Running engine without water

[Bondo]

Re: Running engine without water

However when I am just idling (in the water) it goes up to about the middle of the green, halfway on the gauge. When I take off it comes right back to cool.

That's the Classic Symptons of a Junk Impeller.............

 

[Darrendude]

Re: Running engine without water

Bondo it is still within the safe running temp at both WOT and Idle. <br /><br />I have never changed a impeller before, I am very mechanically inclined and have a service manual. Im still alittle hestitant. Is this a tough job? Guess Im worried about surprises and the boat runs great now.

 

[Don S]

Re: Running engine without water

No the boat does not run great, it gets hot when it shouldn't.<br />Read the MERCRUISER manual and look at these How To's <br />Yet you still posted earlier that you had no problems, you just didn't have any problems you wanted to admit.<br />I'm Sorry, but when you post that you ran with no water and had no problems, you are telling others that it's ok to do. But you did have problems just didn't want to tell anyone...... while suggesting it was ok. That my friend is not good.

 

[Darrendude]

Re: Running engine without water

What do you consider hot? It never goes past half way. Just as it did when I got the boat. I never told anyone it was OK to start dry. I simply stated what I did before I KNEW it was bad.... period.

 

[jlinder]

Re: Running engine without water

Just miscommunications guys. A common problem on these boards is the tendency for people to either forget to post details, or not think something is important.<br /><br />How many times have we seen people ask specific questions and forget to even say what king of boag/motor/drive they have.<br /><br />General rule of thumb - give every detail. Someone may draw information from something you never thought of.<br /><br />Bondo is right - your impeller is not working correctly. It may be cool enough now, but I suspect you will see the temp rise when idleing in the future when more fins break off.<br /><br />Don't know how hard it is to replace your impeller. At least the one thing easy on my cobra is replacing the impeller - just a couple of bolts and screws.<br /><br />Maybe someone with experience on your drive can help.

 

[trog100]

Re: Running engine without water

with american boats spending most of their life out of the water.. firing up the engine for a few seconds just to check that it fires up okay every so often must happen one hell of a lot.. okay folks that read this board might know.. but i would imagine that most boaters are in total ignorance of this "built-in" disaster waiting to happen..<br /><br />strikes me as a piece of design idiocy.. i consider myself knowledgeable about things mechanical.. and it would never occur to me that such a thing would happen after a few seconds of out of water running.. and i am sure it dosnt occur to many others either..<br /><br />i can also only assume that many a boat has a knackered impellor and that probably explains why the things need changing so bloody ofter..<br /><br /><br />so what do we have.. a rubber impellor that melts or goes brittle then the blades snap off.. hmmm.. designed by f-cking idiots is all i can say..<br /><br />yes.. its not the folks who break em that are stupid.. its the buggers that made em that way..<br /><br />trog100

 

[jlinder]

Re: Running engine without water

What I hate is not that so much that the impellers will be damaged by running dry, but that on some boats they are so hard to replace.<br /><br />Designers please - if you have a componant that will need maintenance on a regular basis make it easy to get to.

 

[butlp]

Re: Running engine without water

Darren,<br />It is time to learn how to change the impeller, this is a regular maintenance item on any I/O rig. If you don't you could be putting a lot more of your mechanical skills to test if the impeller starts to disintegrate. In my case the temperature gauge suddenly went up as the impeller blades went through out the whole cooling system. They blocked the feeds to the exhaust manifolds, which very quickly overheated and melted the flapper valves and all rubber hoses in the exhaust system. The $20 impeller ended up causing approx $200 worth of damage in parts alone and a week out of the water. I felt I was lucky, overheating a motor could have caused some serious damage to the motor.

 

[BRG25]

Re: Running engine without water

Originally posted by Darren Darnell:<br /> Bondo it is still within the safe running temp at both WOT and Idle. <br /><br />I have never changed a impeller before, I am very mechanically inclined and have a service manual. Im still alittle hestitant. Is this a tough job? Guess Im worried about surprises and the boat runs great now.

Darren...you spent $2000 refurbishing the boat but you don't want't to service the drive? Time to pony up the cash dude...it ain't that expensive...even if you pay a mechanic to do it.

 

[vrod2002]

Re: Running engine without water

Anybody got some kind of aftermarket engine shutoff or alarm for this problem? You cant always be looking at the temp gauge.

 

[TwoBallScrewBall]

Re: Running engine without water

Replace the impeller. You made one mistake which was just an innocent mistake a lot of us made (I did it, I admit it). If you don't replace the impeller, no offense personally, but it's just stupidity. Check any manual, impeller breakdown happens in as little as 8 seconds. If you lose water pressure out there you're looking at a best case scenario of a tow in and a worst case scenario of a tow in and engine replacement. Pay a little now or a lot later. Take everyone's advice here, we're not trying to sell you a part, we're trying to help you. <br /><br />Got it?

 

[butlp]

Re: Running engine without water

barry2002,<br />I was surfing the web and came across this site that has engine alarm systems.<br /> http://www.aqualarm.net/store/Detectors.asp#2

 

[Don S]

Re: Running engine without water

Here are some pitures Mercruiser did years ago on the Alpha pump impellers running dry.<br /><br /><br />

 

[Kiekhaeferscurse]

Re: Running engine without water

I might have missed this,but everyone has been warning about the impellor & justly so, and forgive me if this has been mentioned, But there are the flappers to consider also without the cooling water exiting from the riser's those poor flappers melt away (even those fancy new ones merc designed).<br /><br />For some boats this is never a concern and the owners never know about, but for the guy in a following Sea, or one that backs Up Hard, or even launching boat, this can lead to expensive loud banging noises from the rear 2 cyl's

 

[Darrendude]

Re: Running engine without water

OK I did it. New impeller and upper housing. I will post some pics of the old impeller when I can , but beleive it or not it wasn't that bad IMO at all. I was shocked It was completely intact and I didnt see any cracks. Made the mistake of not putting the skeg bolt in before I mated the upper/lower DOH!!! Had to drain and drop it again.

 

[16Pilot]

Re: Running engine without water

I just yanked my impellor and sure as **** it is toast. I ran it a couple of times(20 sec or so) to make sure it fired up. I now know first hand thats a pretty retarded mistake! Fortuantly changing the OMC's are easier than installing a new prop. I would send pics to prove to you what can happen.(If Don tells me how) when I posted that topic about smoke around my cover. Guess what it was all melted and broken. Man up and put er in. You will feel better in the morning.

 

[Don S]

Re: Running engine without water

Posting a picture is easy. Once you have your picture on the web some where, just copy the url of the picture, then where you post your message, click on "Full Reply Form" just below the message block is a button that says "image" click it and paste the url of the picture in it and click ok. Then when you are done with your post hit the "ADD REPLY" button and your picture will show up.

 

[trog100]

Re: Running engine without water

course i have another problem with this only way to be sure is to rip it out take it apart maintainance kinda thing on outdrives..<br /><br />my boat is a river boat it stays in the water all the time.. any out of water type maintainance however minor requires a £150 or lets say $250 bloody crane lift out.. hmmm..<br /><br />i cant even look at the damn thing for less than 250 dollars.. he he he<br /><br />trog100

 

[16Pilot]

Re: Running engine without water

Thanks Don

 

[KaGee]

Re: Running engine without water

Originally posted by trog100:<br /> course i have another problem with this only way to be sure is to rip it out take it apart maintainance kinda thing on outdrives..<br /><br />my boat is a river boat it stays in the water all the time.. any out of water type maintainance however minor requires a £150 or lets say $250 bloody crane lift out.. hmmm..<br /><br />i cant even look at the damn thing for less than 250 dollars.. he he he<br /><br />trog100

You mean you never pull your boat for maintenance?? Ever?