Saving Old Seagulls

Your no spark issue on one plug will 99% of the time be due to a bad powerpack. Powerpacks fail largely due to a poor ground.
No sure why you pulled apart a clean powerhead like that? Was there some other issue you are dealing with?

Michael wrote:Not sure why you pulled apart a clean powerhead like that? Was there some other issue you are dealing with?

Yes I was reluctant to strip the power head but there was play in the crank top needle bearing.

H-A

Nice engine. I used to use one of those a lot in the late 1970s and 80s in the sea scouts. It used to make our 18ft rowing boat move up to 10 knots on open water. That will make a small racing boat go like the clappers. Pehaps a different prop designed for a quicker boat also?

Iv had a crankshaft reclaimed some years ago. The bearing surface is built up with molten metal & then reground to orig dimensions.

Daryl wrote:Bearing surface where needles run should be as Smooth as. If not perhaps its been run with the wrong oil mix. The 1970s specs further up should be close for clearance specs.

Bearing surface is good very minor marks, hard to see them.

It measures just under 1/2 thou under size.

So should be ok to use. Big ends I am not so sure about, will post more on the AOMCI site about Evinrude conrod play.

H-A

May i ask a question as i have a 6hp fisherman model, not sure of its age as the ID plate is missing.
My question is, ive no spark on one of the plugs. Are the HT leads supposed to be carbon or solid copper cores as i have one of each on the engine??

xtaffy2 wrote:May i ask a question as i have a 6hp fisherman model, not sure of its age as the ID plate is missing.

If you go on this website http://www.crowleymarine.com/ you will be able to find the year of your engine by looking at the hood decals.http://www.crowleymarine.com/johnson-ev ... /41121.cfm

Also the main change was 1980, pre 1980 had rounded lower mount housings.

Not sure of the leads, my guess would be copper, if you have no spark look under the flywheel and test the coils.

This is worth a look http://www.youtube.com/watch?v=kRUb9nnZ9Dg , let her rev

H-A

This is worth a look http://www.youtube.com/watch?v=kRUb9nnZ9Dg , let her rev

That run out of water a little quicker than expected.

If you have a Jon/rude from around early sixties, it will need new coils, I have four OMC's, all with cracked coils, also all have copper leads.
Coils are just over a tenner each, still waiting for a set to go on my 58 18hp Evinrude, the coils are pretty easy to get, other parts are a lot harder to find, especially the older stuff.
The only motor that you have to unscrew and remove parts to open the lid, makes sense.

I took the CDi apart, what a job it was never designed to see the light of day.







I have tested all of the diodes and they are high resistance one way and low resistance the other.

All of the resistors have continuity.

Not sure about the capacitors?

Measured from gate to cathode on the SCRs, and there was continuity, no continuity on the other leg.

Are the SCRs latching

Now i need to identify the component, so I can buy a replacement.

H-A

The SCRs do latch on but they switch off when the voltage drops to 0V on firing the coil. I f you know which cylinder is not firing trace the wire back to the SCR on the board, that circuit is where the fault is. Will get back to this later as half day on radio duty with Sea rescue.

Thanks HA and Kieth for those links.
Turns out i hav a 1972 model 6202D or 6203D. Both coils have been replaced by previous owner and are working fine, as with the HT leads both have nasty kinks in them and the carbon one is the worst. so i will replace both leads with copper.
Geoff.

There is only 2 SCRs the faulty one may not want to turn on. I use BT151 SCRs 500V @ 12Amp, $2.50 each here. I would just replace either the faulty one or both at that price.

Thanks Daryl.

I have ordered 2 new SCRs.

The similar looking component on the right, is that the triac? It looks like it has been hot, is it worth replacing that as well?

If so what sort of value should that have?

I did wonder if it was worth replacing the big capacitor while I am at it, I assome it is 1Micro Farad 500v dc from what is written on it.

H-A

If one coil was giving a good spark then the condencer & the triac are probably ok. Id start with the SCRs first & see what happens when you get the motor back to gether. Leave the board as is for testing. Any chance of some nice clear pics like you have done, of a full view of the component side & one of the copper track side looking straight down on them? The voltage across the condencer when running should be around 350V dc. If it is then the triac should be ok.

xtaffy2 wrote:Thanks HA and Kieth for those links.
Turns out i hav a 1972 model 6202D or 6203D. Both coils have been replaced by previous owner and are working fine, as with the HT leads both have nasty kinks in them and the carbon one is the worst. so i will replace both leads with copper.
Geoff.

Here is another useful site Geoff.

http://www.sschapterpsa.com/ramblings/OMC_6hp.htm

H-A