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#46
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I'm gonna have to get my act together and get that finding TDC thread I've got planned up and running - one of these day eh? I hope you join in when I finally get round to sticking my neck out!
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#47
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TDC or not
I have considered making a hydraulic TDC tool out of an old injector body. Using a clear pipette attached to a hard injector line. A small amount of diesel could be squirted into the cyl and the engine rocked back and forth( I know that is not great but just for the sake of argument) The same level checked before and after TDC & split the difference on the harmonic pulley. Seems like it should work to me. Easier than removing a prechamber & using a dial guage. Accuracy would depend on attention to purging air and the diameter of the pipette. Comments anyone. Cheers Dan
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It's always something simple 91 300D 603.960 (from japan) 194K 92 Toyota Diesel Landcruiser HDJ81-t 116K 02 Golf TDI new head courtesy of PO 87 300D 97 BMW 525 TDS Wagon 5spd bunch of Onan and other diesel generators |
#48
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Libby, I'm glad you have it timed so that it will run good. The problem is that this could be a sign of an impending problem. If the balancer has indeed been incorrectly installed, it is likely that it will come off some day while on the road, or it will turn further making the engine run poorly again or quit altogether. What you described was an indication of this problem. It wouldn't be too much of a job to pull the pulleys and inspect the balancer to crankshaft fit. Best of luck with it.
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2001 SLK 320 six speed manual 2014 Porsche Cayenne six speed manual Annoy a Liberal, Read the Constitution |
#49
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AND it does not even require any measurement..... except to split the marks on the crank... the piston to top distance can be done with a mechanical device having no measuring capability...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#50
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BigblockChevy.... you are dealing with needing a very accurate measurement of liquid... at the same time that liquid will be seeping down past the piston rings...LOL
The correct method has already been found and described..no use re inventing a lesser method....
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#51
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#52
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In this thread I initially described three vehicles. One runs well and shows the correct timing on the scale. That one is mine and there's certainly no reason to mess with it at all. The second runs well, and shows timing off the scale. I am completely convinced that the balancer is on 180° out. It is a friend's car and so I'll let him decide if he wants to mess with it in the future. That car is in such rough shape I doubt he will do anything to it that isn't totally necessary. The third car showed relatively correct timing but ran like crap. I advanced it a few degrees and in the process discovered that the inlet banjo was not tight and very likely sucking in air. The combination of tightening the inlet banjo and getting the timing correct has significantly improved the cold start and running. That car is also not mine and so I will let my friend decide if more work is necessary. That said, I don't see any reason to think that the balancer has ever been off of that engine and wouldn't mess with it if it was mine.
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#53
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Anything less than that will not allow you enough pre and after piston placement to be accurate.
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#54
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I'm not familiar with the degree of interference of the Merz engine with the valve open, but on the VW, which I know have a more significant interference, one can add a shim between the cam and valve and have the engine clunk to a stop quite accurately. I'm not a fan of rotating the engine backwards, tho, so would personally opt for pulling a pre-chamber and measuring with a dial indicator if I had to find TDC.
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#55
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No suggestion of rotating the engine backwards..... very bad idea pretty much forbidden by the FSM.
You can not get an accurate reading crankwise just noting the top point hit by the piston.. You can use a dial indicator and mark on the pulley or flywheel a place as you get near the TDC and note the position of the dial indicator... then rotate the engine in the CORRECT direction to past TDC to that same indication on the dial indicator... you have marked that position both times... then you measure half way between them and mark that... that is TDC... Any other way has too much ' margin of error' ... since there is almost no movement of the piston for several degrees of crank rotation at near TDC... crude at best... want it accurate... choose places where there is observable movement, mark them and interpolate between equal distances from TDC.. This has been standard procedure on all sizes of engines for many decades.
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#56
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When you said that I assumed you meant it. How are you recommending to "do the piston to top distance" without a measuring device? Now you are saying to use a dial indicator which definitely does have a measuring capability.
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#57
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You can make something like a ' stop' ....mark going up, fold up or unbolt, replace as it goes down, re- mark... split the difference on the crank or pulley or flywheel...
There are pics someplace.. However, HF has nice dial indicators with huge faces on them plenty accurate for this really cheap.... you may need the screw on extension for the end ... You are just needing to mark equal distance from the top of the bore... thus you do not need the actual measurement.. Dial indicator much more fun....
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#58
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The dropping the valve on the piston crown and then measuring the motion of the piston crown via direct contact with a DTI is the official procedure in the FSM. It is described in chapter 03-345 for the adjustment of the tachometer mount on the pointer next to the crankshaft pulley.
With the OM617 / 616 / 615 you've got a vertical valve "drop" onto the piston crown whereas the per-chambers are canted at an angle. Measuring small changes in piston height is likely to be more error free in a vertical sense than when done at an angle.
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#59
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Thanks for doing the research and calculation. I measured a spare VW idi injection line which uses the same injector body as Mercedes. Let's assume the injector lines are the same.
o.d. is 6 mm , i.d. is 2 mm so the wall thickness is 2 mm. Can you recalculate using these numbers? I am too lazy. My digital vernier has a resolution of 0.01 mm so would not be able to measure the tiny amount of flex. Quote:
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85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#60
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Quote:
With a wall thickness of 2mm I expect it to be even smaller. I do wonder if the vibration of the engine (as a result of ignition) is producing a bigger signal at the line than the flexing of the pipe due to pressure build up. In an ideal world it would be nice to compare the output of this type of piezo-electric sensor clamped on the outside of the pipe with the output of a pressure sensor that directly measures the pressure in the line - all done as a function of time. This might explain libbybapa's observation that 10 - 12 degrees BTDC is better than the 14 degrees BTDC suggested by Brain Carlton (in the the thread I linked to way back when). I wonder where Brian Carlton got this value for 14 degrees BTDC? (Calling BC!)
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
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