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Matt
Matt, Engineer
Category: Volvo
Satisfied Customers: 20612
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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65 volvo b18d engine uses to much gas twin su carb hs6 why

Customer Question

65 volvo b18d engine uses to much gas twin su carb hs6 why thank you
Submitted: 11 months ago.
Category: Volvo
Expert:  Matt replied 11 months ago.

Hello

the official mileage rating for this car at the time was about 26 mpg so if its much less than this I'd 1st check that the ignition timing is set correctly and that the vacuum advance mechanism works correctly

One other thing is to ensure that you're running on the correct grade of engine and gearbox oil as if its too thick or overfilled this will really hurt the fuel economy and that the tyres are fully inflated

also check for

Binding brakes

Check that all the wheels can be turned freely by hand, and free off any sticking calipers

Incorrect wheel alignment:

Check all the tyres for signs of uneven wear if it has any then get it checked out at a place that does 4 wheel alignment not just front tracking and ensure tyres are pumped up to their recommended maximum

Injectors are clean and not dribbling - add a bottle of injector cleaner to the tank

Use good quality fuel - from my own findings its worth paying the extra for BP or shell as typically you'll get another 10% fuel saving which outweighs the cost over supermarket fuel.

And the biggest thing is driving style, by not labouring the engine ( too high a gear up hills etc) and not accelerating hard away from the lights etc you can usually improve things by another 25-30% or so.

Binding brakes:

Check that all the wheels can be turned freely by hand, and free off any sticking calipers

Incorrect wheel alignment:

Check all the tyres for signs of uneven wear if it has any then get it checked out at a place that does 4 wheel alignment not just front tracking and ensure tyres are pumped up to their recommended maximum

Injectors are clean and not dribbling - add a bottle of injector cleaner to the tank

Use good quality fuel - from my own findings its worth paying the extra for BP or shell as typically you'll get another 10% fuel saving which outweighs the cost over supermarket fuel.

And the biggest thing is driving style, by not labouring the engine ( too high a gear up hills etc) and not accelerating hard away from the lights etc you can usually improve things by another 25-30% or so.

Expert:  Matt replied 11 months ago.

Hi

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it.

If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues and its best to have the boost pressure measured actually measured with a boost gauge to check that the turbo is healthy and that the sensor is reading correctly

If its a variable vane turbo (they’ll be an actuator on the turbo body - but not a wastegate) then check its vacuum pipework as above and check the connections to the diaphragm / solenoid valve

Also worth checking that the glow-plug relay is switching off as they can stick on and leave the glow plugs also on - on some cars this can force it into limp home

Also worth considering adding a bottle of injector cleaner into the tank as a clogged injector nozzle will reduce power and give poor combustion - the next stage on from this is to remove all the injectors and have them ultrasonically cleaned and flow checked

Also check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.