Great video Mario. I agree, a failed RC test could easily send you into a wild goose chase. This is a good point you made because it isn’t talked about often.

As ScannerDanner says there’s always variables. Great video Mario. Thanks for sharing.

Thank you for the time and trouble of posting this valuable educational video, yes often the gremlins can be miss fueling or water in the tank, or cheap fuel sourced from unreliable sources (junk yard) customers are not always very upfront or truthful in dissecting the core issues that could be resolved fairly quickly, i cannot understand why some car owners will use any narrative to sway the diagnostic procedure, misguided by a degree of vagueness and in asserting ignorance hoping that will bring about sympathetic results and a cheaper price! 🤔

Great video! I agree with you on being careful man. This point is not brought up nearly enough. You know my thoughts on fuel contamination LOL

It amazes me how people manage to do that (fill a gasoline car with diesel). The size difference of diesel and gas nozzles prevents people from putting diesel in a gasoline car. But as the saying goes, "If you make something idiot-proof, someone will just make a better idiot"

Here the importance of following notes. I now write down down all possible possibilities when diagnosing no start and go thru them chronologically. Sometimes you just forget... Nice tip

Brandon Steckler had an awesome case study with the same issue. Cylinder wash down screwed the compression

Great video, definitely something to keep in the back of your mind. I could see that being overlooked very easily. And would not be a fun rabbit hole to travel down! Thanks for all the great content. I’ve learned so much from your videos, keep it up man!

😱😱. Awesome Mario. Very useful tips. I know I would've been down that wrong path. But not anymore thanks to u 😇

What a great video it shows that you never know what a customer is capable of and the never ending things that can enter in to diagnostics thanks for sharing.

More and more cars coming in with diesel in then. I never thought it might influance a RC test. Thanks for the heads up!

Great advice and example bro. This could have easily thrown even a seasoned tech for a loop.

Subbed...you are a good mechanic giving good advice

Mario, thanks for your video, great info on the cylinder walls getting washed down. Had a BMW come in.. So much time spent on it.. If we could get it running, it actually ran fine after warming up.. The way it was figured out that there was diesel in the gasoline was by accidentally spilling a little bit of it on the ground and realizing that it wasn't evaporating...

Quick and easy when you know what your doing. Nice video

Excellent tip Mario.. Something to keep in kind for any future similar issues..

Thank you Mario. Good job. I appreciate your videos. Have a blessed and safe week.

Hey mario. I had a vw tdi fuelled with petrol/diesel mix. Wasted time on loads of test till i did a leak off and the fuel was yellow. Wish i had of videoed it. Cheers dave

Awesomeness 🙌💯🍻

I've experienced cylinder wash a couple times. I also used brake clean to try to start a car i pulled the engine apart and had to throw the pistons away because it welded the rings in the grooves

Wow thats spot on bud. Thanku loads

i worked a week once on 3.8 Buick with maybe a small amount of diesel in it, only complaint rough idle on start-up for a few seconds then cleared out

GO MARIO , IT LOOKS LIKE IT'S BEST TO ADD A FUEL SAMPLE TEST IT CAN'T HURT THANKS AND PLEASE KEEP UP THE GREAT WORK !

New subscriber. Older DIYer but just learning scopes. Have many years of mechanical background but but self teaching with techs like yourself,Paul Danner, Keith Defazio, SMA, Cody diagnostics, PHD Ivan leading the way. Thanks for sharing. Artie 👍

Great tip Mario and should help a lot of techs out there! 😀👍

Great tip my man.

Great video Mario! -Glen

Customer questions 1 have you recently refuelled 2 how much fuel 3 do you have the receipt. Misfuel is massive effective questioning minimising Diag time.

Cylinder wash would kill some compression but can it kill all of it?And diesel can wash the same way as gas? Diesel is "thicker" than gas so it should keep the compression and maybe seal those rings even better? The car will not run because it will wet those plugs and even if were dry it can not ignite diesel anyways. Sometimes is very hard to detect fuel contamination especially if you are not familiar with diesel. The fuel in the dipstick was from lots of cranking and the fuel would leak down past the rings at rest.If this car is gdi than would make the spraying of fuel worse if it ran leaner at start up. The thing is that it was not 100% diesel so maybe thats why you had irregular compression values. You didnt show the values on each cylinder.Were they low or some of them higher than spec? Hope you like my comment.Really like your videos and im learning a lot with them. Thanks Mario.

Excellent video, another variable, great tips Mario! Can you put link to related video in your description for us? I'm going to watch it, but it's nice to have quick link, because I'm slow...lol! She's got power now baby, rockin' the diesel!

So if diesel washed down the cylinder wall, and it actually ran like that, was there any immediate critical damage caused to the engine or fuel tank? How did you handle the fuel system?? Did you, or COULD you directly jump power to the fuel pump with the fuel line off, running a hose from the pump to a fuel can to pump out the old gas? Did you have to remove the tank to clean it? And what work did the engine need afterwards besides new oil?

I think I would've been caught going the wrong way on that one. Good job of staying in the diagnostic funnel. I think I'll subscribe to your channel. 😉

Well done Mario this was a good one for sure. What happens now that you found Diesel, what type of damage can or was done? Great job ... Jay

I see a lot of gas in diesel (vs here was diesel in gas) and a couple things I have seen when the two are mixed. Gas obviously has a stronger smell so you can smell it when it is not supposed to be there. If you put a little of the mixture on your fingers (just a drop or two) it will be a little oily. Where straight gas will not and straight diesel will be really oily. Lastly put about a teaspoon of the mixture on a workbench, when it spreads out you can watch the gas evaporate out of the mixture and you will be left with just diesel fuel. That will give you a good idea how contaminated the system is.

Smart tips must be taken in consideration in ever RC or C testing Very smart 👌

Great info, I have not come across that problem, but with some gas stations even there gasoline pump handles are green, I think BP is one of them.

Very interesting Mario, thanks for sharing bud 👍

great video wouldnt this wash all cylinders causing low amperage across the board? and not cylinder specific?

Mario! que buen video en definitiva esas son algunas experiencias que dejan marca y nunca se nos olvidan, me había tocado gasolina y agua y provoca falla, pero gasolina y diésel no. Gracias por compartirlo!!

I had a Rogue with Bad Gas last week. I should have made a video about it... Awesome tip BTW!

I had a customer replace a 750,000 engine put it together same problem I went in Turns out bad fuel Recommend every one have a hydrometer in there box to test fuel I did a video showing the test device Great video mario

Great video! Thanx...wish I could of had a better or at least a longer view of the RC wave...teased me with a quick glance lol👍👍👍

How about cutting the fuel when doing the RC test

Thanks for sharing your knowledge.

How do you do a relative compression? Did you disable fuel or ignition? It would be nice to see how you got those results to either see what the problem is.

SUPER MARIO DIAGNOSTICS /// ,,, when one or more pistons are NOT giving any compression. What would be the problems on the cars engine? /// Do you have to replace the piston or the actual engine block is cracked inside that piston cylinder and have to replace the whole engine block?

This was very interesting. In the early days of unleaded fuel, the pump nozzle, and the car filler port, were a smaller diameter, preventing putting leaded fuel in an unleaded car. Do diesel pump nozzles have something similar? Thank you for sharing. Did I just give my age away? Haha

I’m on my way to the Taurus. Super Mario!!

Great information thanks, yes i have seen this before only just last week i got call out to a workshop that i car went in for just a service when they went to start the car it crank very slow on a low battery it got wash down and we had almost no compression the fix was put oil down the cylinders and then the car started and after a few minutes the car was ok . This all happened because of a low battery. So yes your right be very careful with Relative Compression test .

this is the very reason I use external fuel supply on drivability issues.....very simple to rule out fuel as an issue or in your case, the main issue!....great vid Mario.......

Oh no that's not a diesel car,thx for sharing mario

That's some great information Mario.

nice case study💪🏻

Quickie... but good info there!

Thanks your knowledge is no cuestionable but you need to used the graphics to explain the problems.

What a video man! Good information and thank you for sharing your knowledge! Tienes un suscriptor más! Saludos!

I have never smelled anyone elses dipstick. Haha Couldn't resist. Nice find Mario!

yep it happens on jaguar a lot of the time a cold start rich running condition will cause a low compression on cylinders

Didn't see that coming good observation 👌

Great share Mario. Nice job 👍

Good video with great advice.

Brilliant thank you. We see a lot of this in Europe.

Interesting.Thanks for the helpful info ! I thought diesel nozels won't fit in the filler neck? Or is it the other way around ? 🤔

Wow... diesel.... great diagnosis and fix....

Holy Frijoles Nice job. Mario

So if we do RC test with injectors sockets disconnected, can we have a reliable RC test? Great video 👍

great video Mario just wondering arent the nozzels at the pump fool proof? thanks

yes that a good tip.tks

Wish I could work with you and learn a lot from you. What state are you from? Thanks for the tip!

Nice. That could easily be a huge time waste.

Low compression in all cylinders?

🤔🤔🤔great job !!!!

Great catch, Mario! At 2:20 you mention compression math by ScannerDanner. Is it a reference to his video or some other materials? Thanks!

Ok so I gotta ask. What is crazy about the wave from that made you wonder something else. ?? Thank you

good thinking Mario....that would been an easy left turn....diesel....maybe that's why its called flor...I .....DA ! only kidding

Taurus bad starter with comutators that have higher resistance?

Mario did you get that link??

😀👍🏻