ive been having a few random break downs in a 1988 1300 polo with the 2e3 carb engine
seems to happen any outside temp
i can be crusing along and the engine will develop, a stutter..not really a noticable miss fire, at this point the car will not accelerate and tend to gently fade away, once ive pulled over the engine just chugs away barely running at all..does not rev
turning off and re starting it doesnt make any differrance..at this point i usualy open the bonnet and start poking around for loose leads or anything obvious..after a quick poke around it usualy starts up and drives normaly..not that ive fixed anything
so....does that sound like carb icing?? are 2e3 prone to it and whats the fix?? i had it happen in september would they still ice in warm ish weather..or could it be dirt in the carb?? are they alright to rebuild?? what do i need to rebuild one
i know a weber conversion would be a nice idea, but i cant justify over £200 on a old banger
btw..sinse the first break down ive fitted new plugs/leads/fuel filter
|
Steveo
Although a blocked fuel filter also comes to mind; the description is textbook VW carb icing. Basically as the air is drawn into the carb it's pressure falls and it cools rapidly. Evaporation of the atomized fuel also cools the metal of the carb housing; frost forms on the mouth of the carb and grows across and restricts the airway until the car is virtually on full choke. [The power loss symptom.]
Once stopped for a few minutes [engine off] rising heat melts the frost and everything returns to normal. The usual time to encounter icing is after a sustained period of cruising on an open road; not around town, where slow movement means low airflow and underbonnet temperatures are high enough to warm the incoming air.
VW's are the most prone cars because their carbs are mounted on [very fragile] rubber-bonded insulators that prevent the heat in the inlet manifold being conducted into the carb's body. They've tried all sorts of tricks to overcome the problem - even electric heaters in some of the carb's idling passages. [The wires break on those; particularly the brown earths.]
Check:- the exhaust manifold tin oven and the foil hose to the air filter; [still present?] then ensure that the vacuum-operated air diverter valve in the filter intake and it's capsule, temperature switch and manifold vacuum pick-up hose is fully functional. If not; secure the flap in the hot position with self-tapper.
Icing in September is possible if unlikely. It's most usual if the temperature is 0-10 degrees C and fairly high humidity. [Cool and damp.] Once fully below freezing the air is considerably drier and it doesn't seem to happen.
|
|
|
It's probably the carb-to-manifold gasket (a rubbery block with four studs poking out) - search for one of my earlier posts on this
|
thanks guys
the rubber base plate does look past its best , so i think i'll replace it
not really sure how to check the cold air flap is working right?? and the pipework is in place...maybe i'll secure the flap in the hot air position anyway..cant hurt an old heap can it
what about dismantling the carb incase theres dirt in there?? am i likley to mess things up?? are gasket kits avail
|
Stevo
Get yourself a proper old-fashioned Haynes Workshop Manual; [a couple of quid on e-bay.]
That'll show you where the hot-air pick-up system components were before they all went missing. Don't bother with the mega-bucks rubber insulator; I've never seen a split one cause this - just endless "failure-to-idle" grief.
Dirt in the carb is so unlikely with three filters in the system, that you'd be better off leaving it untouched. Just check those heater wires aren't broken.
|
The 2E3 carb is a bit of a pain to set up correctly. I would not discount dirt in the carb, they can suffer from this quite a lot, even if you put two filters in-line.
These people are helpful:
www.carburettorspecialists.com/
If you want a Haynes manual for this car then drop me a line. I have one id good condition. My e-mail is in my profile.
HTH
Xileno
|
This item on carb icing is for aviators, but makes the important point that relative humidity is a greater factor than outside air temperature.
www.caa.co.uk/docs/33/srg_gad_webSsl14.pdf
|
cracked jet surround is probable.not looked at any sites but was a problem many years ago.but meant getting a new carb,as the carb itself was faulty
--
Steve
|
|
|
Bromptonaut
It doesn't just happen on a Bombardier-Rotax two-stroke. You've no idea how many cases I've seen - and cured - on cars over the years. If you can recognise it's trademark symptoms; you quickly see that it's far more common than is generally realized; particularly by some manufacturers.
Even the good old SU on a Mini was well-prone on damp winter mornings if the filter's metal spout [yes; that old] wasn't turned to pick-up hot air off the manifold.
|
|
Bedford Cf vans used to suffer from carb icing ,cured by turning the air filter intake over the exaust manifold.Alfa's used to suffer from the rubber carb mounting going porous but this only manifests when trying to start from cold.I would start with the carb icing up.
|
|
okay carb icing does sound like a good possibility...although on one ocassion it did it after a hot start and around one mile of driving in town...could it ice so fast??
|
I had one of these cars for 12 years and never experienced carb icing, despite a number of really nasty winters in central France where -10 to -15 is not unusual.
I put my money on it being dirt in the carb.
|
i just cant see that dirt would fix itself after a few minutes standing?? although i did change the head gasket in the summer so i may have sloshed the carb around and disldged some dirt
im going to dismantle and clean the carb , and fix the hot air flap into the winter position, i may as well fit a new rubber base as it looks past its best
|
|
Not sure where Rotax came in, link was to a CAA general information leaflet on carb icing in carburreted aircraft engines and was meant to illustrate the principle that humidity and dewpoint combined with retarded throttle rather than low air temp precipitate carb icing. In UK at least it's less common in extreme low temperature (think clear air and moisture condensed out as frost)
The SU in my Mini was well prone to icing. Was it not carb icing in the prototype that led to the engine installation being rotated 180 degrees; leaving the distributor to pick up road spray.
|
|
|
|
|
|
