Assessing a used Yanmar 8HP diesel engine

[mcpusc]

if the warning on CLR scares you off, Rydlyme is advertised as safe for cast iron.

[HorseshoeBay]

Back at it.

The exhaust elbow rusted through and is being cut off with a hack saw.

Does anyone know about exhaust elbow replacement bolt specs, diameter, lengths and thread?

[Wotname]

99% sure it is a M8. I can't recall the length(s).

[HorseshoeBay]

The rusted exhaust elbow was removed by using a hacksaw to cut around each bolt.


The remaining cast steel around the bolts provided leverage, allowing them to be unscrewed.


The size of the bolts can now be seen.

[HorseshoeBay]

The valves were lapped with two grades of compound.

Is there a leak test that doesn’t require special equipment?

[Wotname]

Hopefully one of the real mechanics will give you a precise answer but in the meantime here is my rough and ready approach. With the valves and springs in place, fill one side with petrol and see if any leaks through.

[HorseshoeBay]

Pulled out the cylinder liner.

[mcpusc]

Originally Posted by HorseshoeBay

Is there a leak test that doesn’t require special equipment?

pour some light solvent (acetone/naptha/brake cleaner/etc) on top of the valve on the combustion side, it shouldn't leak through... or at the least it should leak through very slowly.



thanks for keeping the thread updated!

[MicHughV]

what a great thread...love reading comments, ideas and suggestions presented by people that know what they are talking about....well done !!!!

[deltaten]

Given the OP's comments and photos.....
What you have is a pile of rusty, worn out parts. Sell/give away to someone wanting a project. At this point, it will be easier/cheaper to replace. Prices on good, known, used engines are down. Find a likely candidate, hopefully something with a bit more oomph and swap it out.

Best of luck to ya

[HorseshoeBay]

The head area of the engine has light rust due to water dropping from a cockpit fitting leak, which has been sealed.


The rest of the engine has the original silver paint and appears much better.



The boat is for sale and the aim is to get the engine to run again.


I have a rebuild kit with new cylinder liner, piston and rings, and other service items: thermostat, impeller, filter and fan belts.



Rust converter is coming.

[MicHughV]

please keep us updated...would love to hear you got it running again...

[HorseshoeBay]

"What can go wrong?" from now seems an important question to consider.


Need:
- compression
- fuel injection
- air
- timing.


Right?



Other service matters include filters, fan belts, impeller servicing and reconnecting the electrics.



Ideas appreciated

[MicHughV]

Google is your friend in these matters....Google and Youtube as someone is bound to have done it all before.

[HorseshoeBay]

So much online experience is from amateurs, like me.


Expert diesel professionals have deep knowledge.