Question about 2000 60hp 2 stroke

[sutor623]

Hey guys,

Recently bought a used engine from a private dealer. I was wondering a few things about operating temperatures.

Engine is a 2000 60/45 jet and serial number on the transom sticker is OT006027. Oddly enough the serial number on the block is OG211795. So obviously the engine had blown up at one point and received a donor powerhead. Either way compression is 120 on all 3 cylinders.

The guy I bought the motor off of assured me that he put in a new water pump. He didn't mention anything about thermostat.

Got home and set her on the boat, and dropped the lower unit into my big 55 gallon bucket to do some diagnostics. Let her run for about 2-3 minutes and the bottom of the block was at 110 degrees. Just above the top spark plug the temp was 174. Top of the block was 170's as well. Right at the thermostat housing was around the 140-150 mark. Water was constantly flowing out of the tell-tale, so I believe there is a good water pump.

Anyways I cut the motor off because I felt like the temps had risen too quickly. These jets are a pain because you cant rev em up in the bucket.

Does anyone know what temp the overheat sensor goes off at? There is a tan wire with blue stripe for temp sensor.

 

[Texasmark]

I don't know if the 60 has a high rpm pressure relief valve (pop-off) like my 90 hp or not. It does have a thermostat and it is probably located where mine is located on the rear of the block, upper left corner under a little cover attached with screws to the water jacket cover that covers the rear of the block. The thermostat is stamped with the opening temperature on the bottom of the copper pellet part of the stat. It's probably 143 (F). From that temp on up 15 give or take degrees it continues to open as temperatures rise till full open. At speeds above 2500 rpm (for my 90) the pressure relief is knocked off it's seat and allows significantly higher water flow through the powerhead for increased cooling at the higher temps.

Your tell tale is probably plumbed off the exhaust manifold on the left (Port) side of the engine block. That is a direct line and not controlled by the tstat or popoff. Just because you have good pee, doesn't mean that you have a good impeller.

The engine is probably equipped with the same 195F over temp sensor as mine which is embedded in the rear of that water jacked cover previously mentioned with a tan or tan with light blue stripe emanating from it that you noticed. The sensor closes upon reaching the over temp shorting out the low side of the warning horn if the key is on.

Need more, ask.

 

[sutor623]

Thanks Tex. So I found out there are two 60hp powerheads of this era. One is equipped with a 110 degree stat and no poppet. The other has either a 120 or 143 stat AND a poppet valve. I pulled my stat cover. I have a 120 degree stat and poppet. I checked the stat and it seemed to open a little late, maybe 150-160 degrees. After running it to about 200 degrees and cooling it off with cool water a few cycles, it seemed to behave like it is supposed to. So I think the stat may have been sticking some.

Does 170 degrees on the top of the powerhead seem a bit high at idle?

 

[sutor623]

Oh and I assume you meant that just because I have a good pee, doesn't mean I have block cooling (not impeller) because the telltale is pre-thermostat right?

 

[Texasmark]

Follow the tube on the pee. If it is routed off the large flat plate on the left side (facing forward), toward the rear of the engine block it is plumbed off the exhaust manifold water jacket cover. Since a running engine generates hot exhaust gasses, water needs to be supplied to the cooling plate 100% of the time, unlike the engine block that is more efficient and all running at warmer temperatures.

Time for a new stat. I am not an engine designer and have no earthly idea why 2 identical engines essentially, of the same year(s), from the same mfgr., designed for the same job, would be designed so differently.

Swags: The low stat temp would tell me that it opens pre maturely so that you have a head start on the engine getting hot whereas the 143 that I have found in several Merc engines may be a physically smaller diameter and require a larger opening for higher hp engines at higher rpms.

150-170 isn't all that bad if running a 143 stat at below 2500 rpms. If running a 110 stat I'd say way too hot.

The 195 alarm has a tolerance obviously, probably something like 10% subject to change with age. 195 isn't all that hot. 4 stroke car/truck/tractor engines ran stats with opening temps of 160, 170 for years, had a '90's Chev 350 running 196, and my 2011 Silverado temp needle sits on 210 and doesn't move with 2 sequential electric fans to keep it there.

 

[Silvertip]

Auto engines run "closed & pressurized" cooling systems to raise the boiling point well above 212 degrees so they can survive at temps of 250 - 260 degrees. NASCAR engine dudes show panic when the driver says 260 and climbing. That's usually followed shortly after by an "oh oh" and things get quiet. Outboard engines do not have pressurized systems so 195 is getting pretty toasty otherwise the overtemp switch would not be rated at that temp.

 

[sutor623]

Thanks for all the input guys. I replaced the 120 degree thermostat and gasket. and checked out the poppet assembly. Started the old girl up and let her idle for 10 minutes. Block temp on startup was 43 degrees. Once warmed up she wouldn't go up past 130 degrees anywhere on the block.

I'd say that the old thermostat was faulty and dirty, for sure. Luckily these motors have poppet valves so the thermostats wont affect temps at WOT, or Im pretty sure the previous owner of this engine would have locked her up. Funny what some people will neglect to do to save 15 minutes and $30.

 

[Texasmark]

Thanks for all the input guys. I replaced the 120 degree thermostat and gasket. and checked out the poppet assembly. Started the old girl up and let her idle for 10 minutes. Block temp on startup was 43 degrees. Once warmed up she wouldn't go up past 130 degrees anywhere on the block.

I'd say that the old thermostat was faulty and dirty, for sure. Luckily these motors have poppet valves so the thermostats wont affect temps at WOT, or Im pretty sure the previous owner of this engine would have locked her up. Funny what some people will neglect to do to save 15 minutes and $30.

When I bought my 2 year old then, 2002 90 on my first outing I experienced an OT alarm as I was clearing the no wake zone markers. I hammered down on it and after 30 seconds or so, alarm went off. Had a good test run. On the way back, slowed down for the same markers and alarm sounded again.

Later at home and with some references as I did get a manual with the sale, I found out about my "frozen shut" thermostat and bypass poppet valve.

 

[sutor623]

When I bought my 2 year old then, 2002 90 on my first outing I experienced an OT alarm as I was clearing the no wake zone markers. I hammered down on it and after 30 seconds or so, alarm went off. Had a good test run. On the way back, slowed down for the same markers and alarm sounded again.

Later at home and with some references as I did get a manual with the sale, I found out about my "frozen shut" thermostat and bypass poppet valve.

Hammered down on her when the alarm was going off? I bet that's because you knew that motor had a poppet valve on it!!

 

[Texasmark]

Hammered down on her when the alarm was going off? I bet that's because you knew that motor had a poppet valve on it!!

Interesting you should ask. No, I figured I could get some ram cooling from the lower unit pickup at high speed and that might tide me over till I got through testing. I didn't know the answer to the performance I mentioned that occurred till I got home and read about it in the manual. Yeah it was an "edge" thing but nothing ventured, nothing gained or lost. That time I won the toss.