1987 36 Mariner - back to life!

[Viper]

Qr Bbpost On the back of the tachometer,you should see 468 cyl screw.Put a screwdriver on and go back and forth between numbers and then set back to 8.I had the same thing going on and I did replace the tachs a year later because they were different from each other.

I agree with the above Fred. It's a pretty common symptom as the contacts inside get corroded. That's why I asked what they were doing. The above is a common first thing to try in an attempt to repair before tossing them out. Some require that you depress the switch slightly before turning. Turn it back and forth several times in hopes of removing the corrosion. Not all units state "4,6,8" some simply have position 1,2 or 3 or some other OEM code so take note of the position before you start or you'll have to look up the position for an 8 cyl engine. Give it a shot.

[waybomb]

I'll give that a try.
These things were exposed to the elements for 10 years.would be nice if that's all it is.

[Brownie289]

What a great save with a happy ending, love seeing that neglected old boat brought back to better than new.
Great job!

[waybomb]

Thanks Brownie.

Once again, wife and I reviewed what we bought and what we did.

Our thoughts are mirrored - what the hell were we thinking!!!!!

But the boat has been awesome. I still haven't attacked my tach issue, but I'll do that once it's in storage this winter. It has been a wonderful summer.

[cpoint]

I had this issue on one of my postings, and finally thought it was fixed along with the engine work I had done. But looks like still I get RPM fluctuations. I did try the moving 4,6,8,12 back and forth. I thought it worked, maybe coincidence, but second time I went out it was doing fine, then about 15 minutes into the ride it started going up and down by about 500 rpms. This is only happening on the port side. Occasionally sync gauge also acts up by going towards port or sometime starboard side. So I am going to try to get the possible corrosion of by trying this method again. But if it fails I am looking to get new gauge. I am searching everywhere and can not find same type. I found 2 that looks sort of like what I have but not exactly. Any one have any idea where I may be able to get one that came with 2000 carver 356 aft cabin? I got the front/back pic below. Or can anyone tell me what model/brand this was? I did not see anything in the documentation.

[tomschauer]

If the tach and sync are acting up at the same time, there is a very good chance it is a connection issue at the engine as the sync "piggy backs" off the tach wiring at the helm.
Worth checking I believe.

[mjk1040]

Check the main harness plug too, seen a lot of them being the issue this season. Great job waybomb btw, kind a partial to that era mariners.

[g36]

the guages most likely are by Beede i had issues with my engine sync and while not mandatory to have i like thing to work. i called beede they were friendly but it was more money from them than i wanted to spend at the time i did some searching and found a replacement guage from ebay that corrected my problem. the problem is finding an exact match which may be challenging for an older boat. another option if the guage is bad is to send it to a guage repair shop there are several on the internet that could repair it, but it may not be a lot more than you want to spend. hopefully corrosion or wiring is the problem

[cpoint]

Qr Bbpost If the tach and sync are acting up at the same time, there is a very good chance it is a connection issue at the engine as the sync "piggy backs" off the tach wiring at the helm.
Worth checking I believe.

You are saying check engine side connection? if so I need to wait till next time my mechanic is there, as I have no idea what to look for or where.

[cpoint]

g36, thanks looking for beede I did find one on ebay, but the seller pulled it back in last minute looks like I will continue looking for one