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SPNetricks 07-10-2019 10:22 PM

Just an Update
 
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After spending a few months cleaning and rewiring my A4, it was time to bring the boat to the yard for a haul out. I am having some work done on the hull and I will do some work on the mast. The yard is an hour and a half away and the conditions were good for a quick jump. So I fired up the A4 and set out for the yard. About halfway I thought I would get a pic of the gauges and Lowrance to share on the forum. In the pics you can see the Alt gauge is zero, O/P is 20, RPM is 1300, (hard to see with the vest reflection) Temp is at 158, Battery is 12.8 The Lowrence is showing a speed of 4.8 knots. I was taking it easy on the A4 and did not want to push it till I can do other work in the yard. But all in all, I would say it was performing well. If you gentlemen could review this post and pics, I would be happy to hear any comments. Go easy on the gauge panel it is a work in progress.

sastanley 07-10-2019 10:38 PM

SP, looking good. If you look at the ammeter straight on, it is likely above zero. One of the problems I think that ammeter has is the scale is too big for our boats. The Motorola amp will NEVER send 35 amps to the batts, so even if it is just "off zero" it is probably sending 3 or 4 or 5 amps in which is about right if the battery is not depleted. I put in a Blue Seas shunt ammeter this past winter, and I love it. I ditched the long run ammeter years ago even before adding the new one and just used a voltmeter in the panel to make sure I was getting voltage out of the alternator.

The oil pressure is a little low, but Don Moyer says 10 PSI for every 1,000 RPM is OK, so you are on the Ok side, and I do not think it is any cause for alarm. I run about 37-40 at 1,800-2,000 RPM, but I have the Indigo remote oil filter set up with the adjustable oil pressure feature, so I can dial it in.

Is the voltmeter reading directly off the battery, or is it reading alternator output? If reading battery directly, probably just fine.

Everything seems square for cruising at 1,300 RPM, but the boat might be a bit over propped..typical of most A-4's, and was for my Cat 30 before I went to the Indigo prop.

I was going to ask what type of boat, but I see Catalina in the avatar. What LOA and what hull number?

SPNetricks 07-11-2019 08:43 AM

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The volt meter is off the ignition purple wire. The oil pressure did look a little low, but I will run it more leaving the yard and check it again at different rpm's. 10 psi per 1000 rpm's is what I read too. So it may be fine.
I don't know about the prop situation. It is probably the stock prop. Here is a pic of the prop. The boat is a 1976 Catalina 27 #2713. I am happy with the performance on the way to the yard. On the way back I can push her a little more as the work has been done and I feel more confident.

joe_db 07-11-2019 09:17 AM

20 PSI seems low for oil pressure and 12.8 volts is quite low for voltage. Also - how is the ammeter wired? The way the A4s were originally wired with center-0 ammeters was not very functional and contributed to a lot of voltage drop between the alternator and battery.

SPNetricks 07-11-2019 08:15 PM

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I striped the engine of the old wires and completely rewired it according to the Moyer A4 wiring diagram using the specified color and gauge of wire. The only difference between the diagram and my A4 is that I used a 20a and 40a breaker instead of fuses. Diagram attached.
I do have my concerns about the oil pressure. Maybe I should adjust the O/P adjustment screw a little. On the return trip from the yard I will be a little more confident and increase the speed and rpm's to get more readings. As I said, I was taking it easy on the way to the yard.

zellerj 07-12-2019 07:09 AM

Test the oil pressure with a mechanical gauge. Mine appeared low with the electrical gauge, so before messing around with oil pressure adjustments, I hooked up a mechanical gauge in place of the electrical sending unit. Mechanical gauge showed 40 psi, while the electrical gauge read 15 psi.

JOHN COOKSON 07-12-2019 11:10 AM

Quote:

Originally Posted by zellerj (Post 117605)
Test the oil pressure with a mechanical gauge. Mine appeared low with the electrical gauge, so before messing around with oil pressure adjustments, I hooked up a mechanical gauge in place of the electrical sending unit. Mechanical gauge showed 40 psi, while the electrical gauge read 15 psi.

+1 on this.
It would be good thing to confirm the oil pressure readings by another method.

TRUE GRIT

Al Schober 07-12-2019 02:53 PM

I agree fully with not putting too much faith in those little gauges in the panel. Too many ways for the indicated reading to vary from the truth. In addition to oil pressure, this applies to the current and voltage readings. A decent multimeter should be used at least to check.

joe_db 07-16-2019 08:19 AM

1 Attachment(s)
Quote:

Originally Posted by SPNetricks (Post 117602)
I striped the engine of the old wires and completely rewired it according to the Moyer A4 wiring diagram using the specified color and gauge of wire. The only difference between the diagram and my A4 is that I used a 20a and 40a breaker instead of fuses. Diagram attached.
I do have my concerns about the oil pressure. Maybe I should adjust the O/P adjustment screw a little. On the return trip from the yard I will be a little more confident and increase the speed and rpm's to get more readings. As I said, I was taking it easy on the way to the yard.

That diagram is accurate as far as being how many A4 powered boats were wired from the factory, but it is not a good way to wire a boat at all. The long run of relatively thin wire from the alternator to the ammeter and back does nothing for good charging and the meter is not ever going to work as designed, it only shows alternator output. You will never see it go negative and unlike what you think a center-zero ammeter should read, sitting on 0 with the engine on is bad. If you want to read alternator amperage, get a meter with a shunt.
Try this way:


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