Starter Testing
rasbury
Member Posts: 8,410 ✭✭✭✭✭
I have been having suspicion of a start issue since I purchased 10 months ago, "slow"start, on a 5.7 350 MPI 2005 motor. I solved one problem replacing starter slave cylinder so that is ruled out. When you turn the key, sounds like the starter wants to turn, you hear an electrical buzz going on, almost like it is jambed. I also just up graded my battery, brand new today. I looked at the service manual and going through that process step by step.
First step I can tell you the result but the results in the printed has me confused. The first step should tell you if you have a wiring/ground issue, or if you have a problem with the starter/selonoid. I thought that a good approach, kind of start in the middle. Book says connect a meter up to the positive terminal on the selonoid and then the negative to bare metal on the starter itself. I connected to one of the nuts for the long bolts that holds the starter housing together. And then the book goes on to say turn the key on for a few seconds and the should me no more than 1/2 volts drop than when you tested the battery itself. CONFUSING! When I tested the battery itself, 13.6 volts. When I hooked the meter to the selonoid as described above, I had 13.6 also but without the key on. Why would there be voltage when the key was not on? Is that correct? Then when you hit the key it drops to as low as 12.5 (starter is not turning). So that is a 1 volt drop. If the starter is working properly, there would not be any more than a 1/2 volt drop as your cranking on the motor with it?
The book is saying that if the volts drop more than 1/2 volts with the key on, must be something in the wiring, which it does, but I likewise do not under stand getting the volts when the key was not on...anyone help with this test? Then I can move on to the next when I understand better the results of this one! Is there a way to manually turn the starter like an automotive one? Can the gears get meshed? I did look at the grounds on back side of motor, all terminals clean and tight...
Comments
Dream 'Inn III -- 2008 400 Express
so if the starter were turning properly, when you hit the key, the current will still be within 1/2 volt? And with the key off and the meter hooked up the way I did I should get battery voltage? I read another similar method of testing but it said make sure the battery tested above 12V and then hit the switch and record the voltage drop at the battery, then do the same as above at the starter selonoid and record that drop and then compare those results for the difference. The Merc book says check at the battery with no load and then check at the starter under load and look for a drop, that does not make sense to me but that is what it's saying?- I did inspect the back side of the isolator switch- everything looked clean and tight. I dug down behind the motor to the engine ground-looked like three or four wires on that and all the connections looked like galvanized connectors or otherwise clean. I did put a wrench on that to make sure it was tight. The book also states if you have at least 9 1/2 when your hitting the key, the starter is getting enough juice for it to work...it's very confusing. I noticed also on the transom a panel of wires or like a bar...what's all them for??? This is my boating season!!!
Dream 'Inn III -- 2008 400 Express