new member--- prop ?

[dspark1952]

hi, I just bought a maxum 2005 1800 sr3--4.3 liter--- a few days ago. I have not had it in the water and have not even heard it run, its still winterized. it has 70 hours on it. I have all the maintenance records back to 2010 and don't see any record of an impeller change. so I guess , based on time, it needs one. Im not sure if I will do it myself. also, the prop is alum. 23p probably the original. id like to get a s.s. can anyone recommend a brand and should I stay with 23p ? boat looks new, was kept inside a garage. I gave $8000 for it, which I think was an ok price if all is well under the hood. I am located in central ky. also, I would really like to know how important it is to use 25w40 oil. I have a good supply of royal purple 15w40 syn. but don't know whether to use it in the 4.3.----dale

[mmwjr]

Welcome aboard

The impeller should be changed every 2 years. You need to drop the lower unit to do do. I suggest you get a manual and learn about the engine and dive.

Regarding the oil I use what merc recommends however the royal purple will probably be ok, main thing is if you switch to a synthetic you need to stay with it.

Buying a 10 year old boat without hearing it run is a risk, yea I know it looks good but you never know. Hope all is well.

[mmwjr]

One more thing I would run the boat with the current prop and see if you are happy with the performance before changing it.

[dspark1952]

thanks for the info, guys. after I bought the boat, the seller offered to take it to the dealer he uses and have it summarized and checked over.which made me feel reasonably confident, but theres no way around the fact that its a risk to buy a boat that way. -------

[shrew]

Welcome aboard. I would stick with the Mercruiser/Mercury/Quicksilver 25-40 oil regardless of what I had or close it was. Whether the records show an impellor change or not, I would have it done.

I would start a new thread on re-propping. That is its own sizable discussion.

[dspark1952]

yeah, I think I will keep the 25w40 in it . I just bought a prop off ebay --its a 21p s.s. cabelas high performance 3 blade---$152.50. -----

[shrew]

I would have waited until the boat was launched and assessed how it performed with the current prop. I would have determined the max RPM at WOT and determined if I were within the specs. I would have then used the Mercruiser prop calculator:

https://www.mercurymarine.com/en/us/...tor/#/step-one

Propping uses the following metrics:

Diameter
Pitch
SS vs. Alumuminum
# of blades

Aside from a desire to use an SS prop vs. Aluminum what problem are you actually trying to fix?