merc 170 slow crank help

[buckeyedoll]

I have a merc 170 and last season I turned her off while out on the lake. She would not restart. Trying to restart it the negative wire off the battery got very hot. So I replaced it. After that I still could not get it started. This brings me to this season. the engine this year would not even turn over. I noticed that the slave starting solenoid was not functioning. After a few taps and cleaning the contacts it is again funcioning but with a brand new battery it will only crank for about 5 seconds with plugs in and 10 with plugs out and then I have to recharge battery. I have also recently replaced pos cable from btry to starter and it seemed to help very little. I have also cleaned terminals on starter and still very slow crank. I can turn engine over with socket on crankshaft but it is not easy nor is it hard with plugs in and out. A friend thinks that the engine is to hard to turn and says car engines with plugs out are turned very easily. I dont know about his info? Can anyone help. Also two years ago the guy I bought boat from replaced slave solenoid and starter. Do I need to do the same with both. And is there something else that is causing these to go bad. Can an auto store test a starter to determine if it is bad even if it is still turning some. I know there are alot of questions i have asked but I like to try give all info for proper diagnoses so please bear with this post and help me!!!!

 

[bowhuntrrl]

Re: merc 170 slow crank help

I don't have the answers to all your questions, but maybe I can add something that will help. These motors are notorious for slow cranking due to their massive bore and stroke for a 4 cylinder. I read about something that will help and am in the process of doing this to mine. What you do is replace your positive caple to the starter with a larger cable 2 gauge was reccomended, but I'm going with 0 (ought) gauge for mine(bigger) for little extra cost. You must also replace the ground cable with a similar gauge cable. I got mine locally from a tractor/equipment store. This will reduce any voltage drop caused by the long run of cable from your battery to the starter. Also, check all your connections to the starter. Are there any loose terminals on the starter??? How's the ground connection at the block ??? Is there any rust on the starter showing possible water intrusion into it ??? If you go through replacing the cable, cleaning connections, etc., with no improvement. Then you should do a starter draw test. Unless you have the proper meter, this might mean taking it somewhere and having it done. Only other alternative is rebuild/remanufacture yours or buy a new one. Hope this helps.....<br /><br />Rich

 

[buckeyedoll]

Re: merc 170 slow crank help

I have already changed pos to 2 gauge and reduced the length. the negative is 2or4 gauge and new except put on a few months ago. I reduce its length with a shorter 2 gauge one. The connections have been cleaned up recently. I will clean again but dont know if this will help that much. can auto parts store do a draw test?

 

[buckeyedoll]

Re: merc 170 slow crank help

Ok, ive sat and read for hours on this site and it is clear that the 170(3.0) is a mother to turn over. Is there any way to get this turned over more easily? How about a large btry charger . One of the large ones with wheels. Is this feasible?

 

[MrBill]

Re: merc 170 slow crank help

I've got the 1989 3.7L (about the same as yours) and located a dual battery set-up port side. My battery switch (Perko) is located close enough to the starter that I use an 18" #2 gauge cable, with #2 18" cables running to each battery. I also use #2 gauge grounds. Also, this year I've installed group 27 - 1000 CCA combination Starting/Deep Cycle batteries (I got tired of toughstarts/no starts). Last year I carried a jump start battery pack that also worked very well.<br /><br />Regarding starter testing...bench testing starters should be within the capability of your local marine dealer or auto parts dealer. The Auto Zone store near me has a bench on the floor. I should also mention that last year I bought a new starter (a great move) and retained the old one to refurbish with new brushes, etc., the armature was still in great shape. Here's where I got the new one from:<br /><br /> http://www.mercruiserparts.com/mercruiser_parts.asp <br /><br />Good luck....

 

[buckeyedoll]

Re: merc 170 slow crank help

thanks guys for info. Update: today put 2 gauge 24" pos cbl from starter to btry and 18" 1 gauge negative cabl to btry and main ground. Took main ground bolt out of engine and wire brushed it and all related connectors. Also took slave selonoid off and cleaned all terminals(4) and two on engine. My battery is 850CCA and brand new. Still only turned over 4 times. Prior to this negative and positive cables on btry were getting worm now neither did. But after trying to start it three to four times the starter became very hot. What does this mean? IS this normal? Is starter easy to remove? any tricks? any other suggestions?

 

[MrBill]

Re: merc 170 slow crank help

I can't say that I've ever checked the starter to see if it's warm. With your new battery you mentioned that it turned over only four times?...Does that mean it didn't have enough power left after four starts to start a fifth time?<br /><br />The starter is easy to pull if space in engine compartment is not an issue, four bolts (2 to flywheel housing, 2 to support bracket, plus solenoid electrical connections). I'd bench test the starter...how old is it? The brushes are a cheap, quick fix. When you look inside you'll no doubt find alot of fine brush grindings, since marine starters are well sealed and there's no exit for the particulets. Clean out with suction or pressure.

 

[horndog]

Re: merc 170 slow crank help

starter could be the issue, drawing too much power or something.. Everyone is correct on this one, have it benc tested. If you don't feel comfortable taking off your starter take it to a marina and have them test it for you on the motor or they will take it off. Of course, it would be more expensive the latter route, and even some auto part stores do them for free or like $5 if you bring it in

 

[buckeyedoll]

Re: merc 170 slow crank help

I took it off, and that was very easy. Autozone tested it and it turned a few times and froze up. Why couldnt I have done the same test they did? So I ordered one from mercruiser parts web site that i have seen mentioned. Can I rebuild this myself? if so where can i find a kit so I can have a backup starter. by the way it is a delco. if i can't rebuild then i am going to have alittle fun with it. for that matter why isnt their a core charge for a marine starter? and if their is not a core then where do they get marine rebuilds to sell. sounds fishy. so after the new starter comes i hope i am back on water soon.

 

[MrBill]

Re: merc 170 slow crank help

Glad you were able to diagnose so quickly. If you were to buy that starter over the counter at a marine dealer they would have a core charge or expect an exchange. Buying on-line isn't as flexible due to shipping charges and return freight, crediting etc. Sounds like your starter had more issues than the usual simple ones like worn brushes, you've probably got worn bushings which bound up and perhaps a bad armature. The site you got the starter from displays parts costs, and you can eat up the cost of a new starter fast if replacing some expensive parts, so now that you've got a spare....tinker a little. Glad everyone was able to help.