mercury 650 tell tale routing / low compression

[CamaroMan]

Hi guys - got a 650 merc for a 64 larson im converting to outboard. motor stood for a while- pulled carbs, cleaned em good, set points gap and everything. starts real well..

Some issues: #2 is 35 psi on cranking :0. plan to run/decarb her with seafoam and see if the rings free up otherwise ill have to dig in and do the cylinder/rings.

Found a pin hole in lower water jacket, lucky very easy to access- sanded wide area.. scraped out as much flaky material till ot was solid alu and jb waterweld overnight.. shd hold up-

Problem is when i attach garden hose to water tube - hardly anything comes out the tell tale. Also - the tell tale tube it connected to the lower part of the head, usually they come from the top of the head? There is also a stainless screw in the top (where I would imagine the tell tale should really be connected to) - what is this screw doing? should/can I reroute the tell tale here?

Also - planning on running/soaking some descaler in this thing, any experiences? trying to be cheap - citric acid / coca cola / vinegar? Any tips wd be welcome!

fyi i unscrewed that plug and it seems like it goes intot he water cooling section - so i would much rather prefer a tell tale from there as opposed to the bottom of the block. Shouldnt the lower water outlet connect to the top here and then out to the tell tale?

Thats how my 85 mariner is setup -

 

[Faztbullet]

Don't waste yer time as #2 is what fails on them 4 cly 650's.

 

[racerone]

Remove bypass cover on side of block.----Inspect piston / rings.

 

[CamaroMan]

Sorry for the late update- head is off, new rings and gaskets. Will do a light hone and put her together.. Rings were frozen but no major damage so hopefully one more merc on the water soon.