11 replies to this topic

[afoggo]

The car cut out on me yesterday morning, no hesitation, spluttering or anything. Then the car wouldturn over but not fire, after leaving it 5 mins or so it turned over and fired. Was minus 1 yesterday morning so pretty chilly but I've driven the car in cooler conditions than that!

Is carb icing my problem ? And how do I prevent this happening ? :)

Edited by afoggo, 29 January 2012 - 03:54 PM.

[imvarma]

I'm also interested in this, I opened the bonnet yesteday after a long drive with the car wanting to stall all the way and the carb was white with ice surrounding it. never seen that before...

[bmcecosse]

Yes - could well be - it's most likely when the temperature is just around freezing and there is still moisture in the air. Blank off the grille! Plastic sheet or even aluminium foil works reasonably well.

[redhot-mini]

i had this problem back in september after a 4 hour drive home i got carb icing my trick to keep it running once oyu have got carb ice was to put a cloth on the engine to worm up then wrap the carb in it to worm back up (probably not a good idear but it worked untill the head gasket went maby thats why it blew :/

[valve bounce]

ive been struggling with this all winter. i will just be driving along and it would slowly lose power and then eventually stop, so what ive been doing is when its cold i stick a carpet mat over the grill and its held it place by my spot lights. no more carb icing, i plan to make a more permanent solution for next winter

[sonikk4]

Carb icing tends to affect cars that have had their original airbox removed to fit a K&N filter TIG etc etc. As said normal symptoms are loss of power, increase in fuel consumption. Many types of airbox's have an adjustable air intake to pick off warm air from the exhaust manifold.

Blanking off some of the front grill will benefit or modify the air intake to suck hot air from the exhaust manifold. (A section of the concertina aluminium foil type ducting that can be bought from most motor factors.)

[jaydee]

Similar problem happened to me.
Firstly,
- car set up was spot on (before it start to snow)
- i've blanked off part of the grille and changed oil for synth 10w40
- took the car out for a run on the snow :)

Now, after just a couple of miles at a constant 60mph speed:
- idle speed rises to about 1.5k rpm or drops just under 750 rpm
- got pinking when i open throttle at 2k-2.5k rpm

At first my suspects were that i've touched the dizzy (123 electronic ign) while blanking the grill off, so checked timing and vac pipes, but they're fine.
No troubles when running round the block though, it happens after some miles at speeds higher then 50mph.

Is that carb icing or fuel condensation?
I've fitted a plastic airbox too, but still no joy.

I've never dealt with such stuff, so opinions/ideas are welcome thanks.

[ianmini]

Glad others have the problem. I cannot now fit original air cleaner due to head mods and new pipework and so have a K and N filter. After a few miles the carb is pure white! Sometimes the reves go up to over 4K which is a biot frightening.... I really cannot see how to catch the exhaust temperature and currently have done a lash up of attaching the heater hoze to the carb. Worked fine until today which is super damp, windy and 2C. Could only get 50 mph on our local wonderful dual carriagway (A14). Yes, lots and lots of lovely white stuff and the carb was incredibly cold.....

Ideas please???"""£££$$$

Thanks Ian

[Notay]

i may be wrong but you can get intake manifolds that can take a coolant feed (from the pipe return from heater matrix) and is sometimes used to rectify this cold problem - here it is for a SU carb.
http://www.minispare...pid=35083=
Someone may be able to clarify if I am correct.

Edited by Notay, 05 March 2012 - 06:38 PM.

[Dan]

Heated manifolds are not intended to cure carb icing and if fitted properly wouldn't be able to. The carb should be thermally isolated from the manifold by a spacer, but also the reason carbs ice is because they are essentially the same as a freezer in how they work. Heating the manifold won't stop the carb body itself being cold. Heated manifolds cure the problem of fuel condensing in the manifold, an effect many people think is the same as carb icing but which is quite different.

[Bergy]

it's most likely when the temperature is just around freezing and there is still moisture in the air

Interestingly carb icing can occur in relatively mild temperatures, the venturi effect in some carb engines can create temperature drops of up to 30c. During my commercial pilot training I tended to notice carb icing more in the summer months than the winter. Other important factors are the relative humidity, dew point, engine rpm (more likely at low rpm) and if there is any visible moisture.

The biggest drop in rpm I've ever had in an aircraft was on a warm summers morning with the engine at idle while parked on grass which was covered in early morning dew. This was in an aircraft fitted with a piston engine known for not being prone to carb icing.

The "fix" in piston aircraft is to change the air source for short periods at regular intervals. A mechanical lever is moved which draws the air from around the exhaust manifold, this being rather hot will melt any carb icing. Confirmation of any carb icing comes from noting the rpm before moving the lever and then seeing if there is any increase in RPM once the lever is moved back to its normal position.

As a side note this has been the prime suspect in many light aircraft accidents,unfortunately it is difficult to prove beyond doubt as any evidence quickly melts! Selecting the air source to hot is a "memory item" should you develop engine problems in most piston engined aircraft.

Off to work now to fire up the two turbine engines, no issues with carb icing on those bad boys.

[jaydee]

it's most likely when the temperature is just around freezing and there is still moisture in the air

Interestingly carb icing can occur in relatively mild temperatures, the venturi effect in some carb engines can create temperature drops of up to 30c. During my commercial pilot training I tended to notice carb icing more in the summer months than the winter. Other important factors are the relative humidity, dew point, engine rpm (more likely at low rpm) and if there is any visible moisture.

The biggest drop in rpm I've ever had in an aircraft was on a warm summers morning with the engine at idle while parked on grass which was covered in early morning dew. This was in an aircraft fitted with a piston engine known for not being prone to carb icing.

The "fix" in piston aircraft is to change the air source for short periods at regular intervals. A mechanical lever is moved which draws the air from around the exhaust manifold, this being rather hot will melt any carb icing. Confirmation of any carb icing comes from noting the rpm before moving the lever and then seeing if there is any increase in RPM once the lever is moved back to its normal position.

As a side note this has been the prime suspect in many light aircraft accidents,unfortunately it is difficult to prove beyond doubt as any evidence quickly melts! Selecting the air source to hot is a "memory item" should you develop engine problems in most piston engined aircraft.

Off to work now to fire up the two turbine engines, no issues with carb icing on those bad boys.

Infact I know they have carb icing issues in california due to the moisture..
Next year will try if fitting a standard air box with the little metal air-duct that takes warm air from the manifolds (i dont remember the name atm) will fix the problem.