1978 Merc 260 Slow to Crank, no Start!

S

Starvin48

New Member
Aug 11, 2008
64
New Baltimore, MI
Boat Info
1978 SRV 240
Engines
Mercruiser 260
Greetings to all. This is my first post and I'd like to ask a question about my first Sea Ray.

I had it out over the weekend and ended up at full throttle on the way back (to beat the ugly weather coming in on Lake St Clair). We ran for about 25 minutes. All was well, until I got back to the launch. Upon easing the throttle back, the motor shut down. It would not restart, and cranked more slowly than usual (usually cranks pretty slow).

Help? Thanks in advance as I am mechanically inclined but boat-motor-challenged :smt001

Marvin

PS - I did a search, but the search feature didn't seem to work. I then went through 30 pages of great information, but nothing answered the questions I have. Thanks again!
 
Last edited:
I see everyone who read this is as puzzled as I. What more information would be useful in diagnosing the issue?

Again, thanks for any thoughts.
 
It didn't get overly hot, according to the temp guage which I believe is working correctly. It never left the range at which it normally operates.

I haven't been able to get back to the boat to try it out since Saturday; I'm attempting a run tomorrow. Regardless, it seems to be slow to crank all the time. Just this time, after 25 minutes or so of pinned throttle (can't be good for a 30 year old motor) it cranked even slower and would not start.

Thanks for the inquiries. Any ideas?
 
More questions.
How was the oil pressure?
Engine temp?

Heard of more than one of these locking up after a hard run and NOT cooled or slowly bought to rest.

On the cranking slowly all the time.
Battery conditions?

Cable condition (corrosion, condition, tightness of the terminated ends)?

Starter condition? Need to do a current draw test. What is the voltage BEFORE you hit the key? After?

Check all available B+ conditions.

DG
 
Oil pressure and engine temp both normal according to previously tested and working gauges. Batteries both new and alternator seems to be charging them, as I thought they were suspect earlier only to find they were fully charged.

I'm going to get right on the cable conditions (should've done that in the first place), but don't know much about the starter. Is it known for a starter to crank more slowly before it craps out? In every dead starter I've encountered, it's either cranking or smoking and dead.

Thanks much for the input; I'll be checking everything out before launching tomorrow afternoon, so any other input would be awesome!
 
It is definitely possible for a starter to crank slowly when it is older, has bad connections or potentially bad wires/connectors. You're on the right track to go and check your battery/starter connections - remove them, clean it all with a stiff brush and reconnect everything. Check your connections at the battery switch (if you have one) and the solenoid(s) - you may have a starter solenoid and a slave. Good luck.
 
UPDATE -

My oil is the color of cappucino and has the consistency of pudding. And there is much more in there than should be.


Analysis -

Uh oh... :(
 
I have a guy that will tear it down this weekend. He says that the motor is most-likely not destroyed, which is somewhat of a relief. Just wondering if this has happened to anyone else here. I'd really like to know the outcome.

And I thought it was electrical.

The amazing thing is that we got all the way across a very large lake and it died just twenty feet away from the dock. Someone was looking out for me!
 
Ran hard.

Seized when brought to idle.

Since then, it cranks hard.

Oil looks like pudding.

Is this pretty much what happened?

I have heard of a similar deal, but it was a bearing starvation issue, not an oil dilution thing.

I'd scrap any moving part and start over. The block , unless cracked, after crack check, might be OK or at least fixable.

Heads most likely where the water came from. Or intake manifold area.

Lots of great buys in JEG's or SUMMIT for crate truck engines, like this. Cheap, complete, new if you're in the market.

Keep us posted on the outcome!

dg
 
the cyl. head(s) are probably cracked i have done many of these, one just two week's ago. not sure how many hrs. you have on this eng. (1978) but you may want to consider a replacement over a repair as the lower end (crank and bearings) has now been compromised because of the diluted/contaminated oil...
 
Motor overheated in 2003 and head(s) replaced. The previous owner kept meticulous records and passed them on to me. The motor has never been abused, but has 1073 hours. I plan on doing whatever I should do, as the boat is pretty spotless and almost preserved.
 
Not a huge deal. Inconvenient for sure and a cost you didn't need. Good time to review options. Might want to upgrade!

Good Luck!

dg
 
Well sucks to hear about that but a new engine in an otherwise nice condition boat(as per your description) will give you peace of mind after you get back out there.

Best of luck and keep us posted.
 
Thanks, everyone, for the kind words and advice! I have one more question:

Is this motor a 2-bolt or 4-bolt main? I am just assuming it's a 4-bolt, but don't know for sure. Thanks in advance for helping this newbie get back on the water before the leaves change!
 
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