Boost and air leaks are a way of life for zed owners and making sure that your engine is not drawing air or loosing boost is vitally important for correct engine performance and acceptable fuel economy.

 

However sometimes the cause of leaks are self inflicted and one such mistake we see many times is pictured below and refers to the balancer bar. The bar has a bracket on the drivers side which sit on top and is secured by the same fixings that hold the balancer bar itself down.

 

A common mistake is for the bracket to be fitted in-between the bar and the plenum rather than on top of the bar, the outcome of this is a substantial air / boot leak. This leak can effect both turbo and non turbo zeds and will lead to bad fuelling, a grumpy tickover ( my name for it) this also can cause failure to pass emissions testing at MOT time.

 

The most common time for this mistake to be made is when the bar is removed to change the two rear spark plugs, and often we see this problem some months after they have been done which is testament to the zeds self learning ecu trying its best to calibrate and keep re-calibrating, even so high afm readings and odd O2 sensor readings will also be a clue to this particular problem but a non specialist garage will fail to spot this.

 

Another common issue is the rubber hose that connects the balancer bar to the auxilary air valve, they can get real brittle over time and when the bar is moved whn the rear plugs are changed they can split.

 

These issues are common and is one of the main reasons we do not advocate ecu upgraded by post or e-bay as chipping an engine with issues is a no, no.

 

Jeff TT

 

 

 

 

as always superb advise, can you advise what the max pressure to use when doing a boost leak test?

 

dan.:biggrin:

you would have to be a pleb to do that :lol:

you would have to be a pleb to do that :lol:

 

Exactly what I was thinking! :yes:

as always superb advise, can you advise what the max pressure to use when doing a boost leak test?

 

dan.:biggrin:

 

 

Not an exact answer to that, if you have a big leak then the amount of air you will need to find it will be significantly more than a small slow leak.

 

Its more about volume of air rather than pressure, by that I mean the air supplys capacity to keep up the supply of air as it leaks away. Of course in our workshop situation we have a large reserve tank on our compressor so have ample volume, having said that in a slow leak situation if excessive air was injected you will likely blow a pipe off such as a vacuum one that in general do not have securing clips on them so caution is required and equally a foot pump or a battery powered tyre inflation compressor is not going to be of use unless the leaks are very small.

 

 

Jeff

Edited February 19, 201114 yr by JeffTT

Would a non leaky engine hold any pressure? & for how long?

Would a non leaky engine hold any pressure? & for how long?

 

Yes to a degree, if there is no pipework leaks at all you can pressure it up and should be able leave it 30 seconds or so and pull off one of the small vacuum pipes there should be pressure still present.

 

Jeff TT

Ok & is it poss to lose air through the zorst ?