Classic Austin mini fume box saga

[garellikatia]

Hi guys some of you might have noticed a few posts back of my classic mini. 

At the minute, I have her back on the road as I figured why not just drive the thing instead of it sitting in the garage. 

I got It Taxed, insured etc.. and headed out on the road after a good coating of Dynax UB seal to the underside.

Then about 10 minutes in I realised the biggest niggle that I need to sort out. 

I leave the car with my clothes stinking of exhaust fumes. I can smell it a little in the car from time to time but my clothes stinking of it is no good.

Here's the plan of action:

New boot seal, and boot hinge fixings (seem worn) 

Buy a bulk pack of rubber bungs and seal all the small holes where cables pass through into the bulk head, and where the fuel overflow pipe runs through the boot

The mini has two small holes in the parcel shelf presumably for fitting aftermarket speakers at the time. I will be making a tin panel which will be riveted and tiger sealed over the holes.

All the exhaust fittings have been checked however I will be renewing the exhaust manifold gasket, in case. 

Ironically the car does smell a little rich, but I've tuned it with a colour tune and it seems bob on, so I'm not going to fiddle with the carb settings and timing just yet. 

Once it's all sorted they'll be a lot more interesting updates and little adventures, but there's no way I can drive it that far as she is now. Here's a few pics 

[Zelandeth]

Both Metros I owned were an absolute pain with regards to getting the manifold to downpipe joint to actually seal properly.  I did eventually get the one on the yellow one gas tight, but it took many attempts.  I assume the Mini uses the same style of clamp - in which case I'd be taking a really careful look at that with a mirror on a stick to make sure there's no signs of any leakage.

Also worth asking whether the exhaust runs well proud of the rear valance?  I've seen quite a few aftermarket systems where it seems really short, and could really contribute to fumes getting into the cabin.

Other than that as you say, make sure all the seals at the rear of the car are in top shape and hopefully that will sort it.

[MiniMinorMk3]

I see from the picture of the engine bay  that the fresh air duct is missing from the front of the car. Where does the heater get fed with fresh air? You maybe getting some fume from the engine bay into the heater.

Also I see your car is fitted with a central gauge unit. Is there anything between the back of the speedo and the engine bay, like some sound deadening, to obstruct the flow of dirty air into the cabin?

[Bren]

I think this afflicts a few BL products. My SD1's were the same - bad  headache and I looked like Lloyd Bridges in Airplane.

[Merryck]

1 hour ago, MiniMinorMk3 said:

I see from the picture of the engine bay  that the fresh air duct is missing from the front of the car. Where does the heater get fed with fresh air? You maybe getting some fume from the engine bay into the heater.

I'd put a tenner on this being the issue. Without the fresh air duct your vents are just pulling air directly from the engine bay (well, wheel wells, but essentially the same thing. I had the same issue on all of mine because some bellend kept taking things off them in an attempt to make them go faster!

That, the exhaust manifold gasket and the downpipe connection were a perennial issue with all of my Minis. Bunging up all the extra holes and making sure the hole in the floor for your gear selector is at least somewhat sealed should see a decent improvement.

[garellikatia]

2 hours ago, Zelandeth said:

Both Metros I owned were an absolute pain with regards to getting the manifold to downpipe joint to actually seal properly.  I did eventually get the one on the yellow one gas tight, but it took many attempts.  I assume the Mini uses the same style of clamp - in which case I'd be taking a really careful look at that with a mirror on a stick to make sure there's no signs of any leakage.

Also worth asking whether the exhaust runs well proud of the rear valance?  I've seen quite a few aftermarket systems where it seems really short, and could really contribute to fumes getting into the cabin.

Other than that as you say, make sure all the seals at the rear of the car are in top shape and hopefully that will sort it.

Ah yes absolutely.  Originally it had the manifold you speak of, but I upgraded to a Cooper maniflow long centre branch manifold, which simply bolts to the head, and the downpipe Is joined under the car, but I will renew that gasket for sure. I remember me and my old man trying to seal the manifold similar to the metro. Absolute nightmare one pushing up from the bottom while trying to bolt the clamp together flush! Hahaha 

[garellikatia]

2 hours ago, MiniMinorMk3 said:

I see from the picture of the engine bay  that the fresh air duct is missing from the front of the car. Where does the heater get fed with fresh air? You maybe getting some fume from the engine bay into the heater.

Also I see your car is fitted with a central gauge unit. Is there anything between the back of the speedo and the engine bay, like some sound deadening, to obstruct the flow of dirty air into the cabin?

Ahh I never actually thought of that. I removed all the ducting to do a bit of welding and left it all unconnected, probably thinking I'd use it as a fair weather car. Great suggestion , I'll try and find the ducting or attempt to feed it with cold air. As for the centre binancle, it does have a big metal plate behind it, but no sound deadening, but it does have a little hole for the speedo cable with no grommet on it  so that could be another way fumes get in I guess

[garellikatia]

29 minutes ago, Merryck said:

I'd put a tenner on this being the issue. Without the fresh air duct your vents are just pulling air directly from the engine bay (well, wheel wells, but essentially the same thing. I had the same issue on all of mine because some bellend kept taking things off them in an attempt to make them go faster!

That, the exhaust manifold gasket and the downpipe connection were a perennial issue with all of my Minis. Bunging up all the extra holes and making sure the hole in the floor for your gear selector is at least somewhat sealed should see a decent improvement.

Haha yea I can imagine!! They should have just bought a 2nd hand 1275 lump. 

Can't believe I didn't even think of the air intake until you and @MiniMinorMk3 mentioned it . I'll get that sorted ASAP . 

Cheers guys

[Merryck]

6 hours ago, garellikatia said:

I upgraded to a Cooper maniflow long centre branch manifold, which simply bolts to the head, and the downpipe Is joined under the car, but I will renew that gasket for sure.

Just in front of the hole in the floor where the gear selector comes in.

[Asimo]

Also, where are the fumes from the crankcase breather going? Originally they would have been inhaled via the air-filter housing but as that has been deleted…

[garellikatia]

On 31/10/2023 at 20:58, Merryck said:

Just in front of the hole in the floor where the gear selector comes in.

Yes that's the one!! 

[garellikatia]

23 hours ago, Asimo said:

Also, where are the fumes from the crankcase breather going? Originally they would have been inhaled via the air-filter housing but as that has been deleted…

Ahh they are plumbed back onto the carb. (One of those red silicoln tubes) but yea absolutely something quite easily I could have overlooked! 

[bigstraight6]

I once had issues with exhaust fumes entering the inside of my Ford Zodiac, a new boot seal cured the problem. 

[FakeConcern]

On 31/10/2023 at 14:05, garellikatia said:

Ah yes absolutely.  Originally it had the manifold you speak of, but I upgraded to a Cooper maniflow long centre branch manifold, which simply bolts to the head, and the downpipe Is joined under the car, but I will renew that gasket for sure. I remember me and my old man trying to seal the manifold similar to the metro. Absolute nightmare one pushing up from the bottom while trying to bolt the clamp together flush! Hahaha 

Sorry for thread drift, but this reminded me I used to put a scissor jack under the exhaust pipe to push it up hard onto the manifold while I did up the clamp.

[garellikatia]

Yes I remembered doing that job as a kid and my old man at the top swearing like mad every time he wrapped his knuckles Hahaha 

[garellikatia]

Lovely drive out to the gym this morning, 

Always funny to get the "how do you fit in that" comments 😂. 

Followed by a little trip to B and Q for some grommets. Popped a few in  whilst in the car park. And ended up filling about 6 holes. All potentially leaking fumes into the cockpit. Smelt a little less on the way home. 

Also I fitted a new boot seal this week. So we're getting somewhere. Just gonna finish my brew then head out under the bonnet to see what else I can seal up. 

[garellikatia]

Best hole I've filled in a long time 😂 

[danthecapriman]

I used to get a lot of exhaust fumes in the Capri cabin. But, the exhaust was broken off below the floor and there were rust holes all over the floors so it was little surprise really!😆

I doubt very much this is your problem though. Your Mini looks great👍

[garellikatia]

Thanks mate, Hahaha sounds like fun mind!! 

[garellikatia]

So some progress. I bought and fitted a new boot seal, and RC40 twin box exhaust. The smell has gone to the point where I can't smell anything nor do my clothes smell. I do get a little light headed at times when I get out of it, but whether that's because it's so close to the ground I'm not sure. 

 

I intended to remove the exhaust manifold and replace the manifold gasket but also feel at the minute the mini Is a big gutless with modern day traffic. 

After much deliveration, I've bought a rather cheap 12g202 head . Originally fitted to 997 coopers, 1100 Morris minors and Midgets. 

It looks to be in rough but hopefully workable shape. It will need a good de coke. Then probably about 40 thou taking off it.

 

  

[Rusty_Rocket]

12G202 is a good cylinder head, with those late collets I'd say it's most likely from a Clubman 1100.

Have you checked between the rear wings and seat back for the foam strips?  They were fitted there to every Mini saloon and further stop fumes entering the cabin.  Most get binned when the cars are repaired as they get damp and encourage rust, but they're there for a reason.

You can never totally seal the boot compartment from exhaust stink, too many small gaps and ill-fitting grommets!

[garellikatia]

Ahhh no I never even thought of that. Nice one I'll check that tomorrow thanks.

 Happy days. To be honest the valves seem fairly smooth in the guides after a good clean up it's not looking too bad. I'm tempted to see how it runs with a skim to get the compression up and replace the seats and valves if they're badly worn.