valve problem

[blackbob]

My moms 89" 300 SEL has a vavle tran problem. Well last night when we went to Merrit Island to get a car. On the way there the oil was a little low(abut half way down). But we didn't realize it till we got there. Anyway, my mom promtly went to the local gas station in the area of the car we bought. Purchased some oil and was on our way home. This morning I checked and replaced all fiveplugs because somewhere between the time we got there and back. The car started running "wierd" almost like it was misfiring. I'm thinking "man I hope she didn't drop a vavle." Wich I'm positive she didn't becuase there's no sound of metal in the last cylinder. After replacing the old plugs with new ones here's what I saw, the #6 plug is cacked in oil. According to the plug diagram in my haynes manual it says oil depoisitis something about it either being slipping past the piston itself(rings) or vavle seating. I'm pretty sure it's vavle seating. Because it doesn't burn that much oil. But I did notice it goes low fairly quickly but not fast enough for it to be the piston rings.I checked the other 5 plugs as well. They where placed under "too hott" also caused by either poor valve management ,so far as fuel to air ratio in the cylinder or cooling. So in a way my moms car isn't having all that bad of a problem. Just annoying,however it's firing on 5 sounds like. The even more messed up thing is that when the car was originally purchased(few months ago). It needed a new head gasket,fine,no big deal was fixed and all. But the mechanic my mom had do the job claimed he went over the vavle tran and checked everything. Obviously not the case now that we are in this perdicament. The car always burned a little oil but went unnoticed because never showed so far as seeing it out of the muffler. You know like black smoke or nothing.So anyone have any suggestions along with a better mechanic in the Orlando area while we're at it?

~BB~

[SPEC_Tech]

The vehicle you said had previously had it's cylinder head gasket changed out. The mechanic who did the cylinder head gasket cut a corner that you never can with a mercedes engine. Whenever the cylinder head comes off of a mercedes engine, the head must be serviced. Part of this service includes new guide seals. often times when the head is removed, if the valve geometry is disassembled while the valve is in the open position, that particular valve guide seal if ever previously over to super heated, will crack upon disassemby. The oil that leaks down into the cylinder via the valve shaft subsides once the oil level is lower because the bath area atop the valve train is lower too. once low enough of oil level, the leakage subsides. Depending on which valve it is, this can be proven by heavy acceleration or braking dependant on if the leaky valve in on the rar or front of the motor. Usually it is toward the rear. This test naturally does not well apply to the two center most cylinder although they just as well are less likely to be the leaky ones. In short, the mechanic failed to have the head serviced, or said he did when he did not. proof is in seeing al new valve guide seals after cover removal. If this is true, as much as I hate to say it, someone should call the BAR on him if he is charging for a service that he did not provide. If he did not provide the cylinder head service through someone else, than his repair was done in a sub standard fashion by /per mercedes specifications. You can check the torqueing on the head without having to service it, but that is about it. You canot even do a complete loosen and retorqueing of the head without the specification of cylinder head service for the reason I mentioned above in regards to the valve guide seals. Only over enrichment of fuel will cause Black smoke from exhaust. Oil being burnt will result in a cloudy blue color smoke out the exhaust. This is not very good for the catalytic converter by the way if left to settle in the exhaust system. In some cases you may need to even retard the spark and labor the engine up a hill in order to get the oil in the converter hot enough to burn and blow out. If this is not done the vehicle may very likely fail the HCppm portion of the emmissions test. The timing s then afterwards set back to it's norman position. This is a pretty common error, failure to service the cylinder head. Whether or not Haynes says the service is warranted, I assure you sir in my 30 some years of MBZ experience that it is, or at least a very thorough inspecton with the right equipment and replacment of the valve guide seals. This engine is very much unlike a SBC for instance. Tolerances are much tighter and the possibility of having a bent valve, even in the very slightest amount is far greater than a more forgiving motor such as the small block. I suggest you and your mom seek recourse at the mechanic that did the work or tell him you will take it to the dealer where they will indicate the substandard work for small claims court and he will have to pay their bill instead of doing the work himself. The mechanic should however be given the opportunity to correct his error without someone else doing the job. This involves cylinder head removal, cylinder head servicing and reassembly with another new gasket. If all I mentioned is done, the repair will be satisfactory and no loss of oil will occur and the particular fouled plug will no longer be evident of showing oil foulage. Lastly, he is probably not too bad of a mechanic, only that he is not greatly experienced with Mercedes-Benz engines.

[blackbob]

Well this is all VERY good information and thank you for all of your imput ! But anyway teh problem was solved but I will comtinue to post questions when I don't have any answer. nice to know I know where to come. Thanks !
~BB~