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Oil pump failure or balance shaft module FAQ B5 VW Passat or Audi TDI engine-part 2

Dec 27, 2013
Oil pump failure or balance shaft module FAQ B5 VW Passat or Audi TDI engine-part 2
  • How to repair a VW Passat TDI, Audi A4 TDI or Audi A6 TDI engine that has oil pump failure or bad balance shaft module
    Please see page 1 of this article for background information and videos and 1000q: balance shaft assembly removal - part 1 for the DIY procedure

    While I rate the procedure at rated 5/5, it's just many projects of moderate technical difficulty in a row. In my opinion, it's near the limit of what a shadetree mechanic can do in their driveway but well within the skill of any competent professional mechanic who follows the service manual. Since the timing belt has to come off during the repair, it's highly suggested to put on a new timing belt kit as well.

    If the failure occurs while you are driving

    If your oil pump fails and you get a STOP - low oil pressure warning, shut off the engine as soon as is safe and practical. Do not get into a car accident by suddenly shutting off the ignition or swerving to the side of the road. Remember that turning the key to off will lock the steering wheel and no engine = no power steering and only 1 or 2 pumps of power brakes, so turn the key back to on but not start to prevent steering wheel lock. The first priority is keeping yourself and other drivers safe. If the engine was driven after the warning, additional damage to the engine may occur. Just remember that it's not worth saving the engine if the car/you get destroyed so concentrate on safe driving first.

    If the engine was stopped immediately then replace the assembly and examine main bearing #1-4. #5 can't be examined without removing the transmission. Some repair kits include 2 replacement main bearing bolts (you'll need 2 per bearing cap). Also do a compression test (see 1000q: Passat compression test for more details) and remove the valve cover to examine the camshaft (see 1000q: pumpe duse camshaft inspection). If the engine is damaged don't do a compression test until after you repair it.

    If you hit something on the road and lost engine oil pressure the extent of damage depends on how long the car was driven and how fast oil pressure was lost.
    [​IMG]

    If you just bought a car in unknown condition

    If you bought the Passat TDI in unknown condition, are doing the repair yourself or are you paying someone else to do it? Do you have another car to drive while this one is being repaired? In addition to the replacement balance shaft assembly, you'll also need to at least remove the main bearings and rod caps to check their condition and clearances. After the repair, do a compression test (see 1000q: Passat compression test for more details) and remove the valve cover to examine the camshaft.

    How to test engine oil pressure on a Volkswagen Passat TDI

    With sufficient engine oil quantity, start the engine and warm up the engine oil to at least 80oC. The coolant fan should have run once. Shut it off and then remove the oil pressure sender on the filter housing. To the right is an exploded diagram of the Passat oil filter housing. Plug in the VW tester tool 1342 or equivalent and start the engine. The tester's led should light up at between .55 and .85 bar of positive pressure. At 2000 rpm oil pressure should be at least 2.0 bar. At higher rpm the oil pressure must not exceed 7.0 bar.

    Detailed repair procedure
    Remove the oil pump/balance shaft assembly. See 1000q: balance shaft assembly removal part 1 for detailed steps. Also remove the oil cooler (the metal cube with coolant hoses sticking out of it) and flush the oil passages.

    If you want to examine both the rod bearings and main bearings, first examine the rod bearings. If you only want to examine the main bearings, skip to the section below. Once the oil pump/balance shaft assembly is off, remove the 2x 10mm 12-point bolts on each cap. Immediately mark each cap. Note the painted stripe on each cap - each cap should have a different color. Each rod cap is also crack split at the joint instead of machined - this produces a stronger rod. Each cap will only fit the exact half it came off of in the same up-down position. Also note and mark the up-down orientation of each bearing.

    To examine the main bearings, once the oil pump/balance shaft assembly is removed, first loosen each 17mm bolt a 1/4 turn. I suggest loosening them in order 1, 3, 5, 2, 4. This minimizes the stress on the crankshaft. Then loosen each bolt another turn, etc. until the bolts are loose. Remove each main bearing cap - make sure the crankshaft doesn't fall down. Note the up-down orientation of each bearing, it has a retaining tab that must fit into the a notch. These tab/notches hold the bearings and prevent them from spinning. #3 bearing also has thrust bearing washers - the groove faces out. You should also see wear marks on the thrust bearings. This is what holds the crankshaft from moving in-out axially.

    If you just want to take a peek, remove cap #1 because that end had the worst wear on my engine (had low oil pressure for a while), getting better as you moved towards #5.

    Note: there is low clearance on main bearing #5 due to the rear main seal flange. The transmission must be removed so that the rear main seal flange can be removed.

    Examine all the bearings for pitting, chipping, and gouging (abnormal). Visible fine scratches on the crankshaft journals and bearings are acceptable. If you can feel the scratches with your fingernail then the crankshaft should be removed and polished.

    When installing bearings, make sure the retaining tabs in the main bearings fit into the notch on the cap. Thoroughly clean each bearing and use assembly lube on the bearing faces except when using plastigage. Make sure the bearings don't spin out of position during installation. The rod bearings do not have notches so make sure they're centered and not spun when installing them.

    To check clearances, use green plastigage or a micrometer. Plastigage is a waxy calibrated thread that measures clearances by being placed on the bearing surface, tightening the cap, and then seeing how much it's squished flat. The flatter it's squished, the smaller the clearances. The other colors are a different diameter to check larger clearance ranges. The plastigage package has a scale which you can use to measure the width of plastigage deformation. This tells you how much clearance you have.

    The clearances are important because the crankshaft normally rides on a wedge of pressurized engine oil. When you lose oil pressure, the wedge of oil fails to support the crankshaft. This can also happen if the clearances are too big. This lets the crankshaft touch the bearings, wear them down, heat them up, and transfer material.

    To plastigage your BHW TDI engine, first clean the bearings and journals free of oil. Put a strip of plastigage on the bearing surface and put the bearing/cap over it. Using your old bolts, tighten the bolts to the specified torque without the final 1/4 turn. Remove it and look at the width of the strip vs. the scale. Use wd-40 or oil to remove the plastigage when done.

    If the crankshaft needs polishing then remove it and take it to a professional machine shop to be polished. The problem with hand polishing using emery cloth or sandpaper is that there's no way to control taper or tilt of the sandpaper. While a DIY job can make the surfaces shiny you could be polishing it with flat spots or into an oval which can cause problems. A professional machine shop can quickly and cheaply polish it correctly.

    If it needs rings, Hastings Ring Set 2C4871 will fit a BHW engine about $130 for the set. (thanks for the tip 82Date)

    Before starting the engine, remove the oil cooler, flush the oil passages, and change the oil filter.

    To do a compression test, see 1000q: compression test and glow plug removal/recall. Lightly tighten the compression tester to about 10 ft-lb and crank the engine until compression stops rising. Excellent for a broken in engine is 450-550 psi. New spec is 360-450 psi (25-31 bar). Worn is 275 psi (19 bar). Max allowable difference between cylinders is 73 psi (5 bar).

    Test results and corrective action
    If the bearings are in normal condition and the clearances are good, complete the repair and do a compression test. If the compression test if good then the engine is fine.

    If the bearings are worn but the clearances are good, remove the crankshaft and have it polished, replace the bearings with standard sized bearings, complete the repair, and do a compression test.

    If the bearings are worn and the clearances are bad, you need to have the crankshaft machined and put in oversized bearings to account for the difference in clearances. Also inspect the rest of the engine for excess wear due to low oil pressure. This includes the cylinder head, pistons, and turbo. You should consider a used replacement engine due to cost and downtime.

    All rod and crank bolts are single use torque to yield bolts and should be only tightened to their final torque (the last 1/4 turn) once. When plastigaging the bearings, use your old bolts and just tighten to the torque minus the last 1/4 turn. The rod bolts should be lubricated when tightening them.

    Main bearing cap bolt torque: 48 ft-lb + 1/4 turn
    Connecting rod bolt torque: 22 ft-lb + 1/4 turn

    (quantity 10) main bearing cap bolts VW# n 908 897 01
    (quantity 8) rod bolts VW# 045 105 425

    The part numbers for standard sized BHW crankshaft bearings are:

    (quantity 5) main crank bearing upper: VW# 038 105 561 am 007
    (quantity 5) main crank bearing lower: VW# 038 105 591 am 007

    (quantity 4) piston connecting rod lower: VW# 038 105 701 b 007
    (quantity 4) piston connecting rod upper: VW# 038 105 701 a 007

    The main bearing part numbers also apply to the 2005-2006 BRM Jetta 1.9L TDI engine built after 4/2007 and the 2009+ CBEA Jetta 2.0L TDI engine built after 9/2008. Engines built before those dates used main bearing upper: 038 105 561 a 007, lower 038 105 591 a 007. The difference is the "a" vs. "am".

    A cheaper source of rod and main bearings is from Rock Auto if you use equivalent European engines. (thanks for the tip 82Date)

    The connecting rod part numbers also apply to CBEA engines after 9/08 and all BRM engines except for 4/2007. Engines under those dates used upper bearing 038 105 701 "k" 007, lower bearing 038 105 701 "j" 007. The difference is the "b and a" vs. "k and j".

    BEW engine 2004-2005 Jetta/Golf/New Beetle and 2006 Golf/New Beetle TDI used the crank main bearing upper: 038 105 561 a 007, lower 038 105 591 a 007. The difference is the "a" vs "am". This is the same bearing as the early BRM/CBEA engines.