Seconday throttle actuator replacement

[Fetnas]

I was poking around under the bonnet this weekend, familiarizing myself with where things are, when I found a vacuum line that was disconnected. After feeling around a bit and looking through the workshop manual, I figured this line is supposed to be connected to the secondary throttle actuator. The problem is that the spigot on the actuator has been broken off and was in the end of the vacuum line. Someone has tried to glue the spigot back on with epoxy but it failed, most likely due to the heat.

2 questions, is it possible to replace the actuator without removing the intake manifold? It seems to be an extremely difficult location to access but I'm not keen on removing the manifold at this stage. Should the vacuum reservoir be securely fixed? Currently it's loose down the back of the engine which may have lead to the spigot being broken in the first place.

If I can't replace the actuator at the moment, I think I'll just block off the vacuum line and try to run the engine above 4000 rpm where the second throttle would normally open anyway

[dapinky]

Hi Fetnas,

If you go to this thread, there are some diagrams and photos which may help a bit. I assume you are talking about the grey cylindrical vacuum reservoir, not the black throttle activator??

Either way, it shouldn't be hanging loose. The activator is securely bolted to the plenum chamber, and the reservoir clips into a metal spring clip just to stop it hanging about.

If you can pull the reservoir out, it may be worth trying a repair with fibreglass resin, or trying to source a new one (wouldn't have a clue how much. or where from, though!)

[Fetnas]

Hi Dapinky,

I've been trawling around the forum and found the photos you linked to of the back of the engine out of the car. Very useful in explaining where all the bits are supposed to be, much better than trying to use a mirror and a torch! I now know where and how the reservoir should be fixed, but I still can't see how the actuator is attached! On the up side, I've come up with a way to fix the broken spigot. I've drilled out the spigot internal diameter to 2.5mm and siliconed a smaller diameter tube inside (it's actually a extension tube from a can of WD type spray)!

Now I need to buy a pin vice so I can manually drill out the hole in the actuator in situ, to the same diameter and silicon the spigot in place, if that make sense! It's going to be a painfully awkward job but if it works it'll be a lot quicker than taking the manifold off. If it doesn't work I'll be no worse off than I am at the moment so worth a go!

I'd still prefer to remove the actuator and fix it on the bench so to speak, so if anyone can explain how it's fixed to the manifold and secondary throttle, I'd be very appreciative!

Thanks

[dapinky]

Your repair sounds like something i'd do.......

....or at least, like i did on the old engine in the red car

I had the inlet plennum on the bench, so it was easy, and having put the pipe in situ i fixed it with silicone and left it to cure - i cant see why it won't work with it still in place, apart from the access to it.

It may be better to initially 'hold' the pipe in place with a dab of superglue, so that gravity doesn't pull the pipe off whilst the silicone is setting????

[Fetnas]

Thanks, Dapinky, like the super glue idea!

I was thinking of taping the spigot in place with electrical tape whilst the silicon dried, but it might be a tad difficult to set up by feel. I'll probably have a go at fixing this over the weekend.

If I can't get tape to work, I'll crack out the super glue.

[Fetnas]

All fixed! I did have a bit of a false start though, whilst gluing the spigot in place I must have accidentally put some glue (probably the silicon) in the end of the smaller diameter tube, blocking it off. But after removing the hose and feeding a straightened out paper clip up the spigot, it worked perfectly and no more vacuum leak to boot!

Also found another vacuum leak, whilst running the engine I could hear a "sucking air" sound coming from the area on the back of the manifold where the vacuum lines connect. A rubber elbow that connected the line to the heater controls had badly split. It had been wrapped in a few turns of electrical tape which disguised the split, that's a rather poor repair effort!

I have also freed the turbo waste gate (it was only just seized and freed up rather easily) and replaced the heater valve (which cracked as I removed it) which was badly rusted and weeping with the plastic Volvo version.

The list of jobs is getting smaller, now I just need to take of the wheels to closely inspect the front suspension. There is some medium surface rust on the upper wishbones, I need to have a closer look to make sure their structurally safe. I just hope the lower control arm is OK!

Wish me luck!