skandix still stock them. I prefer to just remove the corrugated hose and the air filter stays cleaner for longer as well! Mine were going black after a matter of months, mixture of oil (slightly leaky rocker cover gaskets) and road dust was clogging the air filters and costing me an arm and a leg in new filters prematurely. The one in there now has been in about 3-4 years and is still like brand new!

Cheers Dave. I’ll take a look at the bushings and see if I can see any issues.

[bob12]

As Dave said ^^^^ if never changed (which highly likely due to it's location and difficult acccess which involves opening up part of the air filter box intake) the small bullet air thermostat inside the filter box which regulates the flow of air from front grille or off the exhaust manifold your engine will be seized.

It's not an easy task to open up the filter box but it can be done and as said the only place I found a few years ago that supplied the 'proper' oem Wahler air stat was Skandix.

The secret to keep them moving is to spay them (up the filter box air entry) once a year with a few shots of WD40 or the like .... something I forgot to do last year!!

Bob

[Laird Scooby]

Originally Posted by bob12

The secret to keep them moving is to spay them (up the filter box air entry) once a year with a few shots!!

Bob

That typo makes it sound painful Bob!

[Ian21401]

Bob, some advice please.
I’ve suspected for some time that mine is not working but have not devoted much time to investigating it. I hope to be servicing the engine within the next few weeks: oil change, oil and air filters, throttle body, PCV, cam belt etc. so may also address that valve whilst I have the air filter box out.
Is it necessary to perform major surgery on the air filter box to access that wax capsule, or is it simply using some careful dexterity.?

[bob12]

It's not difficult Ian but you need the air box out of the car and on a work bench or the like.

The awkward bit could be likened to 'spaying' (now don't get too excited Dave!!) as it's a bit of a bitch!

You cannot get the stat out from inside the filter box. Basically, the section of the filter box that contains the stat is a separate plastic molding containing the diverter flap that slots into the filter box. This has to be separated from the filter box.

Time will have had its way and whilst originally the two parts just slid together now they will have formed a solid friendship! It is necessary to get the two parts at a suitable angle (like over a large vice) so that with a hammer and wood drift you can carefully 'whack' the parts apart!

Somewhere in my mind I seem to recall that there was a plastic rivet holding the two together and you had to drill that out and when all back together put a self-tapping screw in to replace it.

In reality it's not that difficult.

Some years ago I did a thread or added to a post on the subject with pics. I'll see if I can locate it and put up the link.

Bob