Any tips for installing an Exhaust Gas Temp probe in the engine cooling hose?

[silvercreek]

I would like to measure the exhaust gas temp just after the exhaust elbow where water is injected. This means I'll need to drill into the 90mm diameter heavy duty exhaust hose. Any tips for this to ensure a leak-free connection?

This is the sensor I'm planning to use: Exhaust Gas Sensor YDGS-01

 

[Supertramp]

Just installed a Nasa one. Very straightforward and just follow the instructions. The kit came with a drill bit to drill the soft part of the hose not a reinforcement bit. No leakage. More time spent sorting wiring runs and ignition connection.

Your kit is different but should be similar.

 

[VicS]

This is how the sensor for the Nasa Marine EX-1 is mounted

 

[Bilgediver]

I would like to measure the exhaust gas temp just after the exhaust elbow where water is injected. This means I'll need to drill into the 90mm diameter heavy duty exhaust hose. Any tips for this to ensure a leak-free connection?

This is the sensor I'm planning to use: Exhaust Gas Sensor YDGS-01

The kit seems to be arranged to suit a tapped hole in the elbow . this should work. If going into the hose then need two washers and nut and drill near enough to end to reach.

 

[Martin_J]

There are some instructions on the YachtDevices website but even after reading them it's not clear..

https://www.yachtd.com/downloads/ydgs01.pdf

It does look like it is designed as a threaded connection into the elbow though but maybe, as above, a nut and a washer will clamp it through the hose. Don't drop the nut down into the exhaust hose though!

Nice having the NMEA2000 part but like others, I went for a simple sensor that was designed to go into the flexible exhaust hose after the elbow.

 

[Martin_J]

The YachtDevices bolt has 20mm threaded section.. It must be long enough to go through the hose, with nut on the end

 

[bikedaft]

Tbh I just cable tied the sensor to the outside of the soft hose, where it is over the elbow. It works- noticed temp rise when there was a kinked hose between inlet seacock and water pump... you can see the thermostat works on the engine too, the temp settles at much the same, no matter the inlet water temp.

 

[Kwik Decision]

The silicone marine sensor needs only a 5mm hole in the exhaust pipe, and is held in place with a jubilee clip, so all done from the outside. Very reasonable price for the full kit. Fitted one a couple of yrs ago and it works well. Certainly let me know I'd forgotten to open the sea cock a couple of minutes after starting the engine last month...

SM010

 

[jamie N]

I made mine with this, the sensor fastened to the exhaust directly by the water inlet into the manifold indicates perfectly by virtue of the fact that exhaust manifold's have very little difference in internal and external surface heat,
It works perfectly, and is much cheaper with 3 spares included FFS.
It requires no invasive drilling and has a very simple output to an alarm if one wants. I fitted this one, and found it very easy to calibrate to a temperature of 50°C, which gives an adequate warning of pump failure. I did find out the hard way, as I did have a pump failure!
The control electronics come with good English instructions online, it's dead simple to wire up, and you're able to place the indicator(s) where ever you want.

 

[jamie N]

Had a look at the NASA item. It's pretty much this with cable ties and a £30 'Yottie' uplift.

 

[silvercreek]

Thanks all for the helpful tips! I will give it a try with a nut and a couple of flat sealing washers.

 

[Lomax]

Forgive my ignorance, what will measuring exhaust temperature give me that I can't already see from coolant & oil temps?

 

[silvercreek]

Allows you to catch a dangerous overtemp condition affecting the waterlock (wet muffler) which melts below the 220°F alarm set point of most engines

 

[Lomax]

Allows you to catch a dangerous overtemp condition affecting the waterlock (wet muffler) which melts below the 220°F alarm set point of most engines

I see. Pretty sure mine's stainless steel. The hose connecting to it is rubber though.

 

[VicS]

Forgive my ignorance, what will measuring exhaust temperature give me that I can't already see from coolant & oil temps?

You will see the effect of loss of water flow much more quickly.
Hopefully the monitor will also have an audible alarm which can be set a few degrees above the normal temperature range .

 

[AngusMcDoon]

Forgive my ignorance, what will measuring exhaust temperature give me that I can't already see from coolant & oil temps?

They do different things. The coolant temperature alarm will tell you when flow is insufficient, typically because the heat exchanger is partially blocked or the impeller has lost a few vanes. The exhaust temperature alarm will tell you quickly when coolant flow has stopped suddenly and completely, as could happen in an intake blockage or an impeller core stripping failure. The coolant temperature alarm will not respond quickly enough to a sudden complete loss of flow before damage is done. The base engines are designed for small industrial applications and come with a coolant temperature alarm so that is what the marinising companies use. However, the exhaust temperature alarm is the more useful for preventing damage, but the small marine engine suppliers don't provide it.

 

[silvercreek]

I see. Pretty sure mine's stainless steel. The hose connecting to it is rubber though.

If stainless, the worry is much less. The rubber will be fine until past the 220 of the engine alarm. The plastic water locks start to melt when they get above 170°F sustained (measured at the muffler inlet).

 

[AngusMcDoon]

If stainless, the worry is much less. The rubber will be fine until past the 220 of the engine alarm. The plastic water locks start to melt when they get above 170°F sustained (measured at the muffler inlet).

If you have sudden total failure of the raw water flow it may take minutes before the coolant rises to the point where the engine temperature alarm goes off in a fresh water cooled engine. In the meantime you have 500 C dry exhaust gas going into your rubber pipe. You need an alarm that goes off in seconds to avoid damage in that situation. The exhaust alarm is not about detecting that the coolant is too hot. It's about detecting that it's not there at all.

An exhaust alarm is recommended for situations like the French canals where weed blockage of the raw water inlet is common.

 

[earlybird]

I used something like this to measure the elbow temperature, which is sensitive to loss of water fow. Saves drilling the rubber hose. the device will also operate an audible alarm for a pre-set temperature.

 

[silvercreek]

If you have sudden total failure of the raw water flow it may take minutes before the coolant rises to the point where the engine temperature alarm goes off in a fresh water cooled engine. In the meantime you have 500 C dry exhaust gas going into your rubber pipe. You need an alarm that goes off in seconds to avoid damage in that situation. The exhaust alarm is not about detecting that the coolant is too hot. It's about detecting that it's not there at all.

An exhaust alarm is recommended for situations like the French canals where weed blockage of the raw water inlet is common.

Yes, this is what I was explaining. I mentioned coolant because most (all?) of our inboard engines already have a coolant alarm that will eventually go off, but is typically too late to prevent exhaust-related damage.