# atomic 4 thermostat question



## cnc33voodoo (May 15, 2008)

i have found that the previous owner of my boat was too brain dead to mention he forgot to put the t-stat back in and i tested the spare and its no good.
can anyone tell me what a fair price to pay should be as the only local guy who has it wants $280 for just the t-stat.
i also found excessive corrosion inside the housing so im planning to replace both.im just not sure if he has both as their buisness is on a reply to messages only system.
i checked moyer marine and their prices are a fraction of the local guy.
problem is im planning an excursion this weekend and they cant guarantee they can get it here in time.
is there an aftermarket part # i can use or if anyone can suggest a place that does overnight shipping.
anyone have a good used unit they want to sell me?
any help will be greatly apreciated.


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## nightowle (Aug 2, 2006)

where are you located?


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## sailhog (Dec 11, 2006)

They ain't cheap:
Moyer Marine Online Store


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## cnc33voodoo (May 15, 2008)

im in toronto,ontario,canada.
found a t-stat housing flange.$47.perfect.
no-go on the t-stat.
check this-the distributor for universal in ontario (westerbeke) sells the part for $150.
they are on back order.
in fact, everyone sells them for $150 in my area,but they all order from the distributor above mentioned as does the marine store that wants to grease me for $280.
im probably going to have to eat it and pay the $280.
my freinds took time off work so i just want everything together so i dont let everyone down.
it will cost more in beer and excuses.


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## sailhog (Dec 11, 2006)

The link I sent you doesn't work... so try this: Moyer Marine Atomic 4 Engine Rebuilding and Parts and type in thermostat. I noticed different prices for late and early model engines. Looks like you should be able to save $100 minus the shipping...
Good luck.


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## Rockter (Sep 11, 2006)

If it is only one week-end or two to wait for the cheaper version, then use the motor without the thermostat. It will run a bit cool, but it will survive.... it has for some time.
Do not pay anyone $280 for a thermostat.
Do not.


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## JimsCAL (May 23, 2007)

You definitely can run the engine without the thermostat, but be careful. My Universal 5411 diesel is raw-water cooled like the Atomic Four, in fact I think it uses the same 140 degree thermostat. I once tried to run without one and it overheated. Seems that as the water heats up, the thermostat closes and forces more of the recirculating water out the exhaust. Without the restriction of the thermostat, the water just recirculates and gets hotter and hotter! Clamping the hose returning the water from the thermostat back to pump fixes the problem. In fact some A4 owners just put a valve in that line and control the temp manually.


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## djodenda (Mar 4, 2006)

I agree that it won't hurt to run the engine cool for a bit longer. Your fuel economy will go down, but no significant short-term problems.

Do replace the thermostat, however, as it does cause long-term problems.

David


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## cnc33voodoo (May 15, 2008)

i really have no choice as far as the $280 goes.all the other shops say they are on back order and it could be 3-4 weeks.and thats a maybe.
yeah, i know its a rip off but i just want it fixed properly so i dont have it lurking in the back of my mind.
plus, i think by the time i get the parts from moyer to my door the price will be the same with shipping and border transfer fees.
i just cant see how someone could charge that kind of money for a thermostat.i work for vw and the most expensive one we sell is $45.
ive worked on a few yanmar's and i think their most expensive one (3gm engine)is $80.i thought that was high.
the thing that gets me is tons of boats have these engines and even more have had them swapped out.
there should be tons of parts out there for these things.
last week i saw a complete a4 for sale on craigslist for $400.now the listing is gone.i should have bought it for parts.


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## cnc33voodoo (May 15, 2008)

JimsCAL said:


> You definitely can run the engine without the thermostat, but be careful. My Universal 5411 diesel is raw-water cooled like the Atomic Four, in fact I think it uses the same 140 degree thermostat. I once tried to run without one and it overheated. Seems that as the water heats up, the thermostat closes and forces more of the recirculating water out the exhaust. Without the restriction of the thermostat, the water just recirculates and gets hotter and hotter! Clamping the hose returning the water from the thermostat back to pump fixes the problem. In fact some A4 owners just put a valve in that line and control the temp manually.


im pretty sure i need to have one in as its not getting to operating temperature so its giving me stalling issues if i shut off the choke.
the engine runs fine but if the engine is idling and i shut the choke off it runs for 5-10 minutes then stalls.if i restart it stalls untill i pull the choke back on.
ive had this issue on cerbureted cars a couple times due to stuck open t-stats.


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## chtaylor (Feb 19, 2007)

A while ago, I found that the previous owner had taken out the thermostat. I installed one of Moyer's conversion kits and my engine runs at about 140 - 150 degrees at cruising RPM. You may want to get the kit so that if you have problems in the future you can use a normal automobole type thermostat.

Charles


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## cnc33voodoo (May 15, 2008)

i thought of that but you still have to use their t-stat.


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## Rockter (Sep 11, 2006)

Maybe I stand corrected. Perhaps the lack of thermostat will make it run hotter???!!! On the Atomic, perhaps a stuck thermostat will overcool the motor??? 

On the Volvo MD17C it will run cooler.

Pls be careful. Watch that temperature.


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## jaschrumpf (Jun 22, 2002)

cnc33voodoo said:


> im pretty sure i need to have one in as its not getting to operating temperature so its giving me stalling issues if i shut off the choke.
> the engine runs fine but if the engine is idling and i shut the choke off it runs for 5-10 minutes then stalls.if i restart it stalls untill i pull the choke back on.
> ive had this issue on cerbureted cars a couple times due to stuck open t-stats.


I have a Newport 28 with an A4 in it, and last week while testing the t-stat I ran it for 40 minutes at full throttle (in gear, tied up to the dock) with engine temps sitting at 135 deg F. with no choking problems. If you are suffering fuel shutdowns after 5-10 minutes of opening up the choke, you probably have carb issues. The A4 will run just fine at those low temps, but the incomplete combustion will foul the plugs faster than normal.

For a short-term fix, you might try "calibrating" a pair of vice grips to partially close the line from the pump to the t-fitting on the water jacket side. That would reduce the amount of water going into the cooling jacket and would let the engine get to a higher operating temperature.

If you haven't posted your problem to the Moyer Marine forums yet, you should do so. There is a wealth of knowledge there, and Don Moyer is the patron saint of A4s. I'm sure you'll get many more suggestions to help solve your problem until you can get the much less expensive Moyer t-stat delivered.

Good luck!


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## cnc33voodoo (May 15, 2008)

im sure the problem is the operating temps.btw,its only at ilde after i shut the choke off before i go anywhere.when its running in gear all is well.
i dont know if i would ever run my engine at full throttle,in gear,at the dock,for 40 minutes.
that would probably get me kicked out of the marina. 

its like starting your engine cold without the choke.it will stall untill you let it run with the choke long enough to get the engine warm enough to push the choke off.
well, at least ill know when i replace the parts.
i ordered the parts earlier from marineparts.com
its an oem holley t-stat with gasket for 130 plus shipping.
problem is im a child at heart and need everything now now now
so taxes and overnight shipping was $230 total.
still a rip off as far as im concerned but better than the local guy who's greed lost him a sale.
now maybe i can sail this boat instead of fixing it for once.
thanks.


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## timebandit (Sep 18, 2002)

Before I paid that much for a thermostat I would take the dementions to a auto part store like NAPA that has books with all the part numbers and the measurements.
I have been doing this with motorcycles for years.

If you can try to get one that sticks open when it goes bad.

Rick


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## cnc33voodoo (May 15, 2008)

timebandit said:


> Before I paid that much for a thermostat I would take the dementions to a auto part store like NAPA that has books with all the part numbers and the measurements.
> I have been doing this with motorcycles for years.
> 
> If you can try to get one that sticks open when it goes bad.
> ...


i looked thru rows and rows of t-stats.
ive been to all local parts suppliers(napa,uap,parts source,carquest,canadian tire),parts stores,freinds shops etc.
i spent hours on the net and phone, called every shop in ontario that deals with a4's or universal engines and found nothing.
there were 7 or 8 shops that are known for repiaring/selling parts for these engines and they have no stock.
i even called the manufacturer/distributer in toronto and vancouver-backordered.
there is no t-stat that has the same design.a few were close but not close enough.
the a4 has a specific t-stat.they have a flat top that rests against the flange housing where a bypass flows thru.the head is also very shallow for most standard sizes so if they fit on one end, they didnt on the other.
i was even looking at ways where i could install a new flange that would accept an automotive t-stat but nothing fit perfect and i wasnt into doing a hack job to save a couple bucks.
i was sick to my stomach with this whole thing.especially after i spent all of last week running around to fix a furling system with equally challenging parts support.
im just itching to go sailing.


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## Valiente (Jun 16, 2006)

cnc33voodoo said:


> im in toronto,ontario,canada.
> found a t-stat housing flange.$47.perfect.
> no-go on the t-stat.
> check this-the distributor for universal in ontario (westerbeke) sells the part for $150.
> ...


The thermostat is called a Holley and comes in two temp. ranges: 140 F for sea water (not applicable) and 180F for fresh water. I assume you have raw water cooling and not a separate cooling circuit.

I will tell you now that the 180F are preferable because an Atomic 4 runs cleanest and best at that temperature. 140F is a compromise due to the precipitation of salts in sea water in the ocean-going Atomic 4s. I will also tell you that a working 180F thermostat is hard to find these days and people like me hoard 'em.

Sometimes the temp is not marked on the thermostat. You get a beer making thermometer (range 100-212F) and pour hot water on the thing in a glass until you see it open. If that's circa 180F, you are good to go.

See here: Atomic 4 Updates

"Volvo #875781-7 thermostat replaces Holley thermostat on newer engines if you put it on top of a 1/8" thick spacer (in the shape of the gasket)."

You can talk to Paul at Eastern Marine on Leslie St. about this. It's a quick fix if they are in stock.

If push comes to shove, Lake Ontario is still only 12 C/53 F. You could simply put in a brass ballcock in the 1/2 inch rad hose between the side water passage plate and the thermostat housing, put it at full open, and run the engine under load for 15 minutes. If it stays at 120F, start shutting the ball valve until it gets to 170F-180F (I assume your water temp. sensor is working).

A lot of people do this, particularly where the problem isn't overheating, but "underheating".

If you are really pressed, maybe I can loan you a spare if you leave some kind of ransom but the path of least resistance is four hose clamps and a two-barbed 1/2 inch Home Depot ball cock...and some patience.


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## Valiente (Jun 16, 2006)

Oops, I guess you've moved on this already.


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## cnc33voodoo (May 15, 2008)

Valiente said:


> Oops, I guess you've moved on this already.


no, thank you.im going to try that idea of adding a ball vavle to the 1/2 hose.
i never thought of that.
unfortunately i ordered a 140deg t-stat,but i was told this is oem?
one way or the other i can use that idea to regulate it.
thanks.


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## TSOJOURNER (Dec 16, 1999)

Have you tried soaking your thermostat in viniger overnight. This can clean them nicely. I have the moyer manual. It describes this there. If you need anything looked up in the manual, let me know.


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