TDC - Top Dead Center and how to find it on a Jeep 4.0

In this video we explain what TDC or top dead center is on an internal combustion engine. This is a critical point for engine timing and is often used to set the synchronization of sensors on the engine. We show what happens with the valves and pistons during the rotation of the engine. At the end of the video we explain the easiest way to find TDC by removing cylinder 1's spark plug and using your finger to feel for the compression stroke. This video shows how to do this on a Jeep 4.0 engine commonly found on Cherokee XJ's, Wrangler TJ's and YJ's as well as Grand Cherokee WJ's.
00:00 - Introduction
01:17 - TDC description
02:29 - Two timing mark discussion
02:58 - Power stroke
03:44 - Exhaust stroke
05:02 - Intake stroke
06:35 - Compression stroke and TDC
07:32 - How to find TDC
09:18 - Cam position sensor
10:03 - What to do if you cant find your timing mark

[@Tony-fg4rf]

please keep making how to videos. You have a natural talent explaining how things work. Hope you end up with millions of subscribers

[@theshop392]

Thank you - I really appreciate the compliment! We do plan on more videos but certainly will shift to explain more.

[@scottlund4562]

Very thorough and understandable, all bases covered, especially the simple and effective dowl method which I needed, thhanks!

[@troybarnes5557]

Hello my friend, you absolutely rock. That's the best explanation I 've heard. Thank you Troy. Now off to cam sensor

[@theshop392]

So glad it helped, good luck with your project

[@matthewgarcia8544]

I did exactly this, and it worked excellent! Thanks for your video support!

[@theshop392]

So glad it helped!

[@titaniumman_22]

Awesome and thorough explanation!

[@theshop392]

Thank you

[@MysticRiverRC]

Thank you so much! I'm feeling a bit less dim now.

[@theshop392]

Glad that the video helped!

[@franklinjmoultriesr5222]

Great Class! Thank You

[@theshop392]

Always a pleasure

[@dariomendoza1518]

You went past the Normal Typical Explanation Mate!!Excellent Details THANKS FOR SHARING!!!!!

[@theshop392]

Thank you - I hope you have been able to use the info!

[@dariomendoza1518]

@@theshop392 definitely!!

[@davidsmith2394]

One of the best videos on explaining this. Thank you

[@theshop392]

Glad that this video has been helpful!

[@dkhallal]

The single best practical video on how this works. Having the valves to see open and close is the best part. Am I right in thinking the timing gears marks should be alighted as well, facing each other? Also, the distributor should be pointing at cylinder 1 correct? Thanks for this video, really helped explain it. I would love to see this with the timing gears and the distributor exposed. I am replacing my timing chain/gears and have looked for an explanation like this everywhere and yours is the best.

[@theshop392]

Dean, I would have to go back and look, for some reason I recall the timing marks do not align at TDC, they are aligned at exhaust stroke.

[@cjc2936]

Excellent, concise and informative. Thank you!

[@theshop392]

Glad it was useful - good luck with your project!

[@wheelinndealin]

Perfect video

[@theshop392]

Thanks

[@user-sg2xs1cr9d]

Great video, thank you for sharing.

[@theshop392]

Thank you for the good feedback, hope it helps you get your projects done.

[@rustygehl]

Sub'ed, good vid explaining this. I hope you have more coming out about Jeeps. Im failry new to it, but have Dyno'ed Nuttered 258, 258 with 4.0 head, and now slapping in a 4.0 long block. It's addictive, lol. Hope to see more, you have gkkd explanations!!

[@theshop392]

Glad that the video has helped you. We have had a rather large life change but yes back to creating content again. We hope to have new videos rolling in soon!

[@henrysuarez9155]

You’re the fucking man !!

[@theshop392]

Glad it helps!

[@sarahm.2053]

I have an issue. How to you find TDC if the harmonic balancer has been replaced and it doesn't have a mark on it? There's no mark on the harmonic balance in order to align with the indicator on the engine. What's the simplest way to get it to TDC?

[@theshop392]

You can do it without the balancer, use your finger over the spark plug hole to feel for air (compression stroke). Then use a wooden dowel through the plug hole to feel for the piston reaching the highest point and then moving down, rotate backwards and feel for top of stroke.

[@sarahm.2053]

does the piston come up twice then its the compression stroke? I thought the piston comes up once for first valve to open then down and up again for second valve to open then its the compression stroke. Or is is ok to align the distributor up as long as the piston is at the top at any time?

[@LuisAstudillo-l8l]

Traduccion en castellano porfa se agradrseria saludos desde chile

[@theshop392]

Unfortunately we cannot translate at this time yet. If you need specific help let me know and we can walk you through the video