Mercruiser 140, starts when cold, won't start when hot?

[Jason]

These are the spark plug adapters in your kit.


I have the exact same tester. The tuff part is getting your 140 on TDC as they don't have a crank shaft bolt to manually crank the motor.

[Neutron68]

These are the spark plug adapters in your kit.

Yes, I know those are the adapters.  I tried them both. 
Neither will thread into the 14mm spark plug holes in my engine block.
It feels like the threads never engage at all.

The tuff part is getting your 140 on TDC as they don't have a crank shaft bolt to manually crank the motor.

I was wondering about that.  Please tell us how you made it work.

Eric

[hemi RT]

These are the spark plug adapters in your kit.

Yes, I know those are the adapters.  I tried them both. 
Neither will thread into the 14mm spark plug holes in my engine block.
It feels like the threads never engage at all.

The tuff part is getting your 140 on TDC as they don't have a crank shaft bolt to manually crank the motor.

I was wondering about that.  Please tell us how you made it work.

Eric

Are your plugs long reach? You may need a longer adapter, maybe check with a Snap-on tool dealer as they do have all the different adapters.

[Neutron68]

Looks like a normal plug.

[hemi RT]

Looks like a normal plug.

Yup, normal reach plugs.

[Plugcheck]

Is it possible the threads are the same, but the adapter has too wide a shoulder to fit into the recess?  One possible solution, and I did this for a Toyota v6 once, is take an old sparkplug, remove the insulator, center electrode, and weld on a fitting that allows connection to your tester.  No welder?  Could jb weld it possibly?

[Jason]

I was wondering about that.  Please tell us how you made it work.

Eric

I've never done it on a 140. Only used it on an outboard. Tapping the starter might get you close. Or maybe put a pipe wrench on one of the supporting ribs on the crank pulley?

[Plugcheck]

If all four plugs are out, and dizzy cap is off, I just turned the crank with the alternator pulley/belt.  The rotor will point to the cylinder you need to test. 

[Neutron68]

If all four plugs are out, and dizzy cap is off, I just turned the crank with the alternator pulley/belt.  The rotor will point to the cylinder you need to test.

Thats a helpful trick.  Thanks!

Sent from my SM-G920P using Tapatalk

[Neutron68]

I FINALLY got to try a lake test with the boat, since Dan took off the exhaust manifold and exhaust elbow and changed their gaskets.

We put the boat into the water with my new/old Ford Ranger and we drove around the lake for about 45 minutes.  I ran primarily at 2000-2500 RPM to get the water pressure up there, to stress any leaks that may be inside the engine.

At the end, we got it back on the trailer and shut off the engine. 
I towed it back to the cabin and checked the spark plugs - all dry. 
I ran the starter with all the plugs out - no water sprayed out of the plug holes.

I'm finding it hard to believe it was cured by changing exhaust manifold gaskets, but it sure looks that way.

Eric

[Plugcheck]

The gasket between the manifold and elbow can allow water into the exhaust.  If you look inside the elbow you can see the jackets open up after the turn.  Let's hope you found the fix, and can enjoy you boat for a few weeks before winterizing.

[Neutron68]

Let's hope you found the fix, and can enjoy you boat for a few weeks before winterizing.

Thanks!  I hope so too. 

My hesitancy to believe it's solved stems from Dan's comments to me that the old gaskets didn't look bad when he removed the manifold and exhaust elbow. 
Also, the photos of 3 of the mating surfaces to the gaskets that didn't appear to show any signs of water leaks:
http://forum.cgoamn.com/index.php?topic=6789.msg100026#msg100026

Eric

[Neutron68]

Would it be a bad/dumb idea to buy another engine as a backup?

If I were to find a reasonably-priced (around $1000), known-good Mercruiser 140 engine, should I buy it and keep it for insurance or parts?

[Plugcheck]

     That's really a judgment call, no one can tell you how to spend your money.   If it were me, I go through the engine over the winter, probably the drive too.   Hard to say what is a reasonable cost for a 140 engine, never had to buy one.  The one I owned was ultra reliable, but that's after going through a gasket set, rebuilt carb/starter, and all new electronic ignition, which I believe is where your at now.   All boats, even new ones, can leave ya stranded so having a plan, cell phone, or buddy with another boat is always a good idea.   Best of luck to ya, Michael

[rmorit01]

I went through the "water in the oil" on a mercruiser 140 but the damage was already done to the cylinders.  So I went with a rebuild on the existing engine, but through my local marine mechanic who sent it out - problem solved but it took time and it was an expense that I didn't plan for.  However, it was worth it in the end.

The main issue I think you will encounter is finding the "known" good engine for the $1,000.  I watched craigslist looking for an engine and then the various versions of the 3.0 would require many parts to be moved over from the old engine to the donor.  Most of what is out there is some unknown where someone pulled the engine and can't guarantee how it will run.

For example - here is one for $150 http://minneapolis.craigslist.org/dak/bpo/5817304213.html - but I if it is any good I bet it is gone and you would have to get it checked out or just use it at the basis for the rebuild.

[Neutron68]

For example - here is one for $150 http://minneapolis.craigslist.org/dak/bpo/5817304213.html - but I if it is any good I bet it is gone and you would have to get it checked out or just use it at the basis for the rebuild.

I nearly fell off the couch when I saw that price and ad content!  My imagination is on fire!
Even as a parts doner, nearly any engine is worth more than $150, isn't it? 
Take all the major parts off and each one could be sold for $100, I'm betting. 
I mean, that's what you'd pay for used parts on Ebay or Craigslist - $100 each.

I was thinking about this $1100 (OBO) boat in the 507 area code (southern Minnesota):
http://rmn.craigslist.org/pts/5783826649.html
It looks to be an SSV-177, like mine, only in a super ugly color scheme (brown and yellow).
"Engine head recently redone".  Doesn't that mean the head has been machined flat and the head gasket has likely been replaced, too?
I would guess the piston rings were at least examined while the head was off?

Have pickup, now...can travel and haul!

[Jason]

Would it be a bad/dumb idea to buy another engine as a backup?

If I were to find a reasonably-priced (around $1000), known-good Mercruiser 140 engine, should I buy it and keep it for insurance or parts?

That's why everyone should have at least two boats. If one goes down, at least you got a spare till you get other one back on the water!!