Batteries for brisk engine starts.

[jr438234606]

I have a Perkins 4.108 on my 44' Cutter. The Thermo-Start has gone bad on it and it is a bear to crank in cooler weather. Basically, if the weather is in the 60s or below, the engine will generally not start. However, if the batteries are FULLY charged and both House and Start bank are utilized, it will start easily due to a brisk cranking speed.

My question is, what should I do to get my cranking speed up? Should I get a battery with the highest CCA/MCA available? Or, would a bank with large capacity that is able to maintain higher VOLTAGES for a longer time be the way to go to get that extra "kick". What is it that actually makes the starter motor spin faster? Higher amps? Higher voltage? Both?

[Gene T]

Most people ignore the most important items, wiring. Big wires with short runs and properly done connections are necessary to get the power to the starter. Many boats are under sized. Big batteries with big plates can deliver more power for longer periods, but a group 27 starting battery should be fine if the wiring is good. Note that the starter must also be in good shape.

[cardiacpaul]

Get the thermo start fixed. Starting a diesel without glowplugs or decompression is a pita to begin with, to do so without "heat" is a recipe for destroyed batteries and a burnt starter, both items much more expensive than the thermo start.

[sailingdog]

I'd second getting the thermo-start fixed. Over the long run, it'll be far more expensive not to do so.

[btrayfors]

In addition to the good advice to use large wiring and ensure your connections are clean and tight, and to replace the thermo-start, I'd suggest that you check your fuel system.

I have lived with a 4-108 on my 42' sloop for 17 years now. It has NO preheating device, and will start very quickly in any kind of weather....even in winter. Usually, in moderate temperature conditions it fires within a couple of seconds.

The only time I had hard-starting problems turned out to be due to a fuel problem, NOT to the starter, cranking speed, etc.

Bill

[jr438234606]

Originally Posted by btrayfors

The only time I had hard-starting problems turned out to be due to a fuel problem, NOT to the starter, cranking speed, etc.

Bill

What exactly did you determine was the problem with the fuel?

[btrayfors]

John,

Well, actually, I oversimplified in saying it was a fuel problem. You know, they always say there are three reasons why diesels have problems:

1. fuel
2. fuel
3. fuel

That's not far from the truth. But in the case I referred to, there were other problems as well.


My principal problem turned out to be an incredible amount of sludge in the crankcase/oilpan which was developed over the years because of my practice of changing oil by using a pump to suck oil out of the dipstick. Bad idea. You never get all the oil out, and especially the really dirty stuff in the pan.

One day, one of my mechanically-inclined sons pulled the oil plug out of the pan and you can't imagine the mess he dug out. Just incredible. After we got everything clean, by using some cleansers and multiple oil changes, I installed a special plug connected to an oil XChanger which allows me to change oil completely in less than 5 minutes, sucking it out of the oil pan and pumping it back in the same way with a reversible electric oil pump. Great system. I keep my oil and filters clean now, with little effort. Picture of this little puppy can be seen here: http://gallery.wdsg.com/Miscellaneous-Stuff/OilXchgr

A secondary problem turned out to be poor electrical connections on the ground side.

A tertiary problem was questionable fuel (I was then in the Caribbean), so I installed an onboard fuel polishing system, consisting of a humongous Raycor filter and a small electric fuel pump which takes the fuel from the bottom of my tank, runs it thru the filter, and pumps it back into the tank top. This system is completely independent of the regular Raycor filter bank on the engine, and has worked like a champ.

Once these three problems were fixed, and with clean oil in the engine, the 4-108 spun over like a top and became its old self again, starting easily in just a few seconds.

Never again had a starting problem.

Bill