TOPIC: Merc 500 - No spark

Picked this baby of CL for $75. A deal yes..now couple issues.





First hookup/turnover to check compression and the timing belt broke. Managed to borrow one from my Mark 55 and installed it after a 50 mile round trip to a friends to borrow that special Merc flywheel puller(yes I lined up the TDC mark on flyweel with the arrow on the mag pulley).

Then battery was nearly dead so while I had it on charger, checked compression manually with a pull rope. It was good for being cold and dry..about 110 all around.

Now I am about to see if she'll fire but I get no spark. Pulled the Mag off...cleaned/gapped the points, and cleaned up inside the cap etc. Put her back together and still no spark.

Will order new points/condensor today but any other thoughs in the mean time?

Thanks,
Tim

Did you try it with the throttle lever in neutral Tim? In the pic it appears to be pushed forward, or if defective it could be the neutral safety switch preventing spark? Just a thought, hope it's something simple. Nice find, BTW!

Nuetral safety switches normally prevent cranking in gear or open throttle situations.

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See if someone has a MERC-O-TRONIC ignition analyzer to test the coil.

neutral safty switch does not prevent spark only the operation of the starter.

MarkS wrote:

Did you try it with the throttle lever in neutral Tim? In the pic it appears to be pushed forward, or if defective it could be the neutral safety switch preventing spark? Just a thought, hope it's something simple. Nice find, BTW!

Throttle and shift are not connected(only harness) and it is in neutral. I read one of Chinewalker's posts on I-boats and he explained that the points had to be 100% clean so I will remove mag and do it again. Also I should have the coil checked while I have it off I guess. I'll post a picture of insides when I get it apart.

Thanks,
Tim

Tim,
I seen you called again yesterday I apologize for missing the call. Was it in ref to the lack of spark? Seems that you are on the right path.

My apologies Gentlemen, I'll sit down and be quiet.

g3jim wrote:

Tim,
I seen you called again yesterday I apologize for missing the call. Was it in ref to the lack of spark? Seems that you are on the right path.

Jim,

It was indeed in regards to this issue.

Thanks,
Tim

Update: SHE LIVES AGAIN.

I pulled the Mag off again and did a good job of sanding the points down again and ensuring the gap was correct etc. I knew I was in business when before I even bolted the mag back up, I pulled one plug and grounded it and turned the spindle on the mag and had spark.

Sure enough I put it back together, hooked up the battery, harness, and hose and BANG...she fired right up and idled like it was meant to do. I was pretty happy as you might imagine. Let it run for a couple of minutes but of course not pumping.

Shut her down... ran a weedeater line up the tell tale and there was some junk in there but couldn't get it to pee.

Did the inevitable and pulled the lower off and impellar was just fine...soft intact and held by the keyway. Without a new replacement impellar(though I had a good used one to use in the mean time if necessary before I replace) I decided to put it back together.

DeJaVu from last year when I was waking up a '60 Merc 300 that was sleeping forever....cannot get the shift shaft to line up properly...it is just pushing up on it. Like before I have fought with it for a long time and can't get it to mesh. Unlike the 300 which had the shift cable connector arm outside the motor so I could wiggle the shift arm as I slowly tightened the foot up and it would eventually engage.

Oh well ...two steps ahead and one back as usual. I'll get back at it tomorrow cause I ran out of daylight.

Any tricks I need to know? I have the lower in forward gear and the shift arm in forward for sure btw. I wonder if it has something to do with those cam's that fit together on the shift shaft. The top one can only feed into the leg one way but should the top one be turned so it meshes with the lower cam initially or turned 180 so it is separated...if you know what I mean?

Thanks for the help as always.

Have a great weekend.

Tim

yes, snug the 2 nuts up on the lower then look under the bottom carb and you will see the shift shaft lifting up take a looong screw driver and hammer and tap it down that usually works for me.

Yea Dave I was trying that....will continue with good light tomorrow. These old girls are certainly a challenge. I am still riding the "high" for now by the fact that she woke up and was purring like a kitten without even going near the carbs.....at least for now right?

Thanks for the idea though.

Tim

Well I finally got it figured out and back together. The trick I figured out was to get it up far enough to get the water tube lined up and inserted and then a half in of bolt threads thru the leg to get the two nuts started. Then while using a large set of channel lock pliers with one hand squeezing the lower to the leg by the anti-cavitation protrusions, and reached around the front of the leg wiggling the exposed shift shaft until I felt it engage into the lower shifter and she slid right up tight.

Started up great again but still no tell tale. However the block was not getting too hot and the water jacket side was cold so I am pretty sure that the water pump is working....warm water coming out the prop exhaust also.

I stopped the engine...got out the power washer and set to as fine and strong a spray it could and flushed up the tell-tale drain line but it is still not expelling water. Must have something block the exit out of the water jacket into the hose. It is so tight down there where it connects I dont really want to attempt to pull it. I have run a small weedeater line as far as I can...assuming to the block.

Not sure what else to try.

Btw ... it is running/idling really nicely and I confirmed that I have F_N-R

sometimes they get so pluged the only way to clean it is when you break the motor down, something to consider is to drill and tap the top of the block, install a brass fitting & hose for a new telltale..
this is a better location than at the bottom

if interested in this solution let me know Ill post pics where to drill and what size etc

Last weekend, Dr. Frankenmerc was helping a friend light off an 800FGS that had been sitting for some time. Water wasnt coming out the telltale hole properly... so he grabbed a good sized tie wrap and fished it around inside the hole and it started peeing like it should.

Yea Madprops that was gonna be my last option. I installed one before on a 74 Evinrude that didn't have one.

Dean..as I mentioned I fished a heavy weed-wacker line as far as it would go...because I did have some resistance at first and some crap falling out...I fear I may have just pushed whatever was obstructing all the way to the blcok.

I'll keep at her.

Gonna start a new thread about replacing the busted leg with a newer one.

THanks guys.

Tim

Hang on now... I just noticed what appears to be a screw/plug with a slotted head already in the top of the block. It may be spot welded or soldered though on the one side. Gonna take a pic and add it here shortly. Hopefully I can use it to tap into and re-route the tell tale?

that plug is used with a sealer. remove it and replace it with a elbow for a tell tale if needed

On mine, I use that hole with an elbow and run tubing to a water pressure gauge on the dash.

On my spare 68 Merc 500 powerhead, the telltale was clogged too. I removed the exhaust cover and baffle plate to find severe blockage of the water passageways with sand. In the process, I broke several bolts, as they were corroded into the block badly. A common issue. Heat and PB blaster were no match for the corrosion.

I would NOT remove the cover plate. The outlet for the pisser is at the very bottom of that cavity - right where any sand, grit, old impeller bits, etc. want to collect. Add a little corrosion, calcium deposits, etc. and it isn't going anywhere without major surgery. Just move the outlet, as noted above, and be done with it. They did it on later models from the factory...

Well I certainly don't want to get into pulling off the jacket for fear of the same problem. I'm gonna pull the lower off it again just to double check and make sure impeller still fine and water tube is lined up....might even rig something up to run water up the tube while off to confirm blockage in jacket or line.

Stay tuned.
Tim

Well the $75 Merc 500 is pumping and purring and with a little sprucing up.... looking pretty good.

Last two things... It needs the fuel line connector(using an omc right now ...still looking for one I have here somewhere) and the little tilt lock lever is broken off. I might even throw on the stainless prop I have just to make her look her Sunday best.

I'd love to throw her on the Custom Craft when I finish painting it but unfortunately this is a long shaft.