[MNBoxster]

Hi,

It would be wise to consult another Service Shop or a Dealer, to compare diagnoses, prices and any alternatives.

But, if you had a headgasket leak, it is likely that coolant contaminated the oil system. Ethylene Glycol, Water and Oil will emulsify into a Gooey Mayonaise. This is definitely a problem. The main two being that you may clog the oil galleries and/or risk Hydro-Locking the engine, as one poster somewhat alluded to.

So far as the bearings being soft and absorbing the mix, I do not see how that is possible. Bearing shells are soft, in fact, they're usually a laminate of soft metals such as Lead, Copper and Brass on a Steel backing. This is so when there is Metal-to-Metal contact with the Journal Shells, Big-End Bearing Shells and the Crankshaft (such as immediately upon start-up), the soft metal of the bearing shells do not score the Crankshaft and in fact provide some level of Dry Lubrication to it until the Oil is pressurized sufficiently to 'Float' the Crankshaft.

But, I have never known any of these Metals to be water absorbant. In fact, Motor Oil normally absorbs and contains water (which is a natural Combustion by-product) and it's not unusual for the oil to contain as much as 2% water just prior to being changed, so the bearings do have some contact with it anyway.

That said, a much higher concentration of water or water/glycol could cause the Steel backing of the bearing shells to corrode and cause the soft metal laminates to separate from it, which would be bad. The only sure way to assess the level of damage, and to clean the oil galleries, is to disassemble the motor. I am not so familiar with the M96 engine in the Boxster, and so do not know if other methods are possible, although I suspect removing the Sump Pan would allow you to visually inspect the Journals and Shells for corrosion and possibly give access to the Oil Galleries as well.

But, I do have extensive experience rebuilding Lotus 910 Engines in Esprits (I've rebuilt 10 of them, including my own), Datsun L-24, L-26 and L-28 Engines and the 1.3L VW engine in my Formula Vee and have come across this issue with several of them. The first, we (owner and I) totally disassembled the motor, cleaned the oil galleries and found some corrosion as I mentioned above. We ended up doing a full rebuild to it.

Subsequently, another friend's Esprit had a minor headgasket leak (noted by the presence of Mayonaise on the Dipstick). At his insistence, we only replaced the headgasket and flushed 2 fills of fresh oil through his system, running each for 300 and 200 miles respectively. The second batch came out virtually clean. We refilled it and to date, the owner has put 8,000 trouble-free miles on it. But, it was a risk, never having visually determined the degree of corrosion which may have taken place, but one which the owner chose to assume (I wouldn't have).

Back to your issue. First, I lack confidence in your Mechanic for not checking the oil until this late date, especially when the Headgasket was suspect. It should have been at least the second thing he checked, perhaps after a Leakdown or Coolant System Pressure Tests. Second, giving him the benefit of the doubt, he may just be poor at explaining the bearing issue. If not, it's another sign that he isn't so knowledgeable. Both of these things combined would have me looking for another Service Shop to do the work. Finally, $9k for a motor rebuild may, or may not, be the going rate in your area. But new or reconditioned Boxster Engines can be had for as little as $5k (plus installation). It's surprising that he didn't offer this alternative to you, but something you might consider nonetheless. Good Luck!

Happy Motoring!...Jim'99