I mentioned previously that splash day didn’t go so well. I’ve got parts on the way to, hopefully, resolve a leaking OEM Chris Craft-branded seacock. But there’s actually a problem with my starboard Cummins 6CTA that’s got me stumped.
I test fired both engines at least a half-dozen times on land as part of my pre-splash punch list, with no impeller installed because there’s no raw water source. And the engine lit off reasonably quickly and had a stable idle even on splash day. But then it stalled and wouldn’t restart. Even stranger was that the engine wouldn’t even roll over with the starter after it shut down. Check out the video and watch it as it happened.
Scroll to the bottom of the video screen and click Cancel after the video is done or the host will roll another randomly selected video.
The Travelift operator hollered “GOOD WATER!” just before the engine shut down, meaning plenty of raw water was starting to exit with the exhaust. Then the engine flat-lined.
I also started the port engine, which lit off and ran perfectly for a minute or so, until I turned it off. So, two Cummins 6CTA engines with identical run time, recent maintenance (i.e. aftercooler service during the refit), similar dry-stack exhaust, identical waterlift mufflers, new batteries, new start switches, and tight wiring connections, but one starts and runs and the other starts, runs, dies, then won’t even turn over.
Once the boat was hauled and blocked again after the failure to splash, I put a wrench on the starboard alternator pulley bolt and rotated the crank through 8 revolutions. It feels perfectly normal. But when I try to start it with the starter, the starter engages but won’t turn the crank far before it stalls. If I manually rotate the engine a bit and engage the starter, it will start rolling the engine over but quickly stall out.
I presumed that raw water had somehow gotten into a cylinder, since the problem manifested just after the Travelift guy hollered GOOD WATER! I thought maybe I’d miscalculated the spillover height for the wet exhaust out of the muffler. If the muffler output loop is higher than the dry stack loop, I’ve been warned that water will naturally find level and pour over whichever spillover point is lowest in the event that the muffler overflows.
Dry and wet spillover heights look pretty similar from this angle
Similar spillover heights are a recipe for disaster. The dry side MUST be substantially higher.
But from this angle, it’s clear that the dry spillover height is at least four inches higher
There’s 2″ of insulation on the dry stack exhaust tubing, and even the lower edge of THAT was approximately level with the midpoint between the bottom of the wet loop (spillover point) and the top of the wet loop tube, which is 6″ OD. So there’s plenty of safety built into my riser.
But just to be sure, I pulled the wet loop and looked inside the muffler. If it’s filled to the brim, raw water may have somehow backed up into the engine.
Not a pleasant task
OK, it wasn’t a pleasant task, but I really appreciate that whoever designed this system gave some thought to future maintenance needs so everything is relatively easily accessible. 😉
Raw water is 1″ above the bottom of the exhaust pipe inside the muffler
The pipe inside the muffler ends ~2″ off the bottom of the muffler, so there’s only 3″ of water in it. The muffler was working right, and there’s no way water from the exhaust backed up into the engine.
But what if I misinstalled an O-ring when I serviced the aftercooler? The raw water goes through the gear cooler, then the aftercooler before continuing on to the heat exchanger and then the exhaust showerhead. If I botched an O-ring in the aftercooler, it could flood the intake air circuit. But if that happened I’d expect the engine to be waterlocked, and I wouldn’t be able to manually roll the crank over with a wrench on the alternator pulley bolt.
Better check anyway.
I pulled the tube from the aftercooler to the intake manifold
The tube and hoses were bone dry inside
Flexclaw pickup tool with a piece of cotton cloth probed the depths of the aftercooler
Bone dry
It appears the engine didn’t ingest water from the intake or exhaust. It was just a coincidence that the Travelift guy reported GOOD WATER just before the engine died.
If the problem was fuel related, the engine would turn over and not start.
I’m stumped. If anybody has any ideas, please leave a comment below.
In the meantime, here’s the video from Splash Day, the most interesting part of which was using the forklift to pull the Travelift out of the soft gravel while it was lifting my Roamer. Never seen that done before!
Next up in our 1969 Chris Craft Roamer 46 Refit: Starboard Engine is Back in Business!
1969chriscraftroamer46 
Your motor appears to be hydro locked. Pull all injectors and see what spits out of the injector holes. It may be a head gasket failure.
That’s what I thought, too! But there wasn’t enough water in the muffler or any water in the intake system to make its way into the cylinders and hydrolock it.
But I found the problem and solved it today: A single starter bolt was only finger-tight! The starter was getting intermittent insufficient ground.
What a relief!
Cheers,
Q
Try swapping the starters.
I might do that while troubleshooting the electrical system today. But a problem with the starter wouldn’t explain the sudden shutdown.
Stay tuned…
My cummins did something similar and it was fuel pump related
Hmmm. I just replaced the fuel lift pumps with brand new Cummins ones.
I’ll have a look-see today.
I can never resist a good puzzle.
Let’s not assume that the issues are connected; the engine cutting out could be due to a fuel issue – air in the line or other dirt/debris as a result of moving the boat.
Separate and unrelated to that, you might have an electrical issue with the starter or starter wiring – if something’s fused or grounding in the starter it would pull a lot of current and result in the lights dimming.
Just guessing – you get the fun of doing the actual diagnosis work 🙂
Good point about not assuming the issues are connected, Rob.
I’m going through the electrical system today.
Stay tuned.
I’m sure you checked this already, but could it simply be bad connections at the starter?
Thanks Bill.
Confirming all of the connections were tight was one of my pre-splash punch list items. But I’m going through all of them again today, from key switch to starter.
Stay tuned….
Do you have a battery parallel switch? If so try paralleling the batteries. If no crank When you try starting does the starter solenoid click. Does the Bendix just engage the flywheel and stop there? If the Bendix just engages the flywheel and no crank with the batteries paralleled I would suspect the starter.
Hi Bob.
If you watch the video in today’s article, it shows exactly what happened on splash day. The starter bendix engages and the starter turns the crankshaft a bit, then stalls. It’s all in the video. The batteries are paralleled, but they’re also brand new. It’s not a battery problem.
It’s a real head-scratcher.
Keep the ideas coming, though!
Q
I still like the starter.
I think you have an electrical issue at the engine – not enough voltage to hold the fuel stop solenoid open and not enough voltage to properly crank the engine over.
Thanks for the suggestion, Warren. But I don’t think that’s consistent with what the video shows. The first two cranks were… enthusiastic, and the engine ran great for ~10 seconds. So the battery has plenty of juice, and it’s getting to the starter. The fuel ‘hold’ solenoid only draws 1-2 amps @ 12v and is energized when the ignition is ON. The ‘pull’ solenoid draws 50 amps and engages with the starter. If the electrical connection was so bad that it couldn’t supply 1-2 amps @ 12v to keep the engine running, I don’t see how it could engage the starter and try to roll the engine over, as seen in the video.
But I plan to crawl over the on-engine electrical connections tomorrow.
Cheers,
Q