How to tel if boat will over heat in the water

[Serf27]

Hey everyone.
I have an OMC V6 sterndrive.
Is there anyway to tell if it will over heat in the water by just testing it on land?

Im installing a new water temp gauge and I’m not sure what the condition of the impeller is.
Ive had it for about 2 years and have only ran it about 5 minutes around 10 times with the Water hose hooked up.
I was rebuilding it and it’s finally done this year.
The impeller does look rather difficult to replace.

Its ready for the water now, but I’d hate to take it out and have it over heat on me.

thanks in advance.

 

[GA_Boater]

Either replace the impeller yourself or pay someone. Impellers are a wear item and should be replaced every 2-3 years depending on use. With a new to you boat, replace the impeller. It may be original because too many owners only replace at failure, which you are correctly trying to avoid.

What OMC drive do you have?

 

[Serf27]

Either replace the impeller yourself or pay someone. Impellers are a wear item and should be replaced every 2-3 years depending on use. With a new to you boat, replace the impeller. It may be original because too many owners only replace at failure, which you are correctly trying to avoid.

What OMC drive do you have?

Thanks for the reply and help. I think I’m going to ask around Monday and see if anyone can replace it for a decent price. Here is a diagram of the omc I have.
from the diagram, it looks like a lot of parts have to removed to replace the impeller, right?
I know it is a 1984 OMC v6 3.8l sterndrive. Engine code: [h=1]382SPMRCRJ[/h]

 

[GA_Boater]

southkogs This may be up your alley, SK. I never messed with a stringer.

 

[southkogs]

Impeller change on that drive is pretty easy. Get a shop manual (look HERE by model number). IF you can find a tech who'll do the work for you, make sure they know the drive. Many techs haven't seen one before ... and the ones who have, don't like workin' on 'em.

Once you pull the drive, separating the upper and lower is easy-peasy. The impeller is at the bottom of the upper gear case, and easy to swap. You can change it while it's on the boat (without pulling the whole drive), but I think that's harder. You're working upside down. When you pull the drive, mind the shift cable. That bugger is expensive to replace - when you can find 'em.

 

[Serf27]

Impeller change on that drive is pretty easy. Get a shop manual (look HERE by model number). IF you can find a tech who'll do the work for you, make sure they know the drive. Many techs haven't seen one before ... and the ones who have, don't like workin' on 'em.

Once you pull the drive, separating the upper and lower is easy-peasy. The impeller is at the bottom of the upper gear case, and easy to swap. You can change it while it's on the boat (without pulling the whole drive), but I think that's harder. You're working upside down. When you pull the drive, mind the shift cable. That bugger is expensive to replace - when you can find 'em.

Thanks.
I just ordered the service manual.
I need to get familiar with the names of parts again.
last year I did pull the lower drive? I serviced the shift cable. So whatever I pulled off, was enough to service the cable. Pulling the drive off to service the cable, does that leave the impeller pretty close to replace? As in I won’t have to remove much once the cable is being serviced?

my cable is still a bit stiff even after the service and new cables on the shifter lever. So I’m thinking of pulling the drive back off to see if I installed everything correctly.

 

[Serf27]

A marine shop is wanting to charge about $550 to replace the impeller. I ordered the impeller for $20. I’m going to give it a shot and try it myself.
For as old as the boat is, I’m surprised there are no videos or DIYs on this job.

 

[southkogs]

LOL ... most of 'em were gone long before YouTube :lol:

Impeller swap is easy enough that I could handle it, so the average mechanic should have no trouble. The manual was enough. I did look for a video a while back, but didn't find one that I thought seemed right.

 

[Scott Danforth]

the only videos for old OMG what did I buy stringers are done by TC electronics.

here is the link http://sterndrive.info/

these guys built their business supporting OMG customers after OMC started to go belly up in the early 90s

 

[Serf27]

Yea that makes sense.
How much time do you think it would take someone who is familiar with mechanics to do this job?

I’ve seen the TC electronics page and some videos, but can’t really find anything on my engine exactly. But a lot of them look the same.

This is the only video that looks close to my boat diagram.
https://youtu.be/O8z8kNKyZ5Y

Im jealous of the videos I see online where they pop a cover off and swap the impeller in 10 minutes!

I will take some photos of the drive tomorrow and maybe you guys can point out what needs to come apart.
Thanks.

 

[southkogs]

I could do an impeller swap - including pulling the electric shift drive - in about 90 minutes. And frankly, I'm not that good at it. I'm thinking the first time I did it, I probably spent a couple hours monkeying around. But real time in wasn't too much more than an hour or so.

 

[Serf27]

I got the service manual and it still
looks confusing. It doesn’t say how to remove the impeller. It just shows what to do once the impeller is removed and I’m still not sure what exactly I have to remove.
If I have, the drive standing straight up while it’s still installed on the boat, can I still drop the gear case assembly?
Do I have to remove any ball gears to get to the impeller?
From what I have seen, removing this top cap should drop the upper gear case and just have the impeller cover sitting in plain view right?

 

[Redrig]

No , the impeller is in the bottom of the upper unit . If you remove that top cap while still on the boat all youre gonna accomplish is getting a look at your gears.

Pulling the drive is quite easy on a stringer . Here is a very crude list

Tilt all the way up
Mark ball gears
​​​​​​Remove shift cable from converter
remove pivot caps on both sides
Very carefully pull shift cable through intermediate
Remove drive
Remove top cap
Pull out upper and flip it upside down , impeller is right there

Lots of things to do while you are in that deep though , inspect and lube all splines and reseal what you can

 

[Serf27]

Thanks for the list of steps. I’ll give it a shot this week and see how far I can get.

 

[Serf27]

Anyone there?
Bitter sweet moment today. After a year, I finally swapped the impeller.
took about 3 hours.
I was expecting to pull out the old impeller in pieces or very fragile. It looked brand new! Still soft and rubbery. Oh well.
Next im going to install a new thermostat and a coolant temp gauge.
Back to the original question, is there anyway to tell if I’ll over heat on land vs in water?

 

[southkogs]

You can put it on muffs and run it in the driveway. But a water test is the only way (I know of) to know everything is working correctly for sure. The Stringer needs to be submerged when it's running to draw water properly.

 

[GA_Boater]

Anyone there?
Bitter sweet moment today. After a year, I finally swapped the impeller.
took about 3 hours.
I was expecting to pull out the old impeller in pieces or very fragile. It looked brand new! Still soft and rubbery. Oh well.
Next im going to install a new thermostat and a coolant temp gauge.
Back to the original question, is there anyway to tell if I’ll over heat on land vs in water?

If you can find a non-busy ramp, back the trailer down a ramp until the drive is deep enough, keep the boat tied down on the trailer and fire her up. A few minutes of idling should let you know if it reaches normal temp without overheating.

Now you know you have a good impeller. You know what would have happened if it wasn't checked.

Have you taken the boat on the water?

 

[Lou C]

Agreed water test is the only way. Try to do it early in the AM when no one is around, let it idle to warm up and see what it does. Perferably till the thermostat opens, you may have to run it above idle a bit (1200-1500 rpm) to get it up to temp. Just make sure the water is deep enough to fully submerge the lower unit.

 

[Serf27]

Thanks all.
the nearest ramp is a lake about an hour away. I’m not sure how long the unloading wait time would be since it’s usually busy.
Best to just plan a like day with family and
Hope for the best? Unless I can get away going on a weekday just myself.
I’ve never taken the boat out. It needed so much work. Had to start making lists of what I was working on with it because I’d forget where I left off.

I’m changing the thermostat today and will try to install the temp gauge.
I can’t remember if there was a temp gauge from factory on the engine or if I was going to tap into some hoses.
These are the hoses I’d tap into.

 

[Lou C]

If its the same as the Cobras that housing has a rubber ring inside to hold the 'stat in the housing. Might want to replace that ring too if it hasn't been done in a long time. The standard stat was a 160* unit.