How to Properly Break In Your New or Rebuilt VW Engine

[Gene-C]

How to Properly Break In Your New or Rebuilt VW Engine



Many people do not understand the importance of the following the appropriate steps to prepare an engine to run for the first time. The steps are very important, and can mean life or death for a high performance engine (no kidding). The information in this article can also be a useful guide to starting an engine that has been sitting for a long period of time, since it ensures proper oiling before the engine fires.

Engine Assembly

Use good quality engine oil (20-50 or 30 weight) 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. We prefer Torco cam lube, and supply it will all our camshafts.

In your oil pump, lube the gears up with STP or a HEAVY 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!

Lubricate valve stems and valve guides with engine oil (many people use white grease, or something else, but I 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 use to live a long life later on, so let's use what works!

Prepare 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 pushrods 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 1 ½ turns tighter than "zero" clearance. Make sure you have fuel pressure, and fire it up!

Running the Engine!

This next step is VERY IMPORTANT! Immediately bring the rpm's up to 2500 or higher. I vary the rpm's between 2500 and 4000, 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 and adjust the valves. When you fire the engine up this 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, you want to REALLY heat the engine up by driving it hard! This loads 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 of these engines "never" break in). Find 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 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 of 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 2500. The oil for the cam-lobes comes from oil sprayed off the connecting rods! If the engine is run below 2500 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. 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!

Maintenance Schedule

Schedule oil changes every 1000 miles (no filter), and every 3000-5000 if a filter is present. The oil strainer (stock VW) does NOT count as a filter, and in fact I remove it on engines that turn over 6000 RPMs! I have seen more engine failures caused by this strainer than I care to count (even on stock engines), so I leave it out and change oil religiously. One more thing! The new strainers that are available are of a much more corse "mesh" than the originals, so any "filtration" is minimal. The addition of a magnetic drain-plug is a good idea! I adjust 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 vavle 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.

[dan-b]

Great info Gene. I'm almost to the point of my clone overhaul to put this info to use.

[MELFOL]

Good article. With the ZDDP lower in today's oils cam breakin can be a critical issue. With semi-strong valve springs breaking in the cam/lifters using early 1:1 rockers instead of 1.1:1 or higher will also put less load on the valve train. That may be a bit easier than changing out the valve springs. Lube a lobe followers may also help, but I've seen cam lobes that went flat in spite of them. The oil squirt form the rods for cam lubrication is a point well taken. That is one reason to have rod width within VW spec. Those are getting hard to find. I bought a new set of stroker rods a while back and when I checked them they were already narrower than VW spec. That can affect squirt past the rod skirt, and also reduce oil pressure in the system. I change the oil more often than his suggestion during breakin. Best to get the metal breakin glitter out of the engine.

[MyBlueBuggy]

After the 15
minutes has elapsed, shut down the engine, and change the oil and adjust
the valves. When you fire the engine up this 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.

This is good information. Not a lot of people change the oil just after the high RPM break-in.  I know I didn't, I just changed the oil when it looked dirty.  It may seem extreme to have changed the oil twice just 100 miles after the first engine start but it certainly couldn't hurt.