Starter won't turn when engine is hot

[Peter Lewis]

In the ten years that we've owned Sonrisas (hull 1240, Universal M35AC) we have never had even the slightest problem starting the engine when cold.  This season, we have been having starting problems, but only when the engine is hot.  Turn the key, hit the starter button, and there is an audible "click",  the voltmeter swings left, but the engine doesn't turn.  I found that I could start the engine if my wife hit the starter button and I simultaneously gave the engine a slight manual boost (with my foot; not something one wants to do regularly).   I checked the positive connections (and recrimped several that were questionable) and replaced the ten-year-old starter battery, but the problem persists.  Could this be the sign of an aging starter?  Does a hot engine have greater compression than a cold engine, as suggested by a few web sites I've read?  Finally, is there a home remedy (starter rebuild? brushes replacement?), or should I just order a new one?

[KWKloeber]

In the ten years that we've owned Sonrisas (hull 1240, Universal M35AC) we have never had even the slightest problem starting the engine when cold.  This season, we have been having starting problems, but only when the engine is hot.  Turn the key, hit the starter button, and there is an audible "click",  the voltmeter swings left, but the engine doesn't turn.  I found that I could start the engine if my wife hit the starter button and I simultaneously gave the engine a slight manual boost (with my foot; not something one wants to do regularly).   I checked the positive connections (and recrimped several that were questionable) and replaced the ten-year-old starter battery, but the problem persists.  Could this be the sign of an aging starter?  Does a hot engine have greater compression than a cold engine, as suggested by a few web sites I've read?  Finally, is there a home remedy (starter rebuild? brushes replacement?), or should I just order a new one?

Different things could be causing no crank situation, and being hot may or may not be a coincidence.

First, do you have the Gummy Bear plugs on the harness or have you eliminated those?
Do you have the notoriously undersized OEM battery cables, or have you upsized them?
Do you have the capability to troubleshoot while attempting to crank - eg, testing the voltage at several points?

-Ken

[Mike and Joanne Stimmler]

Hi Peter,
One of the most common things that causes  problems like yours and a few other things is the main ground wire connected to your engine block and if you haven't already you should check this connection and clean and re-crimp if suspicious. 
If you lived near by, I'd be willing to bet a beer on this one. 
Good luck,
Mike

[Stu Jackson]

Hi, Peter, and Welcome to our Fun Little Group.  

1.  If you haven't had the opportunity, please read the "Critical Upgrades" topic, which contains many items related specifically to your issue.

2.  99 & 44/100th% of electrical issues are related to connections, connections, connections.  Ken's advice is well taken, and the Critical Upgrades cover the wiring harness connections quite specifically.

3.  The "connection" is that its the connections.  

Get the drift?  

All the best, please let us know what you find, because there's always something new, and the feedback loop is quite important to us all.

[Peter Lewis]

Thanks for all the sage advice guys.  A couple comments:  1) Previous owner did the wiring harness upgrade, and I've taken care of most of the other critical upgrades that apply.  2) I've replaced the original electrical with  dedicated starting battery (under aft cabin), golf cart batteries, appropriately sized cables.  3) I admit that I failed to check the starter battery to engine ground connections- was focused on the red cables because there were more potential trouble points (it's a much longer run and includes a switch and a fuse block).  I hope you've diagnosed the problem correctly Mike, in which case I'll use the funds saved from unnecessarily replacing a starter to Fedex you that beer.

I'll be working on the boat this coming weekend and will send an update.

Peter

[KWKloeber]

Thanks for all the sage advice guys.  A couple comments:  1) Previous owner did the wiring harness upgrade, and I've taken care of most of the other critical upgrades that apply.  2) I've replaced the original electrical with  dedicated starting battery (under aft cabin), golf cart batteries, appropriately sized cables.  3) I admit that I failed to check the starter battery to engine ground connections- was focused on the red cables because there were more potential trouble points (it's a much longer run and includes a switch and a fuse block).  I hope you've diagnosed the problem correctly Mike, in which case I'll use the funds saved from unnecessarily replacing a starter to Fedex you that beer.

I'll be working on the boat this coming weekend and will send an update.

Peter

Peter,

1.  Harness upgrade
    - was the entire wiring replaced or
    - only up to (BOTH?) gummy bear connectors or
    - only the connectors removed and replaced by the terminal strip or butt connectors?

If the OEM wiring remained in place, and only the terminal strip or butt connectors used, then the problem could likely sit at the "S" terminal of the solenoid -- I have had that 1/4" quick connect literally fall off the wire (corrosion.)  The OEM terminals are all non-marine grade, and owners think that eliminating the gummy bear plugs solves the ills - which it simply does not.  ALL wire terminations right at the engine/alternator/glow plug connections need to be replaced with sealed, heat-shrink ends.  Ditto for the connections on the panel/gauge/switch end of each harness wire.

You can troubleshoot the solenoid quickly - short the "S" terminal to the 12v power post (screwdriver, aux start button, etc) -- if the solenoid clicks in strong and the starter spins, then the solenoid is okay (at least during your test!)  Then look for:

Bad connections on the panel - (key switch; start switch.)

As Mike said - a bad battery ground on the bell housing is one notorious cause.

The harness ground connection on the block (a nut on the exhaust manifold is a BAD location!) does NOT affect the starting and glow plug circuits - only things at the engine panel (gauges, lights, blower, etc.)  The solenoid, starter, glow plugs pick up their grounds directly from the engine block and battery negative return.  (Both Neg and Pos cables should have been upgraded from the undersized OEM gauge.

If you have the wherewithal, you can check resistance across the panel switches, and/or voltage at the switches, solenoid, battery terminals WHILE attempting to crank.  That will help narrow down the cause, if it's not a bad solenoid itself.

- Ken

[Ron Hill]

Peter : As Stu said look at your connections, especially at the battery/s and the starter solenoid!!!!

Sure seems funny that the "Under-sized OEM wiring" worked just fine for 10, 15 or even 20 years and now it needs to be upgraded???
LOOK at the Connections !!!!

A thought

[Peter Lewis]

It's been a while, but I finally have some news to report on my starter woes.  After last season, I had resigned myself to a new starter or a starter rebuild, as I couldn't seem to solve the problem by addressing the electrical connections.  Over the winter, I went to the boat for a routine check, and when I started the engine, the starter button stuck in the depressed condition.  I guess after 20+ years of exposure to the elements, the innards had corroded to the point where it was no longer serviceable.  So- a quick starter button replacement, and everything was back in order.

So far this season, we've had zero issues with starting the engine when hot (and I test it just to make sure every time I shut it down).  In comparison, last season I had a 0% success rate in starting the engine when hot, and 100% when starting cold.  I don't fully understand how this links to replacing the starter button, but I've put off the starter replacement project, hopefully permanently.

[KWKloeber]

It's been a while, but I finally have some news to report on my starter woes.  After last season, I had resigned myself to a new starter or a starter rebuild, as I couldn't seem to solve the problem by addressing the electrical connections.  Over the winter, I went to the boat for a routine check, and when I started the engine, the starter button stuck in the depressed condition.  I guess after 20+ years of exposure to the elements, the innards had corroded to the point where it was no longer serviceable.  So- a quick starter button replacement, and everything was back in order.

So far this season, we've had zero issues with starting the engine when hot (and I test it just to make sure every time I shut it down).  In comparison, last season I had a 0% success rate in starting the engine when hot, and 100% when starting cold.  I don't fully understand how this links to replacing the starter button, but I've put off the starter replacement project, hopefully permanently.

Peter,

Consider it might be a coincidental combination of factors... which is why I always expouse to troubleshoot before an owner randomly starts replacing parts -- usually the parts replaced weren't the root cause and one never knows the exact problem.  Case in pont -- good thing you hadn't replaced the starter.

When engines are hot they are typically easier to start, but when electrical things get hot that can go squirrley.  Resistance increases, parts don't slide as easily, if there's corrosion or a weak solenoid coil --- those sorts of issues --- things bad can happen.   Quite possibly the corrosion on the start button (high resistance, low voltage and current), coupled with, say, a weak or sticky solenoid, could have been the original problems.  Replacing the button may have brought the voltage and current up just enough to overcome the sticky plunger and/or weak solenoid coil.

I don't see where you reported back about the ground connections.  Again, there could be multiple issues, and eliminating one  may just have been enough to overcome the others (until one of them degrades further and whammo, it's baaaaack.)  I'd suggest checking all ground connections and cleaning well and moving the battery negative cable from the bell housing to a starter bolt.

You can also check the solenoid now that you have a good start button - let the battery run down until the point where the solenoid won't kick in and see what voltage that is.  If there's one good investment, it's usually to just replace an aging solenoid (with one that has a threaded post "S" terminal instead of the 1/4" quick connect) and not the whole starter.

Ken

[Ron Hill]

Peter : Look in the marine catalogs and you can find:
1. A rubber boot that will fit over the starter button (it replaces the hex nut)
2. A rubber boot the fits over the key switch (same).
Both of these will help keep out direct moisture.
 
I also made a new clear plastic cover that fit over the entire engine instrument panel face.  I cut holes for the key, starter, blower and a slot for the engine cutoff.

Also if you'll make a sunbrella cover for the entire panel it will keep off rain as well as the suns UV while the boat is parked.

A few thoughts 

[Stu Jackson]

.................Over the winter, I went to the boat for a routine check, and when I started the engine, the starter button stuck in the depressed condition.  I guess after 20+ years of exposure to the elements, the innards had corroded to the point where it was no longer serviceable.  So- a quick starter button replacement, and everything was back in order.

So far this season, we've had zero issues with starting the engine when hot (and I test it just to make sure every time I shut it down).  In comparison, last season I had a 0% success rate in starting the engine when hot, and 100% when starting cold.  I don't fully understand how this links to replacing the starter button, but I've put off the starter replacement project, hopefully permanently.

Peter,

Thanks for reporting the resolution.

Sometimes, what we've learned over the years doesn't always work.  As we've reported, it is rarely the button.  In your case it was.

Good detective work!  

Ron's ideas about covering the cockpit panel are quite helpful.  We've have both the plastic cover AND a canvas cover.  Before Radio Shack closes, also get a can of tuner spray.

Good luck.  I think the SERIES of things you did, and narrowing it down to the "last resort" made a lot of sense.

I'm not sure why you "don't fully understand how this links to replacing the starter button, but I've put off the starter replacement project, hopefully permanently."

Seems simple to me:  You narrowed it down to the final weak link in the chain.  Good for you. 

Thanks again.