Power Head Cross Reference for 1958 Evinrude Fisherman 5516

[fleetwin]

OK, just typed a response, but this website is not responding correctly.

Great information, alot of questions answered.  Were those taper pins bunged up when you disassembled it?  If so, I have no doubt someone was in there before.  Finding two washers under the connecting rod screws confirms this.

And yes, that lower rod is binding on the crank for sure.  I am confident that new rods with solve this issue, but lets try one more thing to be sure.  Bolt the upper rod to the lower journal and see how if rotates, if you haven’t done this already.  We will have to look closer at the crank if the upper rod binds on the lower journal.

Once the new rods come, mark them carefully, and bolt them to the crank to be sure they turn freely.  The new rods should come with new lock plates, they can be ordered separately if necessary.  Do not attempt to use the two old lock rings.

Now, we must look into that ring end gap situation.  I suppose it is possible that someone has bored these cylinders oversize and didn’t do the correctly.  Or perhaps, the rings used were not OEM and just don’t fit properly.  Usually oversize pistons are stamped with the oversize dimension on the piston dome, but maybe not on these older pistons.  So, we may want to measure the piston skirts and cylinder walls to ensure this powerhead is still standard bore.  If it has been bored oversize, we may be in trouble.  I suppose it is possible that someone used oversize rings, but I really don’t think they would fit in a standard cylinder.  You should not have to file the ring end gaps to get OEM rings to fit properly.

Thanks again for all your great pictures/videos/answers, I think we have gotten to the bottom of this issue.   Don

[fleetwin]

Just out of curiosity, who/where did you buy this engine?   Not my business, but curious.  I have my suspicions if you bought it from a guy down south.  D

[Mike Nazarenko]

1. Regarding the paint.  It looks original.  Was the crankcase opened before – – I don’t have enough experience here. If original I would think the pistons and crank rods would be more identical in color .
2. Purchased this engine in Rochester, NY.
3. Attached the flywheel to the crankcase with only the top piston with rings.  There is minimal resistance, guess you call that rolling resistance.  Without the bottom piston it turns freely.  Here is the video   https://youtu.be/3h77KJXe_F4
4. Before I disassembled the crankcase with just the top piston in I did a compression test, all cylinder head bolts and crankcase screws were torqued to 60 in lbs.  Compression test reading was 60 lbs.
5. Disassembled the crankcase and put the top piston into the bottom cylinder, torqued all cylinder head bolts and crankcase screws to 60 in lbs.  Compression test reading was 60 lbs.
6. Disassembled the crankcase put the bottom piston into the top cylinder and gently torqued the crank rod cap screws, secured the other half of the crankcase.  Cranking was difficult, confirming the bottom crank rod journal is bad.
7. Cylinder bore and piston measurements in attached photo.  Not easy to do.  Not sure what to make of the measurements.  If you believe the readings the piston shouldn’t fit into the cylinder.
8. Ordered parts yesterday from EdE, very helpful.
9. Everyone thank you for your helpful comments.

[fleetwin]

Standard bore on this engine is 1.9375″ (1-15/16″), so I’m guessing your engine is still standard bore.  Measure your pistons as close to the bottom of the piston skirts as possible.  As you say, the pistons shouldn’t fit in the bores if your measurements are correct.   So, I would order new standard OEM rings and recheck the end gaps.  Maybe a light honing will remove any debris that might be closing the ring end gaps, looks like minimal ring end gap is .005″.

Were the alignment pins messed up before you removed them?  If so, someone has been inside before you, perhaps they repainted the powerhead.  The engine did not come with washers under the rod screws, those steel lock plates should have been in place.  It is for these reasons I feel someone had the powerhead apart before.  Nonetheless, I feel confident the crank is OK and two new rods will solve the fit issue.  Make sure the new rods come with those lockplates, they can be ordered separately if needed.  The little lock rings that hold the wrist pins in place on the pistons should be replaced also.

[Mike Nazarenko]

1. Regarding the rings, are you suggesting that new ones be purchased.  The only rings available are  0378417 : 0378417 is 0.020 inches oversize and very few available online.  As I mentioned I was able to get a compression reading of 60 lbs on the bottom cylinder with the current rings.  Before I did the cylinder bore measurement I wiped down the cylinders to remove the debris.  If new rings are .020 oversize I will need to file them down and will need some help in how to best do that.
2. On the rings – – if the current rings have gap of .002 and .005 and there is compression reading of 60 lbs, what is the purpose of getting new rings, why not fit them both to .005.  At this point the additional cost is moot, but just asking.
3. Don’t believe the alignment pins were messed up originally but its hard to say now.  With the number of times I have reassembled the halves one came out and I knocked out the other.
4. As far as the connecting rod lock plates they were only on the top piston, not on the bottom one which is the connecting rod with a different color, suggesting that the rod was replaced and the lock plates left off during the repair.
5. There must be an issue with my digital caliper, I measured at the bottom of the piston skirt,  top piston – – 1.934, bottom piston – – 1.935.  I remeasured the cylinder bores,  top cylinder bore .1.9215, bottom cylinder bore 1.9230 which means the cylinder shouldn’t fit but it does.
6. Thank you for your continued comments.

 

[fleetwin]

Replacing the rings is a judgement call for sure.  Do not try to use oversize rings and file them down.  Perhaps the rings were replaced when this unit was apart before explaining the tight end clearances.  I’m sure there aren’t many hours on this unit since it was apart or that lower rod would have probably gave way from the crank and poked a hole in the block.  I am suggesting using new standard rings “just in case” the previous repair included some peculiar/oversize ring replacements.  You want to make sure the ring grooves on the pistons are totally cleaned out also,  oftentimes old rings are used to do that job (break one ring and use its sharp edge in the grooves).

Did you ask Ed if he has new rings?  I will look online also.  Again, replacing the rings is a judgement call for sure.  Using the old rings will be fine,  provided you ensure the ring grooves are clean so there is no debris/carbon pushing the rings out into the cylinder.  This can be done by installing all the rings on the pistons, then rotating a straight edge around the piston to ensure none of the rings are being pushed out past the edge of the pistons.

Again, don’t forget to make sure you have four new lock rings for the new rods, along with four new wrist pin retainer clips.   Review the procedures for pressing those wrist pins out.  Again, you must press the pins out from the tight side through the loose side, then press them back in the same way.   You will want all new powerhead gaskets also, and please make sure all the parts for that lower power head seal assembly are there, replace the carbon seal oring and the round driveshaft gasket.  You will want to check the igntion and fuel system as well.  You will want to review the procedures for using the OMC gel seal to seal the crankcase halves, or use the 847 sealer.

[Mike Nazarenko]

Going to stay with the original rings. There are only oversized rings on line. Was going to “file” down the ring at .002. Any suggestions.

Parts arrive soon.

Was going to use Permatex Ultra black on the crankcase halves. No gasket sealer of any kind on the head gasket. What about the gaskets on the intake side. I’m thinking not.

Will review the service manual for the wrist pin removal install. Will use a jig to support the piston.

Thank you.

[fleetwin]

I would not use anything other than the recommended stuff on those crankcase faces, especially nothing with silicone in it.  This sealing area is critical.  Inappropriate sealers may dissolve when exposed to fuels/heat/exhaust.  Too much sealer will ooze into passages and might actually shim the crankcase halves apart.  Not enough sealer will create leaks that can only be repaired by disassembling the powerhead again.

Like I say, there are two options.  The conventional OMC “type M”/847 sealer.  The upside of this sealer is that it dries hard and won’t leak.  The downside of this sealer is that it is messy to work with and dries quickly.  So, assembly of the powerhead halves must occur quickly after the type M/847 is applied or the sealer will set up and the halves will be shimmed apart.  The OMC “gel seal” is an anerobic sealer, it only dries in the absence of air.   So, there is plenty of time to apply the sealer and bolt the halves together.  The downside of the gel seal is that it won’t set up if the crankcase faces are oily/greasy, then you will have crankcase leaks when you start the engine.  I would contact loc tite, I’m sure they make a comparable product to the OMC gel seal that is an anerobic sealer that is meant for this job.  I can not over emphasize the importance of proper prep and sealing.  Do it wrong/use the wrong stuff,  and you have to pull the powerhead apart again to reseal.

I would not attempt to file the piston rings.  Something is wrong if there is no ring end gap.  I would give the cylinders a very light honing, remove the rings and measure again.  Use the piston to square the rings up in the bore, measure the end gap in a few different areas.

 

• This reply was modified 3 years, 2 months ago by fleetwin.

[aquasonic]

Here’s the Permatex 51531 Anaerobic Flange Sealant that works well for crankcase halves. This is the purple colored version which is a bit thinner than the red one 51813.

Improvise-Adapt-Overcome

• This reply was modified 3 years, 2 months ago by aquasonic.
• This reply was modified 3 years, 2 months ago by aquasonic.

[fleetwin]

Read, and follow the instructions very carefully.  This is such an important step that is often overlooked and done poorly.

[Author]

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