Yeah yeah...now I know.

[acupajoe]

OK first I am a newby so forgive the ignorance please. Bought boat and wanted to see how the engine sounded but.....yes didn't put on muffs. Ran it for like 5 mins. I know ouch!!! OK figured that was a big no-no and took it out. The temp gauge was fine though. Did I get lucky or should I look for other signs that I screwed up the water pump. Are the pumps hard to replace if necessary? Thanks for the advice

Joe

 

[chiefalen]

Re: Yeah yeah...now I know.

Yea yea what kinda motor and out drive you got. Year also would be nice.

 

[acupajoe]

Re: Yeah yeah...now I know.

Forgot that piece of info sorry. 86 mercruiser 120.

 

[JustJason]

Re: Yeah yeah...now I know.

so your saying you ran it for 5 minutes without any water whatsoever?????

 

[achris]

Re: Yeah yeah...now I know.

Ran for 5 minutes without water

The following will be burnt up and needing to be replaced:

1. Water pump impeller and housing, and probably the water pump base too.
2. Water pocket cover in the leg... This is a fun one
3. Exhaust bellows.
4. Exhaust shutter.
5. Exhaust tube, between the elbow and the exhaust pipe.
6. Top box lower seal... This is the one everybody misses (along with #2)

Have fun.....

Chris...........

 

[chiefalen]

Re: Yeah yeah...now I know.

The motor didn't over heat?

How would you know the temp gauge would not have moved with no water for the temp gauge to read.

When you ran it in the water what did the temp gauge read?

You have to pull the water pump and look at the impeller.

Not hard to do. Do you have a manual.

 

[acupajoe]

Re: Yeah yeah...now I know.

I have ran it like three times sincs and temp gauge is in middle or less??? Did a compression test yest, 120-125 all four. Could it actually be ok? I did just leave it in idle when I ran it for that long and did not power the prop. And all I have is the third party manual. Is it really hard to do if necessary? Thanks so much....yet again!

Joe

 

[ziggy]

Re: Yeah yeah...now I know.

Could it actually be ok?

i doubt it. at least go look at the impeller. i'll fess up, like you, before i knew better, i ran an i/o w/o water too.... live and learn. it takes about 1.5 min. for full destruction of an alpha1 type impeller run dry. damage start occuring within about 15-20 seconds.....
achris has the list ya'll need.... be sure and flush all of what's left of the impeller vanes out of the system as good as possible. i did ft. to back and back to front from where the feed hose connects to the manifold and had the lower removed and used the water pocket cover as the back end. i used a bucket under the drain end while flushing. you'll be surprised how many impeller pieces ya'll get out. flush till clear. check the tstat for impeller pieces too. if the water pocket cover aint melted, while flushing from ft. to back, observe the gasket seal at the cover to housing. it'll likey be leaking..... if so. be ready to be real hosed. the 4 bolts that hold it on like to break off real easy.... and there stainless steel mounted in cast aluminum. very unfun to remove and may cost ya a upper housing if ya ain't successful.......

 

[Liquid_force]

Re: Yeah yeah...now I know.

I'm not sure how your temp is showing up ok...?

A friend of mine had an 86 5.0L merc.
I'm not sure for how long (IIRC he said a min. or less), but he ran it dry, then, not knowing he had done any damage put it in the lake and immediately the temp gauge went way up.

He explained what he'd done and I agreed to have a look...
His impeller had a brass "hub/collar" which is supposed to ride on the vertical drive shaft. Running it dry had built up so much heat the brass collar had melted the impeller and fused itself to the drive shaft. I literally had to split it along its circumference with a hammer and chisel, then sand off some burrs to get the new impeller to slide into place.

Several minutes and still working??

Those of you that know this motor -- is it possible the circulating pump is moving enough water to cool the motor in spite of a damaged impeller?

 

[Maclin]

Re: Yeah yeah...now I know.

No, but it is possible for a temp sending unit to cause the gauge to read low if there is no water in the block. In a car for example, the radiator over heats and the gauge rises to above 220 degrees and then the radiator spews out all liquid leaving only steam and the temp gauge will go down because it is not designed to measure steam, it is designed to be immersed in fluid.

 

[Maclin]

Re: Yeah yeah...now I know.

If it is on muffs then the water pressure may be able to feed the engine's pump at idle. Maybe.

So acupajoe,
Just how much water is coming out the exhaust/prop now?

 

[KJSmitty]

Re: Yeah yeah...now I know.

acupajoe,
You mentioned you have had it out three times since. How long did you have it running each of those times? Like 3 days of boating etc.? If so I would say you must be moving water properly (or at least adequately).

I'm not currently a Merc guy yet at a min I would check the impeller. If as fragile as most say you may be lucky yet running on borrowed time...


As for overheating the motor while running on the trailer... Maybe given the age of the motor, cold oil and idling, you had enough water that stayed in the block to keep it from getting "too" hot... Definitely check your exhaust components.


Good luck - if you have any left...

I wish you and your boat well however

 

[acupajoe]

Re: Yeah yeah...now I know.

To be honest...first boat, as Im sure can see/read so not sure how much water should come out. I have sunk so much into this boat fixin it up I was hoping to not have to tackle one more thing, but I am learning so much...actually too much =) Info can be dangerous. I am just going to learn how to change it. From what I read it's not too hard. Its starting to seem easier to have changed the whole front end of my bimmer than it is to figure out this "simple" boat...wow lots to do. Ignorance is humbling.

Thanks a bunch

Joe

 

[acupajoe]

Re: Yeah yeah...now I know.

Each of the three times I ran it for a few hrs. Now I am wondering about my gauges...brain is exploding.

 

[mcleaves]

Re: Yeah yeah...now I know.

Even if by some miracle you didn't completely destroy the impeller and it's still moving water, it's been seriously compromised. Problems are on the horizon, so learn how to change it now before you run it anymore.

It's a maintenance item you want to know how to do yourself. They should be changed regularly.

M