BreakMyWindow 1874 Report post Posted October 13, 2014 So I had recently removed the cats from my M5, and replaced with mandrel bent pipes. This was all good and well, but am now having a bit of remorse since my car is an early M5 and uses about 1litre of oil every 1500 - 2000kms. With having no cats in place, it's a bit smelly and not pleasant on longer journeys. I still have the original cats, but the ends which face the engine are double-walled. This looks like it may pose a problem with re-welding. Can anyone recommend a specialist or a technique that could be used to get these back in? Side of cat facing engine : Side of cat facing rear of car : Quote Share this post Link to post Share on other sites
KwS 2425 Report post Posted October 13, 2014 Wouldnt that sort of oil consumption ruin the cats anyway? Quote Share this post Link to post Share on other sites
BreakMyWindow 1874 Report post Posted October 13, 2014 Wouldnt that sort of oil consumption ruin the cats anyway? You'd think so but the ones used in the M5 are pretty resilient. Quote Share this post Link to post Share on other sites
M5V8 337 Report post Posted October 14, 2014 buggar. luck of the draw mate. My 2003 M5 used oil also. My 2002 - not a drop. Quote Share this post Link to post Share on other sites
westy 614 Report post Posted October 14, 2014 Can you smell it inside the car? Only way to reweld it is to remove the outer wall first, but you probably knew that Quote Share this post Link to post Share on other sites
BreakMyWindow 1874 Report post Posted October 14, 2014 Can you smell it inside the car? Only way to reweld it is to remove the outer wall first, but you probably knew that You can on the odd occasion. Not pleasant. That's what i was thinking, remove some of the outer skin, but the 2 exhaust shops I tried were not keen... Quote Share this post Link to post Share on other sites
BMTHUG 1057 Report post Posted October 14, 2014 I could do it. Easy way to do it is shave a little of the top layer off and weld the inner wall with mig then weld up the outer walls by joining a bigger diameter pipe over them. I used to be a marine engineer and came across these types of pipes on ships quite often and now as a mechanic Ive found Mercedes Benz pipes to be the same. Give me a yell if you dont come right with someone to weld it Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted October 14, 2014 Can you smell it inside the car? What does that mean? I get that in the Van some times, i just assumed it was because its done 450,000km Quote Share this post Link to post Share on other sites
BMTHUG 1057 Report post Posted October 14, 2014 Wow good effort 450,000kms Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted October 14, 2014 Wow good effort 450,000kms original engine and feels like its done every single one no less Quote Share this post Link to post Share on other sites
westy 614 Report post Posted October 14, 2014 What does that mean? Usually exhaust gases are getting into the car somehow. Are you absolutely sure there are no leaks in the system. I'm not too sure how much cats rid the gases of oil smells but would think you'd smell it cats or no cats. Quote Share this post Link to post Share on other sites
Michael. 2313 Report post Posted October 14, 2014 That smell would just be a catless exhaust smell. My new Soarer has no cats and it's really gross. When I re do the exhaust I'll be sure to use magnaflow highflow cats like I did on the E36 V8, much nicer when standing around the car while it's idling! Quote Share this post Link to post Share on other sites
KwS 2425 Report post Posted October 14, 2014 i love the smell of raw, unburnt fuel.... cats are for wusses. Quote Share this post Link to post Share on other sites
BreakMyWindow 1874 Report post Posted October 14, 2014 i love the smell of raw, unburnt fuel.... cats are for wusses. You'd want to remove the gas cap in that case. Quote Share this post Link to post Share on other sites
BreakMyWindow 1874 Report post Posted October 14, 2014 Usually exhaust gases are getting into the car somehow. Are you absolutely sure there are no leaks in the system. I'm not too sure how much cats rid the gases of oil smells but would think you'd smell it cats or no cats. Had a slight leak from where some clamping bushes join the exhaust sections together, but that has since been fixed with new clamps. I'll smoke test the exhaust while I smoke test the crank case and the inlet side of the engine. pretty sure it's tight though. Quote Share this post Link to post Share on other sites
KwS 2425 Report post Posted October 15, 2014 i do wonder, when the cats were removed, wouldnt they have had to weld to the dual wall pipe that was left on the car to fit the new pipe? Surely they could do it again? Quote Share this post Link to post Share on other sites
_ethrty-Andy_ 2132 Report post Posted October 15, 2014 Usually exhaust gases are getting into the car somehow. Oh i thought that whistling was my turbo spooling Quote Share this post Link to post Share on other sites
