DIY Jeep YJ 4.0L Engine Bay OVERHAUL + Tune-Up

Hey folks, in this video, I’m doing a DIY engine bay overhaul and full tune-up on my 1991 Jeep Wrangler 4.0L YJ. The legendary Jeep 4.0L inline-six is known for reliability, but after years of use it needed some serious love. I’ll walk through cleaning up the engine bay, replacing worn components, and giving this classic YJ the tune-up it deserves.

If you’re looking for a Jeep YJ tune up guide or want to see how to refresh the Jeep 4.0L engine, this video will help you get it done at home with basic tools and some patience.

Don’t forget to like, comment, and subscribe for more Jeep YJ projects, builds, and tutorials here at No Guarantees Garage!

🔧 PARTS & TOOLS USED:
Can of black paint: https://amzn.to/4oLh8bq
Can of aluminium paint: https://amzn.to/4oRjs0F
Radiator cap: https://amzn.to/4hEip1G
Valve cover gasket: https://amzn.to/4ozTr6c
Upper radiator hose: https://amzn.to/49Bgl8I
Lower radiator hose: https://amzn.to/3JIg9tI
Thermostat: https://amzn.to/47pbqX3
Thermostat housing: https://amzn.to/3LmoaVQ
Wire loom: https://amzn.to/43TzNd7
Wire tape: https://amzn.to/49xOOF9

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Chapters:
0:00 Introduction
0:27 Removing all the Easy Stuff
1:49 Battling the Thermostat Housing
2:55 Finishing Removal
3:18 Cleaning Everything
3:54 Removing the Valve Cover
5:11 Cleaning Up the Valve Cover
5:39 Painting the Engine and Bay
6:04 Assembling the Valve Cover
8:18 Alternator is Bad
8:55 Installing Valve Cover
9:42 Heater Hose Removal
10:24 Spark Plug Gapping + Install
11:51 Distributor Gasket Replacement
14:33 Cap and Rotor Replacement
15:46 Coil and Plug Wire Replacement
16:01 Thermostat, Housing, and Gasket
17:42 Heater Hose Install
17:49 Radiator Hose Install
19:17 Looming the Wiring
19:27 Oil Change
20:38 Fuel Filter
21:19 Alternator Replacement
21:40 Coolant Temp Sensor
22:17 Air Box and Filter
22:58 Final Product
23:25 How Much Did It Cost?
25:45 Outro