starting bang, nock

[green anchors]

I posted this on a different thread with out much response and hoping I can get some input here. I have searched around and have not found anything on this so maybe you guys(or gals) can help. Took a trip for couple day up the St Lawrence to Brockville this past week and had a couple problems come up... first as pulling into Abay alarm went off and both engines had low unit oil. oil between stringers... filled up ran at dock in and out of gear followed hoses from both to transom and can not find leak, no oil in water behind boat either... I will address this with the mechanic that just pulled motors and replaced both transom assemblies. put marine diapers between stringers and went on our way after topping off with 110 gallons of fuel. The real problem was trying to leave Brockville and the starter would spin out after just a short turn of the engine. lucky to find a marina real close who had a starter on hand and dropped everything to help us with an install. My starter was real hot after some attempts to start at the marina and the selonoid was burnt/melted so replaced that out to. Also wires were loose and the starter could be "wiggled" so was loose. She started and on our way. Here lays the problem, prior week I had the engine "clunk" when starting but she turned over and I figured it was low voltage as we were on the hook for couple hours. It happened several times but always started, large "clunk!!" then start but acted like low voltage. Not every time but hated it every time it did. After new starter did not hear it next several starts but stopped for a pump out on the way home and sure enough short and quick while starting a little "clunk" then start... voltage was good and sounded it as well. Obviously not hydro locked but maybe flywheel? Bendix(what even is that?) I feel like eventually I will shoot this starter if I don't find the cause, please help. I know this is dragged on but trying to paint the picture. When I returned to our home dock started her 5 or 6 times and no problems?

 

[dlvwill]

You may have a bad section in the ring gear on the flywheel. Take starter out and turn over engine manually while looking at the ring gear where the starter usually mounts, you may see a section that has worn or knocked off teeth, if so then engine has to come out for replacement. The bendix is the starter drive inside the starter motor that has the gear/clutch that mates to ring gear on the flywheel.

 

[Mike Blake]

How about the wires you said where loose?

 

[Gary Hill]

When do you hear the clunk? Is it when you first hit the key / switch or after it has started to roll over?

 

[green anchors]

Before the engine actually starts... I will see if I can notice anything on the flywheel, the mechanic who put the starter in said he didn't notice anything but that may not mean much. Wires are now tight

 

[b_arrington]

This clunking sounds like the same issue we had with our GMC SUV. It was broken teeth on the flywheel where the starter gear engages it. The flywheel had to be replaced, with basically a full day of labor.

 

[CliffA]

You may have a bad section in the ring gear on the flywheel. Take starter out and turn over engine manually while looking at the ring gear where the starter usually mounts, you may see a section that has worn or knocked off teeth, if so then engine has to come out for replacement. The bendix is the starter drive inside the starter motor that has the gear/clutch that mates to ring gear on the flywheel.

+1......a tooth or two missing from the ring gear will make a 'clunking' sound when the missing teeth align with the starter and you first start the engine...the gear on the starter spins slightly before it engages the good teeth on the ring gear...since the starter gear is spinning fast when it does engage a good tooth on the ring gear it will make a 'clunk' sound....since the missing teeth on the ring gear do not always align with starter when the engine is shut down the 'clunk' will not always be heard when starting the engine...it will only happen when the missing ring gear teeth align with the starter gear when the engine is shut down...

that may also be the reason the starter was loose....over time the shock from the starter gear slamming into the ring gear teeth could have loosened the starter mounting bolts...

this may not be the problem but the symptoms do match...

cliff

 

[green anchors]

quick update for you... compression test shows numbers all over the board BOTH motors. Port was hydro locking with numbers as low as 60 and high as 198 with water in three, starboard had numbers as low as 30!! high as 200 with water in two but not hydro locking(yet). Having both pulled again(had new assemblies installed on both right after I purchased) probably putting two new long blocks in with new manifolds and risers as well. This is heart breaking having just bought her in June. I am sure I could have both rebuilt but believe with saltwater use in the past I could just be asking for future problems and for possible difference in price this will give me more piece of mind. I had a survey on the boat and although she ran fine at the time I am sure I was not feeling all horsepower. NO compression test and this is an important lesson I hope I am passing on. I still look forward to getting her back in the spring and enjoying her next year. Approximate costs 7k per side. Assemblies both sides was 8k minus 2k from seller making total with purchase of 72k. I know that is high for a 02 300 but it will have a lot of "new" to her.

 

[MancaveII]

What have you typically run your RPMs at before the issues?

The clunk could be a wrist pin that overheated (piston slap). If you ingested water through worn risers or possibly during a quick deceleration, that's all it takes to crack a head or scorch piston.

I had a survey done and only 120 hours on my motors. One has already been replaced and no one can say for sure what caused it to seize a wrist pin. Oil pump would be the obvious, but it's fine. Impeller fine, water pump fine, etc. Guardian mode couldn't shut it down quick enough to save it. It happens. Insurance covered it (less deductible - I have a mechanical policy) and a new long block (with warranty) and it's all good. Peace of mind with warranty.

Get genuine Mercruiser long blocks - even surveyors know how many bad engine remans are out there. You get what you pay for.

 

[SCORPIO]

Why not go with total new units? I installed a new crate engine last year on my port side. Michiganmotorz complete set up was about what you quoted for long blocks. I did labor myself and I suspect most of your bill is labor to tear down and swap parts. I currently have an issue with my starboard engine and will likely put on a mate to the port, again a crate motor. Sounds harder than it is, six bolts are really all that keep mine on the boat.

 

[green anchors]

I was running 3800 at 30, was getting up harder than I thought it should. The insurance company sent out a surveyor to find out where the water came from and if something could be covered. Who knows maybe I will get lucky. Will keep you posted. Thought about new units but am getting quoted about 4k more each side.. I may shop on that one and see what I can find.

 

[green anchors]

quick update: It appears the water entered through the exhaust flappers due to when the new transom assemblies were replaced the Flappers were a new model and did not function properly with the old risers. The surveyor was present when she was torn down and did say they were installed correctly but not able to do the job intended. Should know by the weekend what will be covered, will keep you posted. Want to thank everyone who chimed in on this. The insurance company said the old style flapper is no longer available, has anyone ever heard of this.