Westerbeke W50 potentially overheating

[jimbunyard]

Did the overheating start before or after you replaced the freshwater pump? If after, my first suspect, if the engine is actually overheating, would be that there is still some air trapped somewhere in the F/W side.

If the overheating began before, then the sensor/gauge is a likely place to start. When you measure with the gun, are you measuring at the same spot that the sensor is located? If so, and you're getting a 20 degree difference, I would find out why.

According to Westerbeke, the temp sender P/N is 23571, which changes to a 35109, which crosses to a Sierra 18-5896, which should read 176 ohms at 100 F and 24 ohms a 220F.

I wouldn't worry about the routing of the cooler plumbing if it was working satisfactorily previously, at least not at this point.

You can also use the heat gun to test various points on the engine at various times to develop a better sense of what's going on with it. I like to monitor the engine at certain key points during warm-up to help establish a benchmark for later trouble shooting. For instance, inlet/outlet points of various coolers, exhaust temp rise where the manifold/exchanger interfaces the head, at each individual cylinder if possible, things along those lines. Write them down if you can't remember them, and use them as a basis to identify and hopefully catch issues before they become problems...

[felizcortez]

I see the 35109 and the Sierra replacement as the 23-5840 instead of the one you listed. However I am unable to find the resistance specs.

The overheating started after I replaced the water pump, but prior to that we had not run the engine enough to get it that hot. that is also when I notices. We made a trip to Catalina island I remember it running a little hot on the gauge. The water was also significantly cooler along with ambient as well. We are now in Mexico and I didn't notice this until we got around to about Cabo. But we sailed most of the way and I changed the water pump in turtle bay. So multiple hundreds of miles and warmer ocean temps between them.

I bled the air at the petcock for the thermostat which is supposed to be the highest point in the system. I will run the engine again to get it up to temp at the dock. Will attempt to bleed more air out again. If it doesnt come out how else can I remove it?

.

[01kiwijohn]

I shot the thermostat housing with an infrared thermometer and it is reading at about 180 which is where the thermostat is supposed to open, so I'm not sure whether I have an actual overheating issue or not.

If its a 180 thermostat, that's what it should read. Check the gauge, it may be wrong

[jimbunyard]

Originally Posted by felizcortez

I see the 35109 and the Sierra replacement as the 23-5840 instead of the one you listed. However I am unable to find the resistance specs.

The overheating started after I replaced the water pump, but prior to that we had not run the engine enough to get it that hot. that is also when I notices. We made a trip to Catalina island I remember it running a little hot on the gauge. The water was also significantly cooler along with ambient as well. We are now in Mexico and I didn't notice this until we got around to about Cabo. But we sailed most of the way and I changed the water pump in turtle bay. So multiple hundreds of miles and warmer ocean temps between them.

I bled the air at the petcock for the thermostat which is supposed to be the highest point in the system. I will run the engine again to get it up to temp at the dock. Will attempt to bleed more air out again. If it doesnt come out how else can I remove it?

.

According to these people https://www.ebay.com/itm/Sierra-18-5896-Single-Station-Temperature-Sender-1-8-in/372411270584?epid=1723287246&hash=item56b57105b8:g :r~EAAOSwk~VcmrW9

18-5896 replaces both 35109 and 23-5840.

A couple of other things though...

An air pocket can be anywhere. Sometimes you can get it out by removing the proper hose, sometimes it will work itself out. No easy answer there...and it could help to analyze the flow of raw water through the engine coolers and adapt it accordingly.

Without knowing the actual ohms for the sender, an option would be to read it at cold and then watch it as the engine warms. An old sender could still work, but if it functions as I assume (a wax bulb pushing against a spring), a weakened spring could allow it to read higher but still give valid information. You'd just have to 'recalibrate' it by reading the temp with a known accurate thermometer, and then remember what the new 'calibration' is...

Regarding the possibility that the 'overheating' is a response to different ambient conditions, there is a very real chance that this is true.

The BMC 1.8 diesel the W50 is based on the 1.8 gas engine, which is based on the 1.5 gas engine that was developed and used in England in several British sports cars. I ran a Spitfire for about 20 years (still have it, but don't use it), and I can assure you that ambient temperatures have a huge effect on the running temperature of those engines in that application. You really don't want to get stopped at too many redlights in a row in the middle of the summer in Mississippi...

Don't know how that quirk translated into the diesel conversion though.

[felizcortez]

I ran the engine for a good hour this morning at about 2400 rpm and took thermostat housing measurements with an IR temp gun.

The highest I saw was about 186F at the housing. Accura on the gun is +-2%. So I could be of any about 4 degrees in either direction. Usual was at about 184F or 185F. When I dropped the rpms down the temp would decrease to between 178F to 182F.

Oil temp was about 210F on the pan.

Here is a video of the measurements. Depending on how far away you take the measurement it can change. The IR gun manual says about 14 inches away is optimum. It has a 12 to 1 ratio for measurement.


https://youtu.be/Y_ASXCDo9B8

While running in the video the gauge was reading 200F and was sitting there.

I also stopped the engine and checked the resistance of the sender when the thermostat housing read 180F on the IR gun and the sender was about 100ohms. It definitely decreases with temperature.

With the engine cool last night the resistance was about 700 ohms. This is significantly different from the Sierra specifications.

Below is a pic of the gauge early on. It moved up slightly to the next line, but I didn't get a picture

How far away from 180F should I be based on the thermostat I imagine there is some accuracy variation in them.

I'm leaning towards the gauge being a problem now and that we are not actually overheating.

[a64pilot]

Take your sending unit out, and with either a good thermometer or your IR thermometer put it in hot water, compare the thermometer and the gauge, and then you will know.

Let it sit a few minutes though it might not read correct immediately

[felizcortez]

I checked it this morning. See earlier thread with a video. It is running at about 184F at 2400 rpm verified with IR temp gun. Temp Gauge is reading 200 at the same time. Not sure whether that is within tolerance for the thermostat or if it should be dead on 180F

Which Mr cool heat exchanger did you buy? Yes you are correct it is based on the BMC 1.8

[Steve Bean]

Is it possible that the thermostat is not opening fully, or restricted somehow?

[a64pilot]

Thermostats actually have two temp ratings, one is for when it begins to open, I believe that it the number they are sold as, but I’m not sure.
The other is of course the temp they are fully open at, and those numbers can be significantly different, maybe as much as 10 or 20 degrees F.

[felizcortez]

Originally Posted by a64pilot

Thermostats actually have two temp ratings, one is for when it begins to open, I believe that it the number they are sold as, but I’m not sure.
The other is of course the temp they are fully open at, and those numbers can be significantly different, maybe as much as 10 or 20 degrees F.

I know the thermostat for our boat is a 180F so that would make sense if it just starts to open at 180 the gets wider as temp increases.

[a64pilot]

Look here, under thermostat temperatures.
Assuming the IR gun is correct, I believe you have a correctly functioning cooling system, assuming of course a 180F is the correct thermostat.
http://www.stant.com/index.php/engli...s-thermostats/

[CampDavid]

One other item to consider are the connections between the temp gauge and the negative side of the dc current. If you have any increase in resistance due to a bad connection it will alter the reading at the gauge. Are you comparing the ohm reading at the sender and at the gauge. Are they the same. Ohm out the negative side of the power feed to the panel.

[Sailor647]

Originally Posted by felizcortez

Oil temp was about 210F on the pan.

This temp is really high. Depending on what oil you're running, it is likely breaking down at this temperature.

The temperature of our W46 oil pan is around 150F - hot and under load. I use Delo 400 when I can get it. Otherwise, Quakerstate is available in La Paz.

I removed the original small oil cooler that was on the antifreeze side and replaced it with a bigger unit on the raw water side, as mentioned previously. The old unit was acting more like an oil heater than an oil cooler. The sea water temperature and ambient temperature make a lot of difference.

After changing the oil cooler to the raw water side, the temp on the oil pan went from 195 degrees to 150. This lowered our engine temperature at the gauge from 195 to 180. The thermostat opens at 180.

[jimbunyard]

210 F is well within the operating range of petroleum based oils, synthetics can go much higher before having problems.

Petroleum oils' high end operating temperature should not exceed 250 F or thereabouts.

Any oil needs to get up to around the boiling temperature of water to properly get rid of water and prevent the formation of acids.

As noted above, the t'stat starts to open at it's rated temperature (+/- 3F) and continues to open for about 15-20 degrees before reaching fully open.

[Sailor647]

Originally Posted by jimbunyard

210 F is well within the operating range of petroleum based oils, synthetics can go much higher before having problems.

Petroleum oils' high end operating temperature should not exceed 250 F or thereabouts.

Any oil needs to get up to around the boiling temperature of water to properly get rid of water and prevent the formation of acids.

As noted above, the t'stat starts to open at it's rated temperature (+/- 3F) and continues to open for about 15-20 degrees before reaching fully open.

Couple of counterpoints-

210F was measured at the pan - which is the LOWEST temperature in the system. I'll hazard an informed guess that the oil temps on the cylinder wall and cylinder head are a LOT hotter.

Water evaporates at any temperature. Even the water in ice will evaporate. The higher the temperature, the faster the evaporation. Saying oil needs to be at the boiling point of water (212F) to get rid of water is... well, questionable at best.

Best of luck in solving your problem. We're going cruising.