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Cav 1.6 doing *10mpg* PLEASE HELP!!!

1K views 30 replies 11 participants last post by  cavvysri 
#1 ·
Right, Two probs today...:mad:

First off, my car is definately using too much fuel (about 10mpg by my reconing)...Did a 20 mile run last night used *QUATER OF A TANK* :eek:

Secondly, on investigation I've noticed a rather manky white/oily build-up under my oil filler cap. The exhaust also smells fumie

Any relation between these two problems??? The car also has zero power - especially in second, even when it's floor'd :confused:

My car is an F reg Mk3 Cav 1.6L...Carb model

Thanks for your help :(
 
#3 ·
revalveit,

The stuff under your oil filler cap is commonly known as mayonaisse. It ocurrs when water and oil mix. If it's mixed in your engine, then somehow, water is getting into the oil in your engine.

A common way of that happening, is via the head gasket when the gasket has gone. That doesn't really explain the amount of fuel your getting through though.

I'm unsure of the 1.6 carb, but you can check for things like a stuck choke, which it most likely is. Because the choke is full on, the mixture is far, far too rich, and so the car has zero power because it is being flooded. This would explain the fumey smell from unburnt fuel making it to the exhaust system.

You've probably got a head gasket problem, or the head has gone porous somewhere (Where the waterways have made it through their channels, and into the head)

I think the two may be unrelated, or have you noticed them, appear together?

Brian.
 
#4 ·
Thanks for the info!!! :)

Regarding the choke, would the fact that my Temperature guage never gets out of the blue (exept when stood) have anything to do with it?

And while were on that subject, WHY DOES THE TEMPERATURE GUAGE NEVER GET OUT OF THE BLUE??? A mate of mine has an Astra Mk3 1.4, and his guage goes well up into the 90's and stays there. :confused:

Do you think the engine still thinks it's cold, and therefore holds the choke open???

I really need to sort this problem, I just can't afford to run it at this rate!!!.
 
#5 ·
mayo in the rocker cover can happen if the car is only used for short journeys a lot apparently. It happens in vaux's quite a lot.
I read once that if the ecu thinks the engine is cold, then it will over fuel to compensate. Although yours is a carb, so i dont think it will be the same.
 
#6 ·
Hmm, staying in the blue - sounds like yer thermostat is broken. That'll stop your car from warming up, especially in this weather, which would also result in 'mayonaise' under your filler cap as the oil never warms up enough to burn off the water vapour.

Mark
 
#9 ·
Either your gauge is buggered, or your thermostat is stuck open. You can check by driving fro about 20 mins then feel the hoses - they should be hot - if not, then your engine hasn't warmed up and your gauge is correct.

Mark
 
#11 ·
Yeah - they're cheap so you might as well replace it anyway. When you've done that & it gets upto temperature properly, it's worth changing the oil to get rid of the mayonaise crap.

Then see what mpg it does - let us knoe how you get on.

Hope this helps,

Mark
 
#15 ·
Oh yeah!!!...Coming to think about it, I think I read somewhere that the Pierberg carb (The one the 1.6 uses) uses the cooling system to control the choke Mechanism...

This would mean if the thermostat is stuck open, the carb won't be heating up...hence, choke not opperating right!!!

Any thoughts???

:)
 
#17 ·
rgv_stu said:


definately change that thermostat
Yup, I will!!!

One thing though. When I do the test, will the water pipes be *Stone* cold if it's a faulty stat?, or just warm? Mmm.

And if the stat's OK, will the pipes be like red hot to the touch?

I ask coz I need to be sure the stat's bumed lmao







:)
 
#20 ·
UPDATE:

Right then.

I've changed over the Stat (quite a big job...had to remove timing belt, cover and top sprocket to get access!!!) :mad: Good thing is though, it's done the trick and now my temp gauge goes to just under 90 :) ...which I think is about right.

As for how much fuel it now uses, I don't know yet as I've just done the job...I'll let you know when I know. ;)

Thanks for all your help.
 
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