Manifold to downpipe coupling.

[VosperD]

i took the Yaris (1.0, 2001) in for two new front tyres and they checked the exhaust that has recently started blowing.

Their diagnosis was that the coupling between the manifold and downpipe needed tightening. As the bolts were well rusted and the leak wasn't too bad they didn't attempt a repair as they were afraid the bolts might shear and they wouldn't get a replacements straight away.

Am I right in thinking that these bolts are shouldered and it's the two springs that hold the seal in place?

Had a quick look and can't shift the bols myself so far.

Don

[sproutdreamer]

On the 1.3 engine 04 they are shouldered bolts and the 2 springs give the correct tension to the manifold ring gasket. You can get at the top of the threads of the bolts to apply penetrating oil. A few doses of proper penetrating oil (not WD40) should help avoid shearing off the bolts. If you did shear off the bolts I think you can probably get at the top to drill out the broken stud. Good luck with it.

[Stevie J]

The early model Mk1 1.0 had quite a common issue with the exhaust manifold itself rusting through, being on the front of the engine and exposed to water coming through the front of the car when driving, these thin metal manifolds were prone to rusting and the individual pipes running from the block to the downpipe flange could actually rust through, and you'd get the blowing noise. I would check the manifold carefully across all its pipes for holes, and if it is rusted through, then you;ll need a  new manifold. The Mk1 1.0 does not have a manifold cat (maniverter) as in newer models, so the manifold is not as expensive to replace.

[bathtub tom]

1 hour ago, sproutdreamer said:

A few doses of proper penetrating oil (not WD40)

Thank you! WD40 stands for Water Dispersal formula number 40. Although a reasonable substitute if you can't get hold of some Plusgas, or even better, a mix of acetone and ATF.

[VosperD]

Thanks for the replies.

I understand that WD40 is not much good as penetrating oil. Haven't seen PusGas in the shops for a while but I'm sure it is still available , . . at a price.

I don't have any ATF to hand at the moment but I see that vegetable oil is a possible substitiute so I've tried that with some acetone.

The manifold looks ok but I can see some signs of surface rust in places.

Don