Bringing a 740 back to life

[bob12]

I couldn't find my earlier posts about the air thermostat in the air filter box.

It appears threads started on 'Stats' after 5 years are consigned to the bin and I am not going to wade throught my posts!

However, I did happen to find an 'opened up' air filter box in the garage with a dead air thermostat and attach pics herewith. The thermo fits into the the plastic end of the spring and locks/slots into the clip to hold it in place.

I notice that the air thermo and flap part is held by two plastic tags top and bottom rather than plastic rivets as I imagined earlier.

The tags just push inwards to release before you hammer the two halves apart. They are brittle and you will have to block them off with duck tape on re-assembly and then drill a couple of holes into the re-joined assembly to fix with a couple of self-tappers.

Bob

[Ian21401]

Knowing that two parts are meant to come apart, rather than not meant to do so, is half the battle. Then one can devise a method to attempt to separate them without damaging them beyond redemption.
Thanks for the pics. Is that first pic showing part of the filter box, on the left, with the air intake where the flap and stat are partly removed?

[bob12]

Originally Posted by Ian21401

Knowing that two parts are meant to come apart ..........................
Is that first pic showing part of the filter box, on the left, with the air intake where the flap and stat are partly removed?

Yes 😂🤣🤣. I replaced the diverted flap and air thermo part half back in the filter box to show where It went after I had whacked it out.

Bob .

[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!

Are these the spaceship bushes highlighted in the photo?

[Laird Scooby]

Originally Posted by Challo

Are these the spaceship bushes highlighted in the photo?

No, that's the bottom ball joint from what i can see Chris. You've captured the front spaceship bush in your image though, the rear one is behind it as part of a "mirror image" highlighted in green :



They are generally known as "control arm to tie rod bushes" when you go hunting on fleabay if you find play in them. You'll need a crowbar or other similar lever to detect it though.

[griston64]

Go for superflex poly bushes if you do replace the spaceship bushes. You can buy direct from Superflex

https://www.superflex.co.uk/proddeta...=SF420-1023KSS

[Challo]

Originally Posted by Laird Scooby

No, that's the bottom ball joint from what i can see Chris. You've captured the front spaceship bush in your image though, the rear one is behind it as part of a "mirror image" highlighted in green :



They are generally known as "control arm to tie rod bushes" when you go hunting on fleabay if you find play in them. You'll need a crowbar or other similar lever to detect it though.

Cheers Dave. Will give them a closer look tomorrow and see if I can see any wear. Might be worth changing anyway.

[Laird Scooby]

Originally Posted by Challo

Cheers Dave. Will give them a closer look tomorrow and see if I can see any wear. Might be worth changing anyway.

Originally Posted by griston64

Go for superflex poly bushes if you do replace the spaceship bushes. You can buy direct from Superflex

https://www.superflex.co.uk/proddeta...=SF420-1023KSS

If you do change them Chris, invest in a wire brush for your drill, something like the "rod bowl" version of this :

https://www.ebay.co.uk/itm/393618696744

Also if it's a keeper, follow Marks suggestion and go for polyurethane bushes, you should be able to re-use the washers but you'll need some Loctite 431 or similar thread locking compound and a good torque wrench for the centre bolts - if memory serves they're about 90lbft but i'd have to check and confirm. Also once you've fitted them, fit the centre bolt without threadlock to start with and bounce the car a few times to settle them then re-torque and bounce again and check the torque is still as it should be. If it is, remove the bolt, add some threadlock and refit, torquing to the correct figure - note that the bolts should be tightened with the weight of the car on the wheels, they wheels can be turned for easy access.

If you'd prefer to go for a wallet-friendly bush :

https://www.ebay.co.uk/itm/324790068913

You'll need 4 (2 each side) and there used to be a kit available of 2 bushes, sleeve, washers and new bolt but that seems to have disappeared.

[Challo]

Changed the bushes this morning. Quite easy compared to other repairs I have done on the car. They didn’t look too bad in terms of wear.

Got it booked in Friday to get the alignment checked. Hopefully the new bushes mean the front can get aligned properly this time.

[Laird Scooby]

Originally Posted by Challo

Changed the bushes this morning. Quite easy compared to other repairs I have done on the car. They didn’t look too bad in terms of wear.

Got it booked in Friday to get the alignment checked. Hopefully the new bushes mean the front can get aligned properly this time.

I bet the steering feels a lot more positive now Chris, even if the alignment is way out! Don't forget to check-tighten the central bolt in a few days! Unless you used Loctite and the method i described before of course.