great video Darren! I have a pulse sensor I've built and use it in the expansion tank as well. On a recent car that I was asked to repair the owner indicated he had a coolant leak I used the pulse sensor, my picoscope pressure transducer and sync'd on an injector to identify where the leak was. The owner couldn't argue with the diagnosis (I provided him a printout) and it was just so great to be able to diag this car with only a spark plug removed and my pico connected. It needed new head gaskets of course. Truly a fantastic diag tool and one I can't do without. I look forward to more of your videos!
The small ones in the cooling system are likely from the crankshaft speed increasing on the combustion stroke and you’re seeing that through the water pump spinning faster during those periods. I’m still amazed from time to time at some of the small details you can pick up in some of these captures.
Hello Darren. I really appreciate your videos. As a person who does not have English as my first language (I am Danish), I appreciate your very clear and easy to understand English. it's easy to understand your videos, and follow instruction even for forigners. Sláinte Mick
Lots of good theories about that ripple in the expansion tank. I would add that it might be due to expansion noise being transmitted into the water jacket through the cylinder walls. Remember a knock sensor is measuring the acoustic pressure wave traveling through the block. What you have there might be a secondary knock sensing effect.
@@MechanicMindset try this one: shift+windows button+s you can then select a part of the screen where windows takes a screenshot and puts it directly to the clipboard :)
Cheers, it can be difficult. I will also have to follow up on this as the intake and exhaust waveforms are a lot simpler on NA engines (this one's TDI) - the turbo definitely confuses things.
Why would that be more complicated on diesel engines? They're spool are not spinning until about 1.500 rpm.. not many internal things are moving when the engine just runs at 800rpm..
@@MechanicMindset yes they have and listed price is 220 us for 8 channels not sure abut specs didn't check.I was about to try their in cyl pressure transducer for 105 us but it is out of stock at this moment.take a peak at their web store they have a lot of interesting gadgets.cheers!
Great video as usual. The pulses you see in the expansion tank are water pump rotational pulses. As each blade of the impeller pushes more coolant you will get a slight pulse
Someone added another dimension to this theory; the pulses are inline with the 4 stroke cycle because of the crank & water pump speed increases on each power stroke. What do you think? 👍
@@MechanicMindset very very interesting this theory!!!!wow.i wouldn't think of this. But I think, it's a way to find out. Just make a video with the engine running, and then with the engine just cranking (disable ignition and injection/ or diesel injection,depending of the type of fuel ), and I think will we find out the results.
darn good video, ive gotten into this style of testing and love it and this video definitely helps clear things up and greatly aids in education on it.. great job man!!
Great video!!! From what I understand the pulses on the expansion tank could also be from the cylinder expanding a bit on the compression stroke moving the coolant creating the ripples I think the become more pronounced during a Cranking waveform where there is alot more pressure.
@@MechanicMindset only ever use this once on aux belt idler pulley , but to be honest my infrared camera had already pin pointed failure on idler pulley bearing.
@@MechanicMindset just reading thru comments and seen yours sir...buddy of mine got the Seek for his and it is pretty good....I have a Fluke VT04A and the Seek hooked to phone does better bc of phone camera interface....thanks for all the vids and knowledge Cheers
Good point, I did hold it / isolate on some of the ‘shaker’ measurements, it didn’t make much difference in this sensor. Must be well built. More than I can say for my DIY job 😂
Great video. Might not be very practical on all vehicles but you might try the cooling system test with the belt off. The crankcase test is definitely cool. It's quick and easy too.
@@MechanicMindset I would agree, could be cooling system air pockets that’s why I mentioned removing the belt. Also on the crankcase test I try to isolate the system by blocking off the pcv.
I have used delta sensors many times. I do my best to try to isolate the sensor from vibration because just bouncing around will generate a waveform. Looking at the test you did with the intake were you inserted the Delta sensor I would have to think the turbo is affecting that waveform. I’m gonna test that Theory Monday when I get to work. I Also suggest doing your pressure pulse in your intake and your exhaust while cranking instead of running. When I take a intake pressure pulse test I usually try to attach it right to the throttlebody and block off the intake
For sure, I need to get a hook or something for it. I agree on the turbo theory and was going to try the same (go in at MAP sensor). I would say the same applies to the exhaust waveform too. I never tried revving it to see what happened. Any reason you prefer cranking opposed to running the engine? Cheers 👍
@@MechanicMindset I think cranking to me defines each cylinder better than actually running. Now the Crank case and the cooling system obviously you would need the vehicle running. Now depending on how bad the crankcase blow by was you wouldn’t need for the vehicle to be running. Something I see that some technicians that make pressure pulse sensors if you just have them hooked up you will see a voltage isolation depending on your millivolt range does that make sense?
Mechanic Mindset To be fair with those pipes even just the thought of removing the intake will snap them .....! Was thinking this pressure pulse diagnostic method would be a lot handier for diagnosing suspect ingeniums than using the compression tester as the glow plugs are a bit of a PITA
I suppose it depends on what you are testing. For pistons rings or head gasket I would think engine running would be best (capture high pressure from power stroke). For valve train issues, I don’t suppose it matters. Worth looking in to further 👍
These pulse sensors are just pretty much sensitive microphones. That leafy piezo element you've shown in the video is a sensitive sound pickup element. Even if you had the best head gasket ever possible, the walls of the engine block is gonna flex because of combustion events and a pressure wave(aka sound) is gonna travel through the coolant system. Hell you'd even see such small spikes even if you'd only just place that pulse sensor near the car while it is running, since you can hear the engine running by ear. Bonus: pressure sensors and microphones measure the same thing. However, pressure sensors are properly calibrated for a certain range and microphones mostly respond to speed of pressure change, not the actual pressure itself.
Great video though! Even though I knew such details about the sensors themselves, I'd never imagine such an application, it's genius! You've opened a whole new view for me with both your videos of in cylinder pressure sensor and this pulse sensor.
For sure, these are so sensitive. It’s amazing how much sensitivity we get for so cheap. Pulse sensor diagnostics is really a game of comparison; and as you have raised, you need to understand what they are doing to be able to interpret any meaningful data from them. Cheers! 👍
I suppose theoretically yes, you would have to use cam/crank sensor to reference and be sure exactly where TDC was. For example, the gap on the crank signal isn’t always exactly TDC. There are some other things to consider like pre injections and the flame spread time. Like your thinking!
@@MechanicMindset This test would be to check cam and crank in relation to tdc... indeed we would need to know manufacturers cranking degrees and do a little maths. Beats the hell out of removing plugs in diesels. Perhaps theres an option on dealers scan tools
@@MechanicMindset thanks for the reply, but it will effect everything? If I go to high one peak will go into another section? Can you recommend any reading material that will clear this up?
If you got a CO2 sniffer you might be able to detect the exhaust gasses themselves using the scope. I mean, sure the old-school blue to yellow shows SOME contamination, a digital sensor is much more sensitive to detection. Got a great video on a DIY version I could recommend if you wanted to replicate it as opposed to purchasing a pre-built one since you seem to like to show off affordable methods. And the same tool can be used on the tailpipe to detect leaking/faulty injectors.
Yeah we used to do the same with the 4 Gas analyser in the dealer 👍. Block tester was always a bit hit/miss. Well that sounds interesting! Not come across something like that before, share the link 👍
@@MechanicMindset ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CpffDP1VQg4.html He's got a few videos including one to make one on that gas analyzer. There's a 3D print file if you've got the options. But I don't personally and am in the process of designing a basic prototype model for myself until I find a better box or decide to pay a printer.
@@MechanicMindset Also be sure to check out his whole channel. Full of DIY tools on a budget for those who have the ability. The telegram group is very friendly and about learning/improving always. Super nice guy too talking to him.
Personally would never of thought about using a oscilloscope for diagnosing engine mechanical faults. Just wondering what your opinion is for the pros and cons of this method compared to say Compression, leak down and a sniff tester
It’s a great method. I think this could be quicker if your scope is always handy. I suppose the first measurement would be relative compression with the amp clamp. I would say this method is faster, but only if you have the knowledge of waveform analysis. Get some reference waveforms! This method checks all cylinders at the same time, where as cylinder leakage would have to be done individually. There are probable more but not sure. Some people would probably be more comfortable with the traditional method. Thanks👍
Compression has flaws too! You can get good number with closed (stuck) valves (exhaust). Using scope in the car diagnostics is a top level (mediocre clowns are afraid of it or think it's something "new" or inferior to "old-school" parts swapping). You can diagnose ALL possible mechanical faults using scope and proper probes, transducers etc.
Yeah sure, but some cylinders are a pain to remove a plug (diesels….even longer), and this set up could be quicker with practice with the scope ready to go on a diag stand. I’d say this test is about convenience but will require a bit of practice 👍
I just tried this test with a scion XB that has coolant standing in cylinder during pressure test but only show little differences in pulses while piston at top dead center? In my stall now
@@joshuawood6588 Are you getting any gasses in the coolant system/over pressurising? Another trick I saw is to remove the cap tie a latex glove around the hole. It inflates if it’s blowing in to the cooling system
Would it be possible to measure cooling system pulses to identify power stroke events of each cylinder? Let's say you had a plugged fuel injector on a cylinder so good compression but no fuel or vary little.
hey, could someone explain the overlay to me. How do you know which cylinder is doing what if he sets them in the middle of 3 and 4-such as at 6;46 in the video.... i get the colors but just dont get how to sync the waveform with the colorsfor all the cylinders. thanks
I see what you mean. The horizontal position of the waveform has no significance. Some people actually keep it down blow out the way, but still lined up. The overlay just helps us identify what each cylinder is doing in that segment of the waveform. Let say we had a spike on the pulse sensors on the intake, we could assume an inlet valve was leaking. We would look at which cylinder was on a compression or power stroke (depending on engine state) to identify which cylinder is at fault
