Refurbished 1983 Bayliner 85HP over-heating?

[Benz Mondi]

Here are the facts: (bear with me, I've noted as much as I can remember in the order they happened)

Per the receipt I got from the prior owner, in 2004 an "annual service" to the Powerhead and lower unit were performed (R/R cylinder head, repaired spark plug hole, installed heli coils, water pump, gear oil, greased splines, replaced fuel pump diaphragm), after I got it, in 2010, a Bayliner dealer performed a "minor 2-stroke service" (replaced spark plugs, changed the gear oil and replaced the over heat alarm).

I've since taken it out 6 times and it's run like a champ, save the hard starting regardless if hot or cold (I added a power tilt so I easily tilt it to get it started and then quickly lower the motor and put it in gear) and the 16 volts output after 10 min of 35 mph (my revamped dash now includes a voltmeter among other new gauges and switches).

Yesterday, while only cruising about 10 miles an hour exploring the new islands that have become visible as the lake level at Folsom Lake gets progressively lower, I ran it aground briefly. I quickly put it in reverse and was able to get going again. The motor never stopped and the tell-tale and the water pressure (new additions) never stopped.

10 minutes later, we stopped mid lake to do some tubing and the engine would not start when I turned the key, no voltage. After a couple of attempts at jiggling the key while turning, I decided that perhaps the 16 volts output form the outing a week ago might have "cooked" the battery. I disconnected the battery and replaced it with the one I use for the trolling motor. It started right up (after tilting).

After 5 minutes of 30 mph cruising to get in position to again do some tubing, I noticed a rattle coming from the motor and slowed to about 20, 5 min later the overheat buzzer came on even though the water pressure was normal, and the tell-tale flow was normal, I did notice the smell of burned oil, so I turned the engine off.

At that point, I called off the tubing and decided to call it a day. I hooked up the trolling motor to the battery that was the one originally hooked up to the motor. It powered up and we started toward the boat ramp at 5 mph. After about 15 minutes, I turned the boat ignition on and found that the buzzer didn't sound any more so I quickly turned on the motor and ran it for about a minute at 20 mph before the buzzer came back on. Again the tell tale flow was normal and the water pressure was normal. The motor did seem to shake a little more than I remember. We repeated this pattern three more times. The fourth time, since we were about 200 yards from the boat ramp and I reasoned that as long as the tell-tale flow was normal, water pressure normal, and that there wasn't any disturbing sound (rod knock, banging, etc.) that it would be OK to continue cruising at about 15 mph. After about 1 minute of cruising, the alarm went silent as we kept the motor on for another 2 minutes until we docked.

Once I had the boat trailered and I could inspect the motor, I found that there were no disturbing signs of anything wrong. Nothing burned under the hood, no damage to the propeller, intake vents, nothing to suggest that there would be a reason that the buzzer should be on.

Any ideas on what happened?
More importantly, what should I do next?

Thanks for the help.

 

[Jiggz]

Re: Refurbished 1983 Bayliner 85HP over-heating?

You can verify the thermal sensor by dipping it in hot water (with grounding wire connected to ground) and it should start buzzing around 160~180 degrees. If it's lower than this it could be the sensor is going back. It if is still working OK, then you could actually be overheating and need to investigate further. Because you ran aground, you might want to check your timing which would mean a sheared key in the flywheel. An improperly timed motor will overheat really easy. Second, check compression just in case you have water leaking into the cylinders which co-incidentally happened with the grounding.

 

[Benz Mondi]

Re: Refurbished 1983 Bayliner 85HP over-heating?

Thanks, Jiggz. I'll check what you suggested over the weekend. In the meantime, any recommendations for a temp sensor/gauge set up for my rig?

 

[Benz Mondi]

Re: Refurbished 1983 Bayliner 85HP over-heating?

OK finally had some time after finally fixing the patchwork of wiring the previous owners had done...

Cracked open the thermostat housing, pulled out the thermostat and found some sand in in it. After covering the rest of the motor in plastic bags, I ran a water hose into the thermostat cavity. It won't let you do it very hard or you end up with it squirting back at you just as hard. Didn't notice any more sand coming out anywhere. Put the thermo cover back on without the thermo itself. While at it, I went ahead an replaced the fuel pump diaphragm and gasket, as well as, new gasket. Also took the filter screen out to inspect it. I tested the overheat buzzer to make sure it worked. Put the water ears on, I turn the ignition on, pulled out the throttle handle and move it forward to normal start position, primed the bulb, saw the choke solenoid activate and fired her up. It took a couple of starts, but she fired up.

She was stumbled at first then evened out. The tell tale also was sputtering at first, but evened out and looked normal. I ran it for 5 minutes and didn't hear the overheat buzzer. While the motor was running, I put my hand all along the power head and didn't feel any hot spots. I also didn't see any leaks along the head or anywhere . I don't have temp gauge hooked up yet so don't know how warm the engine got, but it did not even get hot.

I guess the sand may have temporarily jammed the thermo closed and caused the motor to run hot.

Fingers crossed when I put her in the water next weekend, she'll keep her cool.

Thanx,

AL

 

[Jiggz]

Re: Refurbished 1983 Bayliner 85HP over-heating?

Well, when you decided to remove the t-stat the engine didn't have a chance to warm up at all since the removal of the t-stat prevented it. Anyways, hope it all works for you but I still recommend re-installing the t-stat back after all your troubleshooting. It allows the engine to run at its designed temperature to maximize performance.

 

[Benz Mondi]

Re: Refurbished 1983 Bayliner 85HP over-heating?

Well, when you decided to remove the t-stat the engine didn't have a chance to warm up at all since the removal of the t-stat prevented it. Anyways, hope it all works for you but I still recommend re-installing the t-stat back after all your troubleshooting. It allows the engine to run at its designed temperature to maximize performance.

After cleaning up the thermo, I tested it to see when it would open. The water temp in the pot got to 158 but it didn't open. I had read, perhaps it didn't apply to my engine, that the thermos open at either 110 or 130 degrees. I later found that they should open at about 160 degrees. I'm going to run the test again and wait to see at what temp it actually open, if it opens at all, all the way up to when the water actually boils (212 deg). Otherwise, I'm all set to order a thermo and gasket. thanx.

 

[Jiggz]

Re: Refurbished 1983 Bayliner 85HP over-heating?

Someone might have replaced the thermostat with the wrong temp rating. T-stats come in different temp flavors and yes the one that is supposed to be on your engine is 130F. If it still continues not to open at this temp, consider buying a new one. They are not that expensive. You can easily test a t-stat using a thermometer and placing it in a pan of water on a stove rather than in the engine.

 

[Benz Mondi]

Re: Refurbished 1983 Bayliner 85HP over-heating?

Update on possible over-heating?

I took the lower unit off and didn?t find any build up of sand or debris. Actually for a 30 yr old motor, it was surprisingly clean. This really does seem to have been used in fresh water its whole life. According to the receipt, the last time the impeller was changed by the previous owner was in 2007, though the previous owner said the boat didn?t get on the water in 2009 and 2010. I decided to go ahead and replace the whole unit with a kit I had ordered from here two years ago when I first bought this boat.
Franks instructions were excellent and the change out went smoothly. Some of the bolt head sizes were different but no worries. Actually the whole impeller unit seemed to be in good enough shape to not need replacing. I decided to keep the old ones as spares and install everything in the kit anyway.

I also decided to go ahead and a back flush by removing the thermostat. It was there where I saw sand. I also went ahead and tested the thermostat and found that it didn?t open even at 160 degrees- ordered another one from here. While waiting for it to arrive I left it out and bolted the thermo cover back on. I decided to do some more testing.

After I finally got the lower unit back in (difficulties noted in another thread), I tested my over-heat horn and found it functioning even though it?s wired differently than others (also noted in another thread). Did some other maintenance and fired her up. Water muffs on, tell-tale flow steady and normal, normal water pressure, no issues. It appears that the ingesting of the sand was a temporary issue heat issue which was complicated by a bad thermo. I'll see if anything changes when I put the new thermo on when it arrives tomorrow.