1976 175hp blackmax cooling problems... one of many

[staceys old boat]

First off hello, this is my first post but i've been lurking around for awhile. I have a 76 175 blackmax that probably has a blown head gasket and overheating problem. Exhaust coming out telltale. No water, just a little spit once in awhile. I have the heads off getting a resurfacing. I'd really like to know the water passage route. I have the poppit out and I'm going to take the lower unit down again and hook a hose up to the pickup tube off the pump. I'd like to know where the water should pour out of first. A little something to ask also is if I have a bad gasket between the engine and lower unit would that keep water from reaching where it's suppose to go. Reason I'm asking is the adapter plate from engine to lower unit leaks around the gasket. I've had two new pumps and no water out telltale, just a hot engine. thanks , stacey

 

[carholme]

Re: 1976 175hp blackmax cooling problems... one of many

Stacey;

Here is a link to the condensed version of the Clymer manual which has a coolant flow diagram. Let the page load for several seconds and download soonest to your computer as the link is short lived.

http://web.ebscohost.com/serrc/pdf?...a7b1-ee668a068f25@sessionmgr113&vid=7&hid=106

What is the s/n of your engine?

Have you given any consideration to removing the exhaust covers while you have the heads being serviced? 1976 is a few years ago and you could have a problem with compacted dirt/salt/minerals etc.

Gerry

 

[staceys old boat]

Re: 1976 175hp blackmax cooling problems... one of many

Gerry, I have the center section off and apart. Nothing there. serial number starts off 430 its the first series.

 

[carholme]

Re: 1976 175hp blackmax cooling problems... one of many

Don't know if we are talking about the same thing. This is what I was referring to:

http://www.crowleymarine.com/mercury-outboard/parts/586_140.cfm

Gerry

 

[staceys old boat]

Re: 1976 175hp blackmax cooling problems... one of many

yes divider plate is off, by the looks of the water flow i should have water come out the top square port at the top between the heads, correct? poppit seems to be the last place correct? never any good stream from telltale even with a hose on the brass inlet tube with stats taken out.

 

[carholme]

Re: 1976 175hp blackmax cooling problems... one of many

Stacey;

Agreed on the the flow. Does your engine have the "Flush" fitting on the LU, close to the "Vent". Do you recall if this engine ever had an impeller disintegration in the past.

If the adapter plate is showing signs of leakage, this would indicate a restriction in the entry to the powerhead at the top of the long water tube.

Have you hooked a hose to the bottom of the water tube yet?

Gerry

 

[staceys old boat]

Re: 1976 175hp blackmax cooling problems... one of many

missing gasket at powerhead between exhaust and water jacket. That was my thought for quite a while.

 

[goodtimes70]

Re: 1976 175hp blackmax cooling problems... one of many

Hi all, I have a 1994 Mercury Blackmax 175hp OB and I needed some help to find out about the beeping sounds(not constantly) at the range of 30-40 mile/hour.The motor starting good and running good for being a 1994. Water pump is working normal but some how making the beeping sounds when the boat got on plane at 30-40 m/h. I stopped the boat and the beeping was gone but will sounded right at 30-40m/h range.Any help would be appreciated.Thanks!