How to / DIY > Engines
SR3 Rebuild
Orion:
Hi all! Only just joined so be gentle with me :)
Background
I recently bought an old Ketch which was fitted with a Lister SR3 engine that was working, albeit by a wing and a prayer, that then died in much the same way as the Bluesmobile did near the end of the movie. There was a loud crunch just as I was maneuvering the boat in position under the shiplift. During the initial restart I did manage to get it running again for a very short time until it became clear that all was not well. Upon inspection of the sump i found bits on the camshaft which apparently is not good!
My experience in mechanictary is less than zero, by which I mean I don't know what I don't know, however I did know a real marine mechanic who fell in love with the old motor and told me that if I could, I should keep it and rebuild it. So i armed with a shiny new spanner I set about stripping it down. For lots of details and photos please visit my blog myketchlife.com and click on the Engine Bay topic.
The engine is back together but obviously won't start because I'm still not a mechanic, however it does turn over nicely but is not firing at all which i believe is a fuel issue.
I had stripped down and cleaned the injectors during the rebuild, tried a couple of different methods of priming the fuel system and turned over the motor without the injectors connected as I don't have a spare pipe which is needed to prove the injectors out in the open (according to the parts manual I have). There didn't seem to be much fuel coming from the 2 of the fuel pumps and none coming from the third. As I had already proved that all the fuel lines are clear I stripped down the fuel pumps but cannot reinstall them yet as I am waiting on a new fuel delivery Vv as there was one missing! Also I am getting a complete new fuel filter as the original was only cleaned not replaced due to the age of the and unavailability of a replacement filter. Sorry about the long winded blurb but I was trying to think of what questions I may get asked.
Questions for the Brains Trust
Once I have the part and have re-installed the 3 pumps what is the best method of priming?
How much fuel should be coming from a fuel pump on each stroke?
I am unable to prove the fuel timing as there is no mark visible on The fly wheel so if this is the problem how do I fix the timing?
Is there anything else I should check before I do a restart?
Thanks in advance 8)
myketchlife.com
ajaffa1:
Welcome to the forum Orion, first question: was this an SR3 or an SR3W (water cooled)? Second question, when a cam shaft breaks it usually does irreversible damage, what where the bits you found in the sump, did you replace the camshaft, the bushes what about the cam followers, did someone line bore the new bushes? Not an easy task for a non mechanic.
Assuming you have had all the above done correctly did you number the injector pumps and the shims that sit beneath them? If not you are going to have to spill time each injector pump to ensure it injects fuel into it`s cylinder at the right time. Then you can think about linking the injectors together and bleeding the fuel injectors.
One hell of a project you have taken on, hat off to you Sir!
Bob
cobbadog:
Welcome Orion and well done so far.
Please dont be offended byh anything I mention it is given as ideas not criticism.
You mentioned that you stripped and cleaned the injectors. This is normally a job that requires specialty equipment when assembling and setting the working pressues, so this thought should go on a list of why it may not start.
In order to bleed the fuel system it is best to do it in stages. May sound silly but confirm you have fuel running freely out of the tank. Easiest way is to loosen the fuel line at the filter body if this is the 1st stage of fuel flow. Next bleed the filter housing. There should be a bleed screw on top of the housing. Next I guess the fuel goes to the 1st of the fuel pumps, ensure fuel runs freely to each pump in order and make sure there are no bubbles. So far this may be all gravity fed, if not you are going to get tired of pumping by hand.
Next with the throttle open wide start turning the engine overand see the small amount of fuel rise from the top of the pump. It is really just a dribble at this stage. Do this for all 3 pumps. Then disconnect the fuel line from all the injectors and crank again until you see the same amount of fuel come out of the fuel line with no bubbles, again on all 3 lines. Connect the fuel lines and attempt a start up but be ready to shut it down just incase.
This is how I bleed a diesel fuel system only mine are single cylinders and I have been able with one engine to remove the injector and connect it to the fuel line, crank it over and physically see the atomised spray. If you see this spray do not try to touch it as it is strong enough to impregnate into your skin and this is painful and dangerous to your health.
As I have never had to do spill timing I am unable to help but ajaffa1 - Bob, can help.
I found my timing marks on the outside flat section of the flywheel which showed a - mark for TDC and a lightning bolt for spark/spill timing I think. You will need to find TDC on compression then really clean up the rim of the flyweel at the 12 o'clock position and use a good light to help you see it. Once I found mine I really cleaned them up with a wire brush and filled the marks up using a white oil base marker pen.
Good luck and keep us informed.
ajaffa1:
The timing marks are stamped into the outside face of the flywheel. They can`t be seen because of the bell housing that surrounds it, there should be a small viewing hole in the front of the bell housing. If I remember rightly there are marks for TDC and injector pump spill.
Bob
Orion:
--- Quote from: ajaffa1 on February 02, 2023, 07:16:00 AM ---Welcome to the forum Orion, first question: was this an SR3 or an SR3W (water cooled)? Second question, when a cam shaft breaks it usually does irreversible damage, what where the bits you found in the sump, did you replace the camshaft, the bushes what about the cam followers, did someone line bore the new bushes? Not an easy task for a non mechanic.
Assuming you have had all the above done correctly did you number the injector pumps and the shims that sit beneath them? If not you are going to have to spill time each injector pump to ensure it injects fuel into it`s cylinder at the right time. Then you can think about linking the injectors together and bleeding the fuel injectors.
One hell of a project you have taken on, hat off to you Sir!
Bob
--- End quote ---
I'll have attached pics of the damaged parts, only damaged parts have been replaced. All parts were removed, photographed and kept together with parts from same cylinder in an oil bath.
The engine is the air cooled version - Hundreds of pics on my website (myketchlife.com)
My thinking behind my restoration project is that to really know my boat I should strip it down as much as I could. This would give me a lot more knowledge and understanding to carry out repairs at sea when there is only me. Mistakes in the workshop may cost time and money but at sea...
myketchlife.com
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