normal temp and oil pressure on 140 merc.

[kleinboy]

I have a 1974 140 3.0 4cyl engine.<br /><br />Can anyone out there give me a basic idea of what the normal engine temperature and oil pressure should be on this specific engine. Also what is borderline safe and borderline low.<br /><br />thanks for any help you can give me!!!

 

[Walter]

Re: normal temp and oil pressure on 140 merc.

Maybe Trent or someone else will varify this...but my factory manual says your engine oil pressure should be between 30 - 60 psi @ 2000 rpm. That spec is listed for the 140 hp four cylinder 181 c.i. (2966 cc) engine.<br /><br />If you have fresh water cooling...I believe your thermostat should open at 143 degrees.<br /><br />Walt

 

[kleinboy]

Re: normal temp and oil pressure on 140 merc.

thanks for the info walter!!! what is a maximum safe operating temperature for this engine?

 

[Walter]

Re: normal temp and oil pressure on 140 merc.

Well...you shouldn't exceed much more than 150 degrees if everything is working correctly. We are talking about a fresh water cooling system here, aren't we?<br /><br />What's the normal/max temp you're running at now?

 

[kleinboy]

Re: normal temp and oil pressure on 140 merc.

yes it is a fresh water cooling system and I usually run around 150 however last week while at full throttle it did go over 180...is that bad?<br /><br />chad

 

[Walter]

Re: normal temp and oil pressure on 140 merc.

It ain't good! Your engine is definitely over heating. Of course, I guess it's possible your temp gauge &/or sender may be faulty...but NOBODY is that lucky!<br /><br />One of the most common causes of overheating is a bad impeller in the outdrive. Replacing it would be a good place to start. There are ways of trouble shooting whether it's working properly or not...however...if it hasn't been replaced in the past few years...it's good preventative maintenance to do so. It's also possible your thermostat is not opening fully...and replacing it is much easier than replacing the impeller. You may opt to do that first...but like I said...higher than normal engine temp is one of the first signs your impeller is about to go kaput.<br /><br />Keep us posted on your progress....

 

[kleinboy]

Re: normal temp and oil pressure on 140 merc.

walter...thanks for all of your information...you are truely a God-send!!...turns out that my impellor is showing wear so I replaced it an all is good now...no temps over 150.<br /><br />thanks again!! kleinboy

 

[Walter]

Re: normal temp and oil pressure on 140 merc.

You're quite welcome...but I think you're giving me waaaaay too much credit. My handy-dandy MerCruiser factory manual is where I get a lot of my information. Also, one of my good buddies is a 30 year MerC tech...that helps a bit too. And, most your questions have been asked at one time or the other...I'm just repeating what I've learned from the experts in here. So, should you be in a hurry for an answer to a specific question and no one has yet to reply...try the search feature. It's possible your question has already been asked and answered.<br /><br />Very glad to help...and pleased you're up and running again.<br /><br />Walt

 

[Trent]

Re: normal temp and oil pressure on 140 merc.

Walter....DOnt ask me.<br /><br />You have it under control!! Guess I will find another board or just go boating!!!!!!!! <br /><br />Im not a expert..Just a guy thats been around boats a few years.

 

[Walter]

Re: normal temp and oil pressure on 140 merc.

Trent...<br /><br />Not an expert, eh? Uh huh...yeah right. If I knew half of what you've forgotten....I'd be in fine shape.<br /><br />Keep up the good work! Folks in here sure do appreciate your knowledge and advice my friend...<br /><br />Walt