Engine Break in Process

It is very important to read the break-in procedure completely, follow all links and become thoroughly informed BEFORE you start the engine!

So you bought the best engine on the planet!  Now it’s time to fire it up for the first time and “break it in”.  This article will cover the basics of “breaking in” one of our engines, Lets get to it.

First things first, triple check EVERYTHING!

  • All hoses are tight?
  • Belts tight?
  • Battery fully charged?
  • Plenty of fuel in the tank?
  • Proper amount of BREAK-IN OIL
  • All grounds in the correct location and properly connected to clean bare metal
  • Distributor “stabbed” correctly? (if applicable)
  • Heater is on and set to “hot”


Fill the radiator with as much distilled water/coolant mix as possible (50/50 mix). We prefer to use a “burp funnel” or “Spill-Free Funnel” for this, as it helps to eliminate the mess and makes it easier to keep track of how much coolant actually made it into the cooling system. DO NOT PUT THE RADIATOR CAP ON! IT IS NOT FULL. I PROMISE! If you are using a Spill Proof Funnel, leave it on and move to the next step.

Get the ratchet and socket off the crank pulley bolt and let’s prime the oil pump!

Priming The Oil System

Fuel Injected Trucks:  Pull the EFI fuse and remove the coil wire, now crank the engine until the oil light turns off or the gauge reads “normal”, if you have a gauge.  This should take about 30 seconds. Once the engine has built proper oil pressure, you can reinstall the EFI fuse and coil wire.

Carb Trucks: Either pinch or cap the fuel supply hose just before the fuel pump and remove the coil wire. Now crank the engine until the oil light turns off or the gauge reads “normal”, if you have a gauge. This should take about 30 seconds. Once the engine has built proper oil pressure you can reconnect fuel supply and reinstall the coil wire.

Priming The Fuel System (NEVER USE STARTING FLUID!!!! NEVER)

EFI Engines:  Cycle the key several times to “pressurize the fuel system”, this is a good time to check for fuel leaks (any major leaks should be obvious with the fuel system pressurized). You can also install a jumper between B+ and FP in the diagnostic box, now turn the key to the run position. This will turn the fuel pump on, pressurizing the system. CHECK FOR FUEL LEAKS BEFORE YOU START THE ENGINE! Once your’e done, remove the jumper.

Carb Engines: They can be tricky to get the fuel flowing, here’s a few suggestions. Disconnect the fuel supply line at the carb, use a handheld vacuum pump to get the fuel up to the fuel pump.  Before releasing pressure, pinch the line with hose pinch pliers then reconnect the fuel line and release the pliers. Or using compressed air and a blow nozzle with a rag wrapped around it, VERY CAREFULLY pressurize the fuel tank to fill the lines, pump and float bowl.  JUST A COUPLE QUICK BLASTS.  Remember this is a low pressure system so be easy if this is the method you choose to use.

It is now safe to start the engine and it should start without much trouble, usually within a few seconds for EFI trucks.  Carb trucks can take a bit longer.

First Start

Once the engine fires up, the first thing you’ll want to do is check for leaks… No leaks?  Perfect!  It’s running decent?  Even better!  Now grab the timing light (you know the one you hooked up earlier) and make sure the timing is at least close.  It doesn’t have to be perfect at this point just close.  You will make the final adjustment once the engine is at normal operating temperature. Do not install the jumper yet. Right now we’re looking for somewhere between 5-15 on EFI trucks and 0-10 on carb trucks.  “In the ballpark” is all we need at this point.

Burping The Cooling System  Keep an eye on the temp gauge!

Make sure the heater is on and set to hot. If you’re using a spill free funnel, fill it about 1/2 way.  If your not using one then leave a little room in the radiator (keep the upper tank about 1/2 full).  Squeezing the upper radiator hose can help to get the coolant moving. Once the thermostat opens the cooling system will begin to circulate, This is when you will need to pay close attention to the coolant level if your not using a spill free funnel. When you have about 2 gallons in the system and the engine has been at operating temp for a few minutes it is safe to remove the spill free funnel and put the radiator cap on. You will need to check the coolant level again after the first test drive. (let it cool down first) NEVER OPEN A HOT RADIATOR! If you cant hold your hand on the cap for 30 seconds DO NOT open it!

Setting The Timing

EFI Trucks: Install a jumper in the diagnostic check connector Between terminals Te1 and E1. This will pause the computer advance and allow you to set “base timing”.  The hold down bolt for the distributor should be snug enough to keep the distributor from moving on it’s own, but allow it to be rotated by hand.  Point the timing light at the timing tag on the oil pump, adjust the distributor as needed. (clockwise to advance- counter clockwise to retard)

EFI trucks should be set at 5 degrees BTDC with jumper installed and 12 degrees BTDC without.

Carb trucks should be set at 0 (zero) with both vacuum lines disconnected and plugged

Cam and Ring Break-In

Breaking in the cam and rings can be very boring and seem unimportant, but it is EXTREMELY important!  Here’s how you do it, vary the RPM’s between 1500 and 2000 for 20 minutes. I know your bored senseless and you can’t feel your right leg, but your done!

Turn the truck off, do one more leak check, All good? SWEET! When the feeling comes back to your right leg, you get to go on the first test drive.

First test drive!

On the first test drive we’re not doing anything extra special, we’re just out for drive to see how everything feels. Don’t go too far, It’s best to stay fairly close to the location the engine was installed (That’s were the tools are). Don’t forget your cell phone, just in case you do have an issue. Drive as you normally would, unless you’re a Throttle Monster.  In that case, drive as you normally wouldn’t. Don’t baby it, but don’t beat it either.  Keep RPM’s under 3500, but don’t lug the engine.  Keep an eye on the gauges and be on the look out for anything out of the ordinary.  Listen for Pinging on acceleration, If you hear ANY pinging head straight back to the shop and get the timing set properly.

Our rebuilt engines will need to run Break in Oil for the first 500 miles.  During this time, DO NOT tow any trailers, over load vehicle, let RPM’s go over 3500 or lug the engine. Also, don’t drive at high speeds, drive consistently in low gears or use cruise control.  Avoid driving at constant speeds for extended periods or sudden acceleration except in cases of emergency.  Check oil and coolant regularly throughout the 500 miles, if you have to add oil, use only Break in Oil of the same brand, never mix oils! Once you have made it to the 500 mile mark, it’s time  change the Oil & filter and adjust the valves. The Oil Choice is up to you after that. Toyota recommends 5W-30, but 10W-30 is ok to use as well.

DO’s & DON’TS for rebuilt engines


  • Check all fluids regularly
  • Vary your speed
  • Let the engine get to operating temp each time it is driven
  • Change oil and Adjust valves at 500 miles


  • Tow a trailer
  • Overload the vehicle
  • Let RPM’s go over 3500
  • Lug the engine
  • drive at high speeds
  • drive consistently in low gears
  • use cruise control
  • use constant speeds for extended periods
  • sudden acceleration (except in cases of emergency)

It is common for 22R/RE engines to develop some valve noise during the first few hundred miles after a rebuild or a valve job. Don’t freak out, this is normal. You will need to check and or adjust the valves as part of  the 500 mile service. Valve lash spec is .008 intake and .012 exhaust. Click here to view our Valve Adjustment Video.

During the initial period of breaking in an engine, make sure that you vary the vehicle speed and the engine speed.  If the cylinders don’t move up and down at different rates during the break-in period, then the pistons rings won’t seat themselves evenly. For a manual transmission vehicle, it’s even more important to vary the load on the drive-train, so that the clutch also sees a variety of temperatures evenly distributed across it.

Proper Break in Procedure is very important to the longevity and success of your new engine, Have Fun & Enjoy your new Yota1 Engine.

Yota1 Performance, Inc.
is NOT affiliated with TOYOTA Corporation.