Can't bleed my 4.108

Author Message   Tim Higgins New member Username: surfergeek411 Post Number: 1 Registered: 07-2009 Posted on Monday, July 13, 2009 - 12:14 pm:    Hi, I've got a fresh rebuild 4.108 in my Formosa 41. I've seen it running on the dry @ 1 year ago. I 've had it sitting in my boat but not installed. I now cannot seem to be able to bleed all the air from the system. I've got mostly new hoses etc.. I've bled from the filter to the injector pump. I can get a solid stream from the side vent screw bot can't get solid stream from the top vent screw on the Anti-stall device. I've cranked the engine over trying to bleed the air from the last vent screw. Can the Injector pump go bad from cranking the engine with air in the system. I do get a little fuel when I crack the injectors. Thanks, Tim   nat wales Member Username: bigtimeoperator Post Number: 6 Registered: 08-2008 Posted on Monday, July 13, 2009 - 12:33 pm:    Hey, this advice may not apply to the 4.108 but I know on my 4.236 I had a similar issue. It was the vent screw. On my bottom vent screw I could just loosen it slightly and get a stream of fuel, but the top screw had to unscrew much further than I expected. Maybe that's your issue. Oh, and to answer your question, I believe injector pumps can go bad from cranking when it's air bound as the fuel provides lubrication to the pump. I would try and bleed that out as much as you can. Again, not sure on the differences between the 4.236 and the 4.108, but I know on my engine the last step is always to loosen one of the injector nuts and then crank the engine for 20 seconds or so before it really starts to spurt diesel and fire on it's own. This is not just a little seepage but a real solid spurts of fuel. It always feels like it's cranking for an eternity. Here's a good article that I found helpful: http://www.foleyengines.com/FreeTechnicalInfo/DrDieselTechTips/BleedingPerkinsDe utzDeereFuelSystems.aspx   Tim Higgins New member Username: surfergeek411 Post Number: 2 Registered: 07-2009 Posted on Monday, July 13, 2009 - 11:23 pm:    Thanks for the advice Nat, I now seem to have a decent stream coming out of the top vent screw. I replaced the O-ring between the body and the Anti-Stall device the vent screw is on top of. But, I can't get much more than a few drops from the injectors. I hope I didn't burn up the Injector pump. I've cranked the motor now but never more than 10 secs. I think a few times the Injector Pump may have been dry but not completely. So, remains to be seen. I guess I'll have to figure how to test the pump without out taking it out. It's not the easiest to get to now that the motor is in. Thanks again.   kit carsen New member Username: taswegian Post Number: 3 Registered: 06-2009 Posted on Tuesday, July 14, 2009 - 04:04 am:    Hi Tim, 1. Make sure you have clear fuel at pump bleed points. 2. Check stop lever turned to 100% RUN position. 3.Set throttle to full noise. 4.Open all injector union nuts 3 turns. 5.Grank until small squirts/lrg drips appear,close nuts, use starting aid as fitted or aero start most 4.108s are slow starters also if the engine has not run for some time compression will be down a bit.You can grank for at least 30sec b4 resting starter if you have fuel at vents, pump will not be damaged by granking Good Luck, Tassie..}   Tim Higgins New member Username: surfergeek411 Post Number: 3 Registered: 07-2009 Posted on Tuesday, July 14, 2009 - 10:36 am:    Thanks guys, It's reassuring to get such great advice. Not knowing makes me worry. I've spent so much time on this motor. Took it out bought another short block and made one good motor from different parts of each. So, it's all a Do it yourself er... As I mentioned. I did hear it run after the rebuild before I had it dropped into the boat. And It sounded like a Hot Rod (:-}. Now my batteries are definitely on the last leg. I can get about 10-12 secs of good revs. then they give up. Also, I think I fried either the realy or the solenoid. Every 3rd or 4th try cranking the motor, the starter keeps running on. If I have to replace either the solenoid or relay, i'm not that concerned at this point. More concerned about the motor just firing. Kit, thanks for that advice. I've only opened the aft injector union nut and had lrg drops (never a squirt). So, I'll try the starter fluid and opening all unionn nuts. First I need a new starter battery. I've presently got 4 dead house bank (6volt trojans) batteries and 2 (6volts with an automotive 12v for the 2nd bank. I can use a starter/charger attached and plugged into 110v also. I'm taking it personally now... lol.. Thanks again, Tim   Tim Higgins Member Username: surfergeek411 Post Number: 4 Registered: 07-2009 Posted on Tuesday, July 14, 2009 - 10:06 pm:    YES, Thanks to all for the great advice. I got the Perkins running like a banshee. I tightened up all the fittings and bled the screws, sprayed a little starter fluid. Yeeha. I'm off to the other hemisphere.

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