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95 MerCruiser 4.3 won't spin over unless spark plugs are all removed!

Deeno

New member
Hey guys just trying to get a little help here. This is my situation one day I went out in the driveway to pre-start my boat before taking it to the lake so I hooked it up to the hose just like I do for the past seven years and the boat wouldn't crank over all I heard was a grinding noise. So from the research I've done I took all the spark plugs out in a little bit a water came out of the far back left spark plug cylinder. So I immediately restarted the engine without the water source for about 30 seconds because I read that it would evaporate all the water that may be be in the cylinders. After that I let the engine go for a couple days I just left it in the driveway we never took it out or used it sense then. Needless to say when I tried to start it again the grinding noisehappened again. Took out all the spark plugs even more water than before came out of the same cylinder and some on the other side the adjacent cylinder as well. So I thought maybe a riser gasket was leaking so I took the risers off both sides manifolds off both sides in the manifolds had a considerable amount of water in them where only air should be . Change the oil which was not milky didn't seem like it had water mixed with it either. So I inspected and leak tested risers and manifolds which had no signs of rust and rebuilt both sides with new gaskets and now today I was trying to start my engine with a brand-new battery and starter and I have the grinding noise again. The engine will only spin over with all the spark plugs out. I even checked the spark plug gaps to make sure they're not hitting the piston tops but they seem fine. Guess my next step is compression test. Any suggestions would be fantastic. Thank you for reading.
 
You need to do a compression check to see if you may have a blown head gasket.

V6 have a history of this....has the motor over heated at all? above say 200 degrees?

If only the last two cylinders have water in them it is possible that either the heads have cracked or the head gasket has gone bad or the heads are warped.

Fresh water use or salt water use? Please give more history on this motor and its usage this season........

Note for future "research", You are better off asking here before you conclude on random answers from many who may not know SH!T.

Do NOT run motor with no water flowing thru lower unit............The RUBBER impeller does not have any other source of lubricant other than water.

the outdrive is also self draining so no water is present after sitting on a trailer. Running the motor with no water causes the impeller to over heat and wear off the outer wiping edges and leave traces of rubber melted to the cup it spins within.

Now you have to replace your impeller!!!!!!!!!!!!!

Also just because you did not see milk in the oil does not mean there is not water in the oil. water is heavier than oil so it would be settled at the bottom of the oil pan. If you were not able to run the motor the oil would not get milky....One sign of water in the oil pan is if you put your normal amount of oil back in after a oil change, say 5 qrts and that showed full on the dip stick, but after use or sitting after running the oil level is now above the full mark this would indicate water in the oil settled in the pan under the oil in the pan.
 
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Thanks for the responses guys. Decision since I have owned it has only been used in freshwater. The impeller is in the water pump right? I'll do a compression test today. As long as I'm on the boat it's never overheated. Like a said after starting it on the trailer with the water supply connected that was when I noticed it had water in the cylinders. The starter is brand-new and the battery is also brand-new. Could be the slave solenoid going bad too. I don't have a volt meter to check that. It just seems as if when I have the spark plugs installed that the starter isn't strong enough to turn the engine over but with all the spark plugs removed it spins over like a champ. Next up is compression test then I'll get back to you....
 
The impeller is in the water pump right? I'll do a compression test today. ....




No the water pump on the motor is a circulation pump. It circulates the water/fluid in the motor.

The outdrive in the middle of the drive (where the lower half and the upper half connect, is a water pump impeller.

when in the water the impeller does two things, it sucks water into the impeller housing then pushes it to the motor (thermostat housing).

Never RUN a motor with no water attached to the outdrive. It is ok to just turn it over and it is ok to start the motor for a couple of seconds without water connected but NO more!!

In 20 -30 seconds dry that is enough to ruin a impeller.

Based on the year of your boat then you should have a alpha 1 gen II

here is a link to the parts break down of your lower half of your outdrive.



http://www.marineengine.com/parts/m...usa/gear-housing-driveshaft-standard-rotation
 
OK I just did a compression test which seemed difficult for the engine to do as it would spin over half a turn and then grind and then spin and then grind again. All cylinders read at a solid 150 psi except for cylinder number five that cylinder proved to be the most difficult to get a reading on as the engine wanted to keep grinding and wouldn't fully spin around. That cylinder prove to be 125 psi with only half a revolution so I'm not sure if that is the bad cylinder or what. Would it make a difference if I had the outdrive off and did the compression test it almost seems as if the driveshaft or something is getting caught on something. an FYI I am starting The boat in the neutral position when doing these compression test ....
 
Yes this boat is in alpha-1 gen twoI'm pretty familiar with these boats in the maintenance required so I just don't know how it's still hydro locking when there's no water in the engine anywhere it won't even spin over barely with one or two spark plugs installed
 
Drain the block completely. pull the two motor/block plugs and let all the water drain.

Put the shift into forward and remove the outdrive for now.

have all the plugs out and after the block has drained crank it over and over until you are sure all cylinders are empty.

Retry compression test on number 5.

If the issue is still there there may be another issue at play here but may be hard to diagnose over a keyboard......
 
The flywheel teeth looked fine. Before I installed the new starter I spun the engine over by hand to doublecheck all the teeth which looked fine. a bit of metal shavings in there but no broken or shaved down teeth. Ill drain the block tonight after work and start taking off the out drive also. The weather is so funny and the day i started working on my boat it started raining it's been raining for the past three days here nonstop LOL. I'm in ohio by the way so I don't have much Time before I have to winterize my boat :)
 
OK so I pulled the outdrive off and I also unscrewed both block drain plugs which a considerable amount of water drained out of the engine and I proceeded to spin over the engine over to clear anything else out of the cylinders. Then I proceeded to do the compression test on cylinder number five and I still have the same grinding issue. What else could it be kghost?
 
Does it grind the same on any other cylinder?

Check starter bolts to see if they loosened???


Maybe record the sound (use video on phone so we can see and hear) and post to youtube and post a link here for us to listen.
 
It makes the grinding noise when I put the compression tester in any of the cylinders but it seems to prove most difficult on cylinder number five. Starter bolts are tight. Ill try to do a video here in a few.
 
Sounds like the starter has crapped out for some reason........double check elec connections........other than that I am not sure what to do next from here......

Unless there is a mechanical issue such as a stuck valve or broken valve spring causing the piston now to move??? just guessing here.....
 
the bendix drive is bad or the flywheel teeth are damaged, only 2 answers I know of that cause a grinding.
You do have all the plugs out for the compression test,right?
 
I forgot to mention that in the beginning of all this happening I pulled off the valve covers and under each one of the valve covers was probably a quarter cup of water. There was no oil mix with it just straight water. Any ideas? I think I'm going to need Torque guides as well. Any links on here?
 
the bendix drive is bad or the flywheel teeth are damaged, only 2 answers I know of that cause a grinding.
You do have all the plugs out for the compression test,right?

I agree

it may be a result of your water issue..............sh!t happens..........I did a head replacement and gasket replacement last summer for a V8 due to a crack in the center head bolt area allowing fresh water to enter the rocker area. This guys starter also took a dump due to excess water in the cylinders.........sometimes when enough resistance occurs the starter craps out.........

New on Ebay around $100.00
 
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