Have you checked the wiring connections at the back of the alternator?

Is your belt slipping? See: [url]http://c34.org/bbs/index.php/topic,3667.0.html[/url](link is external) Each engine is different, as noted in the thread.

As Stu has mentioned it could be as simple as the belt. The tach gets its signal from the alternator. I happened to have had some difficulty with my Tach when I purchased my 36 1990 Hull # 1056. I purchased a manual for the M35 engine I received a page describing the positions for the dip switches on the back of the tach. My settings were all different than what was described on the page. I set mine to the Universal recomendations and the tach worked perfectly ever since.

I would put my money on the tach/indicator itself based on your comments. If its sticks going up in rpm or is slow to indicate, I would think wiring or slipping belt. But since it is not coming down when rpm is reduced it is almost certainly the meter movement in the gauge itself.

The tach is just looking for voltage pulses coming out of the alternator for its reading, a poor connection can diminish the pulses or voltage it sees causing a lower reading but, it is not probable that it will indicate a higher rpm because of this.

The meter too lives in the most harsh enviroment living out doors. This reminds me Saint Patricks Day is coming up.

What is Irish and stays out all night.

Patty 'O' Furniture.
You know like your tachometer.

[QUOTE=nelson;798]I think it probably is not the belt, since (1) I've not heard any squealing or smelled any smoking, and (2) this problem started before the engine was recently tuned up (and the belt replaced)--it seems unlikely (as a matter of odds) that the belt was loose on two occasions--both before and after the belt replacement. I will start by checking the connections at the alternator, and the tach. If that doesn't help it, I'll look at the belt issue.
--[/QUOTE]

Nelson,

Why not do both? Checking the belt, since it sounds like SOMEONE ELSE did the work (a no no in MY book!) then all you have to do is check it: 1/2 inch deflection, 90 bend.. If it's loose, tighten it. See this (again) including M35 ideas: [url]http://c34.org/bbs/index.php/topic,3667.0.html[/url](link is external), particularly #19 & #24, please read BOTH pages.

Nelson,
It is not that difficult to change the harness. Directions from Seaward are self explanatory and easy to follow. Hardest part is running the wire.

I took a picture on the back of the control panel so that I could see how all the wires were connected and what color went where, should I get something disconnected.

Basically you will cut your old harness plugs off each end and reconnect the new replacement wire to the new junction strips provided.
Gary

Nelson

Please see Reply #2 here: [url]http://c34.org/bbs/index.php/topic,4546.0.html[/url](link is external)

You wrote: [I]"I think the fix came from jiggling the connections at the tach, since the nuts on the back of the tach were not loose."[/I]

It could well be that the loose connection was in the old harness at the cockpit end. That tell ya somethin'???

Your boat, your potential fire hazard.

I'm new to the forum; I've looked around a bit but can't determine when of if Catalina/Seaward upgraded the harness. My C36 was built August of 97; do I need to upgrade the harness? I have a new engine panel (like the one on later boats) I bought last year on closeout from Seaward so I'll be in there anyway.

plainolde,

Most likely you are OK with that "late" of a boat.

For others, the two main issues with the wiring harness were the connectors and the ammeter in the cockpit. See this for the connectors, pictures are on both pages of the topic: [url]http://c34.org/bbs/index.php/topic,4546.0.html[/url](link is external). Check the connections at your engine and behind your panel. Simply check your cockpit control panel - if you have a voltmeter you are OK for that part of the check. The older electrical design ran the alternator output power all the way back to the panel and then to the batteries 9via the switch - another story) (ammeters need to see all the current flowing through it compared to voltmeters which measure the difference between + and - and can be done anywhere on the circuit).

Imagine,
As Stu suggested, you are probably OK, but I suggest you check the wiring harness on your boat, to make sure. If it has molded connecting plugs at either the engine panel end or the engine end, the harness needs upgrading. The plugs are about 1" thick, and about 1.5" wide, and most likely covered in tape. They look like a big version of the type of plugs used between a car and trailer. If your boat has terminal strips (about 4" long, and each wire is fastened into the strip with a tiny screw), then you should be set.

Thanks for the replies. I do have a voltmeter at the engine panel. Reading your replies reminds me of this same discussion for the C30; I did replace the harness on my '88 C30 and it had big 'trailer connectors'.

I installed an Ample Power alternater, energy monitor, etc. along with a dedicated starter battery and switch; not a trivial project. So my wiring on the engine end is no longer stock. But I do not remember seeing any molded connectors. I will for certain check though.

THanks again for the replies.

I had a similar problem with my tach this year. Spinning the potentometer on the tach through the various settings and then back to the original corrected the problem. I believe the potentiometer contacts had some problems with corrosion.