Exhaust Fumes.. Mini

[Minornut59]

I have a prob that is causing me to head scratch somewhat. be interested to know what you all think.

Its not on any of my Minors but on my 1974 Mini that has an Austin 1300 1293 engine.
Car was rebuilt by me two years ago and engine was rebored 20 thou oversize. and rebuilt etc.
Unleaded head, single 1.5 in carb, Big exhaust.

I had a problem with exhaust gases entering the cabin so got rid of the LCB i had fitted and Y piece joint underneath for a Cooper Maniflow manifold system which is effectively an LCB with a 2 into 1, that just has one joint underneath into the RC40 big bore exhaust instead of the three it had with the old system. .
Now the car does not seem fumey, untill travelling at speed over 60mph on dual carriageways but only sometimes.
Being a Mini with 10 inch wheels its quite busy between 60 and 80 etc...

The other day i drove from Cornwall to Exmouth up the A30 in hot afternoon sunshine and down every hill the car was fine but up every hill i get a whiff of fumes...
On the way back at dusk,, going up those same hills the other way around as it were, there was NO fumey smell..

Its like this a lot; it only does it SOMETIMES... and only ever at giving it welly speeds and only uphill and then only when it feels like it.

The smell does not smell like burnt oil, it smells more like your normal acrid exhaust smell.
I can't detect a leak from the manifold to downpipe joint and its all new..

Like all Minis it does leak a bit of oil and possibly uses a bit too.
So after returning from the 150 mile dash it had less oil in the sump than it started out with but not by that much. Oil useage is pretty standard on the transverse engines in my experience whereas the in line ones can be very good.
Wasn't the factory spec a pint every 1000 miles or something?

Anyway, i don't think ithe problem is oil being burnt because the engine is a good un and i have driven oil burners before and there are no clouds of oil smoke coming out the back...

So, thoughts. is the fumey smell related to oil level at all do you think?

Or is it something to be with a vacuum created by the car sucking fumes in through the boot, and in that case why does it only do it sometimes...


What do you reckon?

[oliver90owner]

Lengthen the tail pipe temporarily and check it out again?

[ManyMinors]

Were you driving with a window open at the time? I always found, particularly with my traveller, that the exhaust fumes seemed to "gather" around the rear of the car and somehow be sucked back in if I had a window open. As suggested above, an extended tailpipe helped quite a bit.

[philthehill]

In my experience Mini engines in good condition do not burn oil at the rate you are quoting above.
Additionally Mini engines in good condition and well built do not leak oil and I did rebuild quite a few when working in the BMC garage when Minis and FWD vehicles were the bread and butter work
It could be that when going up hill the leaked oil on the engine casing is evaporating off because the engine under power gets hotter. Going down hill the engine is not under power and runs cooler.
Also when under power the engine is most likely breathing fumes more heavily.
My recommendations therefore for what they are worth are:-
Cure the oil leaks and get the engine into a condition where it does not use oil.

[Minornut59]

Thanks for the comments, although i have to disagree Phil; In 30 plus years of owning countless A series engined cars i have never had a Mini that doesn't leak. I have also rebuilt many and i did this one, took my time and used great care on assembly ; and it still leaked! Pretty much only from the gear rod oil seal and its usually only a small spot on the floor.
I have had some that after high mileages spew it everywhere!

As far as suggesting i take the engine apart and spending time and money so it doesn't burn oil; i have already said in my previous post that it does not burn that much because i cannot see any evidence of it doing so; no viisble oil smoke and no pong of oil burning off, and having had it rebored and spent a considerable sum on new pistons and rings why on earth would i want to take it out, and apart again when its currently running well? This course of action could only suggest another set of rings which in my experience isn't always a cure. I have re-ringed engines and had great success but on one 1275 i actually made it worse because those bores were slightly oval.. This engine was bored two years ago and has only covered 8000 since so it won't be worn.

Sorry but daft suggestion!

Thanks for the other more helpful comments about lengthening the tailpipe. I will try this...

The window theory is interesting. Yes i did drive up with the window open and home with it closed.... This could explain it....

[philthehill]

You asked for comment and I gave you my honest opinion.
By your own admission in your original post the engine uses oil and possibly breathes fumes.
You cannot have it both ways in stating that the engine uses oil and possibly breathes fumes and not expect me to say sort out those basic problems before doing anything else.
Oh and by the way I have been building, repairing modifying and tuning 'A' Series engines of all variants for 53 years so have a little 'A' Series experience under my belt so to speak.
I do hope that it is the open window that is the cause of the fumes but that does not get away from the fact that your engine needs some loving attention.
That is a 140bhp 'A' Series built by me under the bonnet of my Minor which features in my signature photo and not a leak or fume in sight.

[Minornut59]

All being well, there should be some pics appearing as attachments showing the tailpipe and how much it protrudes from under the bumper, plus the bottom of the gearbox/pipe joint there, Nice and clean Phil!! lol

Just checked and there is a small drip of oil on the bottom of the box and a ten pence size drip on the concrete so nowt to worry about in my opinion.
Cheers though

[Minornut59]

Blimey Phil!!

I would like to thank you for your input and you definitely win the long service Blue Peter badge or whatever you feel you need but my engine DOES NOT need loving attention. I know my way around an A Series quite well too and this one has been built well. I know because i did it.

I could feel a bit cross at having my expertise called into question like that. I am sure you would too.
Its been rebuilt so i am not going to be doing it again unless there is a problem which there isn't. I did not admit to it burning oil; If you re-read the post above i said it may possibly burn a bit, ie a tiny amount. It does go somewhere but very slowly and that is quite normal for a Mini.
Unlike a Morris there are a plethora of oil seals which can leak and after a high mileage all do....

What we have here, is not oil smoke but exhaust fumes and the point of the original query was, is the slight change in oil level somehow afecting its emission of exhaust. Unlikely but i could not think of a reason why this only happens sometimes.
the window theory has intrigued me.. I will be testing it out..

[philthehill]

Thankfully I do not feel the need anything to celebrate being involved in the 'A' Series for 53 years.

I am sorry if you feel aggrieved by my post but you will only get honest well grounded technical opinion from me.

[Minornut59]

Aggrieved? Perhaps a bit cross at the implication that i had not built an engine properly and then telling me it needed loving attention.
I came on here for help and a chat with like minded enthusiasts to solve a problem, not to defend my engine!!

Perhaps techical advice should be tempered with consideration for others.

Just a thought. We are all enthusiasts here; lets not get distracted by one upmanship and telling each other how we think it should be.

Keep this a happy place....

[oliver90owner]

I'll defend PTH on this one.

He always offers honest advice and overwhelmingly the correct diagnosis of the problem at hand. He also offers comprehensive help with effecting repairs and I, for one, have learned a lot from his posts. But there are times when posters come on here with a problem and we know nothing of their practical abilities or understanding of the technicalities. Indeed, some are posted under completely the wrong section because the posters are not at all savvy with the systems and symptoms of this fairly basic power train.

You said you 'rebuilt the car' then went on to describe the engine rebuild but were not specific as to whether you had done the work on that. Did you rebore it yourself? Most don't. A crank bearing change or reground mains and crankpins? If a regrind, did you do it?

Phil gave his opinion, just as I offered a simple further diagnostic suggestion. You can take the advice or leave it. There are many replies that are irrelevant and some that are downright misleading. His was one suggestion, not daft at all. Perhaps not applicable in this instance, but more often than not a relevant comment.

If you were sure it was exhaust fumes that were causing the problem, why not be specific in the first place? That would have narrowed down the options considerably. You might even have thought of altering the tail pipe yourself, and hence not needed to post a problem at all at this stage.

Turning the tail pipe downwards might be a further suggestion, now that I have seen the position of the pipe end.

[liammonty]

I'd agree with the suggestions regarding tail pipe length and driving with the window down. I had exactly the same problem with my Traveller, largely cured by fitting an extension piece on the tailpipe. Good luck!

[Minornut59]

Ok well defend away but i do happen to think that while any advice is welcomed to anyone usng a forum, making blunt comments of this kind in general to someone hinting that they haven't done their rebuild properly and making assumptions that their quality of workmanship is poor without even knowing them, the car or the thing involved takes away from the helpfulness of the advice and is rude at best, downright insulting at worst and its that kind of attitude that dissuades some people from using online forums.
It was really not necessary. Especially when that person has come on here to have a chat and ask for some input from other like minded individuals and has spent a considerable sum on the car to get it right.
Its almost the equivalent of going up to someone at a show and telling them they haven't go the correct wheels on their car, or the wrong mirrors or telling them that their paint job is crap or tutting at the non standard seats..

Now, lets leave that one there please.

Difficult to know how more specific i could have been. I listed everything i could think of when setting out the issue.
I did not rebore the engine no; i, like most people don't have the facilities or equipment to do this themselves but ask their local engineers to do it as i did. The engineering shop who did bored it to suit the pistons i bought. +20 thou. and polished the unworn crank.
I then rebuilt it. , new bearings thrust washers, timing gears and chain.. block skimmed, unleaded head, etc etc the list is endless.

The pipe is stainless steel so bending/turning the pipe end down will be pretty tough to do; there is no joint there as the next one in is under the rear seat that connects the back section with silencer to the pipe from the front. Thats the way the RC40 is formed.
Pprobably have to remove it and insert a large bar and heave to change its shape but i wouldn't be too keen.

[Minornut59]

Thanks Liammonty,

I will be taking it out at the weekend and will definiately try it....

Will let you know!!

[les]

Just read this thread from beginning to end, and can't believe the reaction!

[Minornut59]

Sadly this is the world we live in. I have had PM's here and on other forums from people over the years who have actually stopped using them due to the unfortunate attitude of some of the users who feel the need to make chippy remarks or such.
I don't think that that is fair or a good thing at all, doesn't help people feel welcomed and doesn't say great things about us car enthusiasts if we have a go at each other.

Politeness costs nothing and should be foremost

[les]

I doubt this will go down well but you are over reacting, there are people here who are very helpful and don't make a habit of upsetting people. Those that are not helpful are easily identified. I think you've got it wrong.

[Minornut59]

But, Les.

I asked a question relating to exhaust fumes and gave as much info as possible to help people make a diagnosis.
What i got was advice that didn't relate to this but seemed to be someone adding 2 and 2 to make 5.
I clearly stated the engine was rebuilt so it should have been evident that it wasn't burning much if any oil; i even said so.
Instead i get told my engine needed loving attention and heavy hints that it hadn't been done properly.
When i question this i get a' i have more experience and knowledge than you' type comment.

When you spend several thousand pounds restoring a car and years of work, that kind of blunt attitude does not go down well.

Definitely not helpful and i do not think that putting someone straight is an over reaction.
I guess most people would just ignore it, but it doesn't make it right.

[les]

Well maybe. ---It's not always easy with the written word, it's sometimes difficult to portray the tone in which a comment is made.

[Minornut59]

Even more reason to not make blunt comments but proof read and maintain basic civility.

Anyway, the window theory proved correct.
last Sunday i took the Mini up to 70 mph on the dual carriageway and kept the window shut.
No fumes.
Then i opened the window and instantly smoke filled up the cabin.

I slowed down again and waited until the fumes had cleared, shut the window and off i went again, up to 70mph.
This time i waited for a quiet stretch of road, opened the wondow again and risked a quick glance over my shoulder to see....

Fumes pouring in from the boot area..

So its being sucked in from the boot.
Last night i investigated and found a 10mm gap in the rubber seal on the lower edge bootlid. It wasn't there when i fitted it so i am assuming it must have shrunk a bit. I removed the seal, turned it around so the join is at the top instead of the bottom, gave it some gentle stretching and restuck it to the lid and ensured there was no gap.

Haven't test driven it yet but am planning to go to a steam rally to exhibit so i will see what if any improvement that has made.