Hit something under water.... Now something is up!

[g0nef1sshn]

Ill get the ser number later. But I have a 92 I believe 2 stroke 4 cyl 40 hp Merc. Motor ran great prior to the opening day of duck season. Then one they way back to the ramp I hit something going 1/2 to 3/4 throttle under the water. It felt fine and it ran fine until I idled down to look at another spot. Then it DIED on me. It would start then sputter immediately. Then it wouldn't start at all. After drifting in the current for a long time I gave it a few more goes and it started! I let it just idle for ten mins or so and put it into gear. It idled foward for awhile but with the slightest throttle it wanted to die again. So I idled to miles back to the ramp and shut her down.

That was late Nov. Fast forward to last weekend and I get the boat over to a recommended guy from a friend for a look see. He couldnt get it to even start. Which Im not surprised. (From talking around I may have messed the timing up?) So he pulled the spark plugs and said one was dirty like one cylinder wasnt firing and the others looked fine.

Question is... If I have had the boat in the water 4 times and it ran fine/WOT/on plane, could it do that with one CYL down? OR: could hitting something in the water affect the switch box (which he is suggesting as to why the plug is dirty and cylinder not firing?). Or was it my repeated trying to restart the engine after hitting something that could have fried the box?

Upon reading into it I am seeing switch box/triggers/stators all kinda in the same grouping of troubleshooting. Any thoughts?

This was the last ride a week before the incident...

https://www.youtube.com/watch?v=i459jbe2rXI

 

[roscoe]

The motor sounds just fine in the video.

Don't assume its the switchbox.

Could be a coil, or a loose wire on the coil, maybe even a ground wire.

Diagnose and test before spending big bucks on electrical parts.

 

[achris]

(From talking around I may have messed the timing up?) So he pulled the spark plugs and said one was dirty like one cylinder wasnt firing and the others looked fine.

Question is... If I have had the boat in the water 4 times and it ran fine/WOT/on plane, could it do that with one CYL down? OR: could hitting something in the water affect the switch box (which he is suggesting as to why the plug is dirty and cylinder not firing?). Or was it my repeated trying to restart the engine after hitting something that could have fried the box?

Upon reading into it I am seeing switch box/triggers/stators all kinda in the same grouping of troubleshooting. Any thoughts

Hitting something underwater should only bang up the gear housing and the prop. It couldn't possibly mess with the timing. What it may have done is jarred something loose. As Roscoe says, diagnose it properly before spending dollars on electrical parts. Those engines are an extension of the old 4 cylinder 50hp that started life in the mid 60s. As far as the mechanics goes, not much has changed, electrically they went from a distributor to 4 coils in about 1972. There should be PLENTY of experienced people around to work on it. Find one with the right tools and test gear....

Chris.......

 

[Scott Danforth]

im thinking crud got knocked loose in the carbs

 

[Grub54891]

Flywheel key may have got compromised. It's rare for that to happen, but I have seen it once in my years of repairing outboards. If the flywheel was not properly tightened in the past it could happen.

 

[racerone]

Black plug indicates an issue.-------Compression test is to be done.-------See if spark jumps a gap of 3/8" on all 4 leads.

 

[g0nef1sshn]

So first step if all i have at the moment is a meter. What should i check? Then if i could borrow a flywheel puller i should pull that off and check the the key and trigger?

I appreciate the input so far and best thing like mentioned id like to do is trouble shoot more before purchasing things.

Ive watched videos on the timing stuff. Ill need alot more time to read up on exactly how that works.

 

[rjcamel2355]

Compression test, and then spark test, make sure the spark is jumping correctly on each plug. If compression is good, and within the specified amount, then make sure the spark test is good. If both of those are good, then clean the carbs. If all of that is done, and it is still having issues, it's not too difficult to check the flywheel key, it's unlikely that is the culprit, but it does happen.

 

[g0nef1sshn]

Did compression today. Top 3 at 100. Bottom would hit 100 but stop just over 95 when i stopped cranking. Can i test spark with out the spark tester thing some how? The plugs in cant be gapped. They are ngk buhw 2's.

 

[achris]

Get a 'normal' spark plug and open the gap right up, try and get about 1/2" if you can. Secure it to a metal clamp you can clamp to the engine. Use that as your tester.

Those compressions are ok...

Chris....

 

[g0nef1sshn]

Got spark plug tester and 2 new plugs (all they had). All wires had spark so i put new plug in the num 4 cyl and cranked the hose and tried to fire her up. She started so fast it actually scared me. Problem now is it seemed to have water comming from the threads of a few plugs.

Quick message to dad he said watch how high i turn the hose up. So i cracked it on and the water def. Diminished compared to the first start.

It peed normal both times and not hot.

Whats your thoughts?

 

[racerone]

Water is not leaking from the threads of the plugs.----Replace the gasket on the water jacket cover.---It is what is leaking !

 

[achris]

What he ^^^ said....



It's not a head gasket, just a head COVER gasket. There is no seperate head on these engines, it's cast as part of the block... The cover over the top of the block creates the water jacket, what's leaking is the cover gasket. Easy to fix. Just remove all the bolts (there's about 10 of them), pull the cover off, clean it and the block sufaces up and put a new gasket on... Don't over tighten the bolts as that can cause the cover to distort and create a leak. (bolt torque is 100lb-in, about 8lb-ft) I'd use a non-hardening gasket sealer on that one too, to be sure to be sure....

Chris.......
BTW, be careful removing the cover, they are No Longer Available....
Cover gasket number is 27-437772

 

[g0nef1sshn]

Not to disagree with either of you. Might be lost in translation here.

But... the water i saw was comming from the thread holes of the spark plugs. At least three of them. I turned the hose to minimal pressure and then only top cyl had a drop danglin out.

So what i think you are saying is although i see the water at the spark plug thread hole with plugs in... the main culprit to the leak is from water jacket gasket causing me to see water from the plug thread holes right?

 

[g0nef1sshn]

Achris, the pic didnt appear the first few times i read your post. It shows now and i understand what you both are saying! Thank you

 

[g0nef1sshn]

Gasket and sealer on order. Once replaced how long should I let it set before cranking again? What can I do for any cleaning/residual water that may be there once opened up?

 

[achris]

20 minutes... All the water should have drained out, but if there is any, just mop it up with a rag. For taking off larger pieces of gasket I use a very sharp 1" wood chisel, then I use a wooden 'brickies float' with a piece of fine emergy sheet attached to clean gasket surfaces of any stuck on or small pieces. The float keeps the surfaces nice and flat... See pictures.

Chris.........

 

[g0nef1sshn]

Sooooo i got the gasket in. Anyone have a good write with pics for these snapped bolts i have? Cant catch a break.

 

[achris]

Oh, that's not good. I'll bet they are at the bottom too... If you have easy access to them, use a oxy torch and get them nice and hot, red hot (be carfeul not to melt the aluminium around them), let them cool, then centre punch the middle of them and carefully drill them and get a 'easi-out' in and unscrew them. To make it easier to centre punch, just file the top flat. Helps the drill and punch to not slip and easier to find the centre.

Good luck.

 

[g0nef1sshn]

Oh, that's not good. I'll bet they are at the bottom too... If you have easy access to them, use a oxy torch and get them nice and hot, red hot (be carfeul not to melt the aluminium around them), let them cool, then centre punch the middle of them and carefully drill them and get a 'easi-out' in and unscrew them. To make it easier to centre punch, just file the top flat. Helps the drill and punch to not slip and easier to find the centre.

Good luck.

Luckily I stopped before getting to the bottom ones. I bumped into a local neighbor at a ramp and he swung in for a look see before I started. He mentioned how if the bottom ones snapped I would have to remove the whole block to tap them out! Im thankful for that piece of advice.I might end up having to do that anyway if that gasket is bad also? Exaughst jacket gasket?