Posted by Paul (in NY) on Saturday, June 23, 2007 at 20:04:48 :
I have been checking a spare 4BTA on my test stand. This engine will go in my Power Wagon when the M37 is complete. The engine runs well when running. However it had a serious starting problem. All of us know that when you start a 'good' 4BT/4BTA the starter engages and the engine is running, no cranking. This engine required 3 or 4 seconds of cranking to start. Then it ran good. Shut her down immediately after start ( no warm up) and she would do a normal immediate start with no cranking. The engine would appear to be normal for over 7 hours ( the longest between tests I ran). After sitting all night, back to cranking to start.
I knew I had a fuel or fuel/air problem, but where. In the process of elimination ( none of the following are in actual test order) , a new fuel source was used, new cummins lift pump, clamped shut fuel source line after shut down to see if fuel was draining back, clamped fuel return line after shutdown to see if fuel was draining back, removed valve plunger in fuel solenoid, checked fuel solenoid for proper operation, checked fuel solenoid pull up voltage,
changed fuel filter. Keep in mind after each of the above tests, it was necessary to let the engine sit over night to determine if the problem was solved as normal restarts were expected after the first start.
I was ready to pull the injectors and do a compression check (which I still plan to do later this year) and have injectors rebuilt. But I had an idea. Maybe a Flare fitting is cracked, so I was going to pull off all fuel lines from the fuel filter to the IP Pump. I started at the
fuel filter. From the Lift pump to the fuel filter is a steel line with a banjo fitting on the input to the fuel filter. I pulled the banjo bolt and pieces of rubber came off with the bolt.
Ha!, this is not right. With the line off, I inspected the 3918191 Washer Sealing that is on each side of the Banjo Bolt. These washers are not copper crush washers as I expected but rather steel washers with a rubber like material on the inside diameter of the washer.
The outer washer rubber like material was all cut up, deteriorated. The inner washer was in reasonably good shape. I ordered two new washers from the "Chrome C'. The part number 3918191 is now super-ceded by PN # 3963983.
I installed the new sealing washers. The engine had been now sitting for over 24 hours. I bled air out of the lines and hit the key. Immediate start, no cranking. For the past 3 mornings and again at 11pm when the dog goes out I start her up, Immediate start !!! I won. So if you have a like starting problem, check these steel washers with the rubber material centers. The rubber like material is to seal against the banjo bolt and stop leaks.
In the Picture the left washer was on the inner side and the right washer the outer. I am sure the right washer was the culprit.
Paul
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