Forums » Ask a Question

Use this forum to post your questions to our experts – you need to be logged on to do it (you can register here ), then scroll down to the bottom of this page and click the blue Post Thread words

If you can help answer the question, feel free to post a reply – you need to be logged on to do it (you can register here ), then hit the reply button on the thread.

 

To go back to the experts page click here>>

AuthorMessage
chris1946
chris1946

Posted: Sun Nov 09, 2008 2:51pm

Post Subject: non startng bmc 1500 diesel

A little history first, the engine is fitted to a Seamaster and when the raw water pump shed it,s blades, overheated. The engine was allowed to cool down and the pump impellor was changed and the engine started fine. When 2 weks later I tried to start it, it turned over but would not start. As the engine had a history of needing lots of heater to get going I elected to change the heater plugs. Two sheared dur to carbon build up so I removed the head to drill out the sheared plugs. Once done new plugs were fitted and reconditioned fitted also. New gaskets, valve clearances done,fuel system bled and new battery fitted. Still won't start. Any possible solutions please. I'm thinking AC mech fuel pump at the moment as the battery charges

Tony-B
Tony-B

Posted: Sun Nov 09, 2008 3:38pm

Post Subject: non startng bmc 1500 diesel

Dear Chris, As long as your stop is in the run position (on the pump)then as this is a 1.5 my first suspicion is that you failed to bleed the primary (low pressure) part of the fuel system well enough at the injector pump. This is a very well known BMC "thing". Look at the exhaust as the engine is spinning over. If its producing clouds of white smoke I am wrong, but if its only a few wisps or none at all then re-bleed the injector pump from the screw ON THE SIDE of the body for at least two minutes. Then bleed the injector unions and recheck the smoke situation. If it is producing clouds of smoke then you have fuel so the suspicion must be lack of compression. If you re-used the old head gasket then it might be a matter of changing it for a new one, otherwise check the valve clearances in case they are too tight and then do a dry & wet compression test in that order. Expect at least 400psi dry at cranking and a little more wet. If its less than 400psi or if there is a variation between cylinders of more than about 10% then I suspect the cylinders, pistons & rings need attention. If you want to eliminate the lift pump rig up a gravity feed tank to the filter inlet and tie it to a hood hoop. Direct any output from the lift pump into a clean jar. Actually if the lift pump delivers close to an eggcup full every two revolutions the lift pump is probably OK. Come back if you need more information. Tony Brooks

chris1946
chris1946

Posted: Mon Nov 10, 2008 12:52am

Post Subject: non startng bmc 1500 diesel

Thanks for that Tony I'll check,but the non starting was happening before I did the head and re- bled. A new head gasket was fitted and also the injectors refurbished.

Tony-B
Tony-B

Posted: Mon Nov 10, 2008 12:50pm

Post Subject: non startng bmc 1500 diesel

I really need an assessment of the amount of exhaust smoke being produced during cranking and also if it seems to be trying to fire on one or two cylinders but not managing to run. The basic rule is no smoke equals no fuel and fuel equals a lot of smoke. This engine is probably over 30 years old and it may have started life as a hire boat so wear is not unexpected and that overheat may have caused a partial seizure that may have stuck piston rings in the grooves so the first stage of diagnosis is to rule out the simple things - like assessing the smoke and then move on to more complex or difficult things. This must be a step by step approach. I note that you gave no details about what makes you suspect the lift pump so as far as I am concerned it can only be regarded as a guess so I must apply my experience to your problem and based on what you say that tells me the lift pump is not likely to be the problem - otherwise you could not have bled the engine (I do not even know if you know how to bleed the engine properly). Let me know about the smoke and we will take it from there. Tony Brooks

chris1946
chris1946

Posted: Tue Nov 11, 2008 8:43am

Post Subject: non startng bmc 1500 diesel

Hi Tony, Thanks for all the info and when I get back to the boat I will go through your suggestions. There are a few reasons I thought of the lift pump, 1) If you go back to the original problem, it was starting but needed a few applications of heater and then with no changes to the system it wouldn't start. Fuel tank full etc so something must have happened. 2)As the primary fuel filter is above the tank and the AC pump is used to draw fuel from the tank this might be the problem. 3) My experiance of AC pumps goes back to Austin Cambridge days, when the pump was up to pressure the manual lever went 'slack', this is not happening here. And finally yes I do know how to bleed a fuel system. Regards.

Tony-B
Tony-B

Posted: Tue Nov 11, 2008 1:16pm

Post Subject: non startng bmc 1500 diesel

BMCs (especially the 1.5) are well know for not being the easiest starters once they get on a bit so the needing lots of heat seems fairly normal to me. I know of engineers who have problems with bleeding 1.5s so this is why I first suspect the bleeding. The carburettor on the A60 completely stops the fuel flow when the float chamber is full so the pump diaphragm is held down and the priming lever goes slack. The 1.5 bleeds a 0.5mm hole's worth of fuel back to the tank all the time so the pump diaphragm will rise as it pushes that fuel back to the tank, hence the lever continuing to work. However it should develop a fair bit of slack and only pump a little. Unfortunately the bolt that holds the banjo onto the top of the filter is where that 0.5mm hole is located and they often snap. I have known a number that have had home made bolts fitted there with a much larger hole. This would allow the priming lever to pump more fully all the time. I have to try to decide if its lack of compression or lack of fuel and short of doing a compression check the exhaust smoke during cranking is the easiest indicator. If it is a lack of fuel I would still not blame the lift pump until I was sure there were no blockages in the system or water filled filters. I would also be very suspicious of the rubber seal around the lift pump's cap, its internal strainer (if fitted) and the soft washer on the cap bolt. However all this depends on it being a fuel fault. This is why I suggested trying a gravity feed to the filter head. Tony Brooks

Most Read

Newsletter Sign Up

Canal Boat monthly newsletter
Sign up to receive our regular email newsletter

Our Privacy Policy

Like us on Facebook



Follow us on Twitter

Cache: Disabled for this object  Total Queries: 43.  Total Objects: 162.  Total Unserialized: 3. Total Runtime: 0.27 seconds.