Mercruiser 3.7 Starting/Starter Question

[86Rinker19ft]

Hello all, new to the Forums. Have a question, well a few questions I have a 19ft. Rinker with a 3.7 Mercruiser, I recently swapped out the engine for one that I pulled out of a parts boat i purchased. When I bought the boat the previous owner was able to start it up and let it run for a while so i could see the engine was good. Now I need to mention that he had a HUGE battery charger/starter deal hooked up because he said the battery was almost dead. I thought nothing of this at the time but now I have some questions about that. SO I get the engine in and try to start it, it acts like the starter is bad or the battery is shot, so I made sure the battery was fully charged, cleaned ALL connection points, replaced the starter relay, added an extra ground cable, and tried again. Pretty much the same result, so at this point I decided the starter must be dead. About this time i also realized that this new engine didnt have the voltage regulator and whats worse is that the two wires that would go to it were just freely hanging!? Now remember, the engine did start and run fine when I purchased it pretty recently. So anyways, I start to remove the starter and notice that the nut AND starter stud are BOTH spinning. So the first question is, how will I get that starter off? Are the studs pressed or threaded? (I have a SICK feeling that I am gonna have to pull the engine, remove the flywheel cover and flywheel to access the back side of those studs and then go from there....PLEASE tell me I am wrong) And the next question is, does that voltage regulator have to be on there to start and run the engine? I have another regulator but it just seems funny that it ran before? Was that possibly due to the BIG car battery charger he had on it to start it? Also, I have the alternator conversion kit but there doesnt seem to be room to install it without relocating the main fuel fill hose?

ANYWAYS, thanks in advance for ANY advice, and please be ready for more questions

 

[boatdiver2011]

Re: Mercruiser 3.7 Starting/Starter Question

HMMMM- I am trying to remember the starter on mine, I believe you can just unscrew the stud and nut together as the stud should be threaded into the housing (no nut on the other side). And yes, without the voltage regulator, the charging system won't work and you will drain the battery quick running the motor, his battery charger in effect replaced the regulator. But the motor should start if the battery is good. Sorry - no advice here for the conversion kit, I still have the original set up.

One thing to look at though- measure across the end of the heat exchanger. they had 2. one was 3" across and prone to overheating, and the 4" that is what you want.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Thanks for the response. I will check to see if I got 3 or 4.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Another point I should add is that, while the nut and stud were moving together, it didnt seem like they were backing out at all. Thats why i was wondering if someone has had this happen before and can verify that either its stripped or the pressed fit has broken free and its free spinning in the bore?

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Any more suggestions from anyone? Someone HAS to have had this starter stud problem, but thats just one of the questions I have.

 

[Don S]

Re: Mercruiser 3.7 Starting/Starter Question

It will be helpful with your future questions if you post the serial number of your engine so it can be identified properly. There were many changes in their 13 year existence.

As far as your starter studs go, they are not studs, they should be through bolts with nuts on the starter side.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Don S, THANK you SO much for responding to my post. I have read several of your response posts and you seem like the guy with the answers I will get that serial number and get back to you ASAP tomorrow morning. I REALLY want to get this guy fixed and ready for next weekend. As far as the stud (through bolt?) removal, how am I gonna be able to do that? I mean yes, there is a nut on the threaded stud that cinches the starter to the bell housing, but what I am saying is that the stud and the nut are both moving when i try to loosen it, and there not making any progress as far as coming out is concerned. They just seem to be spinning like the stud or through bolt is stripped. I have tryed a pry bar with light pressure between the solenoid mount housing on the starter and the bellhousing while trying to loosen the nuts, and that doesnt seem to help either . Thanks again for the response

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Ok Don, I just was able to check the Serial number on the block. It is : A408965, please let me know what you are able to tell about this engine, and thank you.

 

[Don S]

Re: Mercruiser 3.7 Starting/Starter Question

I mean yes, there is a nut on the threaded stud that cinches the starter to the bell housing, but what I am saying is that the stud and the nut are both moving when i try to loosen it,

Use a wrench on the nut, and a socket and ratchet on the bolt side.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

ok, to get to the "Bolt" side the engine would have to come out, bellhousing off, flywheel opulled off, and then I could see the back side of the starter bolt/stud. The bellhousing has a threaded stud OR Bolt Or pressed in something, the starter slides onto these and then 2 nuts thread on to hold the starter on. What I am saying is the nut AND the bolt/threaded stud/ or pressed in stud (whatever we're calling it) are both spinning when I try to loosen the nuts but they are not backing out at all. There is no way to get to the back side of the starter studs without removing what i listed above.

 

[Fordiesel69]

Re: Mercruiser 3.7 Starting/Starter Question

Is there enough room to take the starter apart? If so just take the stator housing off to expose the armature, clean the commutator, and have a local shop install new brush assembly. Thats all you will really need to do. The bendix drive rarly failes and if it does then pull the engine.

 

[Don S]

Re: Mercruiser 3.7 Starting/Starter Question

Is there enough room to take the starter apart? If so just take the stator housing off to expose the armature, clean the commutator, and have a local shop install new brush assembly. Thats all you will really need to do. The bendix drive rarly failes and if it does then pull the engine.

WOW, Just plain WOW. There is so much wrong with your reply it's scary. I'm saying that as a 25++ year marine tech, not as a moderator.
I sure hope no one takes your advise.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

well. Don, did you get what i ment? I am confused as to what your calling the "Bolt" side. The ONLY thing I could put a wrench or socket on is the nut that holds the starter on, the other side of that is inside the bell housing. The nut is on the starter mount stud and BOTH are spinning when i try to loosen them and not making any progress.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Also Don, what did the serial number tell you?

 

[Don S]

Re: Mercruiser 3.7 Starting/Starter Question

IF the bolts don't stick out the back, and they are turning. The only thing you can do is pull the engine and remove the bellhousing to get at the bolts.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

I guess I am asking as a question if there is a bolt head on the back? On the other engine (original 3.7 from my Rinker), with the starter off, I can reach my finger into the starter hole. I feel what I would describe as a "Hump" casting with a hole where that starter stud would come through if in far enough. The other engine (original 3.7 from my Rinker) gave me no problem at all when taking those nuts off. The studs are in there still. So I am asking, since I dont feel any kinda bolt head on the other engine, is it even possible this new engine would have a bolt head inside the housing? That seems strange to me, I imagine they are either a pressed in stud with threads on it (Most likely since the housing is soft aluminum) or a threaded stud that would tighten into a threaded hole on the bellhousing (if this is the case thats a bad design imo).

 

[stonyloam]

Re: Mercruiser 3.7 Starting/Starter Question

Tried to read all the posts, just couldn't:facepalm:, so.... The starter is held on by two BOLTS. Bolt head is on the starter side and you need to get a wrench (open or box) on it and a socket on the NUT on the back side. There are several nuts back there so make sure you are on the right one. Also you need to remove the support bracket holding the other end of the starter. I think you need to remove the bracket from the block. After you curse and struggle to get it out, you could try a permanent magnet gear reduction starter (about 2/3 the size and a piece of cake to install) part #2-2591-DR-2 (try e-bay). Good luck.

Thinking about it the nut might be on the starter side:redface:, anyway it is a bolt and nut, not a stud.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

Thanks for the Response. Is it possible that from one year to the next it could be different? Don said earlier that there were a LOT of changes in the engines 13 year run. I only ask this because I can feel inside the other 3.7 in my garage, and that one DEF does not have bolt heads inside where the starter mounts

 

[stonyloam]

Re: Mercruiser 3.7 Starting/Starter Question

As near as I can tell, they only used 2 different mounting methods. The early style, was two bolts that went into threaded holes in the block, or later (your 86) bolts that went through the block and flywheel housing. If you have nuts holding the starter on, then there should be bolt heads sticking out the back of the flywheel housing. I'll have to take a look at mine (87) to make sure.

 

[86Rinker19ft]

Re: Mercruiser 3.7 Starting/Starter Question

the original engine is an 86, it is the one sitting on my garage floor. I also had nuts on studs which came off easily. Now that it is off I can reach my finger in and feel the casting hump and a center hole where the stud could come all the way through. So this would contradict your thought on only two mount styles because it wasnt bolts holding the starter on, it was nuts, yet there is clearly not a bolt head on the other side. This whole situation must be hard to understand through typing, however if you guys were here to see what I am explaining it would be clear as day. Thanks again for any thoughts.