[John]

Lee,

Regarding your “larger amp output?” question, here’s my experience on a 2006 6BTA 270 HP JWAC.  My original OEM 19SI 105 amp alternator crapped out in 2013.  While I had considered a new, high priced, external regulated, high output Balmar-style alternator, my local alternator guru did a repair putting in a 160 amp stator.  The OEM frame would support up to a 200 amp stator.  Over the years, I’ve had repairs on this original alternator… diodes, trios, regulator, battery posts, broken wires. et al.  After 19 years, 2,800 hours, it is still running strong with the 160 amp stator.  Repair costs to date, half the cost of a Balmar alternator.

[John]

Winter haul next week.  I pull the belt to plastic wrap alternator over the winter (I’ve had alternator components fail over the winter in cold, damp, salt air).  I’ll pull the tensioner off to inspect and replace if necessary.  Thanks.

[John]

If you know a good alternator rebuilder (or learn how, it’s not difficult), you can rebuild the original Delco 105 amp with a 160 amp stator.  This alternator frame will accept up to a 200 amp stator.  I’ve had my 18 year old alternator rebuilt with a 160 stator.  Salt water environment is tough on the puny components and wires in these things.  I’ve had a couple of subsequent fixes (diodes, brush wires, battery posts, etc).  The boat is hauled for Winter, and I either pull the alternator off or wrap it in Stretch-Tite plastic wrap over the Winter.  The old alternator is still pushing a solid 160 amps.

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[John]

Jimmy,

I replaced the Sherwood pump with the SMX pump on my Nordic Tug’s 6BTA. If you need to jack the engine slightly to remove the pump, here’s what I did. The engine mounts are sitting on stringers, and the space underneath the engine, from oil pan to floor, is only a couple of inches, and that space under the engine is an integrated black water tank. No way can I put any load on that floor without compressing the floor, and cracking the tank. What I did was place a pressure-treated 2×6 (much more denser wood) on the floor tight to the stringers where it’s solid. I screwed down a small steel plate with a hole in the center. Remove the 19 mm nut on the isolator holding the motor mount. You should slightly loosen the other isolator bolts as well. Place a bolt under the corner of the oil pan, with the nut sitting on a couple of fender washers, and start unscrewing the nut (that raises the engine). Screw down the nut on the bolt until the washer under the motor mount is loose. You’ve removed enough weight to remove the motor mount. It doesn’t take much lift. It’s possible for one person to hold the bolt and screw up the nut, but with limited access and leverage on my engine, it was easier with 2 people on either side of the engine, one holding the bolt and another turning the nut.

Going with Tony’s recommendation, I shaped a 1/2″ aluminum plate to place at the base of the motor mount. That in theory will gives you access to the bottom inboard bolt on the pump for future removal.

[John]

My average seasonal (April – November) fuel burn includes running 5 knot channel/no wake zones, cruising at about 10 knots, some higher runs for weather/sea conditions, drift fishing, running at high idle to top house batteries when anchored out on cloudy/rainy days (I have an 8 amp, 16.5 volt, 130 watt solar panel). For 15 years, my seasonal average is 2 GPH.

[John]

Thanks Tony. I’ll order a 180 stat. As I mentioned, my 10 knot cruising speed keeps engine at around 1600 RPM. While I can hit 18 knots at WOT (2600 RPM) with the NT’s semi-displacement hull, I’ve been spoiled over the years with my average 2 GPH fuel burn.

[John]

I’m running a 6BTA 270 HP JWAC engine with original 180 degree thermostat. Boat purchased new in 2006, and I’ve put on about 2300 hours. In a previous HX post, I mentioned that with a cold start, temp goes up to about 195 degrees before thermostat opens and falls back to normal operating temp. Tony suggested a sticking thermostat. I’ve kept raw water system clean with periodic acid flushes and fresh water rinses. This engine powers a Nordic Tug, so I’m in that category of running in the low RPM range, where cruising is mostly in the 1400 – 1600 RPM, with occasional higher runs and WOT “clean out” blasts. Normal operating temperature is about 182 – 185 degrees in cool New England waters. If I bump up to higher RPM’s, I’ll see temps move up to 195 or more.

Ten years ago I had a belt shred under WOT and engine overheated before shutdown, so I’m a little anal about running hot. I recently purchased a Seaboard 160 degree thermostat to have on hand. On these 6BTA temperature discussions, Tony is saying that anyone running high RPM engines should have the 160 degree thermostat, and slower running engines should stick with the 180’s. Tony’s comment here… “Original stats are 180F.. Most engines run in the 185-195F range when things are right…” I’ve also seen Tony’s comments that these engine are designed to run a little hot. So it appears I need to keep this engine on a 180F degree thermostat. Right? (Tony’s response would be appreciated).

[John]

Matt,

This is a recent response I made in a trawler forum, on a post asking about Barnacle Buster, and a cheaper solution for a flush.

“I did a Barnacle Buster recirculating flush a few years ago. Works great and something you should do every once and a while. What I’ve been doing every year at the time I winterize the boat, is to soak the raw water system with a product called “Acid Magic”, about $20 a gallon. Acid Magic is a buffered phosphoric solution used to clean pool systems. Much less toxic than muriatic acid and easy on the skin. I just mix up a 10:1 solution in a 6 gallon jerry can, pour it into the top of the strainer (no issues with my SMX pump’s impeller), and let it sit for a couple of hours. If you’re doing a recirculating flush, you probably want to go with a stronger 4:1 solution. Flush with another 6 gallons of water and a box of baking soda to neutralize the acid, then another running flush with water for a few minutes. I then fill the RW system with RV antifreeze. That’s been keeping my system clean without the hassle of a recirculating flush. I should note that while I cruise and fish in salt water, I moved to a fresh water marina a couple of years ago. Recirculating acid flushes aren’t as critical for me as in the past.”

[John]

Does you’re 4BT have a grid heater or glow plug (air pre-heater)? With a pre-heater shut down or not working, my 6BTA is difficult to start in cold weather (below 50 degrees).

[John]

After one of the contactors shorted out, I removed the ECM, all contactors, and wiring harness (that was fun). I could wire the heater grid in the JWAC, and control it with a switch, but I’ve not found the need for the heater. The boat is active from April to November in Rhode Island, and other than April and November, I’ve not had a problem with cold starts. I’m on a slip, plugged in, and the block immersion heater (Fleetguard #3825424) is on during the cool April/November months.

[John]

A good paint match is a 50/50 mix of Rustoleum gloss white and gloss almond. 8 ounce cans are good for touch-ups.

[John]

Have you considered rebuilding your alternator? Any good alternator/starter motor repair guy can do it. I had my Delco Remy 105 amp alternator rebuilt ($160) to include regulator, diode trio, battery post, and a 160 amp stator. This Delco frame can take a 200 amp stator. In 14 years I’ve had this alternator rebuilt twice. Both times where failures in components due to salt air environment. For the last couple of years, I pull the alternator for Winter storage (Rhode Island).

[John]

Kevin,

I see you had the issue with the impeller blades expanding inside the case as you push the impeller in. I’ve found that the easiest way to deal with that is to remove the top hose flange (hose to the fuel cooler). That exposes the interior of the case, and you can bend the blades as needed when you push in the impeller.

[John]

Corey,

I assume Tony’s “this may help” was a reference to Tony’s Tips. I was able to find a couple of articles on air heaters. More than likely he’s referencing the “5-minute Twist Timer or Momentary Switch” schematic and the picture of a contactor mounted to the JWAC.

For now, I’m going to remove all the components and wiring from the ECM and contactors. I’ll mount a switch on my console to activate the heater during startup. Do you guys sell the magnetic switch contactor for this fix?

[John]

Tony,

I generally cruise at about 1600 RPM (Nordic Tug 34). Will run at higher RPM (+- 2000 RPM) only to run from weather, or to push through some section of fast running water. I’ll also periodically run WOT for 15-20 seconds when coming back from a long cruise to “blow out” whatever. To your comment, if thermostat is sticking, when it comes time to replace, would you recommend the 160 degree t-stat on this engine ?

[John]

I’m a little confused by what may be a normal process. I’ve got a 270HP 6BTA JWAC, CPL 2956. For 13 seasons, I’ve had this same process described. I start engine and will take off at relatively slow speed, say 1000 RPM. Over the course of time, depending on water temp and RPM, I watch the temp rise from zero up to about 195-200 degrees, then immediately fall back to its normal running temp between 182-185 degrees, and will maintain that “normal” operating temp throughout the day. I will only increase operating RPM once I see the temp fall back to normal operating range. Temp will increase to a max of 200 degrees as I move towards WOT (2600 RPM). According to my CPL 2956 Cummins spec, the original t-stat has an operating range of 181 to 203 degrees. I periodically acid flush the engine, and have replaced the factory Sherwood 1730 with the Seamax pump. I believe what we’re seeing is the normal operation of the standard thermostat opening up at somewhere around 195 degrees, then allowing cooling raw water to flush through the engine. Some have suggested replacing the t-stat with a 160 degree unit. This may be appropriate in warmer waters, but up here in New England, the factory t-stat seems to be working fine. According to Tony A, this CPL 2956 engine likes to run a little hot. What am I missing?

[John]

OK. I applied a 2-part plumber’s epoxy to the “sweating” areas on the tube edge above the bevel. Let it set for a couple of days. Ran a test today, and NO LEAKS. I have no idea what’s going on. I still don’t see any drips from the cap or gasket.

Once the thick coat of original paint started to bubble off (the paint covered cap, exposed gasket, beveled area, and tube), and after I removed more paint to see what was going on, that’s when I saw the obvious oozing. The epoxy may just be short-term fix. If I start to see significant leaking, I’ll order a new cap, gasket and washer. I will also apply a very thin coat of Permatex Form-A Gasket 2A (semi-permanent, non-hardening) on the outside edge of the cap and the flat outside edge of the HX tube. Will see what that does. At the point where I need to pull the HX to resolve a more serious leak, I’ll first start with soldering that edge and a pressure test before going with a new HX.

[John]

Bob,

I doubt that cap uncupping is the issue. While running and inspection after the gasket change, I had my eyes inches away from the cap and gasket looking for any leakage at the site. Nothing. Edge of gasket and cap remained dry. The water was oozing from the top edge above the bevel. Weird. That cap and bolt hasn’t been touched since the boat left the factory in 2006. The first time a wrench touched that bolt was a couple of days ago when I pulled the cap to change the gasket. If the consensus is the cap, I’ll just order a new cap.

Sorry about the orientation of the photos guys. Just rotate 90 degrees.

[John]

Update… after removing cap on expansion tank and removing a little antifreeze, no additional leaking. I’ll assume freeze/thaw cycle caused pressure and forced some antifreeze out of hoses somewhere. Once in the water, I’ll watch it. Will check hoses and clamps more often, and release expansion tank cap next Fall as we go into Winter storage.

[John]

I replaced my factory strainer with the Groco access door strainer on my Nordic Tug 32+. Pull the door off and clean out strainer and thruhull every Winter haul. With the hull a little over 1″ thick at the thru hull, I bonded and screwed the strainer to the hull. Works fine. No issues after 13 seasons. Make sure you position the strainer forward and the door rearward. Door creates a water ram-jet effect up the thruhull.

[Author]

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