Flush or pull heads

[seabird89]

89 OMC 140 Seadrive, used in salt water, sat for 10 years, now it overheats at WOT. It is peeing great in my opinion.

I am pretty sure the water jackets are crudded up with salt.

I am a novice and afraid to pull the heads in fear that I may break a bolt, or won't be able to get the bolts out.

Should I try dropping the lower unit and flushing/back-flushing using the method quoted here from another site, or am I just wasting my time?

Regarding breaking the bolts in the head, am I worrying for no reason?

I had the same problem with a 115 Yamaha V4 and this is what I did. Removed lower unit, removed thermostat on one side and with a garden hose with a spray nozzle blasted water thru the head and out thru the lower unit did this to both sides, one at a time. Then I cut a section of garden hose and put it over the water tube on the lower unit and blasted water up thru the head out the thermostat one side at a time. Everything drained into half of a white plastic 55 gallon drum. I must have done it 25-30 times to each side, lots of very small pieces of crud came out of the head. Ordered a gallon of marine Rydlyme, I called their 800 number and had it in a few days. Put thermostat covers on. Added Rydlyme and one gallon of water to the 55 gallon drum, rigged up a rule 1500 bilge pump and ran solution up thru the lower unit and rigged a piece of clear hose from the pisser back down into the 55 gallon drum. Ran for approx 4 hrs. The Rydlyme removed tons of crud that I don't think ever would have came out, then I did the same thing again, blasted water from the bottom up thru the top and then back down thru the block. Kept blasting water thru head till the crud stopped coming out. Ran boat and no more alarm at WOT. If there is a next time I will use 2 gallons of Rydlyme its great stuff and the lady the answered the phone was super nice, I think its a great product. Beats breaking head bolts.

 

[seabird89]

Last night I pulled the temp sensors and tested them in oil. Both test within spec, so I guess I either I have a short in the system that only manifests during WOT, or my water jackets are clogged?

After testing the sensors, I am sort of puzzled by something though. The sensors close at ~205 and don't open back up until 165, yet the sound would stop immediately after backing off of WOT. How could my engine temp drop 40 degrees in that short of a time?

 

[Fed]

You could have a fuel vacuum sensor, they are wired into the temp sensor and make the same continuous tone alarm as over temp.

They sense the suction side of the fuel line to guard against fuel starvation, reset quickly when backed off.

Edit: If that's the case you would be looking for a restriction between the fuel pump & the atmosphere.

 

[Faztbullet]

It is peeing great in my opinion.

This means nothing for cooling as it a water pump indicator, just means its pumping.

 

[seabird89]

I thought about that Fed, but on my year/model they only put the fuel sensors on the V6 and V8 models, mine is a V4.

 

[seabird89]

So I figured out the alarm issue this weekend. It seems that when the mechanic disconnected the VRO alarm wire he cut the wire and probably tucked it under some other wires on the transom wall. At some point that cut wire fell and was hanging in the bilge. When I would take off with everyone in the back of the boat the stern was sitting low in the water and all of the bilge water ran to the stern and grounded out the hanging wire causing the alarm to sound. Of course when I would let off the throttle, the boat would level out a little as well as the bilge water and the wire would no longer be under water, so the alarm would stop.

I cut the wire shorter and taped it off. When I took the boat out this time, no alarms!

 

[Fed]

The water is supposed to stay on the outside of the boat.

 

[seabird89]

Good point . We had a large thunderstorm that came up right as I was about to put the boat in. Already had the plug in, and waited it out so had more water in the bilge than normal.