Volvo 5.7 Will Not Turn Over With Plugs In ??

Ok I am hoping some one can give me some light on an issue I have had this weekend with my Chris Craft Concept 25 with a Volvo 5.7 on DP

I spend 3 days at a lake, and covered around 30 miles both on the plane and on tick over. The engine run sweet as, no problems at all. On Saturday night we decided to stay on an island so ran in, anchored off and relaxed for the night. The next day I started her up, backed off and went out into the bay at tick over. On the way out I heard a bit of a grinding noise and thought I had clipped the bottom in shallow water but no mud was kicked up so trimmed up a bit and continued out to deep water. While waiting for my friend to get him self sorted and pull anchor I turned the boat off and bobbed around for 15 minutes. While waiting I trailered my leg to check my prop, no marks at all so I dropped it back down and waited for my mate to come out the bay, once he did I went to start the boat back up but got a terrible loud grinding noise on turn over so I instantly stopped. I checked connections and tried again, same issue so my friend towed me back ( around 2 hours back )

Once back in the marina we pulled the plugs and found water in the cylinders, strange as the boat had run fine but thought this could be to do with a bit of swell on the tow back, anyway we turned the engine over with no plugs in, she turned over fine. cleared all the water out, dried the spark plugs, put back together, only to find the same issue, loud grinding noise then after one or two attempts the starter just spinning.

Tried to turn it over with a bar, very stiff but does turn.

We pulled the plugs again, found no more water but misted oil in and turned it over, once again turned over fine with no plugs. We thought could be a bad starter motor, so pulled that and replaced with a new one, still the same issue so pulled the boat out the water and brought home.

Removed the leg once home to eliminate any possible leg problems stopping the boat from turning over under load so the boat is now at home, on trailer with no leg on but still has the exact same issues.

To recap

Will turn over with no plugs freely
put plugs in, will not turn over at all and a loud grind bang horrible noise
engine oil clean, full history with the boat, rebuilt 3 years 60 hours ago running perfect prior to turning it off while waiting for another boat to join us

Any help really appreciated at this point !!

If the water has been purged from the cylinders, it should turn over as easily as it did before.

As for the grinding sound...... take a look at the ring gear teeth..... your previous starter motor may have damaged several of them or more.


Be very careful using a bar against the flywheel ring gear teeth. You need full tooth contact, or you may break a tooth off.


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RicardoMarine said:

If the water has been purged from the cylinders, it should turn over as easily as it did before.

As for the grinding sound...... take a look at the ring gear teeth..... your previous starter motor may have damaged several of them or more.


Be very careful using a bar against the flywheel ring gear teeth. You need full tooth contact, or you may break a tooth off.


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Click to expand...

Hi thanks for teh reply, I was using a bar against the front of the engine to try and turn it, not against the flywheel

With teh water out the cylinders, it turns over fine with out the plugs but as soon as you put plugs in, no go, I am sure all the water is out as I spent a long time clearing it

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Craig Stephen said:

Hi thanks for teh reply, I was using a bar against the front of the engine to try and turn it, not against the flywheel
Ah.... good!

With teh water out the cylinders, it turns over fine with out the plugs but as soon as you put plugs in, no go, I am sure all the water is out as I spent a long time clearing it

Craig...., Being the Devil's Advocate: water gone..... cylinders dry but lubricated...... spark plugs back in...... why would the cylinder pressures be any different from that of before when the starter motor turned it over just fine?

Click to expand...

If "horrible grinding noise" was coming from the chain driving the cam, and the timing slipped, could account for not turning over with plugs in.

ok quick update, its now just spinning on the starter motor with the plugs in or out, ie sounds like it isnt engaging, just the whir of the starter motor spinning when you turn the key. I took the top cover off one bank, there was some gunk in there questioning of water in the oil at some point, nothing obviously broken. Looking at the engine from inside the boat, I took off the right hand cover. From the top down some of the rockers have a little sideways movement, others are stiff with no movment

from furthest away to closest they are as follows

stiff
loose
loose
stiff
loose
stiff
loose
loose

I look forward to any pointers

By "covers"... you must mean valve covers... correct?

If the engine has been sitting for a while, the cam follower plungers have relaxed hydraulically and would explain why you can easily move some of the rocker arms.

DO NOT adjust these! Not just yet!


Have you looked at the ring gear teeth?
Have you had the starter motor tested?
Is this the correct starter motor for your flywheel?

If the cam is trying to lift a particuler valve or if the valve isn't fully closed, those rockers will have force on them and will hard to move. If valve is closed, little if any force is being exerted and rocker will be easier to move.