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MG Midget and Sprite Technical - Holy Smokes

When ever I start the car with the choke I saw smoke out the back window. After somebody else started it for me, I couldnt believe how much smoke came out. I have taken a photo. The car is 73 midget 1275 and I have pulled the choke all the way out to start it.
Thanks
Allan
ADJ Jacks

Duhh


ADJ Jacks

Is that smoke or steam??
Adrian

Compression is good across all four cylinders and it only happens with the Choke on on start up
ADJ Jacks

Allan,

Are you saying that you can start your car when cold without the choke, and then it does not smoke?

In other words, is the smoke a choke issue, or a cold start issue?

Charley
C R Huff

When it is cold, I pull the choke out to start the car and I get the smoke. Once the car is warm, no choke and no smoke. It is summer here so I only need a little choke and the smoke is not bad. It does it for about 3 seconds then stops. If I pull the choke back out, it does not smoke after the initial 3 seconds.
Hope this helps.
ADJ Jacks

Looks like water vapour to me...

A
anthony

Have you checked your oil filler cap for 'mayo'?
Rich Amos (1330cc Blaze Red '72)

Allan,

Looks like it might be oil smoke, various cars I have seen that started on choke showed visible black exhaust not the white/grey yours shows.
David Billington

No Mayo in the Oil Cap. Head Gasket ok and compression good. I just drove the car to work 30 miles on the Highway, got just above N and Oil Pressure 40P.S.I.
The smoke is like that from a pipe that just floats in the air until it dissapates.
Once I have the car started, if I pull the choke back out, the car starts to splutter, but no smoke.
ADJ Jacks

it does look like water to me. It possible to have a head leak water into the exhaust until its up to temp then seal itself. I'd suggest getting a 'sniff test' done which looks for exhaust gasses in your coolant. or just change the head gasket for the sake of it, its easy and quite quick.
Nick

Allan,

It is probably hard to judge the color of a digital photo viewed on a computer. Generally white smoke is coolant, blue is oil, and black is fuel.

If it is oil and only does it on startup, I would suspect valve seals. If it were coolant, I would suspect the head gasket or head.

I think it is perfectly possible to have good compression test results, and still have a head gasket that bleeds coolant into the combustion chamber when the car is shut off and the pressure in the cooling system is greater than that in the combustion chamber.

You might pull the plugs before starting it and see if anything sprays out of one of the plug holes when the engine is cranked. If it is leaking enough, you might see something.

Charley
C R Huff

I agree, that "smoke" looks and behaves like water vapor.

Nick, you suggested:

>>> It possible to have a head leak water into the exhaust until its up to temp then seal itself. <<<

But Allan says:

>>> It does it for about 3 seconds then stops. <<<

So the vapor is ceasing well before the engine gets warm. Sounds to me like only a little bit is getting in during rest, and then burning off at startup.

-:G:-
Gryf Ketcherside

Jack,
It is terminal. You need to get rid of that car as soon as possible. For a small fee, I can take it off your hands ;-)

In this weather, why would you be pulling the choke all the way out? It would probably start cheerfully enough with no choke at all or at most half-choked. Tomorrow morning try starting it without the choke and see what the smoke situation is.
David "all choked up" Lieb
David Lieb

David,
You would never be happy with it.
I pulled the choke out to take the photo and was showing what it did when I do have to start it with the choke.
Allan "don't choke me because I can't breath" Jacks
ADJ Jacks

Hey jack,

Try putting in the key, and turning it to the "on" postion 1st NOT as far as to crank the engine, for about 20-30 sec. or until you stop a hearing a possiable ticking sound comming from the rear wheel area, then try starting the car...you may not be getting the fuel system pressureised enough if your just jumping in and trying to start the car imediatly.


is the car outside all the time in the rain and snow,....strange enough if it is, it may have rain water in the exhause system...I have no idea how that occours, and seems almost impossiable....but I have experianced this before....

prop
Prop

Prop
I will try the dely in starting.
No the car is seldom in the rain. Stays inside and gets tucked into the garage every evening.
ADJ Jacks

Not wishing to steal your thread but I have a question. I have a 1973 1275 midget with 50K mileage. Car starts fine gets up to temp approx 70 on the dial. It drops to 65 when the thermo kicks in. It smoke under acceleration (even minimal) umtil temp rises to 70 again. Is this rings or valve seals or...... All ideas would be helpful. Declan on behalf of Bridget the midget
D M McGinley

Not meaning to ignore you, Declan, but:

>>> strange enough if it is, it may have rain water in the exhause system... <<<

Not likely... any time you see water coming from the exhaust, this is because water vapor in the exhaust gases condenses out when it contacts the cool surfaces of the exhaust system before it warms up. Water vapor is a normal by-product of combustion.

Allan, I only need to use the choke if the ambient temp is chilly. For normal starts at this time of year, I never need the choke. Admittedly, this is on a 1500 with a ZS carb. Maybe the SUs need choking in the summer.

-:G:-
Gryf Ketcherside

gryf,

thanks for the correction and anyalisis....it makes good scence to me,,,,I never was able to understand how rain can get into the exhaust system,,,,but ever spring and fall I suffer this on my truck when there is alot of rain, and was told by the exhaust man that it was rain comming back up thur the tail pipe.

As to choking on the 1275....I find if I run the car regularly, I dont need to....but Im running a bit lean, so it helps....I find it also helps if the plugs are freash....but properly set-up...shouldnt really need to...esp. if you allow the fuel pump to do its job before actully trying to start the car.

prop
Prop

Just a thought. How long has the engine been run between starts? Engines create lots of water vapour and if not run for long enough the vapour condenses in the (cold) exhaust system/silencer. Next time you start, as soon as the hot exhaust gasses arrive it emerges as steam. That condensation is the reason why it is not a good thing to keep starting the engine without running it till hot (the condensation will rot your silencer).
Chris H (1970 Midget 1275)

This thread was discussed between 08/07/2008 and 11/07/2008

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