Exhaust Blowing

ds001 · October 2, 2017

I noticed my exhaust has started blowing, I was all set for the usual back box replacement but it is actually blowing from just to the rear of I think the Lambda sensor stuck in the exhaust under the passenger seat area.

I can feel it blowing but it seems to be coming from beneath what looks like a heat shield, anyone know what is under that shield, is it just a straight pipe or is there a join? I'm hoping I can get this welded.

Thanks

Britprius · October 2, 2017

The heat shield covers a strait pipe. It seems to be that there is a reaction between the heat shield material, it's clamp and the pipe that causes the pipe to split around beneath the clamp. I had the same problem on the drivers side shortly after buying the car. I am now contemplating replacing the front sections with stainless steel having done the rear section.

Check the "Y" piece at the rear of the car as this is prone to cracking and one side suddenly braking off without warning.

John.

ds001 · October 2, 2017

Thanks for the response John, the rest of the exhaust including the Y piece appear to be ok, the garage told me I needed to change the whole exhaust (both sides) from either the cats back or from the sensors back stating that it was all one piece. When they realised the only place they could source a replacement was from Lexus they said it might be repairable but they didn't do that sort of thing and they didn't remove the heat shield. Anyway, from what you are saying it is possible to purchase the exhaust in sections?

How did you resolve the issue on yours, did you replace a piece or repair it?

cheers, Andy

Britprius · October 2, 2017

Andrew.

It is an easy repair, and can be done on your back raising one side of the car with hand tools.

I repaired the front pipe by cutting the pipe off at the point where it was split.

This just involves removing the heat shield by cutting through the holding clamps. Then undo the front flange just forward of the lambda sensor.this allows the short front section of pipe to be moved away.

A piece of exhaust tube about 6 inches long that just slides over the existing pipe was then used to join the two pipes back together with a coating of exhaust sealant, and a couple of "U" type clamps or welds. Fitting the heat shield back in place using new stainless steel hose type clamps. Ordinary steel hose clamps will rust away in a few months.

Repair lengths of pipe with the ends split for clamps can be bought cheaply on eBay, and make good a permanent repair

The exhaust comes in two sections.

(1) The front consisting of two front pipes with flanges, two cats, a"Y" piece into a silencer (resonator), and into a flange all in one piece.

(2) The rear section consists of a flange in to a "Y" piece that feeds a silencer on each side of the car. Again all in one piece.

There is a picture of the front section in member Carnut 1980 post entitled "GS450H exhaust centre section" , and some a pictures of the rear section that I built from stainless parts in my post "Exhaust problems". These are both in the GS section of the forum.

I hope this helps.

John