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  #1  
Old 07-15-2004, 05:03 PM
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Location: Venezuela
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Angry Update on Head Job: Blue Smoke - Help Needed...

I just finished the head job for W108 280S (M130 engine). All of the usual seals / guides / gasket were replaced. I also replaced the transmission regulator valve.
The bore did not seem to justify a complete engine rebuilt, so I supposed that a head job could solve my oil and coolant consumption (about 1 liter / 200 km).
I just took my car out of the shop and still notice blue smoke coming out at start up from red light or when pushing hard the engine. Also, there seems to be some engine hesitation at high rpm.
I am quite disappointed, to say the least...
Any suggestions?
Thanks.

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280S, 1969
250C, 1972
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  #2  
Old 07-15-2004, 05:21 PM
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Since you just took it out of the shop, I suggest you drive it a hundred kilometers or so first. Considering your past oil usage, you may have some in the exhaust. As to the hesitation, you may have a problem in one of the two Zeniths. Drive it and post back. I may be able to help. I know those carbs very well.

Peter
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  #3  
Old 07-15-2004, 05:54 PM
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Angry Another problem: Alternator

Thanks, Peter.

I now have another issue. After driving my car for about 40 minutes, I found the battery to be totally discharged. The battery is almost new. It's weird because I replaced the OE Bosch 35 amps alternator, with a 105 amps alternator less than a year ago.

The old Bosch did not have sufficient capacity if the A/C, lights and stereo were turned on at the same time.

What do you guys think?
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  #4  
Old 07-16-2004, 10:35 PM
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How much clearance did the shop give you on valve guides? MB recommends none (qute literally, 0.0000' to 0.0005"). Valves MUST fit tight, or you get oil sucked down requardless of valve stem seal condition. this will result in smoke at startup and upon accleration after standing, typical symptoms of bad valve guides or seals.

The best way to check is to remove a couple springs and lower the valve slightly. ANY perceptible side play means the guide is oversized.

If the shop that did the valve wasn't used to Benz specs, chances are the guides are seriously oversized and they need to be replaced with new ones. It's almost never necessary to ream MB guides, they fit tight but work fine.

Tell the machine shop that if the valves will go into the guides by hand when oiled, the clearance is fine, DO NOT REAM OVERSIZE.

Dissapointing to have work done and the same problem reappear!

It's also possible that the seals were not seated correctly and are floating around.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #5  
Old 07-16-2004, 11:18 PM
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The original alternator should do a fine job on that car. If you added mega watt sound system, you need to upgrade the alternator. If you upgraded to a quality product like Bosch, it should be covered under warrantee. If your replacement was an inferior product, then you got what you paid for.

Peter
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  #6  
Old 07-17-2004, 09:21 AM
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I'll second what Peter said about guides. The factory guides are always perfect, because of the mfg. technique used. If you hold a factory guide and an aftermarket guide up and look through them, the factory guide will look like the inside of a shotgun barrel and the other will look like a rifle barrel. Factory guides are finished off by forcing a steel ball of the correct diameter through them. Non factory guides are reamed to the correct I.D.
Also check to see if seals were installed. I've seen that before.

Peter
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  #7  
Old 07-17-2004, 09:36 PM
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Does the alternator/battery light come on KOEO? And go off when the engine starts? If not, you may have a wiring or bulb problem. I recently learned this the hard way. A bad wire from the alternator to the bulb, or a bad bulb, will stop the alternator from charging.

I am not making this up.
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'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #8  
Old 07-18-2004, 11:24 AM
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Thanks for your input. I'll have the valves/seals/guides checked as suggested. I understand that all parts used (including guides and seals) were original MB products (at least, that's what I was charged for). The valves were not replaced because the mechanic mentioned that were still in good shape.

Do you think that the valves could be the source of the problem (i.e. if the valves have some play and allow oil to be sucked into the chamber)?

As I mentioned in my first post, blue smoke appears when the engine is pushed hard (especially when going up a hill), which also makes it hesitate. Also, I can see a puff of blue smoke when starting from red light, which disappears as soon as the car reaches some speed.

As to the alternator problem, I had the belt replaced and the alternator tested. Both the battery and the alternator are fine. It seems that the belt was slipping a little bit which caused the alternator not to work as expected.

Thanks.
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250C, 1972
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  #9  
Old 07-18-2004, 02:07 PM
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Location: Evansville, Indiana
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Smoking under load is more likely rings than valves, alas.

Check for blowby at the crankcase ventilation hose (not sure where it is on that car). If you get significant vapor under load, you have ring problems.

Happily, this will sometimes clear on it's own. If the cylinder walls were recently machined, it can take a few thousand miles to get the new rings seated sometimes.

If just crudded up from poor running, a change to synthetic oil can free the rings up and reduce the blowby, too.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #10  
Old 07-19-2004, 01:55 PM
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Have you done a cylinder leakdown test. Usually recommended before doing any major engine work. How is the compression?

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