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Roger, BMW Master Tech
Category: BMW
Satisfied Customers: 3037
Experience:  10 yrs. experience as BMW Master Technician, shop foreman and dealer.
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Have a customer with a 2000 BMW 528i. It over heated, cooled

Customer Question

Have a customer with a 2000 BMW 528i. It over heated, cooled down and they drove it home and parked it. Water pump was leaking. We replaced water pump and thermostat housing. And did a minor tune up with NGK R plugs. Filled vehicle with coolant. Started
and it runs smoothly for about 2 seconds then engine starts bucking wildly. No knocking or abnormal smoke. Hooked up snap on scanner and have no communication with any controller. Just get a linking error
Submitted: 1 year ago.
Category: BMW
Expert:  Doctor D replied 1 year ago.

Hi, First I assume we are talking about the 2.8L Engine? These older heads go bad real quick when overheated, so that worries me on your case. Second You stated you put plugs in? Ive had several cases where the coils were not plugged in absolutely secure, They will visually appear to be connected but need a little more pressure applied to get them to snap secure. The Snanner communication failure is common on cheaper scanners, have you verified yours does in fact work on other BMW's ? Are you using the OBD2 plug under the dash or the BMW factory port under the hood?

Customer: replied 1 year ago.
Right it's my snap-on scanner with updated European software has worked on every bmw, Mercedes, Vw, Maserati I have came across that is OBD2, using the OBD2 port under the dashI did and C02 block test and found no signs of Exhaust gas in the coolant.Replaced the plugs without unplugging the coil packs from the engine harness but will double check the conecctions.
Expert:  Doctor D replied 1 year ago.

If you have the BMW connector for your scanner use that, its on the left strut tower area. Coils are common to fail on these. The PCV(purge valve) under the intake is super common to get stuck open and will cause a surge. With engine running open oil fill cover and feel if you have excessive vacuum in the engine or the idle changes at all when removed.