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compression test???
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guillermo
2 BBL ''SuperSix''


Joined: 10 Jun 2010
Posts: 22

Post subject: compression test??? (Tue Jun 15, 2010 10:52 pm) Reply with quote

hi everybody. i did a compression test on all the pistons {6} the readings go as follows #1 first crank was 90 then 4 more it increased to 110 2nd was the same # 3 it went to 120 and 4th was 110 but # 5 stood at 90 even after i poured a bit of oil in it and # 6 AT 120 . is that good except for # 5 ? i been having a smoking issue would this prove that the valve seals are bad ??? . curious i connected a compressor to the individual sparkplug holes and 1 and 2 held but # 3 let air go into # 6 piston and # 4 held but # 5 allowed air to go to # 3 literally ? i put my finger to plug the hole # 3 and then the air would come out thru the carb ???? same for # 6 ???? did i do something wrong ???? p.s how can i post images or video ???? [/img]


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wjajr
Supercharged


Joined: 16 Feb 2008
Posts: 4314
Location: Downeast Maine

Post subject: (Wed Jun 16, 2010 4:17 am) Reply with quote

Welcome to the board Guillermo,

The folks on this board are quite knowledgeable, and helped me when I got my Dart several years ago, that needed just about everything repaired.

Glad to see you are conducting tests on your engine, as this will help pinpoint any problems.

One would get leakage from more than one cylinder via the valves, if the engine was not rolled over, so that each cylinder being tested had its valves in the closed position to hold compressed air.

Why did you perform these tests? Because of oil burning, poor performance, skipping, or just wanted to see what condition the engine is in? It is always good to establish a base line of condition, with real numbers, before making any changes.

Have you gathered any vacuum readings, and timing settings as well?

Describe year & model of your car, displacement, auto or standard transmission, and if any modifications have been made to the engine.

Engine smoking can be caused by two conditions, bad valve seals, and bad oil rings. Seals are relatively easy to fix, rings not so easy, as the engine needs to be pulled and probably rebuilt depending on how off spec everything is.

Describe to us when this engine produces smoke. On start-up a big puff; during de-acceleration; under hard acceleration, just while idling with no load; all the time…

Have you a copy of the “Factory Service Manual”? This publication is a must have document to guide one when working on these vehicles. Haynes and others won’t do, as they are full of misinformation, and not very comprehensive.



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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

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Sam Powell
Supercharged


Joined: 04 Jun 2006
Posts: 4009
Location: Gaithersburg MD

Post subject: (Wed Jun 16, 2010 11:50 am) Reply with quote

If pressure comes up with oil added, the problems are likely worn rings. If they do not come up with added oil this would indicate burned valves. In general, the more even the compression, the better. 150 is considered excellent for an older car. 110 will run, but not give the best performance, or efficiency, and your reading of 90 indicates trouble in that cylinder.

Sam



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Doc
Guru


Joined: 14 Oct 2002
Posts: 5194
Location: Working in Silicon Valley, USA

Post subject: (Wed Jun 16, 2010 1:06 pm) Reply with quote

You may want to check for correct valve lash on the low reading cylinder(s).
DD


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guillermo
2 BBL ''SuperSix''


Joined: 10 Jun 2010
Posts: 22

Post subject: (Wed Jun 16, 2010 3:49 pm) Reply with quote

the car is 68 dart 4 dr standard with a 225 inline 6 stock . odometer says 60,000 on it but ? . i did a compression test on it cause it smokes when you first start it but when idling i have cannot see any smoke but, if i revv the engine it smokes again . i have driven the car and no smoke is visisble when driving it . on the compression test i had a remote start i would crank it 1-3 seconds burst of 4 with a screw in tester . and for the air hose in the sparkplug hole i did that as a old timer remedie for finding out if it is the rings that leak or is it the valva stem oil seals . only thing is that the number three leaked into the number 6 and the number 5 leaked into the number 3 but if i covered the hole the air would leak thru the carb???????????????. the smoke smells more like gas ??? not to strong though also engine runs strong idles alright ? and i did a valve lash on it while it was running .10 in and .20 ex. one thing timing is set at 5btdc but there is no more adjustment it is fully turned clockwise and the holding plate touches already ??? i can go counter clockwise .


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hantayo13
Turbo EFI


Joined: 19 Feb 2005
Posts: 1962

Post subject: (Wed Jun 16, 2010 5:35 pm) Reply with quote

there is a second adjustment bolt on underside of dist


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guillermo
2 BBL ''SuperSix''


Joined: 10 Jun 2010
Posts: 22

Post subject: (Wed Jun 16, 2010 8:07 pm) Reply with quote

ok but what about the other issues ??? also i tested the car and it smokes when it starts and when i was accelerating it but as soon as i let go of the gas pedal it stopped smoking ? per my witness


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NspireFX
2 BBL ''SuperSix''


Joined: 23 May 2010
Posts: 15
Location: México

Post subject: (Wed Jun 16, 2010 8:22 pm) Reply with quote

Hello Memo, I think you have a trouble with your valve accents in exhaust and admition, if on TDC point you have air in your exhaust have a problem, the same if you have in this point air in the bore carb. if you don't have air on this points, probably your spark plugs don't burning the mixture, or bad ignition time, check your vacum valve in the distributor.

I think.

I think. Rolling Eyes

si hablas español, escribeme.



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Sam Powell
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Joined: 04 Jun 2006
Posts: 4009
Location: Gaithersburg MD

Post subject: (Wed Jun 16, 2010 9:36 pm) Reply with quote

"That consume your mind, that's controlling your life."

I love the signature quote. The essence of truth.

Doc's advice to check the valve lash is a good one. Did you do that? I cannot remember if you said you did. If the valves are tight you are getting leakage through your valves as they cannot close tightly. If the adjustment is not too tight, then is sounds like you might have an exhaust valve burned.

How long have you had this car? Have you driven it much? Is this new behavior, or old? If youi have not driven it much, there is a chance the smoke is just stuck oil ring that will free with oil changes, maybe some cleaner, and some driving. Don't worry about the oil burning for now.

How does the car drive? If it drives OK, change the oil, adjust the valves, put in new plugs, points, and wires, and just use it. You may need to rebuild the motor, but if it runs now, just use it and save your money for the job. Or, do it yourself.

Sam



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Doc
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Joined: 14 Oct 2002
Posts: 5194
Location: Working in Silicon Valley, USA

Post subject: (Thu Jun 17, 2010 8:39 am) Reply with quote

Sam Powell wrote:
... How does the car drive? If it drives OK, change the oil, adjust the valves, put in new plugs, points, and wires, and just use it.
You may need to rebuild the motor (in the future), but if it runs now, just use it and save your money for the job. Or, do it yourself.
Sam


Good advice...
Even if the compression is somewhat low, just give the engine more & faster spark advance. Doing that will increase the power a little and can help "clear" stuck / dirty rings.
Drive it until a bigger problem presents itself.
DD


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guillermo
2 BBL ''SuperSix''


Joined: 10 Jun 2010
Posts: 22

Post subject: (Thu Jun 17, 2010 6:01 pm) Reply with quote

after several days of research i found out that i had done the compression test wrong . i needed to have the throtle open and the choke open as well. which i did not do so i was robbing the full stroke . as for the air leaking from the # 3 to the #6 and into the carb. i needed to put every piston in tdc before any air was introduced to get a reliable reading . one thing though the chilton manual says the compression at stroke should 125 my car was reading average 110 ? but someone said it should read 150????? and the manual says the timing should be at tdc but in others it says 5btdc ?????


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NspireFX
2 BBL ''SuperSix''


Joined: 23 May 2010
Posts: 15
Location: México

Post subject: (Thu Jun 17, 2010 8:50 pm) Reply with quote

Hello again Guillermo, I read Haynes Manual and I read this:

Minimum Compression on pistons; 100 psi
maximum variation; 25 psi.

what is the color of you smoke?
I'm agree with Sam, I open my S/6 and I found more fails, you can read this post http://www.slantsix.org/forum/viewtopic.php?t=40348

My engine Don't sending signals of "black, blue or white smoke" but some crankshaft bearings and connecting rods with more wear. Fortunately my pistons and crankshaft are in Standard (0") but I need rectified my block, camshaft, valves, heads, crankshaft and connecting rods,about of my pistons I'm buying some new ones. All this round some 260 dlls.



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ESP47
Turbo EFI


Joined: 11 Nov 2004
Posts: 1113
Location: Sacramento, CA

Post subject: (Thu Jun 17, 2010 9:59 pm) Reply with quote

You could possibly be running rich. Does it shoot a black substance out onto the concrete behind the tail pipe when you first start it?


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guillermo
2 BBL ''SuperSix''


Joined: 10 Jun 2010
Posts: 22

Post subject: (Thu Jun 17, 2010 10:19 pm) Reply with quote

it is blueish but then it smokes white not black but you can smell the order of gas though . the spark plugs where carbon coated like a black dust you can rub off no wetness or oil on them . the fuel pump looks new as well as the distrubeter from previous owner. runs strong and 110 per cylinder should be great compression . i have not noticed any loss of oil but i wpould have to mark the dip stick then check . i am really not driving the car because i do not want a ticket. what should the tdc be ? 5 btdc or tdc


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ESP47
Turbo EFI


Joined: 11 Nov 2004
Posts: 1113
Location: Sacramento, CA

Post subject: (Thu Jun 17, 2010 10:21 pm) Reply with quote

Try between 10 and 5 BTDC. If your motor runs at 10 without pinging and idles smooth, then leave it at that.


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