First Time Post, Impeller Question

[HlozekB]

Hi Everyone,

Name is Brian. First time posting here.
My housemates and I recently picked up a mercury 650 engine. It's a two stroke, three cylinder engine. Not sure of the year looks like its out of the 80's or 70's. The motor starts up fine runs and runs well.

Our problem is that the water pump and or impeller is not working properly. There is no water coming out of the pee hole. We haven't ran the motor long because we are wary of over heathing it.

What should we check in order to figure out the problem?

We have been trying to acess the impeller, but can't get the lower unit off.

There appear to be three bolts holding the lower unit on, all of which have been removed. The lower unit is loose and dropped a bit, but still wont seperate from the rest of the motor.

Any help would be awesome.

Thanks
Brian

 

[Killafornia]

Re: First Time Post, Impeller Question

Brian, not sure about the lower unit.I thought there were 4 bolts. Troubleshooting my overheat problem was this.
1) water pump (impeller)
2) Thermostats (2 total)
3) Poppet valve
4) I flushed out the system while the thermostats were off.



The water on my motor starts flowing after about 2-3 minutes. With a temp of 145 deg
The water on my 4 stroke EFI starts flowing right from the git go. With a temp of 78

 

[latin monkey]

Re: First Time Post, Impeller Question

there should be two more bolts holding the lower unit on, look above the prop

 

[egclassic]

Re: First Time Post, Impeller Question

I am not sure how different from an 850 yours is, but my lower unit actually has 6 fasteners. one 5/8" cap nut on the front of the LU, two 5/8" nuts(one one either side, two 5/8" nuts( recessed on bottom of cavatation plate) and one 9/16" bolt up inside where the trim tab sits.

 

[HlozekB]

Re: First Time Post, Impeller Question

Alright thanks for the quick responses guys

first off how do you determine if there is a thermostat. We don't have a gauge anywhere so I'm assuming it would be some kind of internal device.

Second off there appears to only be four bolts. Twoon the side and two recessedbolts above the prop. It's seems like the LU is stuck towards thefront directly below shockdampeners.

Also we tested to see if water comes outthe first supply elbow. Nothing was coming out.

How long does it take appx for the motorto get up to 145?

Thanks a lotguys. This is my first time dealing with a boat engine

 

[HlozekB]

Re: First Time Post, Impeller Question

It appears that the engine is a 1976 or 1975 E or EL.

We have no service manual yet so i have no idea where the thermostats would be.

 

[Wingedwheel]

Re: First Time Post, Impeller Question

I think your missing one bolt. I thought there was 5. two on the front, two on the back and one under the trim-tab assembly. Also check this link to see your t-stat if this is the correct motor.http://www.boats.net/parts/search/M...571651/EXHAUST AND MANIFOLD COVERS/parts.html

 

[HlozekB]

Re: First Time Post, Impeller Question

Yeah thats the motor. Thanks a lot. Where exactly is the trim tab assembly. First time messing with a boat motor, not familiar with any of the nomenclature.

 

[bullbat]

Re: First Time Post, Impeller Question

its the cast aluminum looking peice directing over the prop on the foor it is bolted in from the top of the foot usually a bolt with a 1/2 in head and there should be another bolt under it when you take it off the holds the foot on also

 

[HlozekB]

Re: First Time Post, Impeller Question

So is the last bolt in that crevice beneath where the trim tab assembly bolts on to the shat of the motor. How do you get enough clearance to ge a wrench down in there?

 

[Wingedwheel]

Re: First Time Post, Impeller Question

The trim tab will have a bolt holding it on from the top. Under it is another bolt which you can easily get with a socket from underneath. The pic of the LU in the link I sent you shows the trim tab and the bolts.

 

[HlozekB]

Re: First Time Post, Impeller Question

Alright Im going to attach an image of the bolts that I have removed so far. From what I understand the trim tab is the piece that connects those hydraulic pistons to the stern of the boat? From the way you guys are describing it it sounds like it is the zinc.

The black circles are the bolts which I have removed. And the red circle is the nut and bolt beneath the trim tab that I think you are reffering to.

Is it also possible that the shift linkage is corroded and is holding the unit on there?

I have ordered a service manual but it wont get to my house until late this week or early next week.

Here is the picture of the drive shaft housing. I think it better illustrates where all the connections are.

 

[Wingedwheel]

Re: First Time Post, Impeller Question

Actually I think the bolt you have circled in red is on the front of the housing if I'm looking at the picture right. The trim tab we're refering to is on the rear of the housing and it normally looks like a small fin or skeg. If you're sure you've removed all the bolts and it still won't drop try driving some wooden wedges between the two housings a little at a time and it should pop. If the LU has not been off in awhile, its possible the driveshaft is corroded in the powerhead. It will come off but its takes a little patience. There is a link for free outboard manual downloads at the top of this forum. Yours might be there. Here is a link to the pic of your engine showing the trim tab. http://www.boats.net/parts/search/M...AR HOUSING ASSEMBLY, COMPLETE (G8)/parts.html

 

[HlozekB]

Re: First Time Post, Impeller Question

Thanks Wings,

You've been real helpful. I believe we do have all the bolts off unless that nut on the front of the LU/Drive Shaft housing needs to come off. The trim tab bolts are all off has well. The LU has dropped away from the Shaft housing a bit. Quarter inch id say. I think that the shift linkage rod may be the culprit.

I'll try the wedges and tapping on the top of the linkage rod and get back to you guys.

 

[Wingedwheel]

Re: First Time Post, Impeller Question

For sure that nut should come off.