70 hp 707HF need some help

[Dusty78]

ok I got a 70 hp 707hf from my brother in law for free. the ol motor had been sitting on a old boat out in a field for 11 yrs. me and him parked it after he hit a rock and cracked the hull, so now I have a pontoon in need of a motor so he told me if I wanted it I could have it so I went and pulled it off old hull. I brought it home gave it a good cleaning and to my amazement it runs, just about as good as it did when we parked it. the only thing ive found so far is the water pump, I don't think it is working, also is there anything else I should check before I hit the lake? and would this motor be ok on a 30' pontoon?

 

[jerryjerry05]

Yes it would be ok.
​Don't expect any speed records

The prop will probably need to be changed.

Is the motor mounted right?
​Deep enough in the water?

​If it sat for 11 years?? the bugs might have clogged all the little holes and no water can pass.

 

[Dusty78]

I haven't mounted motor yet and the stand I have it on is not tall enough to take the lower unit off. Just out of curiosity can I put a power trim on it?

 

[Dusty78]

No Title

here's some pics of the 70hp Chrysler and one of my stock 40hp Johnson, it has no lower unit and don't know its condition.

 

[Dusty78]

here's a video of it running ​https://www.facebook.com/duston.daniels/videos/10155600679932878/

 

[Nordin]

Dusty78 do not run it in that bucket. You need a deeper one, the water line should be over the impeller housing.

The impeller is at the split of the LU and middleg.
The impeller is not selfpriming, it need to be under the waterline.

BTW it seems to run pretty good after so long rest BUT pull the LU and check the impeller and change it.
It is regular maintenance and a new impeller is cheap, if you overheat it then you have alot to do get it running.
It is not worth to take a risk.
Change the impeller.

 

[jerryjerry05]

No Title

Nordin's right.
​Deeper bucket or a flush attachment.
The cavitation plate needs to be 2-4 inches above the plate.
​That style lower unit needs a special muff.

 

[Dusty78]

thanks guys I wont run it till I get proper set up, every time I look up a replacement pump I get a lot of options but not sure of the right one. I know I can take it apart and look but was kinda not wanting to leave it apart for a few days while I wait for it. also what kind of oil should o use in the lower unit?

 

[jerryjerry05]

Your 1973 might have 2 different impellers??
Pics of the impeller with a ruler in the photo?
​Measure the height? 1" or 3/4"?
How many blades?
​Mastertechmarine has parts listing that explain the different impellers?

 

[Dusty78]

thank you