Cruizer219
Cadet
- Joined
- Jun 23, 2017
- Messages
- 8
1982 Stingray 17 ft, stored only on trailer. Very few trips to salt water, nearly always freshwater lakes.
1982 Mercruiser 140hp 4 cylinder sn: 6004033
MC-1 sterndrive sn: 5984192
Housing sn: 6001305
First, to all who post to these forums, THANK YOU, very, very much! I have read hundreds of threads in the past couple months and learned sooooo much thanks to you.
My raw-water cooled Mercruiser ran perfectly thru end of 2016. Starting with our first outing of 2017, boat OVERHEATS after 5 minutes at cruising speed, climbing to over 200 degrees before I return it to idle and the temp slowly drops to normal, approx 180 degrees at low speeds. Similar results but temp rising slower if the T-stat is removed. All testing done in the lake after each step:
(PREVIOUS maintenance, in 2015, had included: Impeller + housing, Bellows, shift cable and seals in sterndrive. That ancient impeller was intact, no vanes broken off. Parts of the ancient water shutter/flapper were found in the old bellows and removed. Did not install a new shutter, running without now).
RECENT STEPS and results include (in order):
I replaced engine hoses, T-stat and gasket, no improvement.
Replaced Riser and Manifold (1[SUP]st[/SUP] time ever changed), no help.
Flexible camera-on-a-wire found no obstructions below riser thru bellows.
Replaced Circulating Pump (1[SUP]st[/SUP] time ever; several teeth found worn), nadda
Used clear hoses for testing, found no bubbles in intlet hose to T-stat, no bubbles between T-stat and manifold.
Impeller flow test showed it pumping 1.5 quarts in 15 seconds at 1000rpms, half of the suggested minimum of 3 qts.
Replaced Impleller and pump housing + base (with OEM parts). In disassembly, found some of the (2015) impeller vanes pointing the correct direction and others pointing the wrong way. Repeated flow test and now it pumps exactly 2 qts, only slight improvement. Also overheating slower now (after 10 mins at cruising speed instead of 5mins).
Removed water inlet hose (from engine side) and stuck the end of a sturdy zip-tie into the water tube where it goes thru the transom. It wouldn't go in very far without force suggesting there MAY be some OBSTRUCTION there. It could also be a screen if there is one at that location(?), I dunno.
Am not sure what to check now. My auto mechanic previously ruled out some possible engine causes and engine runs smoothly, no oil light suggesting pressure OK, proper oil level, good belt and tension, etc.
I wonder if the water intake hose (the one thru the gimball, housing) may be the culprit. What I can see and feel of it, rubber seems okay, no kinks. I am NOT skilled enough to attempt replacement of this hose.
Ideas on what my next steps should be?
Much appreciated!
1982 Mercruiser 140hp 4 cylinder sn: 6004033
MC-1 sterndrive sn: 5984192
Housing sn: 6001305
First, to all who post to these forums, THANK YOU, very, very much! I have read hundreds of threads in the past couple months and learned sooooo much thanks to you.
My raw-water cooled Mercruiser ran perfectly thru end of 2016. Starting with our first outing of 2017, boat OVERHEATS after 5 minutes at cruising speed, climbing to over 200 degrees before I return it to idle and the temp slowly drops to normal, approx 180 degrees at low speeds. Similar results but temp rising slower if the T-stat is removed. All testing done in the lake after each step:
(PREVIOUS maintenance, in 2015, had included: Impeller + housing, Bellows, shift cable and seals in sterndrive. That ancient impeller was intact, no vanes broken off. Parts of the ancient water shutter/flapper were found in the old bellows and removed. Did not install a new shutter, running without now).
RECENT STEPS and results include (in order):
I replaced engine hoses, T-stat and gasket, no improvement.
Replaced Riser and Manifold (1[SUP]st[/SUP] time ever changed), no help.
Flexible camera-on-a-wire found no obstructions below riser thru bellows.
Replaced Circulating Pump (1[SUP]st[/SUP] time ever; several teeth found worn), nadda
Used clear hoses for testing, found no bubbles in intlet hose to T-stat, no bubbles between T-stat and manifold.
Impeller flow test showed it pumping 1.5 quarts in 15 seconds at 1000rpms, half of the suggested minimum of 3 qts.
Replaced Impleller and pump housing + base (with OEM parts). In disassembly, found some of the (2015) impeller vanes pointing the correct direction and others pointing the wrong way. Repeated flow test and now it pumps exactly 2 qts, only slight improvement. Also overheating slower now (after 10 mins at cruising speed instead of 5mins).
Removed water inlet hose (from engine side) and stuck the end of a sturdy zip-tie into the water tube where it goes thru the transom. It wouldn't go in very far without force suggesting there MAY be some OBSTRUCTION there. It could also be a screen if there is one at that location(?), I dunno.
Am not sure what to check now. My auto mechanic previously ruled out some possible engine causes and engine runs smoothly, no oil light suggesting pressure OK, proper oil level, good belt and tension, etc.
I wonder if the water intake hose (the one thru the gimball, housing) may be the culprit. What I can see and feel of it, rubber seems okay, no kinks. I am NOT skilled enough to attempt replacement of this hose.
Ideas on what my next steps should be?
Much appreciated!
