Anti freeze reserve tank heat

[cbourne200]

I don't have an engine temp guage, so bought a digital temp gun - point it at anything and it reads temp.
My thermostat is 180*, and digital consistently reads 170-180 after running with load for over 30 min.
My A/F reserve tank (not overflow) is reading 200 and above. Fluctuates into 170-215 range. Should this be that high?
Getting ready to move to marina approx 60 miles away and am sure delivery person will run Westerbeke 10-2 full throttle. Trying to make sure no problems.
Changed water pump (had 2 vanes broken, but couldn't find them). Checked HE and found a few small shells, but nothing else.
Sitting at dock under load & therm is between 170 & 180.
Ideas on A/F tank?

 

[Rich Stidger]

It sounds like the coolant cap on the engine is stuck open and allowing hot coolant from the engine to flow into the coolant tank. If the coolant tank is like mine it is located on the heat exchanger. Maybe the temp at the heat exchanger is a bit higher? I don't know.

But anyway I would check or replace the coolant cap.

 

[cbourne200]

Westerbeke 10-2. Coolant tank is not on HE. HE has much lower temp. I had replaced water pump, and lost some coolant. Thought I could replace through overflow tank, but engine got hit & blew all A/F out of overflow. Replaced coolant through coolant tank. Testing today with full tank, overflow full too. Cap may be problem, Don't know. Have never noticed temp on reservoir.

 

[Rich Stidger]

I am not understanding your response above. I realize that the over-flow or coolant tank is not on the HE. But the pressure cap or coolant cap is on the HE. As I see it the only way coolant can get hot in the coolant tank if if the engine is blowing steam or hot coolant into the tank. Normally that does not occur. But if the coolant cap was stuck open it seems like that would be possible.

The way I had refilled my engines (aux and genset) is with a COLD engine I fill into the coolant cap until the level is as high as it will go. Then I replace the cap and fill the coolant tank up to the maximum mark. As the engine heats and cools over the next few use cycles, any air in the engine will be expelled into the coolant tank and as the engine cools it will draw coolant into the engine to fill any voids. But for these actions to occur, you need a good coolant cap that seals properly.

If you tried to fill the engine only in the coolant over-flow tank and the engine itself was not nearly full, then the engine would overheat and blow steam into the over-flow tank. Is that what occurred?

 

[cbourne200]

Yes. I guess I was thinking of newer cars that don't want you to add coolant through the radiator cap.
My HE is separate from my coolant reserve tank. I won't be back to the boat until mid next week, but can get pics then.
Thanks for responding to my question.

 

[Rich Stidger]

My engines are setup exactly like yours. The coolant tank is connected to the coolant cap with a hose. You normally top-off by adding to the coolant tank, but if the system has air in it, you add directly to the HE through the cap until full and then add more to the tank. The system will automatically bleed any air in the block out as the engine heats and cools.

 

[jviss]

This thready is a bit confusing because of the terminology used. Here's my understanding of the components:

Coolant tank: this is the primary reservoir of coolant on the high pressure side, usually the radiator tank in a car, and often the exhaust manifold in a boat.

Prssure cap: this is the "radiator cap," the cap that has both underpressure and overpresure valves built in. It is usually on the coolant tank, and has a nipple to which a hose attaches to divert coolant overflow.

Overflow tank. This is not pressurized, and not hot, usually made of translucent plastic, to which the overflow hose connects. For a properly bled cooling system, this is where coolant is added, as necessary.

Note that some marine installations will have a secondary coolant tank, mounted up high, higher than the water heater, when the water heater is higher than the engine. This also has a pressure cap. The pressure rating of this cap should always be lower than that on the primary coolant tank.

That's my understanding.

 

[jviss]

My A/F reserve tank (not overflow) is reading 200 and above. Fluctuates into 170-215 range. Should this be that high?

Assuming you mean the coolant tank, and it's the exhaust manifold style of coolant tank, yes, I think it could run to those temps. I don't think it's a big concern. The thermostat is regulating the coolant temperature to 180º, and these work remarkably well. There is bound to be a temp gradient across parts of the engine, and the exhaust manifold is one of the hottest parts.

I'm not an expert on this, though. I will take a couple of temp readings of my Westerbeke next chance I get; I have on of those non-contact thermometers, too. I'll let you know.

 

[Hydro Therapy]

Cbourne200, I have the same motor and I keep a temp gun on the boat. I’m planning on a overnight sailing trip tomorrow. I will try to remember to check it for you. My engine temp gauge always reads at or near 170.

 

[cbourne200]

This is my first use of the 'point & shoot' temp gun. Therefore the 'reserve tank temp' question. jviss - those are the exact definitions I am using to describe my components.
I am 'suffering from the heat' in FL's 105-110 heat index, and wife doesn't want me taking boat on a 60 miles relocation to a different marina, so I'm considering having a 'delivery captain' perform that. $300/day + expenses, so I want the boat as bulletproof as possible. I'm sure he'll motor as fast as possible and I'm trying to eliminate any engine problems.
Thanks for all responders.

 

[jibes138]

Coolant flows from the thermostat into the coolant tank that is part of the exhaust manifold. Part of the purpose of this arrangement is to have the coolant in the exhaust manifold cool the exhaust gases by acting as a heat exchanger. The coolant then flows out to your external heat exchanger that is raw water cooled. Then it goes to your engine where the temperature is modulated by the thermostat. If you have a hot water heater, that also provides some heat exchange until you get to steady state. So yes the manifold coolant housing could be hotter than the thermostat housing.

 

[Hydro Therapy]

I ran my Westerbeke 12c two for 30 minutes. Temp gauge at 170 (normal for me). I used the thermal gun on the coolant tank. First I hit the side of the tank and it read 185. I then hit the top of the tank a few inches from the thermostat. The gun reading fluctuated between 197 and 203. I hope this helps