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#1
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How reliable is loosening the oil cap as diagnostic tool?
I have a 617 engine shake at idle (84 300SD) and intend to do some diagnosing. I thought there was a compression gauge in the shop but can't (haven't) find it.
How effective is loosening the oil cap as a method of testing bow by and by inference, compression? Also, I remember someone rigging an electronic method of checking IP timing but haven't found it. Anyone have it book marked?
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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do. |
#2
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I think it's a silly test myself. What does it tell you? The engine has been driven around for 30 years. There's no precision measurement to be taken, no stats to compute, just "Oh, I guess it didn't roll off the assembly line yesterday after all."
I mean, I guess if you found one that didn't have that then you'd know it might be worth the fat roll of hundreds. That's about it though. -Rog |
#3
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Quote:
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#4
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Years ago there was a thread on here about fitting a 30 gallon garbage bag over the oil fill hole and measuring how long it would take to fill up the bag.
I'm not making this up, LOL. |
#5
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Essentially if your Engine runs the Car OK blow-by is only a nuisance.
I believe there is only 2 fixes depending on the cause. If Piston Rings are sticking there is some possibility that instilling something like Marvel Mystery Oil (or something else) into the Cylinders and letting it work for a week or 2 might free up the Piston Rings. If it is cylinder, piston ring and piston wear is the cause then the fix is to overhaul that area. I believe a few have reduced blow-by by replacing the Valve Stem Seals but most including myself did not have that happen The nuisance issue can be mitigated by piping the blow-by someplace other then inside of the Air Filter Housing; at least that is what I did on mine.
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84 300D, 82 Volvo 244Gl Diesel |
#6
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How long does it take to start without glowing? That's a general compression test. Just make sure your valve clearances are ok of course...
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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making.... 1977 280> 300D - 500,000km+ (to be sold...) 1984 240TD>300TD 121,000 miles, *gone* 1977 250 parts car 1988 Toyota Corona 2.0D *gone* 1975 FJ45>HJ45 1981 200>240D (to be sold...) 1999 Hyundai Lantra 1.6 *gone* 1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist) 2001 Holden Rodeo 4JB1T 2WD |
#7
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Blow a Bag of Blow By
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there were three HP ratings on the OM616... 1) Not much power 2) Even less power 3) Not nearly enough power!! 240D w/auto Anyone that thinks a 240D is slow drives too fast. 80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works |
#8
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Its a general test of condition of the motor. Less blowby is an indication of less wear but they'll run a good long time with lots of blowby. Its a point for negotiation too.
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#9
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Quote:
But nobody uses a garbage bag to do anything like that, that I know of.
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Strelnik Invest in America: Buy a Congressman! 1950 170SD 1951 Citroen 11BN 1953 Citroen 11BNF limo 1953 220a project 1959 180D 1960 190D 1960 Borgward Isabella TS 2dr 1983 240D daily driver 1983 380SL 1990 350SDL daily driver alt 3 x Citroen DS21M, down from 5 3 x Citroen 2CV, down from 6 |
#10
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It was a link to a youtube video if I remember correctly.
Quote:
I think I'll run that test when I get this 617 turbo running in the 1985 SE body.
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84 300SD 85 380SE 83 528e 95 318ic |
#11
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Take a strip of paper inch wide or less, hold it where it does not go completely across the opening, holding it with your thumb on one side. at an idle, it should 'flap' up & down, in & out of fill opening. If you have a lot of blow by, it flaps up more than it flaps down. Never tried it on my 300 but it worked on my old V-Dubs & MGA's. Simple enough to try, , , ,
-c-
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Sometimes, I post stuff just to piss people off! "I applaud your elaborate system of denial" |
#12
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Thanks to Charmalu for retrieving that thread....
I would to add that MB actually has a machine which measures the blowby in the crankcase...... but that does not mean that the garbage bag test provides any useful information.
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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 |
#13
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Here's how Cummins does it on the 6BT's.
Measuring Blow by, The Real Test For Internal Engine Condition - Seaboard Marine Quite similar to the plastic bag method but just a little more "professional". The old school method was to remove the dipstick, place a tightly fitting hose over the tube, drop the end of the hose into a bucket of water and observe the bubbles. The amount and frequency of the bubbles would give you a pretty good indication of the amount of blow-by. Small, steady, slow bubbles meant good Erratic, uneven bubbles meant at least one weak cylinder Frothing like an Alka-seltzer meant you have effectively created a 2 stroke from a 4 stroke design.
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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.” ― Brian P. Cleary, You Oughta Know By Now |
#14
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I guess it would be a good way to check for blockage in the crankcase ventilation system.
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#15
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Not really sure how useful it is, the 77 240D engine that is being put into a 83 300D body for my dad has tons of blowby by the cap test but runs great, he says it has better performance than his 83 240D engine ever had. I could do 85-86 flat out in that car (the 77 the engine came from) with the auto, got it to 95 once.
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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon. |
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