I have been pouring over forums looking for an answer tath I want to hear.
Background-
1998 Mercruiser 7.4L MPI w/Bravo III drive. 740hrs. Purchased this year.
2 weeks ago engine ran up to 180 deg while underway. When I backed doen on throttle at the ramp, the temp went higher and alarm went off. I back up to get to dock and shut motor down. Tried to re-start. Hydrolocked.
Put boat on trailer and went home.
The next day I pulled all the plugs and found water on port side pistons. I turned crank by hand and pumped all of the water out and squirted WD-40 in each and then a little oil. I checked the oil and it appeared clean on dipstick. Thought I avoided disaster.
I ran a compression test on all cylinders. 1-130, 2-138, 3-140, 4-122, 5-145, 6-127, 7-140, 8-135. All seemed okay. Agree??
I thought I had a manifold/riser issue.
I ordered new manifold/riser kit, sea-water pump rebuild kit, t-stat kit, new plugs, plug wires, and hose.
When I pulled port elbow off I immediately noticed water shutter missing half. Explains the hydrolock after reverse and shutdown at dock. I replaced both manifolds and risers anywyas since I did not know the true age of them. Iwas told they were replaced in 2010.
When I opened up the sea-water pump, impeller was in pieces. Explains the overheating issue. I back flushed all of the hoses and found most parts. A few pieces are still missing. I re-built and re-installed. I also replaced the big hose from the t-stat housing to the circulating pump because the belt had shifted slightly on the pulley and burned a hole throught the side of it.
I put new manifolds on, new elbows, I replaced plug wires because one had a burn mark in the side.
When I looked at the new plugs, they were obviously longer than the old ones. I triple checked to make sure that they would not be too long and all literature said that I had the OEM equivalent NGK plugs. I installed new ones. While writing this- I recall I did not check gap-bad idea.
I also replaced the t-stat and gaskets.
I bolted all new parts on and toqued to specs.
I put on the muffs and the motor started right up. I let it idle for a few minutes. I checked the manifold temps with IR thermometer. 68deg on port- 85 on stbrd? Strbrd manifold was hotter than port.-- Could this be becuase of impeller pieces lodged somwhere?Dash temp gauge at 160.
I checked for leaks- none. I am thinking that I should have been a marine mechanic. Short lived.
When I gave it some gas and backed off- The engine stalled. I re-started. Did the same thing- Stalled. It will idle forever.
I checked fuel filter and no sign of water.
I double checked the plug wire order and they checked out fine. I was thinking timing issue, but I changed nothing.
Then I check the oil again-- Milky. No good. I was not sure if it is the water left over from the hydrolock issue that was just not circulated since I had not run the engine since then. Maybe I did not notice water at the end of the stick..
I got nervous thinking head gasket.
I pulled the plugs and checked compression again- No water on plugs-
Compression was good. The only 2 low readings were on 4-120# and 6- 124#. I squirted 3 pumps of oil in each and re-checked. They came up to 127# and 134# respectively. Still not too bad- I am thinking a little leak pass the rings.
I am in the process of changing the oil and filter a couple times to see if the water in oil issue goes away.
I will report my findings. If the water in oil goes away with change I am thinking I only have a stalling issue. If not- I could have a head gasket leak from oil to water passage.
I am not a mechanic by any means. I am pretty mechanically inclinded and read alot of forums.
I realize that I made big mistake by replaceing too many parts at once.
Any idea on the stalling issue? Any idea on the next step.
Any help is appreciated.
Thanks,
Eric
Background-
1998 Mercruiser 7.4L MPI w/Bravo III drive. 740hrs. Purchased this year.
2 weeks ago engine ran up to 180 deg while underway. When I backed doen on throttle at the ramp, the temp went higher and alarm went off. I back up to get to dock and shut motor down. Tried to re-start. Hydrolocked.
Put boat on trailer and went home.
The next day I pulled all the plugs and found water on port side pistons. I turned crank by hand and pumped all of the water out and squirted WD-40 in each and then a little oil. I checked the oil and it appeared clean on dipstick. Thought I avoided disaster.
I ran a compression test on all cylinders. 1-130, 2-138, 3-140, 4-122, 5-145, 6-127, 7-140, 8-135. All seemed okay. Agree??
I thought I had a manifold/riser issue.
I ordered new manifold/riser kit, sea-water pump rebuild kit, t-stat kit, new plugs, plug wires, and hose.
When I pulled port elbow off I immediately noticed water shutter missing half. Explains the hydrolock after reverse and shutdown at dock. I replaced both manifolds and risers anywyas since I did not know the true age of them. Iwas told they were replaced in 2010.
When I opened up the sea-water pump, impeller was in pieces. Explains the overheating issue. I back flushed all of the hoses and found most parts. A few pieces are still missing. I re-built and re-installed. I also replaced the big hose from the t-stat housing to the circulating pump because the belt had shifted slightly on the pulley and burned a hole throught the side of it.
I put new manifolds on, new elbows, I replaced plug wires because one had a burn mark in the side.
When I looked at the new plugs, they were obviously longer than the old ones. I triple checked to make sure that they would not be too long and all literature said that I had the OEM equivalent NGK plugs. I installed new ones. While writing this- I recall I did not check gap-bad idea.
I also replaced the t-stat and gaskets.
I bolted all new parts on and toqued to specs.
I put on the muffs and the motor started right up. I let it idle for a few minutes. I checked the manifold temps with IR thermometer. 68deg on port- 85 on stbrd? Strbrd manifold was hotter than port.-- Could this be becuase of impeller pieces lodged somwhere?Dash temp gauge at 160.
I checked for leaks- none. I am thinking that I should have been a marine mechanic. Short lived.
When I gave it some gas and backed off- The engine stalled. I re-started. Did the same thing- Stalled. It will idle forever.
I checked fuel filter and no sign of water.
I double checked the plug wire order and they checked out fine. I was thinking timing issue, but I changed nothing.
Then I check the oil again-- Milky. No good. I was not sure if it is the water left over from the hydrolock issue that was just not circulated since I had not run the engine since then. Maybe I did not notice water at the end of the stick..
I got nervous thinking head gasket.
I pulled the plugs and checked compression again- No water on plugs-
Compression was good. The only 2 low readings were on 4-120# and 6- 124#. I squirted 3 pumps of oil in each and re-checked. They came up to 127# and 134# respectively. Still not too bad- I am thinking a little leak pass the rings.
I am in the process of changing the oil and filter a couple times to see if the water in oil issue goes away.
I will report my findings. If the water in oil goes away with change I am thinking I only have a stalling issue. If not- I could have a head gasket leak from oil to water passage.
I am not a mechanic by any means. I am pretty mechanically inclinded and read alot of forums.
I realize that I made big mistake by replaceing too many parts at once.
Any idea on the stalling issue? Any idea on the next step.
Any help is appreciated.
Thanks,
Eric