Rectifier A/C current question

[DEADDUX]

I have a 1985 70 hp Evinrude. I took it out today to check some other issues, and a mechanic suggested I check at the battery for any A/C current. He said if I was getting more than 1/2 a volt at the battery, i needed to replace my rectifier. My digital meter would flash 16 then 11 then 8 then 2 then repeat the cycle. On D/C it said it was getting consistent 12.1. I have had some battery charging issues. Is this normal?

The problem with my boat is it will run great at WOT for 5 min or so then drop RPM and pick itself back up. It will go back and forth until it boggs all the way down then dies out. If I let it sit for a while, it will repeat the process again. If I try and restart immediately, it will go severly bogged down. There ar eno problems running the motor at idle, only under way. There is watery oil running out the side of the exhaust plate. The plugs also look like they have water on them when pulled, so I am assuming there is a water leak in the exhaust.

I ran it with the spark arrestor plate off the other day, and I saw fuel spitting back through the carbs on cyl #1. I plan on replacing the reeds.

I have cleaned the carbs thoroughly, and checked the coils with a timing light while the rpm's were going back and forth with no noticeable difference.

My questions are 1. do i need to replace the rectifier? 2. could the rectifier cause my problems? 3. could the water/ exhaust system cause my problems?

 

[tx1961whaler]

Re: Rectifier A/C current question

What is the compression on each of the cylinders?

 

[DEADDUX]

Re: Rectifier A/C current question

it was 140 on each cyl. no variance about 3-4 short trips out ago. Have not checked since.

 

[F_R]

Re: Rectifier A/C current question

Good grief, deadux, you have answered your own question. Get your eyes off those carburetors and rectifier and everything else till you deal with that water getting into the cylinders. Water intrusion will not only make it run crappy, it will destroy the motor. It may already be destroyed. The damage it does is similar to that of dropping the motor overboard. I hope it isn't salt water (?)

BTW, where did you find that "mechanic"? He certainly isn't a certified outboard mechanic.

 

[Barnacle_Bill]

Re: Rectifier A/C current question

Good grief, deadux, you have answered your own question. Get your eyes off those carburetors and rectifier and everything else till you deal with that water getting into the cylinders. Water intrusion will not only make it run crappy, it will destroy the motor. It may already be destroyed. The damage it does is similar to that of dropping the motor overboard. I hope it isn't salt water (?)

BTW, where did you find that "mechanic"? He certainly isn't a certified outboard mechanic.

I'll sure drink to that.

 

[DEADDUX]

Re: Rectifier A/C current question

it is not salt water, and I am still assuming it is a water intrusion, not sure. The plugs don't look bad wet, just a little. The bolt leaking oily water was loose, and today was the first time water has leaked out there. Either way, i am going to pull it all down and replace the seals in there before it is run again. Going to catch the reeds at the same time when i pull the manifold off to get the lower shroud off. If the rectifier needs replacing, i was going to do it then too cause the timing wheel has to come off.

so what about the rectifier? Is that much a/c current going to the battery bad?

The Mechanic works at a boat shop as a mechanic. Just grad from MMI 6-7 months ago. He is a friend of a friend.

 

[Barnacle_Bill]

Re: Rectifier A/C current question

That friend of a friend needs to go back to school. You don't check a rectifier by measuring the AC output. If a diode in the rectifier shorts out when it goes you could read high AC at the battery. However, if it opens then you would have no AC at the battery but still have a bad rectifier. Your manual gives you instructions for testing the rectifier/regulator.

 

[DEADDUX]

Re: Rectifier A/C current question

yeah, the dude has my manual also.

 

[F_R]

Re: Rectifier A/C current question

If he paid attention in school, he knows how to test a rectifier.

 

[DEADDUX]

Re: Rectifier A/C current question

I am just going off what this guy said. That is why I am trying to verify on here. Is it uncommon to read a/c current like that on the battery? He said if I got more than 1/2 a volt it would fry the power pack and coils. Is this true?

Just checking to see if there is a simple fix I can do while I am fixing the other known problems.

 

[petryshyn]

Re: Rectifier A/C current question

The charging system does not supply smooth DC. It supplies pulsating DC which will trigger an a/c meter to read. Even supplying a/c to the battery will not damage the pack. The pack and battery are not connected together.

As F_R says..........address the water problem first.
I highly doubt the reed suspicion if it runs good for 5 minutes.

 

[DEADDUX]

Re: Rectifier A/C current question

ok thanks man. definitely going to fix the water prob. next. I am having trouble finding the exhaust manifold gasket kit on i boats. It doesn't really fit any of the categories. I am sure they have it, and I would prefer to order off here.

The reed problem was pointed out by the mechanic. It was not much fuel coming through the carbs with the spark arrestor off, but it was some. My buddy looked at it and said these motors run a little sloppy and was prob. not a big deal. I checked the reeds when i pulled the carbs. and all seemed to be closing properly.