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n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Tue Jan 31, 2023 6:36 am Post subject: New engine runs a little rough when weather is cold.

Hi Guys (and Gals),



Haven't posted much lately but things going well with my mono. Enjoying it more every day.



One question, and a puzzler for me, regarding engine vibration (yes, I know I am picky about this subject but I hate when things are running well and then change):



My new engine (about 70 hrs now) has always ran pretty good. However, as of late, I noticed a slight (emphasis on slight) vibration when I power down to a low cruise power setting (around 500-5100 RPM). Now, I know that some people will start screaming that I should not keep the power that low but I had no issues with sensing vibration (slight) at that power level before.



Well, I started to suspect that this was happening when the weather got colder (50s-60s °F). EGT looks good at around 1400. And even though I have blocked maybe 1/2 of the oil cooler, it still runs a little bellow 180 (160-170). Coolant has been as low as mid-150s. 



Sure enough, on last Friday's flight the vibration was noticeable. Yesterday we had a warm and humid day, in the 80s, so I decided to test my theory. Lo and Behold the engine ran great. Absolutely no vibration at 5000 RPM.



My suspicion at this point is that the cold air from our ram air induction system is just very cold, and maybe adds a little extra pressure, and the mixture goes lean with the stock 912S carb setting. # 1 and 2 plugs look normal (slight tan) but the #3 and 4 look lean (white). Engine is stock as it came from Rotax with no changes to the carbs made. 



If we get a cold day again I will try moving the needles up one notch but I wonder if anyone had an experience like this before.



Best Regards,

Chris

peterz(at)zutrasoft.com
Guest

Posted: Tue Jan 31, 2023 6:47 am Post subject: New engine runs a little rough when weather is cold.

Interesting.... curious, what prop are you running?  

Cheers,

PeteZ



On Tue, Jan 31, 2023 at 9:44 AM n7188u <chmgarb(at)gmail.com (chmgarb(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: "n7188u" <chmgarb(at)gmail.com (chmgarb(at)gmail.com)>

 

 Hi Guys (and Gals),

 

 Haven't posted much lately but things going well with my mono. Enjoying it more every day.

 

 One question, and a puzzler for me, regarding engine vibration (yes, I know I am picky about this subject but I hate when things are running well and then change):

 

 My new engine (about 70 hrs now) has always ran pretty good. However, as of late, I noticed a slight (emphasis on slight) vibration when I power down to a low cruise power setting (around 500-5100 RPM). Now, I know that some people will start screaming that I should not keep the power that low but I had no issues with sensing vibration (slight) at that power level before.

 

 Well, I started to suspect that this was happening when the weather got colder (50s-60s °F). EGT looks good at around 1400. And even though I have blocked maybe 1/2 of the oil cooler, it still runs a little bellow 180 (160-170). Coolant has been as low as mod 150s. 

 

 Sure enough, last flight the vibration was noticeable. Yesterday we had a warm and humid day, in the 80s, so I decided to test my theory. Lo and Behold the engine ran great. Absolutely no vibration at 5000 RPM.

 

 My suspicion at this point is that the cold air from our ram air induction system is just very cold, and maybe adds a little extra pressure, and the mixture goes lean with the stock 912S carb setting. # 1 and 2 plugs look normal (slight tan) but the #3 and 4 look lean (white). Engine is stock as it came from Rotax with no changes to the carbs made. 

 

 If we get a cold day again I will try moving the needles up one notch but I wonder if anyone had an experience like this before.

 

 Best Regards,

 Chris

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=510082#510082

 

 

 

 

 

 

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DuaneFamly

Joined: 16 Jan 2022
Posts: 22
Location: Chandler, AZ

Posted: Tue Jan 31, 2023 7:26 am Post subject: New engine runs a little rough when weather is cold.

If you pull on Carb Heat, does the vibration smooth back out?



Mike Duane

N377EA Europa Conventional Gear

Jabiru 3300A 

Sensenich 2Blade Ground Adj. Prop



Sent from my iPhone



 	  Quote: 	
		  On Jan 31, 2023, at 7:47 AM, Pete Zut <peterz(at)zutrasoft.com> wrote:



Interesting.... curious, what prop are you running?  

Cheers,

PeteZ



On Tue, Jan 31, 2023 at 9:44 AM n7188u <chmgarb(at)gmail.com (chmgarb(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: "n7188u" <chmgarb(at)gmail.com (chmgarb(at)gmail.com)>

 

 Hi Guys (and Gals),

 

 Haven't posted much lately but things going well with my mono. Enjoying it more every day.

 

 One question, and a puzzler for me, regarding engine vibration (yes, I know I am picky about this subject but I hate when things are running well and then change):

 

 My new engine (about 70 hrs now) has always ran pretty good. However, as of late, I noticed a slight (emphasis on slight) vibration when I power down to a low cruise power setting (around 500-5100 RPM). Now, I know that some people will start screaming that I should not keep the power that low but I had no issues with sensing vibration (slight) at that power level before.

 

 Well, I started to suspect that this was happening when the weather got colder (50s-60s °F). EGT looks good at around 1400. And even though I have blocked maybe 1/2 of the oil cooler, it still runs a little bellow 180 (160-170). Coolant has been as low as mod 150s. 

 

 Sure enough, last flight the vibration was noticeable. Yesterday we had a warm and humid day, in the 80s, so I decided to test my theory. Lo and Behold the engine ran great. Absolutely no vibration at 5000 RPM.

 

 My suspicion at this point is that the cold air from our ram air induction system is just very cold, and maybe adds a little extra pressure, and the mixture goes lean with the stock 912S carb setting. # 1 and 2 plugs look normal (slight tan) but the #3 and 4 look lean (white). Engine is stock as it came from Rotax with no changes to the carbs made. 

 

 If we get a cold day again I will try moving the needles up one notch but I wonder if anyone had an experience like this before.

 

 Best Regards,

 Chris

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=510082#510082

 

 

 

 

 

 

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Mike Duane

peterz(at)zutrasoft.com
Guest

Posted: Tue Jan 31, 2023 7:28 am Post subject: New engine runs a little rough when weather is cold.

hi Chris,

I'd be curious if your dog-tension friction measurement has decreased. Ideally it should be around 30ft-lbs.

cheers,

Pete



On Tue, Jan 31, 2023 at 9:44 AM n7188u <chmgarb(at)gmail.com (chmgarb(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: "n7188u" <chmgarb(at)gmail.com (chmgarb(at)gmail.com)>

 

 Hi Guys (and Gals),

 

 Haven't posted much lately but things going well with my mono. Enjoying it more every day.

 

 One question, and a puzzler for me, regarding engine vibration (yes, I know I am picky about this subject but I hate when things are running well and then change):

 

 My new engine (about 70 hrs now) has always ran pretty good. However, as of late, I noticed a slight (emphasis on slight) vibration when I power down to a low cruise power setting (around 500-5100 RPM). Now, I know that some people will start screaming that I should not keep the power that low but I had no issues with sensing vibration (slight) at that power level before.

 

 Well, I started to suspect that this was happening when the weather got colder (50s-60s °F). EGT looks good at around 1400. And even though I have blocked maybe 1/2 of the oil cooler, it still runs a little bellow 180 (160-170). Coolant has been as low as mod 150s. 

 

 Sure enough, last flight the vibration was noticeable. Yesterday we had a warm and humid day, in the 80s, so I decided to test my theory. Lo and Behold the engine ran great. Absolutely no vibration at 5000 RPM.

 

 My suspicion at this point is that the cold air from our ram air induction system is just very cold, and maybe adds a little extra pressure, and the mixture goes lean with the stock 912S carb setting. # 1 and 2 plugs look normal (slight tan) but the #3 and 4 look lean (white). Engine is stock as it came from Rotax with no changes to the carbs made. 

 

 If we get a cold day again I will try moving the needles up one notch but I wonder if anyone had an experience like this before.

 

 Best Regards,

 Chris

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=510082#510082

 

 

 

 

 

 

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n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Tue Jan 31, 2023 7:31 am Post subject: Re: New engine runs a little rough when weather is cold.

Hi Pete,



I have a DUC SWIRL-3 prop. Quite happy with it.



Best,

Chris

kingsnjan(at)westnet.com.
Guest

Posted: Tue Jan 31, 2023 1:25 pm Post subject: New engine runs a little rough when weather is cold.

 	  Quote: 	
		   


	


Hello Chris,



Just a couple of questions …..



1  Do you have the overflow/equaliser hoses on the sides of the carbs plumbed into your plenum chamber?



2  Do you have the hot water/electric jackets fitted to the carbs to prevent carb icing?



Best regards

Kingsley in Oz

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Tue Jan 31, 2023 2:05 pm Post subject: Re: New engine runs a little rough when weather is cold.

Thanks for the postings guys. Some answers:



1- The carb bowl vents are located in the plenum.

2- I have no provisions for carb heat since neither the stock Europa has it nor Rotax provides it unless I go aftermarket. 

3- The engine has 70 hours in it total but I did check the clutch at 25 hours. 51 NM (38 ft*lb). I can check it again.



Chris

Area-51

Joined: 03 May 2021
Posts: 396

Posted: Tue Jan 31, 2023 3:34 pm Post subject: Re: New engine runs a little rough when weather is cold.

Pull the plenum off and make sure both carburettor pistons are moving full stroke without any binding; bit of dust may of found its way onto one of the piston bores.; should move freely and full with a final clunk.



What altitude are you operating at? Does the vibration alter over 5000' variance?



Next time the vibration happens activate the choke at very small increments from neutral position and see if the vibration alters any.



Does the engine idle quality/smoothness also alter?



Sounds like you are running avgas? Best plug colour is double shot late coffee; light grey indicates lean; light grey yellow indicates water ingress... the difference in plug colour between left right bank should be very marginal if not any. Unleaded fuel should read tad sooty but clean.

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Wed Feb 01, 2023 11:49 am Post subject: Re: New engine runs a little rough when weather is cold.

Thanks to all for the feedback. I think that at this point, given that the engine behaved perfectly during the last flight with higher OATs I decided to:



1.- Recheck the gearbox clutch friction just in case (even though it was OK 40 hours ago).

2.- Tape both the oil cooler water cooler further to get the temps higher on my next cold day flight.

3.- Try the choke idea to see if a richer mixture changes anything.



I'll report back.

Chris

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Mon Feb 13, 2023 11:04 am Post subject: Re: New engine runs a little rough when weather is cold.

Hi everyone,



I promised an update so here it is. 



In a nutshell, I decided to follow my eyes, which were looking at very white rear cylinder plugs. So I decided to move the needle from position #3 to position #4 and enrichen the mid-range mixture.



The jury is still out since I only did two flights since the change but the difference is notable in terms of engine smoothness. But too early for final conclusions. I did pull the plug and it looks a more reasonable light tan now which I think is an improvement. I will report back on the mid-range adjustment once I do a few flights in different conditions.



But what really caught my attention is that for the last three years, even with changing to a new engine, I had to put up with crappy idling 912Ss (at least by my picky standard). I always thought that that was the way these engines idle, particularly the high compression 912S.



Well, I finally decided to play with the idle mixture. I had moved the idle screw a flat or so in the past to see if anything happened but not much did. But this time around I decided to move the screw in or out one flat at a time until something happened. Well, what a pleasant surprise when the engine started to get smoother as I screwed the needle in but not until you are at less than one turn from fully closed. And I mean HUGE improvement. All the roughness went away and now it idles smoothly.



Again, I still have to fly more with these settings but what a difference so far.



I told a Rotax 912S owner friend of mine all this and he recommended I watch this video. I think it exemplifies my newly acquired conviction that the carbs in the 912S have to be tuned beyond just the simple balancing.



https://www.youtube.com/watch?v=GxEORpdJp0w



Best,

Chris

peterz(at)zutrasoft.com
Guest

Posted: Mon Feb 13, 2023 11:30 am Post subject: New engine runs a little rough when weather is cold.

great vid - thx!

I'm gonna pick me up an O2 sensor/readout and find out where I'm at.  Generally I find my plugs to be a bit rich.

Cheers,

PeteZ



On Mon, Feb 13, 2023 at 2:11 PM n7188u <chmgarb(at)gmail.com (chmgarb(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: "n7188u" <chmgarb(at)gmail.com (chmgarb(at)gmail.com)>

 

 Hi everyone,

 

 I promised an update so here it is. 

 

 In a nutshell, I decided to follow my eyes, which were looking at very white rear cylinder plugs. So I decided to move the needle from position #3 to position #4 and enrichen the mid-range mixture.

 

 The jury is still out since I only did two flights since the change but the difference is notable in terms of engine smoothness. But too early for final conclusions. I did pull the plug and it looks a more reasonable light tan now which I think is an improvement. I will report back on the mid-range adjustment once I do a few flights in different conditions.

 

 But what really caught my attention is that for the last three years, even with changing to a new engine, I had to put up with crappy idling 912Ss (at least by my picky standard). I always thought that that was the way these engines idle, particularly the high compression 912S.

 

 Well, I finally decided to play with the idle mixture. I had moved the idle screw a flat or so in the past to see if anything happened but not much did. But this time around I decided to move the screw in or out one flat at a time until something happened. Well, what a pleasant surprise when the engine started to get smoother as I screwed the needle in but not until you are at less than one turn from fully closed. And I mean HUGE improvement. All the roughness went away and now it idles smoothly.

 

 Again, I still have to fly more with these settings but what a difference so far.

 

 I told a Rotax 912S owner friend of mine all this and he recommended I watch this video. I think it exemplifies my newly acquired conviction that the carbs in the 912S have to be tuned beyond just the simple balancing.

 

 https://www.youtube.com/watch?v=GxEORpdJp0w

 

 Best,

 Chris

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=510157#510157

 

 

 

 

 

 

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n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Mon Feb 13, 2023 1:03 pm Post subject: Re: New engine runs a little rough when weather is cold.

BTW Peter, I did check the gearbox clutch friction and it is fine.



Regarding O2 readings, I think it would be nice to do although not fond of pocking a hole on my nice CKT muffler. My question though is what is considered OK. On idle I don't care since I have always leaned my Lycomings to death at idle to prevent plug fouling. At this low power it is stated that you can't harm the engine if ultra lean. I didn't over do it just to leave a margin in case weather gets colder. And I would be careful that the engine will not find itself too lean if suddenly transitioning from fully closed throttle to open. Don't know if the Rotax can be sensitive to that. Experiment at your own peril.



At mid or full throttle I would question what air/fuel ratio is desirable? The guy in the video talks about the mixture being too lean at full power. That surprised me since I thought Rotax would have a very rich mixture at full power, particularly at 5000' were the guy flies. Go figure. I'm personally not going to change the main jet for know. Too risky.



Chris

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Mon Feb 13, 2023 3:53 pm Post subject: Re: New engine runs a little rough when weather is cold.

I’m going to stick to this version of the tread. Why are there two?



Anyway, I do my carb balance at 2500 but also check at 3500. Found that if I make it perfect at 2500 I get smoother low rpm operation but if at 3500 a little nicer at cruise. I’ve been told to split the difference. Not much difference between the two though. My electronic balancer is very sensitive. 



Unfortunately sync will go out as I get to 1800 and just a little off at 4000. Sometimes it is better, sometimes worse. But overall runs nice. Better now after the idle mixture adjustment. Just being picky. I am convinced that if a butterfly farts in front of the airplane the  tuning  changes 



Just came back from a flight. Runs good. 



Chris

Area-51

Joined: 03 May 2021
Posts: 396

Posted: Tue Feb 14, 2023 4:39 am Post subject: Re: New engine runs a little rough when weather is cold.

Checking O2 levels without drilling holes in exhaust systems; see pics...  That's how its done.



Strap the tail wheel securely to a pole or pickup truck's tow hitch and run WOT at engine operating temps.



I've had my 80hp idle smooth at 600rpm while setting idle mixtures and balancing carbis.. the 100hp will probably tick over nicely at 1000rpm without a fuss during tuning... Anything below 500rpm on either spec engine will see the ignition modules shut down.



Once tuning is set it won't have any reason to alter; check it at each 100hr or annual if desired.



1/2 a turn on the idle mixture screw is still fairly broad; 1/8 turn adjustments between smooth and not smooth indicates you have reached optimum... For resetting idle mixture position screw all the way in until lightly stops then 1 1/2 turns out.... lift each carbi piston 1/2" momentarily while idling; the one that speeds up idling slightly is the richer one.



Don't walk into the moving propeller; it will hurt...

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dmac7

Joined: 05 Apr 2019
Posts: 48
Location: Canada

Posted: Tue Feb 14, 2023 10:45 am Post subject: Re: New engine runs a little rough when weather is cold.

Hello Chris, that was a interesting video you shared, years ago I drag raced a mildly modified '70 Ford Mustang 351C engine, I didn't have a oxygen sensor I used the time and speed to tell me how to jet the carb (mostly the speed).



 I was running Shell V'Power and I tried 100LL avgas which slowed me down actually, puzzled I tested the specific gravity of both fuel types...big difference.  100LL is always .72 but auto fuel changes greatly seasonally.  The summer Shell VPower was .82 giving much richer mixture, in winter I tested Shell VPower and it was .75.   

The lesson is, if winter fuel has a lighter specific gravity it will give you a leaner mixture than what you had in summer.  Fuel density matters too

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Tue Feb 14, 2023 6:44 pm Post subject: Re: New engine runs a little rough when weather is cold.

All very good info. Thanks. A couple of comments:



- I have balanced carbs at 3500 and agree found it to work well. But there is so much info out there. Some say better at lower RPM, some at higher. And since Rotax doesn't say, well, here we are. I tried at the lower range this time.



- I saw your O2 setup a while back Area-51. And I like it. But heard that having the sensor too close to the pipe exit can cause outside air to mix with the exhaust and produce erroneous readings. But your solution is certainly attractive. Who sells that short adapter to mount the O2 sensor and coupling hoses?



- The info from dmac7 is very interesting. These issues I am having started this winter (well, if you can call it that in Florida). But we do get winter fuel here too. Per Lockwood, he says winter fuels are terrible for our use. Maybe that is the culprit and the solution is to retune carbs during winter. I have to do the same on my 503 powered Kolb (24 years old now) but since that is second nature and expected in the 2-stroker I never had issues.



I will fly with this new tuning setup and will report back at some time in the future.



Chris

Area-51

Joined: 03 May 2021
Posts: 396

Posted: Tue Feb 14, 2023 7:47 pm Post subject: Re: New engine runs a little rough when weather is cold.

Chris, the setup i just bought the bits off fleabay and made one; the case is 3D printed in PETG with two velcro securing straps and the T'piece for the sensor i had to custom drill and tap to suit... i can make more units ready to use out of the box, and they would be around $600 Aud plus postage; the unit can be used in the cockpit during flight testing for specific altitudes tests also and has self contained battery power or plug into 12v supply and recharging. The tail pipe fitting length negates proximity contamination to external atmospheric air and fits 36mm - 40mm tail pipe sizes with provision for safety cable attachment should the T'piece depart during flight.



Balancing carbis at 3500/4000 etc is fine however its a lazy way of going about it and will only offer Intermediate range tuning, so that would be needle height adjustment only. Adjusting mixtures and butterflies for smooth idle are best achieved at the lowest possible rpm (operational idle rpm is set afterward); have had triple SU Aston Martin DB3's happily idling at 150rpm while setting mixtures... SU and Stromberg CV tuning method would be the most appropriate applied approach for Bing64 series. The only other point to note is symmetry of needle height position; if they are not the same height on each carbi and your tuning is complete then you have an issue remaining either an air leak, high or low float level, or unbalanced butterfly valves; take everything back to default and start again to find the reason for rich or lean side.



Seasonal changes in specific gravity of fuels will alter the tuning slightly on cold startups as it affects the barometric vaporisation point of the fuel (for Darwinian safety reasons modern pump gas is designed not to vaporise, its designed to be sprayed and atomised at high pressure). Avgas however will readily vaporise and has a specific barometric vaporisation point that must be deliverable and adhered to to prevent vapor locking up to a specified pressure and temperature.



Bud might offer a better explanation as i never cease to expect everybody to just automatically know all this stuff! 🤷🏼‍♂️

peterz(at)zutrasoft.com
Guest

Posted: Wed Feb 15, 2023 3:20 am Post subject: New engine runs a little rough when weather is cold.

fwiw, up here in the frozen tundra when spring comes with the warmer weather and the stations are slow to switch their premium tanks over due to lack of volume, we also see  lots of running issues and vapor lock with the "winter gas" formulation.

Cheers,

PeteZ



On Tue, Feb 14, 2023 at 9:50 PM n7188u <chmgarb(at)gmail.com (chmgarb(at)gmail.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: "n7188u" <chmgarb(at)gmail.com (chmgarb(at)gmail.com)>

 

 All very good info. Thanks. A couple of comments:

 

 - I have balanced carbs at 3500 and agree found it to work well. But there is so much info out there. Some say better at lower RPM, some at higher. And since Rotax doesn't say, well, here we are. I tried at the lower range this time.

 

 - I saw your O2 setup a while back Area-51. And I like it. But heard that having the sensor too close to the pipe exit can cause outside air to mix with the exhaust and produce erroneous readings. But your solution is certainly attractive. Who sells that short adapter to mount the O2 sensor and coupling hoses?

 

 - The info from dmac7 is very interesting. These issues I am having started this winter (well, if you can call it that in Florida). But we do get winter fuel here too. Per Lockwood, he says winter fuels are terrible for our use. Maybe that is the culprit and the solution is to retune carbs during winter. I have to do the same on my 503 powered Kolb (24 years old now) but since that is second nature and expected in the 2-stroker I never had issues.

 

 I will fly with this new tuning setup and will report back at some time in the future.

 

 Chris

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=510174#510174

 

 

 

 

 

 

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dmac7

Joined: 05 Apr 2019
Posts: 48
Location: Canada

Posted: Wed Feb 15, 2023 10:38 am Post subject: Re: New engine runs a little rough when weather is cold.

It will vary but winter mogas has typically 10% more butane to help it start in cooler seasons, butane has 20% less energy than gasoline and evaporates easily so it doesn't age well in a vented tank.  

The EPA mandates the Ried vapour pressure =RVP, and butane is how they adjust this. Mogas usually more volatile than 100LL.

100LL has additives to reduce icing and static and anti oxidents to prevent gum build up, it ages well.  I would suggest buy a spcific gravity tester, from Fisher Scientific, only $20 when I bought mine.  Good to know what's in the tank.

peterz(at)zutrasoft.com
Guest

Posted: Wed Feb 15, 2023 11:02 am Post subject: New engine runs a little rough when weather is cold.

nice little summary on that I stumbled across fwiw

https://www.yellowbullet.com/threads/specific-gravity-of-racing-fuel.170626/

PeteZ



On Wed, Feb 15, 2023 at 1:44 PM dmac7 <dmac7(at)outlook.com (dmac7(at)outlook.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: "dmac7" <dmac7(at)outlook.com (dmac7(at)outlook.com)>

 

 It will vary but winter mogas has typically 10% more butane to help it start in cooler seasons, butane has 20% less energy than gasoline and evaporates easily so it doesn't age well in a vented tank.  

 The EPA mandates the Ried vapour pressure =RVP, and butane is how they adjust this. Mogas usually more volatile than 100LL.

 100LL has additives to reduce icing and static and anti oxidents to prevent gum build up, it ages well.  I would suggest buy a spcific gravity tester, from Fisher Scientific, only $20 when I bought mine.  Good to know what's in the tank.

 

 

 

 

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