1975 Mercury 850 Thunderbolt Imperller

[Island_oki2000]

I just dropped my lower unit to replace the impeller. Very easy to do, especially after I found the hidden bolt. Anyway, as I dropped it down I didn't see where the thin black tub came from at the back of the L.U. I do remember I could see it when the unit was put together. So that is where I'm at. I have the L.U. back on and bolted down. Does anyone know what that little balck tube is by my discription? If not I can take a picture and attach here.

Thanks for the help.

Kyle

 

[mike1245]

Re: 1975 Mercury 850 Thunderbolt Imperller

i also have an 1974 merc 850 if u put a pic on here ill see if i can find it on mine

 

[road.ripper]

Re: 1975 Mercury 850 Thunderbolt Imperller

Island_oki2000 did you replace just your impeller or use a lu gasket kit to do all seals /gaskets and impeller ?
interested in cost between the 2.

 

[mike1245]

Re: 1975 Mercury 850 Thunderbolt Imperller

the cost on mine was 15 for just impeller and 45 for whole kit

 

[Island_oki2000]

Re: 1975 Mercury 850 Thunderbolt Imperller

All I did was replace the impeller. I'll take a pic today to see if that helps id the tube. Can't tell what it is in any of the diagrams.

 

[Chris1956]

Re: 1975 Mercury 850 Thunderbolt Imperller

Some of the Merc gearcases had a pitot and tube for a standard speedometer. These had black thin hoses near the shift shaft. I did not think they were on 1975 models however. If this is what you have, it is likely that the gearcase is 80s vintage.

 

[santo101979]

Re: 1975 Mercury 850 Thunderbolt Imperller

I've got the 1974 850 Thunderbolt and just rebuilt the water pump yesterday. I bought the OEM Merc Water pump assembly and it came with all the gaskets, impeller, tube, etc... These kits fit a number of engines so they'll have pieces and parts you wont need. I think the tube you are speaking of is shown in this pic of my lower unit, look at the water tube base going into the water pump housing, is this what youve got?

Let me know what ya think.

 

[Island_oki2000]

Re: 1975 Mercury 850 Thunderbolt Imperller

Here is a pic of the tube, I think Chris is right, the pic Santo gave does not have it there. If you are right Chris, what do you suggest I do with the tube, it might have just been tucked in the side cover.

 

[Chris1956]

Re: 1975 Mercury 850 Thunderbolt Imperller

OK, That is the speedo pitot. Just let it hang, or tape it up, or connect it to the speedo and use it.