Low water pressure and Powerhead removal!!

[outofluck]

I just bought a '88 70 hp Evinrude. I shortly noticed that the peeing pressure was low. I had a water pump kit + impeller put in, but water pressure barely changed. The mechanic mentioned that I may have a blockage in the head or the exhaust cover. I checked the thermostat, head jacket, and the exhaust cover; all are now clean. only a little blockage in the head cover.

I ended up rushing and breaking 3 bolts off,taking the exhaust cover off. These three bolts were below the lower cowlen. I cannot figure how to get this lower cover off. I was told I needed to pull the whole power head. I have taken off about every bolt I can see.

Any advice?

What is causing the low water pressure?
How do I get this head off?
Are there any tune ups I can do now that I have this thing layed open?

Please excuse the ignorance

[fishingdan]

Try the Evinrude/Johnson forum over at www.iboats.com or at www.themarinedoctor.com. You will get excellent advice. I'm not saying that you'll get back advice here. The other forums just have a higher volume of repair traffic.

[DaleH]

Any advice?
What is causing the low water pressure?
How do I get this head off?
Are there any tune ups I can do now that I have this thing layed open?
Please excuse the ignorance
OOL:

My best advice to you now would be to buy the OMC OEM factory service manual for that motor, if you insist on doing it yourself. IMHO do not waste the moment's notice to even consider buying a Seloc or Clymer manual for that motor ... you want the factory service manual (estimated $40) and gets the parts breakdown for that OB too ($12 or so). They could be more pricey for that older model, I'm not sure, but that's what I paid for mine, as I just did a complete rebuild on a V6.

The factory service manual will spell out for you in clear details:
* Detail the water flow for that OB
* Troubleshooting, like causes for the weak water flow
* Complete takedown info specific to YOUR model
* Complete rebuild teardown sequence, lists of tools and materials needed, and torque values for the reassembly

Some OMC OBs were plumbed so that the tell-tale port was fed after or in "series" after water was routed through the head, while some are setup as a "parallel" water feed - one line to the tell-tale and the other through the block. The intent of the parallel feed was simply as a visual indicator that yes, your impeller was pumping water. Whereas with the former method, if the tell-tale line itself gets gunked up (which happens significantly more frequently than a blockage in the head) you lose pressure and the pumping of raw water through the block. With the parallel feed, even if the tell-tale exit is blocked, you're still putting adequate water through the powerhead. Once you get a blockage in the head, you're f$#ked regardless, so that's why most OBs nowadays the tell-tale port is simply an indicator.

Did you happen to see water deflector pins in those heads? Whereas they're an intentional diverter if not an obstruction in the head, those are usually one place where scale or a blockage will build up. If determined to fix this yourself I cannot recommend the OEM service manual enough. You don't say where you're from, but if you get stumped, Paul @ Ipswich OB on Jeffrey's Neck Road is one of the top OMC mechanics around.

PM me if needed and if I can be of any more help ...

Dale

[outofluck]

I sent my wife to the local marine store to pick up there most detailed repair manual for my outboard. She ended up getting a seloc manual. I would go to the OMC for a factory manual, but the model/serial number tab is missing. I will search those web sites, thanks for the the tips.

[outofluck]

nope, it was a clymer. It gave me enough info to get the head off, but this manual sucks. OMC sounds like the better way to go.