New rebuilt merc 5.7 - alarm followed by “ticking”

[Jsilvsta09]

Hello all, first time posting, I appreciate any help on this. Yesterday I was cruising around 4500 rpms, engine was running great then the dreaded high pitch alarm that stays on which usually means 1 of 3 things, none of which ideal. I let the boat idle for a min then shut off the boat. Before I shut the engine, I noticed a “tick tick tick” noise that never occurred before. Anyone have any ideas on what happened? Gauges read normal temps, and oil pressure looked high. This engine has around 12 hours on it as well... This did happen in the same boat with the previous engine as well. When mechanic put the new rebuilt engine in, he mentioned the outdrive was in good shape and wouldn’t have to be replaced. I’m worried because this was the first time I’ve had this engine over 3500 rpms.

 

[Jsilvsta09]

Also I should mention this is carb, not fuel injected.

 

[alldodge]

This did happen in the same boat with the previous engine as well.

Howdy
Can you say a bit more what happened to the first motor?

 

[Jsilvsta09]

Hi AllDodge, thanks for your response. The first engine was having issues last year where the engine would go on plane around 3,000 and after staying at that pace for awhile that same piercing steady alarm would kick on. It wouldn’t happen every time just randomly. Eventually that engine quit and ceased up, my mechanic never had time to open that engine up to diagnose but we believe water got in because of the oil color. Now this mechanic did say he welded by on top of the stern drive because he believed water could’ve got in from there. With regards to this engine my mechanic asked us to change the engine oil after 9 hours which we did (it appeared to be very below the fill line when they put oil in.) was 4500 rpms for a few minutes too much too soon?

 

[alldodge]

Ticking is not good with a new motor. My first thought is to have the Mech look at it before doing anything but I would install a mechanical gauge to verify oil pressure.

What was used from the old motor?

You say the current Mech welded the top of the drive or the top was something else?

 

[Jsilvsta09]

I probably should’ve been clearer, the engine itself is a certified rebuilt engine from merc. 5.7 275 hp. The outdrive is the only piece that we didn’t switch out. I let the engine cool for a few hours last night started it up the ticking was still there and it looked like the rpms were jumping at idle. Doesn’t seem like a good sign.

 

[Jsilvsta09]

Just tried it again today same noise and it sounds like the rpms jump every now and then. Can’t tell where it’s coming from exactly but sounds like it’s around the belt.

 

[alldodge]

Remove the drive, if Alpha attach a water hose to the thermostat housing, if Bravo attach hose to water pump or remove belt off pump and attach hose to thermostat housing

 

[Jsilvsta09]

Let me know if you can view this video. Not sure if This helps or not.
https://share.icloud.com/photos/0SZq6E7qlFZHZDKnGV7BDs5Og#Wareham,_MA

 

[scoflaw]

Don't sound good. So you were redlining it when it was very low on oil ? 9 hours on the first oil change doesn't sound like good advice.

 

[Jsilvsta09]

No I put a full 5 quarts after that initial 9 hours and it’s been running fine since. I’d say about 5 hours or so have been put on the engine since that first oil change.

 

[alldodge]

Doesn't sound good but not ready to say motor just yet. I'm thinking one tap for each revolution or two. So could be flywheel, coupler or spark plug wire arching. See if you can get a Mech stethoscope or short piece of stiff garden hose and use it to listen at different locations

As for the alarm every so often, if you used the original switches (lube bottle, oil, temp) then could be one of those are the issue

 

[Jsilvsta09]

I’m going to order a mech stethoscope and see if I can find out where the ticking is coming from, the occasional drop in rpms worries me the most.