Not Turning Over, Low Compression, Mercruiser 3.0

[alldodge]

The motor could have nothing but water in the oil pan and it will start if all other things are correct (air, fuel, spark, compression)

It has to turn over close to 300 rpm's, and if the rest is there it will run

 

[aerobat]

well , check / clean your distributor and check if the ignition timing is correct .

when you did the compression test - did you applied WOT ? it makes a difference on a 4 stroke .

next step is checking why you have water in the oil . is the oil level much above maximum ?

 

[ronaldreagan]

well , check / clean your distributor and check if the ignition timing is correct .

when you did the compression test - did you applied WOT ? it makes a difference on a 4 stroke .

next step is checking why you have water in the oil . is the oil level much above maximum ?

The throttle was closed when I checked for compression. Should it be open when checking? Found the answer to this, Yes. I'll redo the test and report back.

The oil level wasn't much above the maximum.

I checked the distributor and coil and cleaned it. All of the values (resistance and continuity) seem right per the service instructions although one thing that was odd was there was a thin layer of oil at the base inside the distributor prior to cleaning it. I'm not sure if this is normal or have a negative impact for an EST ignition system.

The only way I could check the timing was to see that the rotor was at the correct position when the marks at the front of the engine were lined up correctly. This checked out. Is there another way to check this when the engine will not run?

 

[alldodge]

Since you motor is out of time, get where you crank the motor and while doing so, turn the distributor a bit back n forth slowly to get it to fire

 

[ronaldreagan]

Okay, checked the compression correctly with WOT, a table spoon of 25w40, all plugs out. What difference. The compression is great, 170, 190, 155, 175.

That's a relief.

 

[ronaldreagan]

Since you motor is out of time, get where you crank the motor and while doing so, turn the distributor a bit back n forth slowly to get it to fire

What indicates the timing is incorrect? I checked that rotor was at the correct position when the timing marks where aligned. Is there another more accurate way to check this when the engine will not run ? (Sincere question)

 

[alldodge]

That is the way for initial setup, and at that point it will be close or 180 degrees off. If you turn the distributor a bit in either direction while the motor is cranking it should fire. If it does not, then need to check spark and fuel

 

[aerobat]

Okay, checked the compression correctly with WOT, a table spoon of 25w40, all plugs out. What difference. The compression is great, 170, 190, 155, 175.

That's a relief.

very nice , so we can close all discussions about stucked valves or worn pistonrings , your engine is fine . put new plugs in it , pump the throttle from idle to full 4 times and crank it with throttle 1/4 open without gear . it will fire . if not we have to check ignition timing closely . it also has to crank happily , otherwise the starter or your battery need a check. remember i can only give you hints via a forum , you need to perform it by yourself.

but initlally : with new plugs pump the throttle 4 times then 1/4 throttle and crank it.

 

[scoflaw]

Adding a tablespoon of oil is not part of the compression procedure and could easily mask bad rings. Oil is used when added to determine if the rings are shot.

 

[aerobat]

scoflaw : yes , but not for a jump from 30 to 170 psi . i do not think he has shot rings , only some rust form moisture and wrong compression check he has corrected now . first step is to fire it up and all the rust will go after two hours of run . of course next time take care of it

 

[ronaldreagan]

That is the way for initial setup, and at that point it will be close or 180 degrees off. If you turn the distributor a bit in either direction while the motor is cranking it should fire. If it does not, then need to check spark and fuel

If it ran with the current timing seeing before why would it need adjusting?

 

[ronaldreagan]

very nice , so we can close all discussions about stucked valves or worn pistonrings , your engine is fine . put new plugs in it , pump the throttle from idle to full 4 times and crank it with throttle 1/4 open without gear . it will fire . if not we have to check ignition timing closely . it also has to crank happily , otherwise the starter or your battery need a check. remember i can only give you hints via a forum , you need to perform it by yourself.

but initlally : with new plugs pump the throttle 4 times then 1/4 throttle and crank it.

New plugs, oil, and filter. Fully charged battery.

It​​​ started without a problem and ran until I decreased the throttle and then stalled and would not start again.

 

[alldodge]

If it ran with the current timing seeing before why would it need adjusting?

You said the distributor was loosened.

The first post said low compression and won't start.
Next I see there is water in the cylinders and some in the oil.
After oil in cylinders and other things, the compression is back.
Right now it sounds like your not getting spark. Going to need to find out why or what ever else your missing. Do you have spark and if not, is there 12V at the coil?

 

[aerobat]

New plugs, oil, and filter. Fully charged battery.

It​​​ started without a problem and ran until I decreased the throttle and then stalled and would not start again.

it started actually or last year ? that sounds like the idlesystem on your carb is clogged and it stalls after the choke disengages . but it is indeed hard to follow up since you report several different problems which have completely different reasons .

no more water in the oil ?

 

[ronaldreagan]

I brought the boat to a mechanic and he said that it needs a new block based on low compression results (30, 30, 30,100) likely caused by water getting in the cylinders through a rusted manifold.

They quoted $7,000 for the new engine. The boat is not worth $7,000 so I'm not taking that route.

Any advice on options? I'm very interested in rebuilding the engine myself, is that recommended or would that not be cost effective? If I take that route can someone point me in the direction of a walk through and suggest where to get the parts (2004, mercruiser 3.0 / 140)?

 

[alldodge]

You can rebuild yours for under $1000, or get a reman long block for $2000 or so

 

[ronaldreagan]

You can rebuild yours for under $1000, or get a reman long block for $2000 or so

I like those numbers much better. Would a machine shop recondition the block? Any advice on where to get a remanufactured long bloxk? I'm in NJ.

 

[fishrdan]

Used engine $500-750 (Roll the dice)
Rebuild it yourself $1000+- ( $500+- parts, $500+- machining)
Reman engine $2000
New engine $3000 (Michigan Motorz)

You'll also want to thoroughly test the manifold and riser for cracks since it appears the engine had water ingestion. I'd just replace the manifold and riser, additional expense, but peace of mind.

Have you ever rebuilt an engine before?

 

[ronaldreagan]

Used engine $500-750 (Roll the dice)
Rebuild it yourself $1000+- ( $500+- parts, $500+- machining)
Reman engine $2000
New engine $3000 (Michigan Motorz)

You'll also want to thoroughly test the manifold and riser for cracks since it appears the engine had water ingestion. I'd just replace the manifold and riser, additional expense, but peace of mind.

Have you ever rebuilt an engine before?

Thanks for the feedback. No, I haven't rebuilt an engine before. I would replace the manifold and riser.

Remanufactured at 2,000 would be nice but I'm not finding that for a mercruiser 3.0.....

 

[Bondo]

Thanks for the feedback. No, I haven't rebuilt an engine before. I would replace the manifold and riser.

Remanufactured at 2,000 would be nice but I'm not finding that for a mercruiser 3.0.....

Ayuh,..... Here's one,....