question on a shut off valve

[garyj4101]

This is a petcock on the t stat housing on a Westerbeke genny -- BCD6.0KW. it looks like a pipe plug installed on a bushing with some thread sealant.
Does this valve open and close like a ball value that usually is quarter turn? for comparison, I have attached a picture of a needle valve on a compression fitting

View attachment 161196



View attachment 161199
a distributor has confirmed the petcock part number is 11471. But the hex base in the photo of 11471 appears to have a sealed end, instead of a through passage. This is confusing.

View attachment 161198

 

[garyj4101]

Thanks for the video.
cheerful music, beautiful life.
on the leaking westerbeke heat exchanger, it was not yet conclusive. see post #58. I'll inspect it this tomorrow.

It opens by turning it clockwise, it is used for bleeding the fresh water coolant of excess air. REPLACE it!

 

[garyj4101]

It opens by turning it clockwise, it is used for bleeding the fresh water coolant of excess air. REPLACE it!

 

[Nick F]

It opens by turning it clockwise, it is used for bleeding the fresh water coolant of excess air. REPLACE it!

Paulga - we know that you are on a learning curve here. Be aware that there may be some versions of this valve that open in the opposite direction. As already discussed early in this string of posts, the thread on the stem can identify which way the valve opens - LH thread means it opens CCW (and vice-versa).

 

[paulga]

The leak is slow, I wrapped it but was not observe anything in 30 minutes.

View attachment 161577

The leak might be from this large coolant hose as I saw some weeping at the connection. So I tightened the clamp a bit.

View attachment 161578

I just checked the plug. It's not dripping. The paper wrap is still dry. It looks like tightening the hose clamp stopped the leak.

 

[SteveK]

Have you run the engine to operating temperature since putting on that paper. It may only leak when it is pressurized when hot.

 

[luna]

Well, as I guessed it was the plug, I was wrong. That happens. Lots.

Good on you for being methodical when diagnosing a problem. That helps. Lots.

Now you would be wise to take your torque measuring screwdriver, ($50+/- on Amazon) stick a 5/16" socket in it and with a few extensions in hand, spend an hour or so making sure that every hose clamp in the boat is snugged up to about 30 in. lbs.
If you want to get particular you can likely look up what torque a t-bolt clamp needs on a used silicone 6" diameter hose, but 30 in. lbs. is going to get you in the ball park with most hoses. Small (narrow) hose clamps unsurprisingly, require less torque. You will soon gain the "feel" for what is right.

Then do it again next year. Do not over tighten.

 

[paulga]

Re the thermostat location, I agree - it is almost certainly in the bulge off the front off the cylinder head. Bulge clearly visible just above the water pump pulley in your lower photo.

As for how the circuit works during warmup, I continue to be puzzled. I have made a sketch of how the circuit appears to be (omitting the air bleed line which is not relevant to the cooling function).

It would seem that all flow stops when the thermostat is closed - weird! However, in practice, many thermostats have a bleed hole so that some coolant always flows.

The purpose of the "U-hose" is unclear. Is it possible that there is a flow passage internal to the header tank that directs flow from underneath the thermostat to the U-hose port? Some thermostats are actually "diverter" valves that do not simply shut off a the flow. I wonder if you have a thermostat like this.View attachment 161640

I called AD today and the manufacturer told me the U shaped hose functions as a passage for water to return from the exhaust manifold into the reservoir portion of the header tank, where the water expands into the plastic recover bottle off the engine
he also confirmed, by pass at the t stat only applies to turbo charge engines. natural aspirated engines do not have a by pass loop. maybe the "by pass" that he talked about is not the strain relief on the t stat.

 

[Nick F]

I called AD today and the manufacturer told me the U shaped hose functions as a passage for water to return from the exhaust manifold into the reservoir portion of the header tank, where the water expands into the plastic recover bottle off the engine
he also confirmed, by pass at the t stat only applies to turbo charge engines. natural aspirated engines do not have a by pass loop. maybe the "by pass" that he talked about is not the strain relief on the t stat.

Unfortunately, not a very helpful answer IMHO.

 

[paulga]

Unfortunately, not a very helpful answer IMHO.

here is the illustration from AD that clarifies the inside of the header tank. the reservoir chamber (blue) and the collant passage through the t stat (yellow) are separated.

it's also confirmed that the t stat does have an air bleed hole on the rim of its disc wheel. and the coolant pump has a port on its flange to help the inner circulation before the t stat opens.

 

[Nick F]

here is the illustration from AD that clarifies the inside of the header tank. the reservoir chamber (blue) and the collant passage through the t stat (yellow) are separated.

it's also confirmed that the t stat does have an air bleed hole on the rim of its disc wheel. and the coolant pump has a port on its flange to help the inner circulation before the t stat opens.

View attachment 162362

Unfortunately, this contributes no further towards explaining the function of the "U-hose" ("coolant expansion access to tank" in this image). Coolant expansion happens slowly and can be totally accomodated via the "air bleed" connection, so this connection would appear to be redundant - perhaps the air bleed was designed in at a later time and the lower connection (now redundant) never got deleted.

Of interest, while warming up (thermostat still closed) there is no flow in the exhaust manifold jacket, which I find surprising. I can only assume that, in practice, this has not shown to be a problem on these engines.

I feel concerned for you, Paulga. You are obviously on a learning curve and eager to understand things. Yet here is something that appears to make no sense and for which no one has yet to offer a valid explanation! Welcome!

 

[SteveK]

@Nick F Not sure if your post is tongue in cheek. I already explained tongue in cheek what the 'U' shape hose does.

Now I have to say that the coolant circulation pump indeed circulates water thru the exhaust manifold before the thermo opens to redirect it thru the heat exchanger.

The 'U' shaped hose redirects the water flow 180* all the time.

 

[Nick F]

Hi Steve - I was not really trying to be ironic (although trying always to maintain some levity). I dont want to go head to head with you but I do have a problem with the claim that flow goes through the manifold during warmup. I have attached my flow sketch again here. There will be minor flow through the small hole in the thermostat - is this the flow you are referring to? As you can see from the sketch, any flow through the manifold must also pass through the heat exchanger.

Of course, my sketch may be wrong - I look forward to being corrected if this is the case!

 

[SteveK]

Unable to support my comments I will defer to what you said Nick.