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perahu
perahu

Posted: Sat Aug 08, 2015 5:12pm

Post Subject: BMC 1.5

Hi I need urgently help This morning when I started engine (bmc 1.5 Thornycroft T90 ) it was stopping on low reeves checked oil level and was rely high have to pump out 2 liters to get to top mark in dipstick, oil does not look like mix with oil is black and thin Culd it be licking shaft on fuel pump or lift pump? or something worst Also I noticed exhaust smoke comng from the pipe connected to air filter I will greatly appreciate any help

Tony-B
Tony-B

Posted: Sat Aug 08, 2015 8:04pm

Post Subject: BMC 1.5

This is almost certainly oil dilution by fuel as you supposed. The fuel lift pump should have a drain hole below the diaphragm chamber so a leaking diaphragm showed by fuel leaking down the side of the block below the lift pump but we can not be 100% sure that yours has one because of all the Indian and Turkish parts now being fitted. Since we went to low sulphur fuel the fuel has been slowly leeching the sulphur out of the seals that had been absorbed over many years. This makes the seals shrink so they no longer "take up" the wear so they leak. My guess would be that this is a leaking injector pump main shaft seal but can not totally rule out a faulty lift pump. If you can find and print out an on-line manual or if you have the original one changing a 1.5 injector pump is perfectly within the powers of any DIY mechanic because there is no timing to undertake save lining up a pointer and line on the pump flange. You will have to know how to bleed the system though.

perahu
perahu

Posted: Sun Aug 09, 2015 8:17pm

Post Subject: BMC 1.5

Thank you Tony The lifting pump is for sure original one fitted by Thornycroft so very old, fuel pump has been reconditioned 5 years ego by professional company, are you suggesting that fuel pump is mine suspect ?

Tony-B
Tony-B

Posted: Mon Aug 10, 2015 7:57am

Post Subject: BMC 1.5

Now you say the injector pump was overhauled 5 years ago it makes it a less likely candidate for being the cause of the leak. As the lift pump has never been changed I would expect it to have that drain hole I mentioned but maybe bit is blocked or your pump never had one so with the extra information it makes the lift pump a more likely candidate. My answers all assume the engine is running smoothly with plenty of power and little exhaust smoke. If it is misfiring or making lots of smoke all the time it could be a leaking or otherwise faulty injector or low compression allowing liquid fuel to pass a piston into the sump. This is a much rarer occurrence than a leaking seal or pump diaphragm so without other symptoms can be ignored..

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