2.1L Rod Bearing Failures

By Stuart MacMillan

September, 2000

Hello to all of you high mileage 2.1 owners, I hope to do the same with my new engine, but I can't stress enough the need for an oil pressure gauge!

These engines can, and probably will, run strong right up to the time of disaster, giving you no warning of immanent catastrophic failure if you don't know the status of your oil pressure! This engine works very hard to push our nearly two ton rigs around, and 150,000 miles is still the recommended point to rebuild the engine. Once a rod bearing starts to go, it goes fast (3000 miles!), and without warning (except oil pressure). This failure is known as "spinning a bearing". I knew I was pushing it, and I pushed too far. Ignorance is not bliss with these engines!

My situation:

  • 1990 used engine, 140,000 miles at failure, heads done at 90,000.
  • Compression: 132-136 psi.
  • High volume oil pump.
  • Acceptable oil consumption (1 qt./1500 miles.
  • Ran perfectly and was very strong, no smoke, no noises, not even valve lifters.
  • Cruised effortlessly for 3000 miles in six days on last trip, mostly at 75 mph in 85-98 degree temps
  • Cooling system perfect, 20w-50 Castrol, factory filters.

    OIL PRESSURE: 8 psi at idle, 24 psi cruising when installed at 130,000 miles. Over the next 10,000 miles pressure steadily dropped to 4 psi idle, 12-15 psi cruising. At the end of the 3000 mile trip idle pressure was zero (red light came on), cruising 8 psi. Blew up at 65 mph just 65 miles from home, still running strong!

    Note: Click on thumbnails for expanded images!

    Killer hardware
    When I disassembled the poor 2.1 engine I destroyed in August 2000, it turned out that rod failure due to a spun rod bearing was the cause of the destruction. This is very common on air-cooled VW engines, and also on the 2.1 wasserboxer. It is much less common on the 1.9 engine.

    As discussed in detail below, the heat generated by a spun bearing causes the bolt to expand, soften and either break or lose the nut.

    Rod bolt protruding from case

    In my case the nut loosened and came off, dropping the bolt which was thrust up through the top of the case by the crank counterweights where it was embedded.

    Fractured rod and cylinder liner Crankcase Ventilation
    After that #4 got hit by some shrapnel from the broken rod, and the cylinder fractured, taking out half the cam along with it and knocking two more holes in the top of the case and flooding the case with coolant. The resulting oil/coolant emulsion was then sprayed all over the engine compartment and the freeway behind me. It took me all day just to clean things up in preparation for a new engine.

    Broken Cam Rod bolt laying inside engine I took what was left of my 2.1 to my rebuilder, Jerry at Northwest Connecting Rod, and after close examination we determined that I had "spun a bearing". This means that the rod bearing shell literally wore away, leaving steel on steel, not a good thing. According to Jerry, at high speeds this will generate tremendous heat, even to the point of the metal becoming red hot with sparks flying off. The heat then will either cause the bolts to stretch, nuts to loosen or the rod or bolt to break, leading to catastrophic breakdown, which ever comes first. And, indeed, the parts of the rod big end I recovered were "blued" from extreme heat!

    These rods are worked hard, and the big end tends to go oval as they get up in miles. This leads to the viscious cycle of increased rod bearing wear causing lower oil pressure - which leads to increased bearing wear - ad infinitum. This means scrupulous attention to maintenance coupled with careful oil pressure monitoring is the key to longevity for this engine, just as it is for any other.

    So, I cannot stress this enough: For those of you that have a 2.1 with more than 100,000 miles on it (the consensus is these engines are good for between 125,000 and 150,000 miles) I strongly recommend that you do two things:

    1: Install an oil pressure gauge!!! This will tell you more than anything else about the condition of the bearings in your engine, and can help you avoid catastrophic failure. If your engine is between 100,000 and 150,000 miles, install the gauge to make an assessment of the bearing condition, and then monitor pressure trends if things are within limits. If you are over 150,000 miles, you can do the same, and watch for the tell-tale signs of pressure dropping on long hill climbs (bearings are heating up) and oil pressure below 4 psi at idle when hot.

    2: Start a savings plan for that rebuild BEFORE 150,000 miles. When you rebuild the engine, have the rods rebushed and the big ends resized to get them round again, and make sure that the "stretch to torque" rod bolts are not used in the rebuild, substitute the conventional 1.9 engine rod bolts as they are simply more reliable.

    Rebuildable 2.1 cores are getting scarce for this reason. If you destroy yours it not only will be difficult to find another engine, but it will cost you the core charge as well, at least another $500 to over $1000.

    My new 2.1 engine with high volume Mahle oil pump runs 12 psi idle, 40-45 psi cruising at 65 mph, depending on temp. I have also installed the Trasko oil filter system, although I will continue to change the oil every 5000 miles. Having worked in the micro filtration business (Millipore Corp) their system of combining a large depth-type filter and a mircon filtration screen makes sense to me. I'll keep you posted on this, I am installing them on all my cars.

    May, 2001

    Update on the Trasko filter.

    I am impressed with this unit. I tested it out on my daughterís í82 Audi. This poor car has 170,000 hard miles on its 1.6 l engine, and not such good maintenance. After 1000 miles I removed the cartridge and was amazed at the amount of fine, copper filings were trapped between the layers of the roll of filter paper. Not to mention the large amount of carbon and crude caught in the screen. Her previous filter may well have been clogged and bypassed this engine was so dirty. I donít think any other type of filter could have worked in this application.

    We unloaded this car very quickly afterward!

    After 5000 miles in the Vanagon the oil was still quite clear and light colored, and the filter element black with the minute carbon particles it filtered out. I will go with Red Line synthetic 20w-50 oil now for 10,000 miles between changes as Trasko recommends. Iíll test the oil at 5000 miles to be sure it is up to snuff.

    Happy motoring!
    Stuart MacMillan

    Webtracker counter

    Please stop back soon!
    Tom Carrington