Mercury 1150 thunderbolt questions

[capn kurt]

Hey all, total boat newb here that just acquired a 197X Switzer Craft 16' with a Mercury 1150 (115hp) thunderbolt ignition 6 cyl inline engine. Was out running around the lake yesterday and everything was fine until I had to navigate through a small connecting channel that had debris on the bottom (stumps and such). In an effort to avoid hitting this crap, I pulled the motor out as far as I could using the trim without any noticeable cavitation. Well, she ended up running hot and stalled on me. After a couple of hours, I was able to start it back up without ANY problem and it idled perfectly.

So, my question is: did I totally destroy this thing, or is it going to be okay? What should I do?

I bought the "earmuffs", put those on and found that there was a rather weak stream coming from the water outlet at idle. The boat sat for at least two years before I bought it - what should I check? I'm pretty good with mechanics, but as I said, I'm a total newb when it comes to boats.

Thanks a lot!

capn

 

[79Merc80]

Re: Mercury 1150 thunderbolt questions

The water pump impeller should be changed at least every other year. I change mine every year, they are not expensive and it doesn't take long, so why not do it??

How do you know it ran hot? Did you feel the water coming out of the tel tale or the engine block after she stalled?

The flush muffs aren't really a good judge of the water pumps ability as the hose is pressurising the system.

Welcome to iboats and take full advantage of the knowlege these people have (Not meaning myself)

Craig

 

[mmf]

Re: Mercury 1150 thunderbolt questions

It only takes 30 seconds without sufficient water, to destroy the impeller. 15 seconds, and its halfway destroyed, replace impeller and pump seals..........

 

[capn kurt]

Re: Mercury 1150 thunderbolt questions

The water pump impeller should be changed at least every other year. I change mine every year, they are not expensive and it doesn't take long, so why not do it??

How do you know it ran hot? Did you feel the water coming out of the tel tale or the engine block after she stalled?

The flush muffs aren't really a good judge of the water pumps ability as the hose is pressurising the system.

Welcome to iboats and take full advantage of the knowlege these people have (Not meaning myself)

Craig

Craig, I assumed it was running hot because it was steaming up quite a bit just before it stalled.

So again, do you guys think that the motor is salvageable? I don't want to put it back out on the water if it is going to strand me again, but I will definitely replace the water impeller/seals before I get it out again.
It never seized up and continued to crank over easily via the starter - just wouldn't fire up until it completely cooled off (vapor lock maybe?).

I've gotta get myself a good manual...

capn

 

[Chris1956]

Re: Mercury 1150 thunderbolt questions

Take a compression test. If you have 100+PSI and the compression is even across the cylinders, the motor is fine. Post back results. You probably should clean the carbs on that motor as well as sitting for 2 years will gum them up. Impeller change out is a must as is change of gear oil.

 

[capn kurt]

Re: Mercury 1150 thunderbolt questions

Take a compression test. If you have 100+PSI and the compression is even across the cylinders, the motor is fine. Post back results. You probably should clean the carbs on that motor as well as sitting for 2 years will gum them up. Impeller change out is a must as is change of gear oil.

Thanks a lot, Chris! That's the info that I was looking for. I will definitely post back results when I get them.

 

[capn kurt]

Re: Mercury 1150 thunderbolt questions

Chris,

I picked up a mercury service manual and parts and got around to replacing the impeller, lower gear oil and checking compression. I have over 100 psi on all cylinders, but they are not equal. On 1&2 I have 120 psi, 3&4 have 140, and 5&6 have 145. Is this going to be okay? After getting it back on the lake with the new impeller, I am getting over 10psi of water pressure, where it was getting less than 1 with the old impeller. The boat starts great, idles nice and low in gear, and does a holeshot perfectly, so can I assume that everything is okay with it? It sat with fuel stabilizer in it for about two years before I got it, and I was thinking about a rebuild for the carbs and the fuel pump, but I feel like I shouldn't bother if it "ain't broke." Oh, and the motor is a '74 1150.

Thanks,

capn

Take a compression test. If you have 100+PSI and the compression is even across the cylinders, the motor is fine. Post back results. You probably should clean the carbs on that motor as well as sitting for 2 years will gum them up. Impeller change out is a must as is change of gear oil.

 

[BatDaddy1887]

Re: Mercury 1150 thunderbolt questions

....I'm thinking you trimmed the motor too high out of the water while it was running, which caused the impeller to overheat and crumble. In the future, take care as you tilt the motor up while running so you don't tilt too high as water needs to be running through the LU always. Your manual states this on almost every page. A change of the impeller is a good suggestion. You may also benefit from a good ol' fashioned decarb (there are excellent posts on the procedure) and get a can of Seafoam and treat your engine. Good luck.

 

[Chris1956]

Re: Mercury 1150 thunderbolt questions

Your compression numbers are probably fine. I would recheck after a few hours running time. 10 PSI water pressure is real good.

Enjoy

 

[Stonnejb]

Re: Mercury 1150 thunderbolt questions

Capn
If you be smart and take care of that 74 1150 and it will last you another long time. That impeller pump will make you or break you, so be careful with that lower unit. It was stated before; water must go through the lower unit at all times while on the water. Because I learned that the hard way, I replace the impeller on my 1150 and I did not start mine I just cranked it over a few time and it cost me another one.

Capn, here is a way you can get away from the back yard ear muffs. I purchased a 55 gallon plastic drum and I cut about 12 to 14 inches down and about 8 to 10 inches from the out edge to the center, then I put in a drain plug and I have a the perfect test tank. I can do a lot of testing in my back yard. I can send you a picture of mine if you like.

Stonnejb

Hey all, total boat newb here that just acquired a 197X Switzer Craft 16' with a Mercury 1150 (115hp) thunderbolt ignition 6 cyl inline engine. Was out running around the lake yesterday and everything was fine until I had to navigate through a small connecting channel that had debris on the bottom (stumps and such). In an effort to avoid hitting this crap, I pulled the motor out as far as I could using the trim without any noticeable cavitation. Well, she ended up running hot and stalled on me. After a couple of hours, I was able to start it back up without ANY problem and it idled perfectly.

So, my question is: did I totally destroy this thing, or is it going to be okay? What should I do?

I bought the "earmuffs", put those on and found that there was a rather weak stream coming from the water outlet at idle. The boat sat for at least two years before I bought it - what should I check? I'm pretty good with mechanics, but as I said, I'm a total newb when it comes to boats.

Thanks a lot!

capn