1987 Mercruiser 1 90engine temp.

[CaptRon66]

I just replaced the raw water pump in a 1986 or 87 Mercruiser 190(470 block) It was overheating prior while running on a hose. With new raw water pump(upper & lower housings,impellar) the engine runs slowly fluctuating between 182 & 186 degrees. Is this normal for this engine? It seems high for running at idle on a hose. What temp range is ok for this? This is my first closed cooling marine engine so I'm not sure.

 

[CaptRon66]

Re: 1987 Mercruiser 1 90engine temp.

I would like to add that while running at the above temperature the back of the riser, outgoing side was cool. The spent water coming out the transom was luke warm. Valve cover was not hot ,I could keep my hand on it.

 

[Bondo]

Re: 1987 Mercruiser 1 90engine temp.

That's Closed Cooling System,....That in itself allows for using Higher setting T-Stats......<br /><br />It Sounds like your's is operating Well Within acceptable Limits.......for a 180* T-Stat....<br /><br />It's Raw water cooled systems that the T-Stat is set to 140*........Which is really Too Cold for Good engine Efficiency......

 

[Don S]

Re: 1987 Mercruiser 1 90engine temp.

That is a little warm. It may have the wrong thermostat in it. Make sure you have one for the 190 which is Merc PN 99155A 1. If you have one for the older style 470's, and may run warmer.<br />It could also be an aftermarket 180° stat, the Merc stat is 160° I believe.

 

[CaptRon66]

Re: 1987 Mercruiser 1 90engine temp.

Changed the t-stat today. The old one was a 160 degree. Also fixed the oil pressure sender before start up. The oil guage was pinned after start up and after running for awhile temp was around 182. Changed oil and filter and had 40 psi at idle when warm. Also temp was just above 160 after the oil change. I should also tell you this engine had not been started in 2 years until a week ago. What do you guys make of this? Cant't be good for the bearings. The engine runs smooth. Not jumping like it's missing. No knocking. Engine has another problem now. It turns over easy when cold. Very difficult to crank when warmed up. Sometimes will not turn over at all. I did a search on here and realize timing ,battery condition and connections must be checked now. Should I do the battery voltage test when the engine is warmed up and not cranking or when its cold and easy? Also what is the min batt V and maximum voltage drop across cables and connections when cranking?

 

[CaptRon66]

Re: 1987 Mercruiser 1 90engine temp.

For whoever is interested in follow ups. The probllem turned out to be a broken "nose cone" on the starter. It was causing everthing to bind. Kinda strange it was only happening when hot. It was caused by whoever installed the old starter. They left a bolt out and it caused twist when cranking. Rebuilt starter in. All better.

 

[Reel Poor]

Re: 1987 Mercruiser 1 90engine temp.

Kewl