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Old 23-01-2012, 23:31   #1
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Location: Seattle, on Lake Union
Boat: Ranger 29, sloop
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Atomic 4 - Troubleshooting Question

Hello all. I have an Atomic 4 that has been well maintained, consistently, since 1974 (I have all the records since 1980) but last week when I was motoring the drive belt that runs from the alternator to the water pump frayed and almost broke. I turned the engine off as soon as I heard something odd and quickly went below to examine what went wrong. Here is what I saw:

1) The drive belt mentioned above was about to break and barely held together.
2) A fair amount of steam was coming from the exhaust, along with the water that was being pumped out from the engine.
3) The temperature gauge rocketed up very high, past 200 up to 225 or so.

Now, here's the odd part: the temp gauge now reads 160 - yet the engine has been off for a week. I am assuming that the needle is stuck and that I need a new gauge, among other things.

I am going to replace the belt, but why the steam? It's been very cold, below freezing, but the day I took her out it was about 40 degrees.

Before I call the Atomic 4 mechanic, I thought I'd solicit some advice from all of you. Thanks in advance for the help.

(Final note: While I would love to repower with diesel, it's just not an option. It's not in the budget. I live lean.)

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Old 23-01-2012, 23:44   #2
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Location: Davilla, TX
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Re: Atomic 4 - Troubleshooting Question

Replace the drive belt. Have an extra one on hand as a spare. Check water pump to see if the impellor is okay. Replace the thermostat. Check the oil level. (If it looks milky you have a blown head gasket. Pretty easy to replace.) Replace the temp gauge. Crank her up and see what happens. It's a cast Iron block and head so nothing should have warped. If the oli is milky and you have to remove the head, have a machine shop check it to see if it is warped. They can resurface it if needed. No you don't have to replace the engine....yet :-)

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Old 24-01-2012, 02:59   #3
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Location: Bayou Chico, FL 32507
Boat: Cal Cruising 46 - SATORI
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Re: Atomic 4 - Troubleshooting Question

[QUOTE=" the drive belt that runs from the alternator to the water pump frayed and almost broke."

In original A4's the alternator to auxiliary drive belt does not drive the water pump.
I sounds like you have an aftermarket closed loop cooling system with an additional water pump driven by the alternator belt. The original A4 waterpump is plumbed to recirculate the coolant through the engine and a heat exchanger. The secondary pump brings raw water in and pumps it through the other side of the heat exchanger, thus cooling the recirculating coolant, then pumps it into the mixing elbow and into the exhaust gas.

I drive the secondary pump off a shaft/pulley ffrom the front of the flywheel if possible, but some boats engine space will not allow that, so it must be placed on the side of the engine and driven by the alternator belt. Example, a Catalina 30 engine box is under the dinette seat in a tight fitting space, with no room in front off the A4, so the pump must be side mounted. This is the alternative location, though some folks are using 12 volt pumps.

Fan belts wear out, so have a spare on board. Keep the pulleys clean and as rust free as possible. Assure the alternator and water pump pulleys are aligned with the auxiliary drive, other wise belts will not last long. Hope this helps. I have been fixing A4's since 1967 and after swallowing the hook have specialized in Atomic Fours. [URL=""][/URL]

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Old 25-01-2012, 21:30   #4
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Re: Atomic 4 - Troubleshooting Question

Thank you both for the help. I hope to keep my old A4 chugging along for awhile. Nothing wrong with a good old engine as long as it is well maintained. I drive a 1984 Volvo with an engine built like a tank, so I've every intention of keeping my A4 going for awhile.

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Old 26-01-2012, 07:05   #5
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Re: Atomic 4 - Troubleshooting Question

I rebuilt my 1973 A4 in 2004 and it's still running very well with good compression. Every spring I change the oil, change the impeller and (usually) change the plugs...I use RJ12Cs or YCs gapped to .040 for a hotter burn.

I also found that a tune-up every three years or so is a very good idea. Cost is about $50.

Always carry spare belts and remember that the "accessory drive" (the proper name for what is belted to the alternator) requires water pump grease (a waxy plug of it...not easy to source) or bearing grease. Give it a quarter-turn every 10 hours or so to keep the shaft from scoring.
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