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Old 11-13-2000, 01:04 PM
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Does about $600.00 sound right for replacing the valve guide seals on my 90 420? When they are in there should anything else be done? Currently 172K on odometer. Thanks All...By the way the 165K EZ service was done on this car. Didn't use oil then though...
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Old 11-13-2000, 08:37 PM
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If it isn't using oil yet...what is the motivation for replacing the guide seals?
I am not sure if this quote is reasonable or not...I assume that the cylinder heads are being removed to do this. If so, in order to get to the guide seals, the valve springs and valves come off at that time...and the valve diameters and guide id's could be measured at that time. The valve faces could be checked as well, looking for wear, burned edges, etc. If the compression is ok, and it isn't using oil, why tear into it? If compression is ok, presumably the rings are in decent shape, the valves are sealing passably, and the guide seals are not leaking. Without dissasembly, if it makes normal power, compression ok, and minimal oil use.....this would fall into the if it ain't broke......category I would think.

Just an opinion. Good luck, dave
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Old 11-13-2000, 08:41 PM
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Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Just to do the seals, the heads do not have to come off. You have to remove the valve covers and compress each spring. You hold the valve up with air in the cylinder. The price is about right with parts.

Donnie Drummonds
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Old 11-13-2000, 08:56 PM
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Yeah I forgot to mention that method. I had assumed that the typical dealer wouldn't
*necessarily* inform a customer that this can be done with air pressure. I've done this great. I guess I have seen and heard too many "Midas" stories. I would give my right (***) for a shop that would offer the "cheaper" and more expedient solution, if appropriate. Would be nice if there were a dealer that would recommend doing it without pulling heads....maybe I'm jaded....been hosed too many times by shops looking to flesh out their billable hours for the week.

e.g. Hey these rotors look to me to be WAY too thin...I just can't grind them.....
(measured fine before grinding)
Hey you need new drums.....I can hear them grinding (hardware loose)
Hey that a/c evaporator is'll be neding a new compressor AND evap
(fitting leaking)

(And I worked for several years as a mechanic myself, so I probably am guilty to some degree as well)

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Old 11-14-2000, 02:30 AM
300EVIL's Avatar
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Join Date: Apr 2000
Location: Lake Geneva, WI.
Posts: 1,676
i know a reliable mercedes tech who did my dads 420 valve seals for only $250. at first i was dissapointed,,,, a week later it didn't use oil and never smoked again. i'm glad i found this guy.
good luck,

87 300E

87 420SEL
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Old 11-14-2000, 08:19 AM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
Sounds steep to me. We done hundreds for 5.5 hours labor. But big city labor rates might put it right on. Backs when I used to do them myself it was real "gravy".

The seals are less than $40 from the dealer (only use genuine MB), plugs could be replaced since they are out and two V/C gaskets.
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Old 11-14-2000, 12:02 PM
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Join Date: Jan 2000
Location: PA
Posts: 5,440
Can't you do the valve seal replacement on a 300SD and other engines by turning the crankshaft to hold the valves up?
If not,is an air adapter available to screw into the glow plug hole?
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Old 11-17-2000, 12:21 AM
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Join Date: Jan 2000
Location: PA
Posts: 5,440
Any answers to my question about holding valves from falling into engine while doing valve seal job by turning engine so that the piston is at TDC when working on that cylinder
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Old 11-17-2000, 07:14 AM
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Yes you can hold valves up with pistons. Be extra careful that the piston for that hole is at TDC before removing the spring.

This is more practical in a diesel because the combustion chamber is microscopic in size. So, with the piston up the valve is almost touching it anyway.

Good luck,

Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles
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