When we bought Honey in 2011, the Kohler 6.5kw genset didn't work. It had very low hours on it (297), but it obviously hadn't run in many years, and there were many parts missing, including the carburetor, raw water pump, coolant circulator pump pulley, and throttle linkage. Also, this was originally a raw water-cooled genset. Instead of using a heat exchanger and antifreeze, this genset originally used river, lake, or ocean water to cool the engine. With such low hours, I was convinced it could be brought back to life if only I could find the necessary parts. But if I brought it back to life, I wanted to make it better than original...by converting it from raw water cooling to fresh, with a proper antifreeze heat exchanger.
This was the condition of the genset as found.
No carburetor. No raw water pump. Mystery parts hanging by wires.
Exhaust showerhead looked serviceable.
The block wasn't cracked, though it could use a paint job. Still, nothing looked like a deal killer.
Fuel pump looks to be all there, though I'm not sure about the two oil pressure senders and cut wires.
Fast forward to 2020.
Over the years, I found a replacement side-draft carburetor (the original was updraft but obsolete and unavailable), a New-Old Stock coolant pulley, and a Jabsco raw water pump. I also acquired a heat exchanger that was absurdly oversized for this application...which means it'll work great! I welded up some brackets for the Jabsco raw water pump and the heat exchanger, then painted the engine in place using Hatteras White Interlux polyurethane enamel that I've had for years. I also bought the following parts to get the fuel system and fresh water (antifreeze) cooling system working:
· Throttle linkage
o 2x Quick Disconnect Ball Joint, Carbon Steel, 10-32 Thread Speedway Motors Part #: 721BJDR3
o 1x 10-32 x 1’ 8-8 Stainless Steel Threaded Rod Mcmaster-Carr
· Heat Exchanger
· 3’ Trident 1-1/4” soft wall wet exhaust hose #110-1146 (coolant hose connections to heat exchanger) Fisheries Supply
· 5’ Trident 3/4” soft wall wet exhaust hose #110-1146 (raw water hose) Fisheries Supply
· Stant 45848 SuperStat Thermostat – 180°
· 2x Parker Hannifin 365HB-10N Nylon, 90° 5/8" Hose Barbs (raw water outlets on HEX)
· 1-1/4" O.D Aluminum Inline Radiator Filler Neck With Cap
· Custom raw water pump mounting bracket made from 1-1/4” aluminum L bracket
· Custom heat exchanger mounting bracket made from 1-1/4” aluminum L bracket
· Dorman coolant reservoir 603-001
Here's how it all came back together successfully in 2020:
The NOS coolant pulley, carburetor, and exhaust showerhead are test fitted.
This part that was hanging loose by a wire is the choke actuator for the down-draft carburetor. Since the carb I have is the later model side-draft version, I'm not sure how that's going to work out.
But the two mounting screw holes for the choke actuator open into the exhaust pipe, so I need to fill those holes with 1/4-20 screws. Might as well mount the actuator even if I don't end up using it.
Ironically, the original choke actuator works perfectly...the one on the side draft carb doesn't.
Side-draft carb choke has seen better days. But the motor is in great shape.
297 hours on a 1968 Kohler genset. It's barely broken in!
122~125psi compression test results for cylinders 1-4. That's outstanding for a flathead engine.
Time to put it all together. The shot above shows the coolant intake port (the circle in the middle of the picture), which will need to connect to the blue heat exchanger you can see in the background.
Spark plug wire #4 (r) is missing the spring needed to make contact with the plug, as seen on the #3 plug wire on the left. I found a copper wire spring (right pic) that will do the trick.
Like many marine gensets of this era, this one didn't come with an oil filter. The L654 that I parted out for the carburetor had an oil filter (left pic above), but the L600 had a specific (and obsolete) adapter plate for the optional oil filter mount. It could be that an assortment of fittings could make the L654 oil filter adapter work with the L600, but it's not absolutely essential. So for now, I'll just run it as Kohler expected: annual oil changes and no filter.
Next, I welded up brackets for a used Jabsco raw water pump and for the heat exchanger mounting bracket.
Raw water pump and bracket test fit looks good!
Test fitting the heat exchanger bracket.
On antifreeze (fresh water)-cooled models, Kohler used a heat exchanger that was integral to the fresh water-cooled exhaust manifold. Mine has a raw water-cooled exhaust manifold that doesn't have any provision for the HEX coils. So I'm using a completely separate HEX that's absurdly oversized. I got it in a box of parts that came with another boat, and I'll never need it anywhere else. Might as well clear some space in my garage and make this old boat genset that much better.
The pic above shows the new (old stock) heat exchanger, new hoses, and raw water pump test fitted to this 50 year-old Kohler.
Next, I removed the OEM head-to-exhaust manifold hose. That's the high point of the system, so that's where I'll put the radiator cap.
I need to find a 1-1/4" radiator cap hose adapter that's less than 4" long.
See parts list above. Amazon had what I needed, and it didn't break the bank. But it was just a bit too long.
I cut off the material that extended past the hose flare. With that gone, it was still too long for the 4" gap where the old hose was.
There's a 1/2" of material on that rusty hose adapter outlet that could be removed so the radiator cap adapter will fit.
That should do it.
The original thermostat has seen better days...
But the inside of the head doesn't look bad at all. I expected lots of rust from salt water being used as cooling water. It could be this wasn't run at all when the boat was on the Chesapeake. Maybe it's only seen fresh water run through it...
New radiator cap and hoses test fitted to the 50 year-old Kohler.
With all of the new cooling system parts test fitted, I removed them and moved on to the fuel system.
New fuel filter/water separator.
New fuel line is plumbed to the original fuel pump, which I disassembled, cleaned, and found to be in excellent shape. Not surprising, since it only has 297 hours on it.
Next, I painted everything but the lower engine block with Interlux Hatteras White polyurethane enamel.
Note that the Stant 45848 in the parts list above isn't a direct fit. I had to carefully grind back ~1/16" all the way around so it fit like the OEM (but obsolete and unavailable) Kohler thermostat. Because this thermostat has no 'jiggler' hole, which helps air escape via the cap, I also drilled an 1/8" hole in the base plate before installing it. I also added antifreeze through the thermostat hole to ensure that even if there are air pockets elsewhere that might cause the coolant circulator pump to run dry, the entire block and pump would start wet.
Ready to top off the antifreeze and burp all the high spots.
Coolant added.
That looks better. But it needs an overflow bottle (see parts list above).
The rest of the process of getting this old Kohler genset running can be seen in the videos below.