Temp on muffs....

[wil7483]

1983 Mercruiser 305 SB Chevy / Alpha 1

Ok, I have my engine back in the boat and everything reconnected and ready for my test run. Question, I was running the engine on the muffs and the temp seemed a little high to me. From the attached picture can anyone tell me if it is out of normal range?

Also, it seems that when I put it in gear that the forward / reverse isn't engaging all the way. You can hear like a clicking sound as the prop rotates. What can cause that?

 

[Don S]

Re: Temp on muffs....

Yea, it's a high. That mark between the 150? and 240? is 180?. From where it's sitting you are around 190?.
IF you have a raw water cooled engine, you shouldn't see over 175?
When was the last time the impeller was changed?
Running on muffs at low rpm with no load shouldn't cause that high a temp. Unless you have little pressure and little flow.

 

[Lou C]

Re: Temp on muffs....

That's definitely too hot, looks like 88 degrees C or 190 degrees F. My Cobra with the 160 stat runs at 160 on the muffs. Make sure your muffs fit well and your hose is not kinked and no one is running the wash or taking a shower in the house when you run the boat engine. Don't laugh it can drop the pressure enough to overheat the engine, depends on where you live and your plumbing.
If you have good water press and the muffs fit well, then you have to do some troubleshooting (impeller, thermstat, risers, etc.)

Oh and one thing, you say you have a Merc, but I see the same 'Cobra Trim' gauge my OMC powered boat has, did you re-power an OMC boat with a Mer system? My 4 Winns has the same type of gauges as in your pic. If the boat is idling, your oil pressure is also higher than normal for an engine at that temp.

 

[wil7483]

Re: Temp on muffs....

....you say you have a Merc, but I see the same 'Cobra Trim' gauge my OMC powered boat has, did you re-power an OMC boat with a Mer system? If the boat is idling, your oil pressure is also higher than normal for an engine at that temp.

Yes, the boat originally had an OMC Ford 460 King Cobra setup. It was trash when I bought the boat and I was looking for something to restore and spend my free time / money on last summer.

The temp was running in the 165 -170 range day before yesterday when I ran it. I completed the final touches on it today and decided to run it for awhile and noticed the temp a little higher than it usually is. The impeller was changed last year and the boat was used only once after it was changed. The mans and risers were off all spring and inspected and pressure tested. I'm hoping it is just maybe the hose or water pressure was low. I do know that when it is on the muffs a lot of water is squirting from around where the muffs connect to the drive. That could be a cause for the engine to not be getting enough water maybe?

I will try it again tomorrow in the water and see if it is a dramatic difference. In the picture I actually think I had the engine reved up to about 1500 rpm's. It usually idles at 650-750rpms and the oil pressure isn't that high. What would a normal reading look like so that I can be sure to check that tomorrow also?

Thanks again for the help.

 

[Lou C]

Re: Temp on muffs....

At ilde rpms wth a cold engine, you might see a little over 40 psi
hot engine idle it can vary from 30 to 40 depending on rpms...
On the muffs you will tend to run hot if you run it over idle rpms for any length of time, the water hose can't deliver enough water to keep it cool.

 

[wil7483]

Re: Temp on muffs....

One more question......is it normal to be able to turn the outdrive from port to starboard with your hand. Should there be a lot of resistance or not. When I push it the steering wheel turns and I am concerned that it will wag while I am trailering the boat. Anyway to tighen it or at least make it stationary while trailering?

 

[Lou C]

Re: Temp on muffs....

I can move mine some from side to side but not all the way, I wouldn't worry about that, but ask someone with a Merc because my OMC could be different....

 

[wil7483]

Re: Temp on muffs....

I ran the boat today in the lake and the temp never got above 165 so I guess everything is fine with it. Thanks, I have another question but I will start a new thread.