The difference between Interference and Non-Interference engines 

I'm not a mechanic but that's about as clear as any professional could have given that thank you I appreciate your time

I like how even when he was right to begin he still explained thoroughly how he could be wrong that’s mad respectable

Outstanding explanation, I think you covered everything, and I don’t see a need in recreating the other video that you are contemplating a redo on.

Another case of the engineers saying; "That's not supposed to happen."

Came to learn the difference between interference and non interference engines and felt like I am leaving with so much more . This is an incredibly underrated channel and I really hope you get the views you deserve sooner more than later! thank you! like and subbed.

I have nothing to do with cars or engines but your video and analysis was brilliant David

well done -- we need more mechanics like you

I like the moral of this story. Never believe what you read but to check it yourself instead.

Man, we all learn something new eventually. I been wrenching on cars my entire life, and stilllearn new things from time to time. You are good mechanic.

Dude, thank you!! This video helped me, a NOVICE at BEST, more than any input I've gotten from multiple mechanic buddies of mine over the last few weeks.. You are the friggin man!!! I'm so stoked, thanks again, bro. Keep rockin', Legend!

David, always a pleasure to see you upload a video! I hope this means we get to see a head rebuild video soon 😏

Nice work, I agree that if you have a problem with something that you should check it out for yourself and see what the problem is and why it is happening, and seeing it with your own eyes is priceless as far as solving the issue. I also like how you did not have a problem with admitting you may or may not have been correct and explained it, too many people would just sweep it under the rug or blame somebody or something else and hope nobody says anything, and move onto something else. Subbed

"Never assume" has served me well in my 58 years. Always learning thanks brother!

it's great when a non engineer can question what's written on the book. GREAT WORK!!

I have been following this series, This video just made me subscribe. Excellent job!

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

Excellent video. Your honesty and self-accountability is to be admired. Never assume. Test, test, test!

Excellent video. Thanks for putting such great content out. Keep the Pentastar 3.6L videos coming! 🤘🏽

This is an outstanding video, and part of an outstanding series, that resolved a long standing question about the 2.4 liter twin cam. You did a great job of forensic engineering, that never would have been needed if those diploma engineers had properly insisted on exhaust valve reliefs at the tops of the piston crowns. That would have only reduced the compression about one, or at most two, percent and saved a lot of trouble for a lot of people. Thanks again.

The coments about my engine (93 Ford Ranger 2.3) being non interference on another video brought me here and I learned something new plus Im glad mine is a none Interference. Thanks, great video and subscribed.

Good stuff! Always appreciate your help, which is always spot on!

Thanks for a thorough discussion.

Awesome brother! Just bought a base PT and you will be my go to guy on these 2.4L engines. 👍

probably the clearest and most technically superb video Ive seen on this issue.

Great stuff. I hope your channel starts getting the views it deserves. Your videos are as thorough as I've seen regarding automotive repairs.

Wow! You have explained this in such good detail with actual real life examples.

Really nice to watch a video by someone who knows their stuff vs some of these videos out there where they just want to show off all their snap on tools. I admire the detail you put in you work. Question: Are you mostly self taught and always just loved working on cars or did you go through a lot of training to get where you are ? Again, great videos David !

Wishing you was my neighbor!!! Love your videos and if your looking for ideas on video content, 3rd gen 6.7 Cummins seems to be popular lol take care David and have yourself a very merry Christmas!!!

This is what confused me to no end. Thank you for clarifying this. Off to the machine shop I go.

...WOW !!! ...I like the way you explained the difference between the two !!! ... Keep on sharing, you are awesome instructor ;) ;) ;) ....From state of Florida

Wonderful job! I love this. I keep promoting your video on the facebook PT forums. Too many people want to drive it until it breaks because it is "non-interference". They're so wrong.

As the original owner of a 1989 Dodge Spirit ES turbo car AND the factory issued shop manual for the car, I can tell you from my own wrenching experience over all these years, a corporation can and sometimes does make mistakes in their printed literature about their own product. It's not often, but it does happen. BTW, the 2.5L SOHC engine in the Spirit is virtually all original except for 5 head gaskets, one timing belt, and a valve grind. Over 300K miles now. Love your channel David. Hope you keep it going for many more years.

From all the videos out there you are the best.

I have NEVER heard of valve to valve interference until this video. It makes sense now but I think in this specific case you're correct. There is just no way they hit each other unless the lash is WAY out of spec. So far out that the valve can't completely close; or put another way, NO LASH AT ALL. Which would cause problems way before the belt breaks.

Again a great video. Technicians such as you are Golden.

Thanks for this awesome vid, David. Super helpful and informative. Keep it up!

Your videos are great on the PT I have a 2004 with 202,680 miles on it

Very interesting. Thank you for sharing, David.

Great video man this taught me a lot

Another great video David. Love the content. How many times I've read incorrectly printed technical information Chrysler....I have lost count.

Excellent video! Thanks for the explanation.

Very good breakdown and analysis. Definitely subscribing. You helped me out tremendously.

Great video! As an owner of two Chrysler vehicles with the 2.4, this is very useful info. I changed the belt on both mine at the suggested interval, and now I can see that I am glad I did. The exhaust valves did come into contact with the piston. Did you have to replace the piston in this case? Is this discussed in a later video?

Great job Sir Motor !

Great video thanks for the help!

Tanks for this video I have this problem for long time diesel drips damage started I start tomorrow to fixed my truck tanks

Got em. Good shit bro. I love it. Real work

Great information and descriptive learning Dave. Valve to valve contact was a prominent issue in early multi valve overhead cam diesel engines with primate electronic injection, where the early belts or chains failed, especially in Australia where extreme heat, multi trailer combos are prominent. In all engines failures I've diagnosed with this description, the valves had not touched the pistons, due to the volumetic concaved pistons (increased volumetric area), but had edge contact with the opposing bank, resulting in major valve head degregation, from chips to complete severance. Other diagnosis of terminal failure include exhaust valve failure due to Jake Brake failing to release after disengagement, Hobbs switched fans causing belts/chains to jump a notch when engaging due to failure of soft start mechanism affecting cam timing, early ECU failures, most notably on Euro trucks with primitive VVT, losing sensor activity, suddenly engaging limp home without warning, and regarding the timing without confirmation of either cam / valve positioning. Add the failure of belts due to atmosphere and mechanical exposure, and overstressed timing chains, and you have very expensive repairs as the engines were usually destroyed by shrapnel from valves and / or disintegrating turbo turbines. Oh....one funny issue seemingly encountered on industrial Detroit diesels was the engines would fall out of timing without warning for no obvious reason but never damaged valves. When the heads were removed exposing the combustion chamber, the valves, usually inlet, had caught the edge of the exhaust valve, rendering retraction impossible. 👍👍

Outstanding explanation! God bless America🇺🇸

From the title, was expecting an explanation for non-interference engine instead of discussion of this particular Chrysler engine whether its non-interference engine or not... But either way, this video gave bit more extra information.

awesome vid bro . you confirmed for me what i thought. cheers man. you rock.

Another GREAT video, and great information.

Really good series of Chrysler PT videos! Have you ever finished repairing the PT?

That was great information. Thank you so much. Keep it up sir. Very well explained.

Superbly done video.

Great video great advice

Another Great video. I believe you, more than Chrysler. Thanks David.

This was really well done. Much obliged.

Was the valve spring for the affected valve weak or damaged? I can see one letting the cam fling the valve further than intended, the intake valve catching it, and pushing it down into the piston. Having that happen to two parallel exhaust valves at the same time would be incredibly unlikely, though.

Great video!

You are a very owhnest and professional clever Mechanic

Thank you EXCELLENT explana tion!!

That was super clear!! It is an interference engine. Congrats on the twins!! On 2016 T&C, would u take the door off when changing door lock actuator, or would u fight it with the door on? Thank u David!!

thank you for the info nice job explaining it i just had a volvo engine interferance type and the water pump seized and the belt jumped and i cranked the engine becuse i was on a set of RR tracks with a train heading toward me when i pulled the head i had valve to piston contac and you could see the damage valves not seating but it only cost me bout 5 benjamins did the removal and replacement and had a machine shop mill the head and do a complete valve job well worth the money and i enjoyed doing it thanks again for sharing info

Excellent video David. I hope Chrysler watches these.

Well done video. Thank you.

Good explanation Sir. I learned that VWs and Nissan motors are interfering engine. That is why it is important to Install a New Serpentine belt at about 60 thousand miles as a preventable measure. I would never own a interfering engine especially after learning all the different ways this event can happen. Thanks for Educating the Serious DIY's...👍👍

perfect explaination sir.... YOU DA MAN!

very interesting subject, great video.

Thanks. Those dents in the piston almost look like they fit the bottom side (radius) of the exhaust valve head, more perfectly than the top side like you demonstrated. As you showed, the leak down test told the story. When you found the factory cam alignment holes were off, I personally would have been tempted to loosen the exhaust cam sprocket bolt, align the cams using the factory alignment holes, retorque the exhaust sprocket bolt do the leak down test and then see if the engine would then start/run. Regardless, once you found the exhaust valves were leaking, you knew you were going to have to pull the head to fix all that was wrong (and do some preventative repairs while you were in there). You are obviously a very good technician and teacher, thanks for making the videos!!! It's an Excellent series, I've shared them with my son and brother that own PT's.

These videos are awesome. Is it possible that resurfacing of the head reduced the clearance enough to allow the exhaust valves to interfere with the piston?

My friend had PT cruiser i warned him about changing the timing belt but it broke and the exhaust valves were badly damaged the pistons hit the exhaust valves

David, What is a reliable resource to determine whether you have an interference or non interference engine? I have a 2008 and a 2009 both 2.4L Dodge Avenger and 2017 Chrysler Pacifica 3.6L. Thank you for your time and effort. Merry Christmas

David, Have you ever heard of a 97 3.5L break a timing belt and not have bent valves? My belt broke while idling at a stoplight ,now worried my intrepid is junk. Excellent video ! Had to subscribe to your channel!

Stumbled upon this video because I wanted to know about interference engines (I'm still not sure if my 2004 Toyota Camry V6 is interference or non-interference, I keep getting conflicting info) and you helped explain to me what that concept means. You made it easy to understand even from a non-gearhead's point of view. This also goes to show why Chrysler gets its reputation as it does - it just seems like "good engineering" wasn't a term in design. They make slick looking cars but they always have these strange faults. A non-interference engine but the valves can still smash into each other, but they're wrong about it? Might as well just should've just added "Yeah, we're stupid" at the end of that service manual blurb.

Great stuff.. David thank you You definitely have nailed it But my question which type is a majority..? What's the percentage of interference & non-interference? And which one is main stream production today and in the past. ?

I WAS VERY IMPRRESED AND IM LeaRNING Lot fromt tgat video good jpb keep up the good work

Good explanation , thanks.

Awesome video brotha 👍🏻 I'm surprised in all your years of wrenching you've never heard about valve to valve contact possiblitys, we learn something new everyday right. But anyway my question is have you thought about notifying Chrysler of your findings of this situation? I wouldn't be surprised if they wanted to hire you on as an engine designer (for real) you definitely know your shit. I've been a mechanic at a Chrysler/Plymouth/Jeep dealership for 13 years so I can tell you got skills 🔧

Excellent.

Well done in your explanation,plus its the first vid ever i saw pass 300 without a dislike lol

Great video Sir. I appreciate this. May I ask if a Ford pinto has a non interference engine??

Great video and info

And the reason I came across your video is because I was looking to see if a 1995 Honda 1.8 engine is a "clearance" or "interference" engine. Would you happen to know? I recall there was a list of all engines listing the ones that hit and the ones that don't hit when the timing belt/chain breaks but I can't locate it :( Thank you for your time making these videos it is much appreciated 👍🏻

I really find it astounding that Chrysler's service bulletin was wrong on this issue. That's a fundamentally gross error. You're not wrong to believe mostly all of the service bulletins, notices, etc. that are released by the major auto manufacturers. Errors are rare, yet they do happen. Step by step analysis is still your best tool. I enjoy your videos and your teaching style. Thorough without boring this old shade tree mechanic. Keep up the good work.

Cylinder head and engine block surface prep video would be appreciated. Thanks

This case definately is a piston- valve impact and the intake valves have good clearance. I'm wondering though, if this cannot be because the cylinder head had undergone excess skimming at some point, or poor quality gasket that thins more than requried on fastening specifications, or both. Any of this can lessen the "safe gap" which then turns the engine an interference one.

U the man

Now I'm worried! My '06 Cruiser has a broken belt and I was hoping to NOT have to remove the head. At least now I'll do some thorough checking before I button it all back together. THANKS for another excellent video! KUDOS again to you!!!

Hello there, thanks for the video. Do you know if the 1984 celica supra 5M-GE is a interference or non-interference engine?

hey, is there any way to know just by looking at the engine if it's an interference or non-interference?

Very informative. I have 2011 equinox with 2.4 interference eng w/81K, Unaware plastic chain guide broke tried to start engine which may added to damaged valves. Having new crate engine installed ($$$). So as to understand all this, you say that pistons on non interference engines can over extend and hit valves and not visa versa? Are all DOHC engines considered interference? When looking for a new car, interference/non-interference engines never come to mind. Thanks

I have an '04 PT GT (Turbo HO). I have seen conflicting info on this topic and have wondered if it was an interference engine or not. Now I know, thinks. Great videos!!! In caution I replace the timing belt at 75k.

Great video 👀🥂👍 . Certainly looks like my 2005 pt is junk after belt broke .

Great video! How many teeth can the motor get out of timing and to not have the pistons hit the valves?

Thank you!! Perfect!!!

Sir, if u could tell Mr. Doug Demuro to tell us if the car he reviews has an interference engine. he hasn't yet. he could include it in his doug score. thanks

Thank you.

Hi David , turns cam by hand with timings belts off on interference engine damage vale ??? Thank

8:25-How about primary interference (piston to valve) and secondary interference (valve to other than piston).?