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VW Engine Break In Procedure

VW Engine Break In Procedure - VW Tech Articles by Aircooled.Net
Many people do not understand the importance of performing the appropriate steps to prepare an engine to run for the first time. Following proper VW Engine Break In Procedure is the first step toward a long life for your daily driver, and a key preventative step to avoid a fast death for a high-performance VW engine. The information in this article can also be a useful guide to starting a VW engine that has been sitting for a long time, since the break in procedure ensures proper oiling before the engine fires up.


How to Properly Break In Your New or Rebuilt VW Engine

Lubrication During Engine Assembly

We recommend that you use good quality engine oil (20W-50 Amsoil Z-Rod Synthetic Motor Oil is outstanding) to coat all bearing surfaces, as well as the surfaces of moving parts they contact. Use an oil treatment (e.g.: STP) for camshaft lobes and the heads of the lifters, and engine oil for the sides of the lifters. You can use a high pressure cam lube (usually supplied with the camshaft), or you can use STP for the lifter heads and cam lobes. It is CRITICAL that you get the camshaft and lifters from the same place, and make sure they are compatible. Mixing/matching this is a recipe for an expensive lesson!

In your oil pump, lube the gears up with STP or a HEAVY oil (20W-50 Amsoil Z-Rd Synthetic Motor Oil). This assures a good oil pump prime (it’s very thick; make sure the brand you use is the SAME as the oil you plan on running, so they are compatible), so you will not crank your engine for 30 minutes trying to achieve oil pressure. Keep your spark plugs out until later; if they are in, remove them. The reason the spark plugs are removed (or left out) is that you do not want the connecting rod or main bearings “loaded” during the “dry” period that exists before oil pressure is achieved. It is only after oil pressure is achieved that the spark plugs should be in place during cranking.
If you have stock valve springs on your engine, you can assemble your engine completely, but this is not the case for an engine with a hot cam, which should have heavy duty valve springs. These engines must be cranked for oil pressure without their pushrods installed, since we don’t want to wipe off the cam lube while we are cranking for oil pressure!
Next, lubricate valve stems and valve guides with engine oil (many people use white grease, or something else, but we don’t think this is a good idea. Grease can keep the engine oil OUT, and galling can occur from lack of lubrication). After all, engine oil is what all these parts rely on to be able to live a long life and continue functioning later on, so use what works! We recommend using a THIN oil for valve guides, like the 10W-30 Amsoil Z-Rod Synthetic Motor Oil.

Preparing to Run

Install the engine into the vehicle or onto your engine stand, and get prepared to crank it over. REMOVE THE SPARK PLUGS AND OIL PRESSURE SWITCH. If you have a T-4, you can just remove the spin-on oil filter. Next, crank the engine over until oil squirts out the oil pressure switch hole (or the oil filter bracket on the T-4). Re-install the oil pressure switch (or oil filter, which you have filled with oil), and connect the oil pressure switch wire. Crank until the light goes out then continue cranking for another 10 seconds or so. The oil system of the engine is now ready!
Set the ignition timing on the engine (you do know how to do this without running the engine, right?) to the proper setting for the distributor you are using, and install the spark plugs and plug wires.
Install the push rods if you have not done this yet, and adjust the valves to .008″ (better loose until things settle in). Hydraulic lifter engines can adjust them to 3/4 turn tighter than “zero” clearance. Make sure you have fuel pressure, and fire it up!

Running the Engine for the first time

This next step is VERY IMPORTANT! Immediately bring the RPM’s up to 2000 or higher. We like to vary the RPM’s between 2000 and 3000, and do this for 15 minutes while keeping your eyes glued to the oil light! A second person back at the engine looking for oil or fuel leaks is a REALLY good idea too, since you don’t want a fire or Valdez in your driveway! Most oil leaks will occur very soon after startup, if at all. Now, this is a nerve-racking experience to have the engine (it sure seems loud!) at these rpm levels when it’s NEW, but if everything is OK, it’s going to be fine. Remember that this engine is not even under a load, so it’s not a big deal.
After the 15 minutes has elapsed, shut down the engine, and change the oil. After the engine has cooled down, re-adjust the valves. When you fire the engine up this second time, you can let the engine idle, and make the needed carburetor adjustments. Drive the car easy, and change the oil and adjust the valves again after 100 miles or so.
Now that the “bearing break-in” is done, we need to break in the piston rings. We accomplish this by driving it hard! This will load the rings and will break the pistons, cylinders, and rings in together. I have found that engines that are missing the flaps or thermostat assembly have a tough time seating the rings in, and the only cure for this (my experience) is to get the engine HOT. Some engines with no thermostat never break in the piston rings. We suggest finding a hill and drive full throttle up the thing a few times, in a gear that loads the engine down a bit. The loading and extra heat burns the glaze off the cylinders and allows everything to seat together well. I do not feel a longer “break in” period is needed (some say 10,000 miles) other than getting the rings seated, and this can be done in 500 miles.
Repeat the oil change/valve adjustment at 500 miles, and then resume your normal VW engine maintenance schedule (which hopefully does not mean oil changes every 15K miles, and/or valve adjustments once a cylinder or two goes dead at idle!)

Now for some explanation…

The reason for the varying engine rpm at initial start up is that the VW flat four engine does NOT adequately oil the camshaft lobes and lifter heads at RPMs below 2000. We used to rev the engines higher, but the changes in modern oil composition have changed our Camshaft break in procedures, and we now recommend a lower RPM than we used to.  The oil for the cam-lobes in the horizontally opposed VW engine comes from oil sprayed off the connecting rods! If the engine is run below 2000 rpm for too long, the cam and lifters do NOT break in together properly (since they don’t get enough oil). They get enough oil for running, but not break-in itself. In addition, you also run the risk (the higher valve spring pressures you run, the higher the risk) of one or more of the cam lobes getting scored and even going flat. Some engine builders (myself included) will run the engine on one set of valve springs for break in, and change to the competition springs (really heavy) after the cam and lifters are broken in. The cam and lifters must work together under a moderate load (valve springs), to allow the metal to work harden before extreme loads are placed on them. This oiling quirk is also the reason for cranking the engine for oil pressure with no valve spring pressure on the camshaft (no pushrods, remember?). With really heavy valve springs, just this cranking alone can damage the cam if racing spring pressure is present!

VW Engine Maintenance Schedule

Schedule oil changes every 1000 miles if you do not have a spin on oil filter, or every 3000-5000 if a filter is present. The VW Beetle Oil Strainer does NOT count as a filter! One more thing! We have both “Coarse” and “Fine” strainers, we recommend the Coarse ones for High Revving engines, and the Fine ones for low Revving engines. The addition of a Magnetic Drain Plug is a good idea! We recommend adjusting the valves to .006″ every 3K miles (it does not take long, nor is it difficult) on old engines, and every 500 miles (until adjustments settle down) on newer engines. Keep a record of valve clearances at every valve adjustment; when a valve gets “abnormally tight” compared to the rest of them for 2-3 valve adjustments, it’s a warning sign that the valve is stretching and is ready to fail! Valve job time ( and replace exhaust valves)!
Enjoy and take care of your new engine, and it will take care of you.
We hope you enjoy this original article written by: John Connolly, Aircooled.Net VW Parts
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article original post date: April 20, 1999
last updated: April 1, 2012


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