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  #31  
Old 02-25-2005, 06:22 PM
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Make sure and change all the plastic guides and tensioner on the 300D.
I worry more about them than the chain..

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  #32  
Old 02-26-2005, 04:31 AM
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wear? chain stretch?

I stated check the manuals or service information for calculation of chain stretch method. Think we all realise just looking at mark is not going to detect stretch. But I did a poor description and regret it. As for wear increasing faster if you have wear the piston rings may be a good example. My 240ds have about 240k on one and 200 k on the other. Both do not use a lot of base oil in fact probably about the same as when new certainly very little more I believe. For arguments sake lets say a quart every two thousand. If the wear did not increase more rapidly as the rings wore I would only be adding a little more oil every 2 k at 400-450k. I cannot see this happening but it would be nice. Instead would expect the oil rings to be letting a lot more by. Why is that happening? My thoughts are general wear once started increases at a faster and faster rate once the wear has really started. It almost feeds on itself. Agree that wear is heavy at break in but stabilizes for a very long time. With little constant wear at slow rate but actually at a slowly increasing rate with use. Another quick example If you rebuilt an engine using new pistons in two cylinders and two old pistons in the other cylinders and pulled them out after 100k and measured them I believe there would be more wear compared to the dimensions at installation time on the older pistons skirts compared to those pistons that were new. The additional wear at time of rebuild on the old pistons has enabled them to slap a little harder with use than the new ones so the wear is heavier than on the new ones because of the previously existing wear. Also the piston lands are not running as square in the bore plus some small amout of land wear and the new rings are perhaps rocking a very small amout more. I would also expect the rings on the new pistons to be in better shape than those on the old pistons. Wear may contribute to wear. Again may not be expressing myself well but trying. A roller bearing may last for 100k but when it starts to go in very short time in comparison to your first noticing it is becoming worn it will destroy itself. Yet it has actually been wearing steadily for the 100k. It is only when the accumulated wear is becoming large that it wears itself to death quite fast it seems. Actually starts to contribute to its own wear to the point of destuction. Well if anyone can add to this to save me please do so or conversly condem me as thats ok too. Think after this am pretty wore out myself this evening. Just reread my note and thought should include that some if not all rollers are surfaced hardened only and once you are worn through the hard suface it's no time at all. Not wise in my opinion only to take up slack in front wheel bearing for example if caused by wear as we did in the old days as surface hardening seems much thinner in comparison to the old days but harder. I never do it anymore just replace bearings. Perhaps theres another explanation like some aftermarket bearings are not very good. Now if someone told me they had a deep surface layer or hardened all the way through I might change my mind. If there is no slop will remove repack and reset but again if detect a little real wear before I remove wheel no at present. Others opinions may vary. Perhaps thats what this site is partially about. I know i am digging myself a deeper hole will someone out there get a shovel and help? At least it's the weekend if nothing else. Lots of time to bury me. I always hope to learn at least one thing every day or correct a previous held belief. More by habit than intent. Of course realise am not always right and allow for that as well. Try to also always respect anothers viewpoint as well plus freely admit I am flawed to some extent.

Last edited by barry123400; 02-26-2005 at 05:41 AM.
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  #33  
Old 02-26-2005, 08:09 AM
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Location: central Texas
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"Agree that wear is heavy at break in but stabilizes for a very long time."

This is important since we were discussing chain elongation.... most items in an engine don't have as many parts to individually wear... and more importantly other wear items like piston skirts don't effect the POSITION of other critical components...like the position of the valves in the cycle and the timing of the injector... so it is important to recheck those settings early on after the installation of a new chain... as per the FSM instructions.
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  #34  
Old 02-26-2005, 03:42 PM
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Your points are well taken and understood. I was mentally dealing with avoidance of disaster. That first check after some running of course primarily is to check and adjust pump timing to optimum setting possibly I imagine or is keyway juggling of cam with offset keys on the list that early as well? Does also verify the expected heavy initial wear you mentioned. I am presently starting to look for manuals for this series myself. May also alert you to problem with tensioner perhaps as well but by and large again only in my opinion missing that check should not have to cost you the engine. this is not a defence as you were right in your posts. Do appreciate your comments though as said earlier I learn something new every day it seems and not by choice always. I have never dropped a chain personally in forty seven years of heavy driving with the exception of rubber timing belts perhaps slipping a cog or two because ice and snow built up on pullys overnight.I seem to elongate my posts as am always afraid to leave much of anything out even though I still do. Remember when things were newer to me plus I am not a proffesional mechanic with a lot of intuitive feel. It also may encourage sombody else that may know a little less than myself out there to try what they are only contemplating. Also try to have a little caution about car types that I am not really familar with and that reduces me to common problems. In my country wanted to mention one can aquire a dial gauge and magnetic stand for about 25.00 in previous post or explain the concept of making things available to yourself if no funds for example as think it has become a lost art form. Should have access to even cheaper price in states.This is more than adaquate for ocasional users and made in china has made it possible. It bothers me a little that newer guys to the mechanical scene do not have paper manuals for the 123 series. They reinforce the desire to tackle things. If nothing else they teach you and let an understanding develop that they may not have and that is priceless. Should make them aware as well even if they farm some jobs out. Actually the manuals should not depreciate if you use them with clean hands so they are really an investment of sorts and may become scarce after awhile. Little we actually buy has more than nominal salvage value after using. I came from a working class family and to ever get anywhere had to always repair, build, maintain everything we owned. Find old habits die hard as today can easily afford to job everything out. Still squeeze in doing almost everything myself as think it is enjoyable besides the pain in the posterior. Plus all the aquired skills should not be wasted. This is my 13th year of retirement and will build a new house by myself for youngest daughter in sping. Have three mercedes cars that need body and paint so will do them as well. Still will find time to live at cottage this summer, Go sailing, spend time with wife, deal with unforseen things, take a trip with wife, do some maintenance on our house as it is twenty five years old and just starting to indicate the need. Today a lot of the younger fellows will have to start the same way as todays cost of too many things have risen beyond reason except for the really affluent. Always have observed the younger fellows and try to encourage them to follow my path somewhat or make them aware that it exists at least. I refer it as one of the roads to freedom. As long as you have to be out there for the buck mind not getting enough of them for your needs you are not free. Strange after you aquire the freedom you can still do what you like or want instead of what you have to do, your choice. Just have learnt in my lifetime unless somebody hands you a bundle of money or you luck in somehow it can be hard. The sooner you start the more it works for you. Never was personally smart enough to find a real alternative but others do. Sites like this never existed when I was young or even middle aged so the young today have a head start in my opinion if they use it. Of course exception again as affluent surroundings allow total completion of university in a specialized and high reward area if you are blessed with a high enough intellect. Some like myself do not posses it. If you did not evolve from an advantaged family it seemed almost a treadmill for most of us out there in the early years. Sady is a good example of the apparent exception but there are many other young guys out there on this site as well that will do well. Now one cannot use the hard begginings as a crutch either because they can be overcome with some effort.if a person learns how. Also they can be of benifit if combined with common sense seemingly the hardest component to aquire but one of the most valuable tools.Too long a post I realise and of course can be attacked easily as we all have different ideals and again I do not mind. This is the only way i can let people know on this site where I am coming from. Of course live in canada. Does my eating my wheaties qualify me as a tiny percentage american? Have a good spring it's on the horizon.

Last edited by barry123400; 02-26-2005 at 04:08 PM.
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  #35  
Old 02-27-2005, 07:22 PM
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Location: Chapel Hill, NC
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I pulled the head today. Two of the cam towers were broken as is the timing chain. The top two rails and the tensioner are fine so the break must be lower down. I have not pulled the vacumn pump yet. No obvious cracks in the pistons, no scratches or dents either that I can see but I guess since they hit vertically they really won't take a chunk out of them. I'll pull the valves out later this week and drop the pan and see if all of the teeth are on the crank gear. Wonder what chunks I'll find in the oil.

One question - the injectors were full of oil - why would this be? Is this from the head lifting and letting oil in?
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  #36  
Old 02-27-2005, 11:56 PM
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Pretty good news the pistons do not seem damaged at this point. wonder if any used complete heads are around cheap in your area? Know where one is in mine. You stated the chain was broken so crank sprocket is hopefully fine. about the injectors being full of oil. I am not quite sure I know what you mean. They will be full to the top of the thread attatchment point with the line as it takes pump pressure to open the nozzle farther in . If one had no oil in it you would most likely have a injector leaking down. You may mean something else. For purposes of reliability and cheaper cost you may want to sit down and consider a used head as your camshaft is probably not straight enough anymore. But until checked you will not know unless it is bad enough to find the bend causing runout at home. Number the individual rockers as they have to go back in exactaly the same positions if you are lucky enough to reuse the same cam. Probably you are going to have to get a used camshaft,towers and of course the rockers that were with the used camshaft numbered as to there exact position on the cam. If you have to do that it may be no more expensive than a used head complete. In fact even cheaper complete is quite possible. Quotes to buy these parts new I think would drive one to alcohol. You could pull all the valves marking what port they came from mount them in a lathe and use a dial gauge to check for any that may be bent.. I would rather than chance reliability or the old expression never enough time to do it now but always time to do it later somehow takes effect.Then with that knowledge go from there.

Last edited by barry123400; 02-28-2005 at 04:33 AM.
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  #37  
Old 02-28-2005, 07:35 AM
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Change the head? Why - there is nothing wrong with the head.

Since the head is off the car you might as well check the valves - I'm pretty sure they will check out fine. You might want to consider a valve job and guides since its already apart. A new cam for your car is a couple of hundred dollars last time I checked, a used cam and towers could be had for $50 or so in a boneyard.

The oil in the injectors is most likely not related to this incident, at some point in the past your car most likely had a bad valve cover gasket, when the oil leaks out between the gasket and the top of the head some of it gets caught in the injector cavity - and since oil does not evaporate it tends to stay there for years. I've had first hand experience with this issue as well.
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  #38  
Old 03-01-2005, 11:05 PM
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Location: Nova Scotia, Canada.
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two heads better than one?

The reason I mentioned used head complete was that if someone around here starts selling cam, towers, rockers they will probably ask more or the same as they would to sell the complete head. You might have to pull it though. In fact they will be reluctant to partially part out the head most likely. With the complete head assembly you just use what you want to. For example if your original head has lower miles than the used one probably the valve guides are in better shape unless the used head had a job done on it at some point. Easy enough to check. Most the posts indicate high cost for proffesional valve work in most of their areas so that is a discouragement in itself. It is still pretty reasonable in this neck of woods in comparison. But probably not very much longer unfortunatly. Must by logic also be variable costs for used parts and valve work in different areas of the states. If I resided in a large city area in canada other than pick your part type operations they would charge on the heavy side. Here 75.00 would probably do it for a complete head.


Last edited by barry123400; 03-01-2005 at 11:25 PM.
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