Wierd Starting Problem - Diesel

[KipHansen]

Folks,

I have a weird problem with my big diesel.

Starts like a champ when cold - two three seconds cranking and runs beautiful.

Run for half-hour, shut off, and won't restart. Barely cranks - huuuuh ----hhuuuh.

Leave it all to cool down (and, maybe, the battery gets recharged by the shoreline charger?) -- anyway, when she's cold, starts right up.

Battery cables get hot hot when trying to start the hot engine, so I think there is enough battery power. Voltage meter says it has 12 volts.

I thought the batteries would charge up nicely with the engine running, and then it should restart easily, but the reverse is true.

Any guesses? or troubleshooting steps suggestions?

Thanks,

Kip

[never monday]

what engine is it?

[spencer53]

Heat soaked starter would be my thought. The windings in the starter can swell due to heat and short our on the housing. Change the starter.

[Samadhi V]

Bad starter.

[Divecoz]

I agree with the rest its the starter . Now I ask you how old is this starter?
When was this boats starter last replaced. I ask that question with concern to heat build up.
Is it just an old starter, nothing last forever or is this a chronic problem like say the Ford Expedition had in 2000.
In other words you may need to find a way to install some sort of heat shielding

[SkiprJohn]

If your battery cables are getting hot there definitely is a problem with the starter or your cables are too small or they are led from a long distance. I had my rare Bosch starter rebuilt for about $100 so if you have one that is hard to find you can have them rebuilt.
Good luck.
JohnL

[KipHansen]

Guys,

Gee, you guys are terrific!

It is a Detroit 8V71 - no turbo, just plain vanilla.

I think I'm going with you guys.

The wires from the battery through the solenoid to the starter do get hot when trying to start the hot engine, meaning, as you say, that the starter motor is drawing (and getting, we assume) lots of power.

They do not get hot when starting the motor when it is cold, the starter whirs right smartly and the motor starts right up, so they seem to be sized correctly for the application.

I will pull the starter and have it checked out.

What should I look for to confirm the diagnosis? Will there be any visible signs? and What is the proper solution? I am in the Dominican Republic, where they re-wind and rebuild all sorts of motors that we would simply replace in the US.....what do I need to make sure they do during the rebuild so that they solve the heating problem?

Thanks you guys, really appreciate your help (good advice is hard to get way down here!)

Kip

[johneri1]

Just another thought: 12 volts does not indicate a fully charged battery; 12.6 is a fully charged battery. Good luck.

[SkiprJohn]

Aloha Kip,
You didn't mention if this is a new problem or something that has been going on quite some time.
JohnL

[never monday]

The Detroits should have a ground cable connected directly to the starter. You might check for a good connection there.

[KipHansen]

SkiprJohn,

First, a confession: obviously this 8V71 Detroit isn't in my 42' Solaris cat...it's one of two on my neighbor's fishing stinkpot.

Second, my neighbor is rehabbing this boat, with several ongoing problems...electrical and mechanical.

This is the current and one of the last remaining problems.

That said, the problem just began after getting all the other problems solved and the engines running properly, this one was discovered to start up briskly when cold, but would fail to restart if shut off once it warmed fully up. A bad feature in a sport fisher...which is supposed to take tourists out for a spin.

I think we are agreed and resigned to pulling the massive starter motor and having it rebuilt....I am still hoping someone here will suggest what we should be looking for and what to insist on when having it rebuilt.

Kip

[georgelewisray]

Clamp on DC ampmeter, and find the spec/normal range of current draw for that engine/starter.
Even if you don't find a spec/normal current draw you can compare the current draw cold vs. hot and it sounds like there will be BIG difference. IF you are mechanical/electrical at all take the starter apart and clean up and inspect.

[KipHansen]

Never Monday,

Thanks for that, we will check that ground cable connection before we pull the starter.

Kip

[KipHansen]

Originally Posted by georgelewisray

Clamp on DC ampmeter, and find the spec/normal range of current draw for that engine/starter.
Even if you don't find a spec/normal current draw you can compare the current draw cold vs. hot and it sounds like there will be BIG difference. IF you are mechanical/electrical at all take the starter apart and clean up and inspect.

We will see if we can scrounge up a DC ampmeter and try this test...I think we are pretty sure that this starter draws massively when hot (but doesn't go properly).

Kip

[Boracay]

I would get the best local mechanic (with assistant if not too expensive) to pull the starter while I watched.

Then I would take it to the rebuild place and watch while they pulled it apart, rebuilt it and put it back together.

The 8V71 Detroit looks to be a very common engine. Locating a spare starter and importing it may be cheap insurance.