Starter or ?...
 

Hello,
I am new to this forum. I have a 1978 Catalina 27.
I recently had a tune up completed - impeller, spark plugs, fuel filter, oil filter, and oil changed. Right after that, the Atomic 4 started right up. A couple of months forward, I tried to start it up, but now get spotty turn over, meaning starts right up and the next try will only get click click. I'm connected to shore power with battery tenders connected to the batteries. And the batteries are fairly new (2 years old Interstates).
Is it time for a new starter (or rebuilt one) or could it be the starter solenoid, or even the alternator.
Thanks in advance for your input.

SGI,

Rather than assuming that the batteries are ok, you might consider making some voltage measurements to verify that. You just need a low cost multimeter which you will find a myriad of uses for down the road.

I would check the voltage across the battery terminals

1) with no load.
2) Then when you try to start the engine

Finally, check the voltage at the starter when you try to start.

If you see too large a voltage drop at the batteries when cranking, battery issue.

If you see a big difference between battery voltage measurement and starter voltage measurement, bad/poor connection to starter.

If all these voltages are fine, then look at starter.

Hope that helps,

Peter

Welcome! This is the best place on the Web for all things A4!

In addition to the other possibilities already mentioned, this behavior could also be caused by a bad spot on the commutator in the starter motor, due to either worn contacts or worn brushes. Temperature change or vibration can make this kind of problem come and go.

I would go ahead and eliminate battery charge and corroded connections as the culprit first, as those things are easier to check.

checking voltage
 

I'm going to take my voltage meter and check the aforementioned items. I am guilty of relying on the volt meter gauges on the vessel. Both showed good volts, but after reading another post, some gauges my not post accurate readings. And will double check all the connections. I checked the batteries and they are good and tight.

Much appreciated.

These were the readings prior to and after testing the batteries (off shore power of course). I checked the batteries and they read 13.1 and 12.7 respectively. Thank you, Peter. My arm and volt meter leads aren't long enough to check the voltage while trying to start the engine. Have to take my wife down there for that.

As of now, I'm leaning toward Edward's comment about the worn brushes. I've since started the engine after multiple attempts.

Onward and upward... solution will be solved.

By the way: I run at 180-200 degree F with RWC pretty consistently, load or no load. Engine temperature poll mentioned RWC is usually cooler 140-160 degree F. Albeit, that is another future endeavor.

There are only a few wiring connections that you need to have so clean they shine. If yours shine, then wiggle them and make sure the terminal is held tightly to the wire. If they shine and are tight, then I would dig into the starter and solenoid.

WRT running hot, my 1982 model ran at 200 F for 15 years, then I finally took off the side plate (easy to do with the starter and alternator off) and found the cooling area surrounding the cylinder walls all full of detritus. Using a dentist pick and other tools, got it all clean and to my surprise, the running temp dropped to 140 F.

Go easy taking off the side plate, because the bolts tend to snap off. Best to use back and forth motion with the wrench and make a little progress with each swing.

Best
Jim

Another possibility
 

Could be the keyswitch too, it's a known problem when exposed to the elements. Before I got rid of mine for exactly this reason I replaced it bi-annually on principle alone.