Exhaust Fumes

[Gary Crutchley]

Here’s an interesting question.  I took my ’65 230SL manual for a high speed squirt up to Healesville (Victoria, Australia) and back this morning (luckily before the rain)– a return trip of 60 or 70 miles and large part of this is open road so mostly 60mph.  Hard top off and soft top down, chilly but layered up and heater on full.  On my return back home I was told I smelt of fumes.  This is not the first time I’ve had this response.  I wondered if the engine was running rich so I did a quick inspection of three of the plugs and they all look like the one attached, grayish brown so in my opinion not running rich.  So my question is: is it possible that a back draught from the tail pipe of exhaust comes into the cabin (even though it’s open) or could it be that I have an exhaust leak underneath the car that finds it’s way in to the “open cabin”?  I wasn’t able to detect any fuel or exhaust smell as I was either driving or idling at the occasional traffic light – so it’s a cumulative thing.  Does anyone have any clues?  Also if Garry M or anyone else from Melbourne is reading this I’d really appreciate some advice on a classic MB specialist – I’m keen on perfection and if anything is done on the car then I’d like it to be to the highest standard (even though the remainder of the car isn’t - eventually it will be).  Prior to the 230SL I had a Porsche 912 and Pilll Hearn of Auto Coupe used to look after it for me, he rebuilt the engine, gearbox, brakes and suspension to very high standards, I believe he is the best in Victoria and I’m looking for a similar MB man.  Thanks in advance for any response.
cheers

[Cees Klumper]

I've never heard of this problem, and, despite having driven open for many times myself, never experienced this. Strange part is that you don't smell any fumes while driving.

[ja17]

Hello Gary,

This is not normal.  With the car at idle hold something flat over the exhaust ends, to add back pressure, and listen for leaks forward. Also check the rear compartment (boot or trunk) for bad rubber seals, missing grommets or rust holes.

[Garry]

Hi Gary,

Agree with Joe and Cees,

Unusual that you don't smell it.  Maybe also leaking from the manifold and coming in from the firewall.

As for a specialist for the car, I have my car with a person called Reinhard Klavers 0419 513177 at Croydon who is doing the engine overhaul and other body work on my car.  Not cheap, nor fast but has the best of reputation, was managing the Fox Collection before going out on his own a few years ago.  Only does old Mercs of all types.

Garry

[Gary Crutchley]

Garry, Cees and Joe, Thank you for your suggestions.  Firewall and boot/trunk are both definate possibilities and i don't know why I hadn't considered them.  It IS strage that I can't smell it myself at the time but can certainly smell it on my clothes afterwards.  Garry your man in Crodon is going to get a call from me on Monday.  Croydon isn't too far from me (Blackburn) so this could work really well.
Cheers and thanks again (this forum is brilliant!)

[Garry]

Gary,

Was out there on Thursday checking how my car is going and he said that he will be away all next week.  He has another mechanic working there as well but you really want to talk to Reinhard so wait a week if you can.

Garry

[mdsalemi]

Gary,

My 280SL is in a pretty good state of tune.  It has passed the "Blacklick CO test"; been adjusted by Joe Alexander himself, runs well, and plugs confirm a good state of tune.  It idles smooth, pulls strong, and runs sustained high RPM at highway cruise--typically 4,000 RPM--for many hours at a time.  It isn't perfect, but it is pretty darn good.  What ever it would take to make it perfect, isn't much.  Exhaust tips have a light coating of dark grey ash, just as they should.

All that being said, I REEK OF FUMES every time I come home.  After each drive, I change my clothes. I think your assessment is correct; with top down, there is a swirl of exhaust that gets into the drivers compartment, even at speed...
Our engines may have been good at the time, but they make (by today's standard) an alarming amount of unburned fuel, astounding amounts of NOx and CO.  They make far greater amounts of fumes when compared to modern cars.  One reason why this lightweight gets 16 MPG, and my daily driver whale of a Ford Flex manages 24 MPG with a 3.5L V6 pulling another ton of metal.  Modern.

Full disclosure: I have a very sensitive nose, and can tell when the neighbor 3 doors down uses dryer sheets doing laundry...

Like you, I don't smell it much when driving, but boy when I get home the smell is sure in my clothes...

[ja17]

Michael,
 I must admit that I do notice that the exhaust of pre-emission automobiles to be much more offensive than the newer cars these days.  After all else is corrected, it can be a matter of "well tuned noses and engines" like yours!

[bogeyman]

Michael,
On my way to last PUB in my '69 (800 miles), it performed as you described yours including the "smell" and returning 16mpg.
After Joe did his "tune up", on my way home the smell was about 90% gone and it returned 20 mpg.
My suggestion is that there may be a clue in your mileage number. Maybe further investigation into your IP setup would alleviate your fume problem.

[Jordan]

Gary, simple way to check if it is coming from the exhaust and swirling back around.  Put your top up or on and windows up and do the drive again.  If you don't smell the fumes it must be coming from the exhaust tips. 

[Gary Crutchley]

Guys, I've enjoyed reading all of your responses and they all throw well informed light on the subject and perhaps I have a combination of factors.  Driving with the top down is like driving a different car entirely, it seems a lot more spritely and of course I enjoy the beautiful soundtrack (which may ironically be the source of the fume smell) – so even in cool weather it’s top off/down.

I like Michael’s suggestion of exhaust fumes swirling into the open cabin – as most of the draught when driving top down is from behind so this seems to make sense but I can’t imagine too many glamorous people putting up with this in the ‘60s.  (Michael you must just about go into a frenzy when your neighbour three doors down is cooking a BBQ!)

Rick, you are very correct – I should check the mileage but I tend to take the lazy (and irresponsible) attitude that at best the car would do about 1500 miles a year and fuel consumption isn’t really an issue – but I’m going check it starting next weekend over an extended period.

I tend to agree with the general consensus that it shouldn’t happen – unless our modern fuels are partly to blame.  I wonder if Australian petrol is any different to elsewhere (as our diesel is generally of lower quality).  I’ll try holding something flat over the exhaust and see if that provides any clues as to a leaky exhaust as suggested by Joe.

Garry, I’ll wait a week or so before calling Reinhard, thanks for the tip – on the top of my list is tuning and exhaust.  I hope you’re enjoying the experience of watching the progress of the work on your car – even though the wallet may not be, I used to visit my Porsche every Saturday morning in Eltham and have a cup of coffee with Phil while he talked me through the highs and lows of an engine re-build – and I’d progressively hand over large sums of cash so I didn’t face a massive bill at the end.  It was all worth it.

Cheers

[ricrose]

Hi Gary

I see you have Garry M's suggestion, he seems the man - but just as a backup my '65 has been VERY well looked after (the few problems I have had) by -

Richard Davidovic
Starline Motors
3/11 Mary Street
Blackburn

9877 6955

Richard is an Independent M-B specialist and I got him to do my pre-purchase inspection. The great thing about him is that he almost encourages involvement, so I never feel bad if I either ask a question on something I have read here or I need further info.

Richard Rose

[Gary Crutchley]

Hi Richard, thanks for the suggestion, I once went to Starline Motors and was so overwhelmed by the number of cars and the congestion that I lost interest – perhaps unfairly, maybe I should drop by again.

Thanks again

[mdsalemi]

Michael,
On my way to last PUB in my '69 (800 miles), it performed as you described yours including the "smell" and returning 16mpg.
After Joe did his "tune up", on my way home the smell was about 90% gone and it returned 20 mpg.
My suggestion is that there may be a clue in your mileage number. Maybe further investigation into your IP setup would alleviate your fume problem.

Rick, with many experts fine-tuning my car over the years, and the end results being "perfect" plug and exhaust ash, I think my IP setup is pretty good.  Last go around we had to richen the mid-range, as the car was tugging slightly upon midrange acceleration, and wanted more fuel.  JA and I did quite a few running tests and I think things are fine now.  I don't doubt that some more precise set up might yield a bit better results, but when you are too rich you have one symptom, when you are too lean you have another, and when you are OK you run well.  Of course you need to do those tests at idle, midrange and high range.  You can be too lean at one range and too rich at another...I think I'm OK all over.

MY MPG might be my driving style.  I don't think there is anything one could do to my car to suddenly get from 16 to 20 MPG.

Gary is also onto something about fuels--there are different blends.  That's what they tell us at least when gas prices go up.  There is always a story about the midwest fuel blend, or a shortage of this additive, or the changeover from summer to winter gas, or some such.  I also distinctly remember my first trip to Europe as a lad of 15 back in 1971--the first thing I noticed stepping out of the airport in Frankfurt was how different the exhaust smelled around crowded areas.  Maybe it was all those diesel taxis.

[IXLR8]

Remember the lines from the Simon and Garfunkel song?

Carbon and monoxide, that old Detroit perfume.....

On the rare occasion that I encounter that perfume, it brings back memories of my days of riding two-cycle motorcycles.

the other Joe

[stickandrudderman]

Many, many moons ago I had a customer complaining of exhaust fumes in his 124 coupe. After some while trying to find the cause I identified a poorly fitted rear panel that was preventing the boot seal from correct contact thereby allowing fumes to swirl up and into the boot area and from there into the cabin. Once the problem was diagnosed it was simple tap with a mallet and a piece of 2x4 to fix.
My point is that you'll be amazed how these fumes will travel given the opportunity.

As a digression:
I flew a two-seat Spitfire last year and as we were taxying out the smell of exhaust fumes was intense. I remarked to my instructor "well, if I'm going to be poisoned by exhaust fumes at least they're from a Merlin!"

[Cees Klumper]

Stick's story does remind me of the time a girlfriend drove me and my bicycle back from Delray Beach (where she lived) to Boca Raton (where I lived); we stuck the bicycle in the back of her Honda Civic; as the hatch would not close, we used the wire trick but, it being a 3rd door, the amount of exhaust fumes that made their way into the cabin due to the disruption in aerodynamics was impressive.
So most likely there is something out of kilter with topic starter's car to cause this problem (that, or his nose is as sensitive as Michael's!)

[Gary Crutchley]

Garry, I dropped in to have a chat to Reinhard on Wednesday, I was up at Lilydale so his workshop was on the way back to the office for me.  What a great guy with a passion for classic Mercedes.  It was also good to see a couple of 280SL's a 190SL and a "bits and pieices" of your car in his workshop.  I appreciated him spending some time to have a chat with me and to show me the work he was currently carrying out on the cars in his worshop.  He was keen to see my SL but I was in my everyday driver (an Alfa 159) - to his absolute credit he admired my Alfa for it's gorgeous looks and he made no rude comments about Alfa reliability, build quality, etc (which I might add has been better than most other cars I've owned) - so he's got me on side immediatley.  Thanks for the Reinhard tip, I'm dropping the SL off to him in a couple of weeks for a full review.

Cheers

[Ulf]

Whenever I've driven such distances I smell of fumes, warm oil, coffee, tobacco and leather - it's a mans smell and someone should really bottle it and sell it ;-)

Ulf