Exhuast Blowing Still After Replacing Gaskets ( Ls400 Mk2 )

ultimatequinoxe · January 7, 2010

I wonder if the rubbish service I got at Lexus parts in Leicester have gone and got me the wrong gaskets. The ones between cat and Y-pipe/downpipe (?) have both gone. So I ordered new ones which came to day, fitted them ( in the snow brrrr ) and they leak just the same, and the car sounds like a feeble dragster. What am I missing here ? Bolts are as tight as a gnats bum, new gaskets, still blows like there were no gaskets at all.

Seriously, because I am just getting nowhere with this car, as fast as I replace something, another thing comes up and I need a daily use car, and the MOT is due the end of the month I'm seriously thinking of flogging it ( or swapping it ) cheap spares or repair for anyone who wants it for spare engine/box/bits/interior etc, I don't have the health to keep on top of it anymore.

Ruud · January 7, 2010

When my gaskets went on my old MKII I think I fitted them with holts repair paste or similar! Worked like a charm!

TigerFish · January 7, 2010

When my gaskets went on my old MKII I think I fitted them with holts repair paste or similar! Worked like a charm!

I did the same when I changed the one on my mk1 GS. New gasket and exhaust paste, warmed up on tickover and then allowed to set full overnight worked perfect.

steveskeggy · January 7, 2010

Are you absolutely sure that the leak is coming from the gaskets?

If you are, then try taking them out , give them a good coat of gun gum, then put them back in again.

While it is off, just check the faces that the gaskets touch, make sure that they are pretty leveland dont come together at an angle.

If that doesnt work, then I would check the rest of the system.

Mybikesacx500 · January 7, 2010

Your local hole in the wall car shop, or Halfords, will have exhaust assembly paste, like runny GunGum.

OR- its too cold, take it to Kwik fit, this much-maligned company changed my engine oil for less than I could buy the oil for.

My car developed a faulty ignition coil just after I got it, dented my confidence in the car somewhat, but it has been completely reliable since

ultimatequinoxe · January 8, 2010

http://www.lexls.com/tutorials/exhaust/fpipe.html

The pic at the bottom of the link, I am 99% sure is the same as what I have been trying to plug with the new gaskets. The flat ring gaskets I got are the right diameter for the inner pipe diameter, and the flange is bolted up tight, but on both sides the flange's have ( hard to describe ) elliptical gap's in the centre between the the two bolts. ( I shall try and get a picture today if I can ).

Its from these elliptical gaps that I can see and definitely feel the gases coming out. But the pic from lexls is a little different it seems, as the flanges are flat on the pipe, mine are not flat. Thats why I thought the gaskets were wrong because I'd have thought they would need to be much thicker to fill the gap.

Since it took me 5 weeks and a great deal of hassle to get these two gaskets off Lexus, I shall give the exhaust paste route a whirl.

As a PS) anyone know a decent place for a pre-MOT and then MOT that won't look to just bag ££££'s of work ? I'm in South Lincolnshire, but with my previous cars I used to travel fair distances for a decent MOT garage as the local ones here are just a joke. I just want to see if I can get another year out of this LS400.

Many thanks for the help everyone ! Really is greatly appreciated !

benfur · January 8, 2010

http://www.lexls.com/tutorials/exhaust/fpipe.html
The pic at the bottom of the link, I am 99% sure is the same as what I have been trying to plug with the new gaskets. The flat ring gaskets I got are the right diameter for the inner pipe diameter, and the flange is bolted up tight, but on both sides the flange's have ( hard to describe ) elliptical gap's in the centre between the the two bolts. ( I shall try and get a picture today if I can ).

Its from these elliptical gaps that I can see and definitely feel the gases coming out. But the pic from lexls is a little different it seems, as the flanges are flat on the pipe, mine are not flat. Thats why I thought the gaskets were wrong because I'd have thought they would need to be much thicker to fill the gap.

Since it took me 5 weeks and a great deal of hassle to get these two gaskets off Lexus, I shall give the exhaust paste route a whirl.

As a PS) anyone know a decent place for a pre-MOT and then MOT that won't look to just bag ££££'s of work ? I'm in South Lincolnshire, but with my previous cars I used to travel fair distances for a decent MOT garage as the local ones here are just a joke. I just want to see if I can get another year out of this LS400.

Many thanks for the help everyone ! Really is greatly appreciated !

Hi

Sounds like the flanges from your Y pipe and Your cats are corroded[ quite common]

Ive seen a few of these that have been welded, and they seem to do the job.

Other than that its a new Y pipe and Cats to seal the gap up as it should be

I would try welding the gap first

Benfur

ultimatequinoxe · January 8, 2010

Thanks ! Well I took some pics of the pipes ( to cold to get the gaskets back out for a picture, sorry ) but you can see the gap there, so as you say, probably corroded. I think due to the state of this LS400 I may just have fun with it if I can get it through the MOT as it won't hold out for many more years.

Anyway, the pipes. ( bare with me while I upload..........or not, I have to figure out why I easily uploaded a picture in the audio section on the forum, but can't upload here......... ).