Downpipe flange warped

SamHendry

SamHendry

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Anyone heard of this happening? On my s3, downpipe doesn't sit flush on the face of my turbo. First thought it was gasket so swapped for new one but exhaust blow still remained and on visual inspection it doesn't look like the two mating surface sit flush together, looks like small gap.
 
What actually happened was I was driving on a local road and suddenly I lost 90% of power. And car developed really loud blow. Was very sudden and limped home. Would a exhaust leak at DP flange cause such power loss?
 
Not exactly sure what problem it may be without pics but it's worth making sure the 3 downpipe to turbo bolts are tight as they should be


When my 2 of the 3 downpipe bolts came loose the s3 blow was really bad sounded like a 18 wheeler truck from ice truckers.
Anyways good luck let us all know if you sort it..
 
Thanks for replies. Exhaust gases are escaping between turbo, downpipe flange, it's very obvious leak, heat shield is black, feel exhaust pressure with hand very easily, nuts holding on DP on are tight,

Using a mirror I can see it looks like the downpipe flange is raised in the middle showing a small gap, but lugs where studs go through are pushed up against turbo.

I run the car for while let's everything heat, expand but doesn't seal.
 
Are you sure it's not the EGT probe that's come loose and blown out of the back of the turbo?
(If it's wideband)

Sent from my iPhone using Tapatalk
 
Last edited:
S3 Hilife said:
Are you sure it's not the EGT probe that's come loose and blown out of the back of the turbo?
(If it's wideband)

Sent from my iPhone using Tapatalk
Click to expand...

Hi mate I have early s3 without EGT. My hybrid has a boss for the probe but it's plugged with a bolt.

I noticed vac hose had popped off the actuator, not sure how long it had been like that but would that cause issues?

I lost so much power, car would hardly accelerate. Can't imagine an exhaust blow post turbo would cause such performance drop off, there must be something I'm missing.

Doesn't help that turbo is total nightmare to get access too!!
 
If the pipe was off the actuator you would be running uncontrolled boost and generating loads of heat... could be whats warped the flange..

I'd be more concerned that running all that boost has lead to lean running if an APY narrowband ECU

<tuffty/>
 
Oh Sh!t. I have no idea how long actuator has been disconnected. Hopefully hasn't caused more damage. I'll check tonight.

I cable tied vac pipe to actuator, that was clearly a really bad idea.

Any recommendations for securing vac pipe to actuator?
 
Can't believe something so small and stupid like a little hose popping off has given me absolute headache to fix ahhhh
 
Your engine is 'built' though? rods etc?

silicone vac hose and a cable tie is normally adequate... if using rubber hose (like the original one) then a hose clip is preferable as rubber needs a bit more mechanical grip to prevent it from popping off...

<tuffty/>
 
<tuffty/> said:
Your engine is 'built' though? rods etc?

silicone vac hose and a cable tie is normally adequate... if using rubber hose (like the original one) then a hose clip is preferable as rubber needs a bit more mechanical grip to prevent it from popping off...

<tuffty/>
Click to expand...

This is exactly what's happened, I retained the oe rubber hose and tie wrap didn't get enough purchase on it. Annoyingly I changed alot of less important hoses to silicone which have stayed put. Was a disaster waiting to happen.

Rebuilt with rods yes, main concern I think is turbo and God knows what else?

badger5 said:
inc turbo
Click to expand...

Ill be checking that this evening. Fingers crossed
 
When the pipe fell off my turbo actuator is was immediately very noticeable, felt like the car gained twice the power. I noted to myself "wow, this thing is going well this morning".

It only took about 4 pulls, out of road junctions etc to realise that something wasn't right, and I clocked my boost gauge reading silly numbers. Like ~38psi silly.
 
hendo#1 said:
When the pipe fell off my turbo actuator is was immediately very noticeable, felt like the car gained twice the power. I noted to myself "wow, this thing is going well this morning".

It only took about 4 pulls, out of road junctions etc to realise that something wasn't right, and I clocked my boost gauge reading silly numbers. Like ~38psi silly.
Click to expand...

Interesting. I didn't feel any abnormal improvement in power prior, possibly these two issues are unrelated and just happen to coincide.

I have checked the turbo and all seems OK, shaft has usual play, hotside doesn't appear to have any cracks from what I can see, is there any other areas of the turbo that would be worth looking at? unfortunately the same can't be said for my downpipe.

Flexi has been rubbing on prop.

fast picture upload

fast picture upload

fast picture upload

Flange isn't warped but as you can see full of cracks which are responsible for exhaust blow, was hoping I could repair this but it's well beyond that and new DP required, more ££££ :angry:
 
I think having the downpipe wedged up against the propshaft probably cause more stress on the downpipe especially around the flange area obviously flexi aswell, the downpipe flange would only ever sit flush on the turbo once it was bolted up. I knew about this but was lazy, now paying the price.

I'm going to utilise the flange of the old downpipe, use it as a spacer, along with the new pipe and hopefully move it away from the prop.

SamHendry said:
I have checked the turbo and all seems OK, shaft has usual play.
Click to expand...

More play that I thought there should after little miles, isn't rubbing housing or anything. Quick vid.

 
This arrived yesterday, gonna crack on with the unenviable task of fitting it this evening
 
audi upgrades
side to side there *WILL* be play. oil takes up that gap. just as long as side to side it doesn't touch. you should be good. It's in and out play you should be worried about. can you make it "chink" when you play with it going in and out? was a little hard to tell with prodigy blasting int he background! LOL

and yeah wrap the downpipe... you might as well while it's out
 
hydro s3 said:
What make is that and will you need to wrap it before you fit it?
Click to expand...

It's a ebay special mate, same as the last one, this one fits better than the first, now I have a small bit of clearance between prop shaft and exhaust but it would have made sense from the start to get one made or real good quality one off the shelf.

Not wrapped it mate, not sure what the benefits are insulating exhausts, automatically I think your just making everything hotter which obviously isn't good for engine performance, I can only be wrong as people with alot more experience knowledge do it so I must be missing the logic.

IanPG said:
side to side there *WILL* be play. oil takes up that gap. just as long as side to side it doesn't touch. you should be good. It's in and out play you should be worried about. can you make it "chink" when you play with it going in and out? was a little hard to tell with prodigy blasting int he background! LOL

and yeah wrap the downpipe... you might as well while it's out
Click to expand...

Yeah was paranoid about my precious hybrid being ****** via me driving around like a muppet with actuator disconnected running uncortrolled boost lol. In out is very minimal and a bit of side play but as you say it's normal.
 
SamHendry said:
Not wrapped it mate, not sure what the benefits are insulating exhausts, automatically I think your just making everything hotter which obviously isn't good for engine performance, I can only be wrong as people with alot more experience knowledge do it so I must be missing the logic.
Click to expand...
You are missing the point a tad ;)

Heat wrap does a couple of things... Keeps heat out of the engine bay and less radiant heat means less chance of melting stuff...

Also keeping heat in the exhaust helps speed up the gasses as they escape... Arguably this is more beneficial to atmo tuning but given how much heat turbo engines generate keeping it out of the bay is generally a good thing

<tuffty/>
 
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Good info tuffty.

Got the pain in the *** downpipe fitted, I think the new pipe has altered the position of the rear silencer and as a result rear box is hitting the heatshield and making alot of noise, and now I've discovered turbo is only boosting to 15-20psi where it should be 24psi.

Car is noticeably slower, quite alot slower, a in general car isn't showing any signs of where problem might be so will need to plug it in for any clues. Unless anyone has any clue? Car is behaving quite 'normal' but as I said will only boost up to around 18psi. Should 24psi.
 
Isn't boost pressure controlled by "load requested" and if your new downpipe is flowing better you are reaching 95% of the requested load without so much boost?

Regarding the knocking, there is a tiny bit of adjustment at the turbo end and more on the downpipe to decat / sports cat. Like 5mm rotation makes a big difference on the bent cat pipe, or is it perhaps the downpipe mount causing the issue, what if you don't connect that?
 
Stuart B said:
Isn't boost pressure controlled by "load requested" and if your new downpipe is flowing better you are reaching 95% of the requested load without so much boost?

Regarding the knocking, there is a tiny bit of adjustment at the turbo end and more on the downpipe to decat / sports cat. Like 5mm rotation makes a big difference on the bent cat pipe, or is it perhaps the downpipe mount causing the issue, what if you don't connect that?
Click to expand...

I'm not sure if boost is controlled by load request, it's all double dutch to me, head hurts when folk ramble on about the inner workings of the 1.8t, absolute mumbo jumbo lol

Are there adjustments on the exhausts, it's the rear silencer box heating the heat shield, I need to get underneath and look, hopefully easy fix
 
When I fitted my down pipe the holes the bolts went through connecting sports cat to downpipe were small slots so it can be slightly adjusted and because it is long and bent it makes a difference. Also I needed to trim off 2 inches of the sports cat pipe going into the centre silencer to pull them towards each other, otherwise the centre box wasn't in the right place.

Regarding the boost, I'm a total beginner but if you need a litre of air through a small hole in 1 second. It needs more pressure than going through a big hole, unless during fitment of the downpipe someone disturbed something, it should not have affected the running. You did have a 3 inch DP last time didn't you?
 
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