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#16
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Hi Tom.
If you turn the engine with the starter motor, AND with the coil or spark plug wires disconnected, you should avoid damaging the engine in case you have liquide in a cylinder. The starter motor is "normally" not strong enough to bend/crack anything. After turning the engine a couple of revolutions, reconnect the wires, and you should be OK to start. (Damage from hydrostatic lock normally only occour if some of the cylinders fire before the compresion stroke of the cylinder that have liquide in it). Good luck. |
#17
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I was advised by several forum members to always ground the high tension lead from the coil after removing it from the distributor to avoid damage to the electronics...
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1986 560SL 2002 Toyota Camry 1993 Lexus |
#18
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The moment of Truth is imminent!
Well, the results on all of this was the removal and replacement of both Heads.
Did them both as I felt that no sense going back in after all of this trouble. It appears, (I need comment on this) that when the one side was done about 70K ago, (Thats when the dummy twisted the valve when he replaced the chain) someone did some creative torqueing. Both sides had some real issues with Head bolts that had been ratched down to tight and not torqued properly. 18 Head bolts had to be recoiled for a solid fit. We used some special coils that are supposed to allow for removal and reuse if necessary. Who Knows? While we were in there we did the chain and the associated parts. Tensioners etc. I had one valve that had a indent on the bottom that I'll post a photo following the cars return. Machinist replaced all of the guides on all eight cylinders. Pistons looked real good. Engine looks super clean with excellent lubrication. Oil changes at 3000 seems to be an inexpensive investment. I don't have the car back as yet and that's the reason for this post. I have watched the process over the last several days and I feel comfortable with the work. The real question is what to look for when I get it back? What are some good questions to ask that might uncover anything that was missed? The real question is: How do you really know what kind of workmanship you get on a job like this. The first chain job was such a disaster that I lost all hope of finding a good mechanic. I searched for three years before I found the current guy. To say I'm nervous about all of this is putting it mildly! How could the car go 70K with heads like I have described? As usual...all help and suggestions greatly appreciated. More when I get the car back! Thanks to all for the direction and support! Mercedes Shop is still the best Forum on the planet!
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1988 560SL Black Pearl/Palamino |
#19
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Late to the party, but I'll bet the " whack " sound was indeed related to water leakage. One possible scenario; water gets in and creates a partial hydrolock; cranking pressure forces the valve open for the water ( steam ?) to escape . Noise is the valve slamming shut ?
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There's no substitute for cubic inches |
#20
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"The real question is: How do you really know what kind of workmanship you get on a job like this. The first chain job was such a disaster that I lost all hope of finding a good mechanic. I searched for three years before I found the current guy. To say I'm nervous about all of this is putting it mildly! How could the car go 70K with heads like I have described?"
You don't know exactly whant kind of workmanship--but you've found someone who in the past has been consistently solid and right; trust that. How could the car go 70K? We all know how long a Benz can go with major suboptimal care (eg 3rd world taxis), in your case limited to one specific issue cuz you take great care of the beast otherwise. The shop I use has a superb rep and does high-end iron for demanding owners (Royce, Ferrari, Lambo, etc) as well as routine work for ordinary folks with imports. I trust them, listen to the vehicle after work has been done, but have never found a problem in what they've done--which, like you, is why I still use that particular source for help.
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Craig Bethune '97 SL500, 40th anniversary edition '04 Olds Bravada (SWMBO's) '06 Lexus ES330 '89 560SL (sold) SL--Anything else is just a Mercedes. (Kudos to whoever said it first) |
#21
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I hate to say this, but I think you need to reset your expectations. If you got 77K on a valve job at 130-ishK, then you got your money's worth. Did you do the guides then or just repair the damage? Did they check the block and heads for straightness?
I would have been surprised if you had not pulled some threads on this job, this is a known issue with the different metals used in the bolts and the heads. I have never had head bolts come out with the same amount of force, even on engines known to be original, so I wouldn't blame that on the previous work. As to your questions about quality, most of the burden is on the machine shop. Did they straighten and mill the heads to get them flat? Did they follow the procedures so that valve stem height comes our right? The repair shop stuff is not rocket science. Did they check the block surface? Be sure the oil coolant passages are clean? Drain the block so no coolant got in the crankcase? Clean all the parts? Use the correct torque in steps? Measure the head bolts for stretch? Use MB head gaskets? Check the pre-tension on the ball studs? When you get the car back, it should run perfectly. Start instantly, no smoke, no chain noise, no valve noise, no overheating. Good power, smooth idle, etc. If it's not right, they need to make it right as part of this work!
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Chuck Taylor Falls Church VA '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 |
#22
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Head Work
Chuck!
You are one of the nicest guys in this Forum. You help alot of people. Your always pleasant and you take your personal time to answer a great deal of questions. I respect you and have high regard for your opinions. I gotta say, that if you are inferring that 70K is normal for a top end replacement on a 560SL then we are going to have to disagree. The current replacement required replacement/recoil of 18 head bolts. How many are there? 36? Now what that says is that the last time it was off, either noone checked that or they just so happened to be lucky that none needed replacement. I gotta believe that someone tightened the head bolts with an air ratchet. I had the previous head inspected after machining last time. So from my take something happened on the old torque down. I never blame anyone because you just never know. You can't stand there and watch the entire prrocess you gotta have some faith. A clue from the last time was that I had to take the car to another shop to get it straightened out following the head replacement. So, unless I am naive, a head job (is that dirty) should go more than 70K. This time, we did both heads. Replaced all guides and seals, replaced 5 exhaust valves, machined the other 3. All are in spec. The head was replaced and Torqued gradually, and the guides for the timing chain were replaced. The car idles dead on at 500 RPM no shake, no quiver. Acceleration and response are great. I couldn't be happier. The reason I believe in the repair is due to the knowledge gained from folks like you and all the rest of the contributors on this site. This is the best auto site bar none!
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1988 560SL Black Pearl/Palamino |
#23
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Thanks for the kind words. I really admire you for stepping up to this repair and I'm glad it turned out well.
But I still think that the original work was reasonably OK, or it wouldn't have lasted as long as it did. I went back through this thread and have questions: I assume that the valves were bent at the 130K chain replacement, and that's when the head(s?) came off. Were both heads pulled then, or just one? Did you have a head rebuild done then, or just the bent valves fixed? Do you know which head had the problem this time? Was there any pattern to the 18 thread problems?
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Chuck Taylor Falls Church VA '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 |
#24
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I assume that the valves were bent at the 130K chain replacement, and that's when the head(s?) came off. Were both heads pulled then, or just one?
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1988 560SL Black Pearl/Palamino |
#25
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You got the question, but what about the answer? :-)
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Chuck Taylor Falls Church VA '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 |
#26
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Results/Follow-Up
After all was said and done here is what we found when we did both heads and replaced 5 exhaust valves. As well replaced the guides in all cylinders.
When the Head was removed the Cylinder Head bolts were not anchored in the Aluminum Block. This required rethreading and inserting helicoil type inserts to get the head to seal properly and to be able to use and apply the proper torque. The Block will generally need this treatment when the Head is removed. At least that what I understand. Makes sense due to the aluminum and steel combo between the Head and the Block. I suspect that the last time the Head was off, little attention was paid to the torque when reinstalled. Block Cylinder threads were original. We helicoiled 18 which is half the bolt threads. Thats alot. anyway, the whole job was 2200 bucks. I thought that was a fair price! what do you guys think? Gotta say that the car runs like new. Since buying the car, I have: replaced the convertible top, replaced the leather interior, tires twice, all vaccuum lines, fuel pump, radiator, stainless exhaust system, A/C interior panel and fan, replaced radio with Blaupunkt, replaced the interior wood trim, removed all rust from car, repainted and restriped last year, Multiple Front end parts and adjustments, of course chain, guides, etc., and the Head work just completed. Car has 213K. Looks new! I'll post a photo and you guys can tell me. This is the finest car I have ever owned! I love it and would never part with it. Always wanted one and believe I have it in the best condition ever! Stay tuned! Thanks to all on the site for contributing to my travails with this 560!
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1988 560SL Black Pearl/Palamino |
#27
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Tom,
Thanks very much to you and the others for discussing your experience in detail, as i'm getting ready to do the heads on my 380sl, along with a mechanic friend, and I was concerned about whether we'd have to helicoil the threads after removing the head bolts. According to my friend, who's an experienced MB mechanic, the threads on these engines rarely have to be helicoiled, if the mechanic knows what he's doing, but he's ready to do so if any threads need it. $2200 sounded to him and me like a very reasonable price for the work you had done if it was done correctly, and according to him, a top end rebuild should last well over 100k miles -- and more like 200k miles -- with proper maintenance. So, hopefully you'll get your money's worth out of what sounds to now be a very nice car. |
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