S Series Cylinder Head

[D87 SMW]

My Vanden Plas Maestro, 1986 car with 66k miles, blows out blue smoke and really strong smelling gases. Replacing the spark plugs and O rings haven't cured the problem as such, but the O rings reduced the lumpy running on choke.

When it was my daily runner, there was no smoke to be seen at all and there was no lack of power. However it has been standing for a while and each time it is run I get the above problems. I'm wondering whether swapping the cylinder head (for an unleaded one) would solve this problem?

TIA

[G51 NAV]

Certainly when I've seen it seems to run really really rich on choke, so rich I was once tempted to catch the drips out of the exhaust and pour them back into the tank :laugh: Off choke it seems fine. Standing and being used infrequently will exacerbate the problem. Is it possible to adjust just 'on choke' mixture to be less rich? Perhaps if that could be tried it would be a place to start. It may not need a new top end.

[Wetfish]

Don’t want to be a prophet of doom but blue smoke is oil burning and black smoke too much petrol. Turn the mixture down and then check the smoke colour, if it’s still blue stick it on the classifieds!
There’s a charge for this advice, please pay £20 through Paypal or I call the Transport Dept and name and shame you for pollution!!

[G Force]

Hi Steve if the engine is running rich on choke, check the vacuum switch diaphragm is not faulty by removing the switch and sucking on the vacuum port. If you can suck air through then fit a new switch.

If the engine has been running too rich for any length of time then the engine oil can become diluted with petrol. Once the cause of the running rich is sorted then an oil change may help reduce the blue smoke.

G51 NAV it is possible to adjust the choke phasing, the adjustment is factory set and it is only needed to be altered in rare circumstances. To do it accurately you really need a special tool to control the stepper motor and a gas analyser. There is an access plug in the stepper motor that once removed it is possible to reach the adjuster with a special tool. With the adjustment screw lined up with the access hole the CO should be set to 5.5% hot engine. I would only recommend using this adjustment as a very last resort when every other problem has been ruled out though.;)


Gary

[G51 NAV]

Good call Gary. I haven't seen the car for a few months but certainly last time I saw it start from cold it was running really rich on choke, but only on choke. Once it got up to normal temperature there was no obvious signs of it still being rich. Well, not excessively so at least.