Throaty Exhaust

[Cotswold Pete]

Noticed on the way into work, that I am getting the exhaust grumble situation.

Will need to get looked at.

From scouring the forum the common problem is likely to be the Y joint, though just poking nose under parked LS, not easy to tell if this is exactly where the problem is coming from.

Just wanted to ask if it is not the Y joint, is there anything else I should be looking out for.

I assume the welding job is quite simple, but if anyone has used a good garage in the Cheltenham / Gloucester area, would be easier than taking it to my place, which is Gas & Go in Swindon.

I also assume once it starts to blow it will last little while before it becomes a complete roar.

Any advice welcome.

[Jake123]

It's probably very rotten once you remove the shields and poke around.

The heat shields hold moisture against it which is where they seem to go.

New y section from lexus is £300ish plus VAT.

Weld a new section in is the way to go.

With regards to other areas the cat flanges are known to rot, these can be repaired but not quite so simple and easy.

The rest is stainless I believe.

[Colin M]

Pete

If it is the Y pipe, I have used Wynn's Black Gasket Maker on both of my LS400s with good results.

It is a silicone based product. It is flexible (so does not crack and fall out like compounds which go hard), is heat resistant and compatible for use on cars with O2 sensors.

It was recommended to me by my MOT tester. I have had it on the Y pipe joins on both cars for well over a year now and there are no leaks there.

Hope this helps and if the leak is elsewhere you can probably use it there too.

Colin

[The-Acre]

It's probably very rotten once you remove the shields and poke around.

The heat shields hold moisture against it which is where they seem to go.

New y section from lexus is £300ish plus VAT.

Weld a new section in is the way to go.

With regards to other areas the cat flanges are known to rot, these can be repaired but not quite so simple and easy.

The rest is stainless I believe.

I was also going to suggest the flanges. The Y piece is of course the most common problem, it needed doing on both my LS400's. No more than £50 to have a section welded on.

[Cotswold Pete]

Had a good read of some other postings (should be working, but the boss is not around), and seems like could be a lot of fun and games if flanges are the problem. Does seem odd to have such a weakness in the system.

Sounds like I need to get my Lexus chap to have a look at and at least let me know what is likely to be the scenario, and then take it from there.

I know he will want to do a 'proper' job, but not keen if flanges are the problem and the hoo-haa that will entail.

The missus will go bonkers if the car needs a lot more wonga spent on it.

[Loathecliff]

The missus will go bonkers if the car needs a lot more wonga spent on it.

Pete, if I may ask? What would she otherwise fritter the hard-earned away on?

I sincerely hope it isn't her hair; or even worse, shoes for the kids!

[Cotswold Pete]

The missus will go bonkers if the car needs a lot more wonga spent on it.

Pete, if I may ask? What would she otherwise fritter the hard-earned away on?

I sincerely hope it isn't her hair; or even worse, shoes for the kids!

None of them, it's her Jag that she is worried about when it has it's MOT in three weeks, I reckon it will be fine.

Also a whole load of money to be burnt on getting the lounge sorted - new oak floor, built in units etc etc.

If it were me, it would a the sofa, the drinks cabinet, the TV mounted on the wall, and the stereo set up for best sounds, job done. But ladies they need it different!!!

As for the kids, well they can go around bare foot if the Lexus needs sorting

Will take the LS to Infinity Exhausts near Bristol on saturday and see what they say, seems worth getting a reasonable job done while I actually have some pennies in the bank account

[Rupert Dubreaux]

Dreaded MOT due next week on my beater ,so had grandson use Colin's Black Gasket Maker method to patch the Y pipe ,the stuff is easy to work with .

So far it seems to have done the trick ,all nice and quiet again , shame about the front splitter though which he has wrecked beyond a simple duct tape repair driving onto his ramps . :iraqi-info-minister:

[Cotswold Pete]

Just got the exhaust sorted today.

Turned out that it was not just the Y piece but the flanges all shot to heck.

So pocket £250 lighter after Infinity Exhausts sorted it.

Took them less them less than 2 hours, while I went for a walk along the bit of the Cotswold way that goes through James Dyson's back garden (big bl**dy garden, mind you).

Car now back to the silence I expect other than a whole chunk of the A46 has had top dressing this week, so nice an noisy surface until it gets bit of wear on it (just before it all starts shedding the top layer!?!?! :mat:

[messi]

When the y section flanges went on my ls400, it cost me £20 to sort out

[Cotswold Pete]

When the y section flanges went on my ls400, it cost me £20 to sort out

Seems like everyone who has had LS400 exhaust pipe problems, it can be a cheap fix of a stupidly expensive fix, depending on what the problem is.

From what I understand my Y piece was on it's way out, and that when they took starting taking stuff apart that was when the flanges came to light.

So I am quite happy that I now have a stainless Y section so in theory future expense on exhaust should be minimal.

I assume one day the Cat will need to be replaced, but last MOT was still well within limits.

[Ruud]

I had a leak from both cat flanges.

A bit of gun gum and it's all quiet again.

I don't have any leaks from the Y-pipe...yet.

There is a slight popping sound from the back of the engine (especially when cold). Fairly sure this is the EGR pipe which always tends to crack at the harmonica bit.

Will need to wait for some good weather before I can tackle that.

[Malc]

.................... EGR pipe, remember reading on here that sans this EGR pipe the car works just as well ...... maybe ask Steve2006 on here who's celsior is maybe manufactured sans EGR pipe at the start of life !

Malc

[Ruud]

Corect. The Celsior doesn't have EGR.

I think I'll just make up 2 blanking plates - much easier

[steve2006]

Not forgetting of course the lack of an EGR system gives me another BHP over the LS400 :)

[Ruud]

LOL

And...with the 1 piece, more aero-dynamical headlights, you'll be leaving us all for dust :)

[runsgrateasanut]

Any chance of putting up some photo's of the repair? As you said, some say a cheap fix whereas I was quoted £450 for the flanges to Cats. Backed out of that and hoping the Black silicone is still holding for tomorrows MOT and CO2 level has dropped since last test.

Thing is with welding you run the risk of someone mucking up the ECU. To take off the "Y" pipe to do a good job fitting new flanges, you have to take off the rear Lambda's. Not only do mine look welded to the car but to remove them requires taking out carpeting so I have been told unless you cut and join which can't be recommended under the car taking all the wet and grit.

So how did they do yours, exactly?

[oldhazey]

Did mine some time ago,and every bolt/nut came undone although it all got a good soaking of penetrating oil the night before.

The sensor wires are just long enough to allow the pipes to drop down to weld the tops of the new pipe insert.

4 6mm plates were cut an shaped and welded to there appropriate positions,then a slight smear of exhaust assembly paste (as its now a face to face fit)

All is well after many thousand miles now :)

[runsgrateasanut]

Excellent photos Paul - surprised someone hasn't marketed these flanges to fit. The guy who does sells the top ones on eBay didn't seem too interested unfortunately. I gave him the measurements and one should slip onto the 3mm stainless pipe part that extends beyond the muich depleted Cat flange making the job easier.

Great job and hope to do something similar -eventually!!

[AndyCheltenham1]

I have now got a slightly blowing exhaust. Took it to 2 exhaust centres ( both Powerflow agents) and the problem is the cat flanges that are rusty/ leaking. Have been quoted £395 for two cats and the y-pipe( seems you can't just replace cats/flanges on their own). Is there any cheaper way to go, ie filling them with exhaust paste or is that just a very temporary fix?  Have read that the flanges can be welded, but not sure if you can successfully weld rusty flanges? I'm a bit worried that the lambda sensors could break when they take them off and that could add another expense on top of the £395!!  Has anyone done any cheap fixes that have lasted a reasonable time or is the only way to pay £395 plus possibly more for lambda sensors??  They said there are two lambda sensors (one each side ) is that correct or are there anymore?  The trouble is that I've owned this car for 9 years and so far have had only 3 faults ( failing dash lights, repaired for £50-drivers window failed, £60 to fix-cd player not working, not bothered to repair)-so when something like this happens I'm in shock at having to spend that amount on repairs, especially when the value of the car is not much more than that!! Any advice would be appreciated.

 

[messi]

When i had a mk4 ls400 i had the flanges on mine welded with no problem at all. But you could always go down the stainless steel road

[Malc]

if it's just the Y pipe mild steel area blowing then that can be the subject of a quick and cheap welding fix.  Mine was done some years ago now and, touch wood, is still silent .. cost about £30

Malc

[AndyCheltenham1]

Malc-the y pipe is perfectly ok, it is just the cat flanges that are the problem

[AndyCheltenham1]

Took the car to a local garage this morning and they welded both flanges no problem and also re-attached rear heat shields that were coming loose. Total price £40!!  So both Powerflow agents I went to told me the flanges could not be welded and would have been happy to charge me £395-con artists. I will never go to a Powerflow agent again.

 

[runsgrateasanut]

3 hours ago, AndyCheltenham1 said:

Took the car to a local garage this morning and they welded both flanges no problem and also re-attached rear heat shields that were coming loose. Total price £40!!  So both Powerflow agents I went to told me the flanges could not be welded and would have been happy to charge me £395-con artists. I will never go to a Powerflow agent again.

 

I had the job done by a Powerflow guy and it cost £200 after quoting a thread on here where a similar price was the cost by other Powerflow branches.  He took about three hours and I'm well happy with the result to have a new Y section welded the the flanges.  As to buy the Y pipe alone would have cost I believe nearly £350 and you'd still need sort the Cat flanges it seemed a good price to pay. It should be mentioned that where the flanges fit the Cats when removed from the car there is a perfectly good S/S pipe jutting out about 3/8" to weld on to.  No new Cats or Lambda's needed. Blowing exhaust bugged me for too long.