Engine O'Heat

[Weasel]

Hi all:

I have found that thru this site I have learned much from my fellow sailors. I really need some help now:
I have a friend on my dock that purchsed an O'Day 39 with a Universal 44 HP engine. He is thrilled with the boat but there is one problem. The engine overheats. We discussed all of the corrective actions and have cope up with zilch.
He has cahaged the impeller, flushed the heat X-chager changed the anti-freeze. Installed new hoses, even checked the small cam in the raw water pup. Belts are tight, hoses have been changed. Start-up the gauge goes to 190 then 210, alarms go off & he shuts the engine down. Water, copious amounts of water come out the exhaust. Water muffler has been checked. All at a loss. Can any one come up with something we may not have considered? Either that or point me in the right direction for assistance. This guy is a former Marine helio pilot that served in 'Nam and he really wants to use the boat as long as he is able. The boat is really nice and I want to see him enjoy it. Please, offer ya'lls advice. Really appreciate it & will keep you posted.

Weasel

" We sleep safe in our beds because brave men stand to do violence on those that would harm us"
Author Unk

 

[Weasel]

I am sorry for the misspellings, I hit send before I could spell check it.
My apologies.

Weasel

 

[Ross]

try "EDIT"

 

[Douglast]

well i am not familiar with this set up...BUT...i did not see thermostat changed..(sticking)...does it have one..??...and as well is it really overheating or could it be a malfunctioning heat sending unit...???

 

[Douglast]

ps....is there any sign of water in the crankcase(corpios amounts of water in the exhaust...??)..like would a head gasket leak or head cracked affect the cooling circuit (pressure and or air lock) like in a normal vehicle application..??

 

[tomfoolery]

I concur with Douglas test the thermostat and the temp sending unit.

 

[Weasel]

Eng O'Heat

Thanks for the suggestions guys, (even the one to use the edit key!) Yes the thermostat was checked out. (Removed & checked, opened when it should.) No water in the oil, & I believe he did check the head gasket. I did not think of a malfunctioning sending unit and or gauge. I guess we could get another and wire them in tandem, right? Or do you suggest we get a new one & replace? I will be at the Nashville WM store later this week so I could pick up a repacement unit. I even suggested he check the mixing elbow off the engine and he said he did that. BTW, the copious amount of water comment was meant to advise that water is going thru the engine & out the exhaust. Most raw water pumps are oversized, tht is why when you loose a blade or two on the impeller usually you don't notice it. ( Data from Yanmar on that one.)

Keep 'em coming, I am going to help him this weekend, good sailing in Sept & Oct coming up so we need to get this fixed.

Many thanks!

 

[Surveyor]

Water Heater

If there is an engine heat loop in the water heater, on the fresh water side of the cooling system, it could have an air bubble in it. O Days had a brass tee at the water heater to bleed the air from the system. An air bound fresh water cooling system would act as you described.

 

[Don12364]

Two suggestions:-
1) Possible airlock in the closed circuit cooling system. Even cars sometimes suffer from this.
2) Try it with the thermostat removed. If it does not overheat then suspect the stat. But don't continue to use it with no stat.
If it does overheat without the stat it could be 1) above or no impeller rotating in the closed circuit system.

 

[Bill Roosa]

Couple of questions

How fast does the temp gage go to o-heat?
Are you loosing anti?

Sounds like the raw water side is ok. If you have raw water flow then you are probably OK on that side.


The antifreeze side could have something wrong with the heat exchanger, not enough anti in the system (check the overflow jar and look in the pressure cap opening) or an air pocket in the pump (there is no impeller BTW on the fresh water side, it is a centrifugal pump, they don't go bad often and not pump, leak yes but they still pump even when leaking), run the engine with the pressure cap off and manually filling it usually gets rid of air pockets.
Some engines have redirect valves that allow you to run the fluid through the heater instead of the heat exchanger. Check all the valves for proper setting. Could also have a valve for winterization that is set wrong.

 

[RichH]

Is this an INTERMITTENT / occasional problem ?????? sometimes the boat temp. runs fine, sometimes it doesnt??????

There is an innate flaw in many 'older' boats that have CAST IRON exhaust manifolds, Universal (Atomic gasoline powered and DIESEL) CAST IRON exhaust manifolds seem to the 'leaders' with this 'flaw'. This flaw is the development of SLAB RUST developing INSIDE the manifold (and the engine). This flaw is exacerbated *especially* when the engine coolant water (either side of the circuit) is REMOVED to prevent freeze-up during long term winter storage.

Cast iron when cast and is cooling in its mold, forms 'stratifications' in the metal .... these stratifications form like the stratifications in an ONION. When the metal at a later date begins to rust the rust penetrates INTO and between these 'stratifications' and the developing pressure drives the stratifications apart ... forming large 'PLATLETTES' of rust. Usually these fall to the bottom of the internal spaces but depending on the flow characteristics can occasionally 'move' and either partly (or totally) block the flow path. When the engine is shut down, and the flow stops, the platelettes fall back down to the bottom.
Anytime, with a UNIVERSAL, when there is a cooling problem and the water flow is verified to be constant and all other components prove OK ..... the NEXT STEP is to remove the exhaust manifold, LOOK at the internals for **RED/BROWN** RUST PLATELETTES .... just invert the manifold and shake them out, if so, then go inside the passages with a stiff wire and break up those that remain.
Note - if there is a heavy accumulation of the RED/BROWN (some will be 'black') platelettes, the manifold should be 'pressure checked' to insure that a pin-hole between the 'gas-side' and the 'water-side' hasnt developed.
DO NOT use any 'acid' to clean out the exhaust manifold.

In future, NEVER EVER drain the water out of the manifold for 'long term storage', instead fill the manifold (and engine) with an antifreeze that contains anti rust compounds.
The BEST way to keep the manifold (and engine internals) from forming internal destructive 'red' rest is to RUN THE HELL OUT OF THE ENGINE FOR LONG PERIODS - hours!!!! This will change the RED (ferric) rust to BLACK (ferrous) rust .... BLACK (ferrous) rust is 'protective'. This is why the US Navy almost NEVER shuts down an engine that has Cast iron components in the cooling system !!!!!!!!!

So, clean out the exhaust manifold (or get a new manifold), RUN THE HELL OUT OF THE ENGINE whenever possible, use a HI TEMP thermostat (even if the engine is 'raw water cooled' ... as you can use proper 'inhibited' compounds to remove the scale), ..... and NEVER EVER remove the water (use a proper antifreeze) for long term lay-ups.

Universal (and other) Engines with thermal problems and 'everything checks out' ... is usually a SLAB RUST problem.

hope this helps.

 

[Stu Jackson]

BURP it. Freshwater cooling side to the domestic hot water heater.

Reply #6

http://c34.org/bbs/index.php/topic,4518.0.html

 

[sailaway78]

Either or

I think the suggestions made already have you covered. First place to look is the hot water heater, as this is more than likely the easiest. An air lock in the hot water heater can and will lead to overheating. I would then check the guage and warning buzzer. For a fresh water cooled engine, 190 is not overheating. Check the manual for actual temps. The buzzer for the fresh water cooled Yanmars is supposed to go off at 200. But they run fairly close to that temp. Likely your not overheating by a great deal.

 

[John]

Get an infrared thermometer. Some are expensive, but some are pretty cheap. You can use this to test if the engine is actually overheating or if the sending unit or something else is wrong.

 

[Don12364]

Bill - Impeller - from Wiki

Impellers in pumps

An impeller is a rotating component of a centrifugal pump, usually made of iron, steel, bronze, brass, aluminum or plastic, which transfers energy from the motor that drives the pump to the fluid being pumped by accelerating the fluid outwards from the center of rotation. The velocity achieved by the impeller transfers into pressure when the outward movement of the fluid is confined by the pump casing. Impellers are usually short cylinders with an open inlet (called an eye) to accept incoming fluid, vanes to push the fluid radially, and a splined, keyed or threaded bore to accept a driveshaft.