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#31
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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 |
#32
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The metal line indeed expands and contracts with every injection event. I would seriously doubt that you will be able to measure the amount or even discern that there is a difference with calipers, tho. Tango's analogy is very apt.
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#33
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Rigid fuel injector lines have and need a degree of elasticity. Without this elasticity the lines would be (more) prone to cracking and failing. The lines that fail are most likely lines that have been bent too much by enthusiastic mechanics so that the metal has been worked into the plastic region (elastic => plastic => bang!). The injector lines pulse - flex in and out - by a very small amount. By how much I do not know but you could in principle measure it with a strain gauge with the engine running and then make a time capture of the measurement on a data acquisition system... (I've got to buy some of this kit soon) Here are some numbers explaining these pulses. At 800rpm (engine idle or there abouts) a cylinder fires 6.6667 times per second. (800 rpm / 60 seconds = 13.3333 rev per sec => 4 stroke engine so one bang for two revs => divide crankshaft rotational speed by two) At 5000rpm (max chat!) a cylinder fires 41.6667 times per second. I think to try and measure it under static loading you would be better off pressuring a line off of the engine. Cap one end of the line and attach the open end to a pop tester then try and measure the change in pipe diameter. I would be really surprised however if you could measure the deflection with a vernier caliper or a micrometer though. I think you'd need strain gauges... ...but as usual don't let me pee on your bonfire - give it a go.
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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! |
#34
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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 |
#35
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#36
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Is this the Snapon model you have? MT257B, Adaptor, Diesel Pulse
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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 |
#37
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A vernier caliper is an instrument that measures static values. There is no way in which it can be used appropriately to measure dynamic deflections. I could drone on about digital signal process and anti-aliasing filter till the cows come home but that is probably (even for me) a bit of a tangent. If you're interested in that sort of stuff though take a look at Anti-aliasing filter - Wikipedia, the free encyclopedia Digital signal processing - Wikipedia, the free encyclopedia Nyquist I think you'll be better off getting an idea of the flex by trying to measure it statically. (If I get the kids to bed on time tonight I'll do some calculations...)
__________________
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! |
#38
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Libby,
I'm a little late to the party and I only skimmed the replies in the post, but there is something that I don't think has been mentioned. In your efforts to time this engine, it is natural to ASSUME that the timing on the harmonic balancer is correct. There is something that you need to be aware of and check: Unlike most other engines from various makers, the harmonic balancer on these engines are not keyed with a Woodruff key. Instead, there are two steel dowel pins that align half holes in the crankshaft with half holes in the balancer. It is not at all uncommon for an unsuspecting tech to simply put the balancer in place and run it down using an impact wrench on the snout bolt. This often will ruin the half holes in both the balancer and the crank snout. Sometimes the balancer will get forced into place but will be out of position. If this is the case, then obviously timing off of the balancer mark will give incorrect timing. To see if this is the problem, simply remove the pulleys so that you can see if the balancer is in place with the steel dowels and the holes intact. If there is distortion with the dowels and/or the holes, I'm afraid you will have bigger problems on your hands than simply getting the timing correct, but it will have to be seen to. Hope this helps
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2001 SLK 320 six speed manual 2014 Porsche Cayenne six speed manual Annoy a Liberal, Read the Constitution |
#39
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The only real way to be sure one is dealing with actual TDC is to measure piston travel with some instrument.... several degrees of crank travel Before TDC and then the same amount After TDC and then mark the place half way between those spots as represented on the crank end..... and this is often easier than taking off the harmonic balancer..... and if the item is messed up ...you will still need to do this to determine proper marking of it once fixed....
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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 |
#40
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Can you calculate how much the injection line expands at 145 bars?
__________________
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 |
#41
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I understand the concept that piezo crystals when squeezed produce electricity....
But science is pretty strange and varied.. What is the possibility they are measuring the magnetic effect of the flow of carbon based fluid in the line as compared to the actual expansion of the STEEL fuel line ?
__________________
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 |
#42
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I got it timed well enough that it starts easily without the clouds. It's good enough for me right now. Quote:
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#43
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Sure thing
Sure I can do a rough calculation. Do you happen to know the dimensions of the line? Sorry I am being lazy... I could go out to the garage but it is so cold today! (And it is bloody dark - crappy winter time - ***** ***** moan moan wish I had a second house in the southern hemisphere) And is the line really made from steel?
__________________
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! |
#44
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The line is steel. Its OD is 6mm. I don't know the wall thickness/ID.
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#45
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Great stuff. Thanks for the data libbybapa.
Here's a really simple rough and ready calculation. I'm assuming the thickness of the line is 0.5mm In order to show you some "proof" that can be found on line I'm using this equation for thin walled cylindrical pressure vessels here Strength of Materials Rather than quoting a more complicated equation from "Mechanics of Engineering Materials" 2nd Ed Benham et al ISBN 0-582-25164-8 !!!! Anyway about half way down the web page on eformulae.com you'll see an equation for Stress at the outer pipe surface = { Internal pressure (P) X internal radius (r) } / pipe thickness (t) Internal pressure P = 145 bar = 14.5 MPa (mega pascals) Internal radius r = 5.5mm = 0.0055 m (metres) Pipe thickness t = 0.5mm = 0.0005 m Bang that into the equation to get a stress of 159.5 MPa Assuming Young's modulus of steel to be 200GPa (see Young's modulus - Wikipedia, the free encyclopedia for example) Strain = Stress / Young's Modulus (E) Strain = 0.0007975 Strain is a dimensionless ratio of the change in dimension to original dimension. For example change in length divided by original length. So the expected change in the radius of the pipe line (from when the pressure in the pipe is the same as the ambient pressure out of the pipe to when it is pressurised to 145 bar) can be calculated by multiplying the original outer radius (6mm) by the strain. This comes out as a change of 0.004785 mm Vernier won't be able to measure it. This is a bit of a meaningless number => in real terms it flexes by a very small amount that is going to be really difficult to measure.
__________________
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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