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Questions tagged [compression]

One of the four internal combustion engine strokes necessary for the complete combustion process to occur. The compression stroke compresses an air fuel mixture and prepares for it ignition by spark.

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How does compression tests work inside of an engine?

Now I understand the concept , that an engine needs compression to make efficient power and I understand the theory , but what I don’t completely understand is how does compression build in a ...
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back compression in skoda Rapid

I have skoda Rapid 2012, there seems to be a oil leakage. Recently one mechanic said there is back compression in the engine but another said Skodas have back compression and nothing to worry. I am ...
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MAZDA 3 2006 no compression?

Okay so I am in need of advice, I have a Mazda 3 2006, the timing chain was super stretched out which caused the car to die at a stop light or if the gas was not being pushed the car would die. So I ...
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Can I use cylinder compression to conclude the valves are adjusted

Today a friend told me that my exhaust gas smelled funny and that I should check my valves. I don't find it very likely since the engine is around 6000kms old. Can I avoid the trouble by checking the ...
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Help diagnosing non peppy\sluggish car after overheating

My car recently overheated due to radiator leak and I got the radiator replaced. Mechanic told me I didn't have any head gasket problem at this point. When collecting the car I noticed it was not ...
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1answer
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Diesel Injector Well full of Carbon

While looking over my friend's 08 Kia Carnival J3 2.9L Turbo Diesel, I noticed a strange huffing noise. After removing the decorative engine cover I discovered this: This injector well is filled ...
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1answer
126 views

No compression with new cylinder

Last year I was riding my motorcycle, and the motor turned off while driving. It was a harsh stop, it didn't die slowly like when there is no fuel left. After checking the compression (which didn't ...
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Lack of compression after adjusting intake valve

I was recently tuning my 4 stroke lawn mower to shoot flames. I messed around with the intake valve, and soon found big flames coming out my exhaust. How ever the next day there was no compression and ...
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If an engine starts does that mean compression is fine?

I am looking at buying a second hand 2-stroke engine. I have seen a lot online about checking compression before buying used engines. I don't have a compression tester, but will buy one if necessary. ...
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How can a model with a smaller engine produce more power?

I am from India, here we have Ford Ecosport. Tt has different models, out of which one model with less cc produces more power than a higher cc model (999cc and 125ps) & (1497cc 123ps). How is this ...
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Help me understand the results of these cylinder compression and leakdown tests

I recently purchased a 2007 Subaru Outback 2.5i, with approx 146000kms on the clock. As its a recent purchase, I'm going through preventative maintenance to ensure its running as good as possible. ...
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Low compression on all cylinders - Flooded Engine - Maybe Washed Cylinders?

I just did a head gasket replacement on my 1995 Acura Legend. Before the replacement, compression was good on all cylinders except #3, which had blown. While the engine was open: I cleaned off the ...
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Engine grease fell into combustion chamber

I was changing a spark plug out on a 2000 Ford Expedition with a 5.4L Triton, with the coils on the plugs (COP), and I'm worried about how dirty it was. I was being as careful as possible, but I know ...
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Does the Dashpot Piston on an SU Carb effect compression test results with open throttle

I just recently got 150 PSI on my 1979 Leyland Sherpa 1.7l petrol Van with SU carb and in my limited experience thought that it sounded too high for such an old vehicle. When you do a compression ...
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possible to replace rings in i4 from the bottom?

I'm checking out a 2007 Nissan Sentra 1.8 inline 4, 170k miles, for a friend. I have never witnessed this vehicle while running so here's what I "know." It takes like 20 minutes of cranking before it ...
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Simple Question: During combustion stsgep do the piston go up all the way?

Does the piston reach the max height the piston can go without fuel or oxygen I would think it can't because the oxygen molecule being squeezed in the middle. I'd say it almost fully go up but not ...
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Honda dirt bike with clone engine lots of problems

So I have a 110cc Honda trail. It has been getting colder where I live and my bike has been acting funny. first problem: At FULL throttle it starts to sputter and crackle. The second problem: does ...
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Compression test

I have a 2002 Toyota Corolla (1zz-fe engine with 236k miles on it) and did a compression test on a warm engine. My readings are: 150 - 150 - 140 - 175 I've read that the difference should not be ...
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2007 KOW VULCAN 800 LOST COMPRESSION

I have an '07 kow vulcan only 6k miles and recently rebuilt carb., now it is losing compression and is killing me to speed up even in low gear, could the clutch plates be shot even at this low mileage?...
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What actually affects engine compression ratios?

I always assumed that the less "square" (or more "undersquare") a motorcycle engine was, the higher the compression ratios it can have. But a survey of several bikes -- from cruisers to supersports, ...
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1991 Chevy Astro - O2 Sensor and Low Compression

I have a 91 Chevy Astro van with 15x,xxx miles. It idles very rough and drives extremely poorly at around 40mph, and, overall, seems to lack a bit of power. A compression test was performed on the ...
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Why can't they add more gas particles to the pressure higher to force a piston down! [closed]

I know that car engines rely on expanding gas to cause pressure to force the piston down. My question is during the compression state, why can't they add more gas/air to cause more pressure and force ...
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How to leak down test a cold engine?

I'm thinking of doing a leakdown test on an engine before I install it in my car. Of course the problem is that the engine will be cold and things won't seal the way they do when they are hot. So how ...
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No compression on my two stroke

I was recently riding racing my Honda 250R (1986) (informally), and, all of a sudden, the engine quit completely. I tried letting out the clutch in second gear (push starting) with my momentum, but ...
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Shouldn't a loss of compression equal a loss of power?

I recently did a compression test on a Nissan B13 GA16DE and got 125, 127, 122 and 140 PSI (cold). A few years ago, all 4 cylinders got 135-140 PSI, cold. Shouldn't this loss of compression have led ...
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More In Cylinder Pressure Testing Questions

So I was looking at a 06 Pontiac G6 2.4l with a complaint of low power on hills. Had been at another shop to have the transmission checked and they referred the customer to us. Road test confirms car ...
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Engine consuming oil and white smoke comes out when starting the engine while cold

my car has been consuming oil for a while now but only recently has started to smoke when it is started while the engine is cold. I thought that maybe because I am using a synthetic oil in a high ...
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Premium vs. regular in medium compression engines

We probably all know that using premium grade gasoline in a low compression engine (less than 9.5:1) is nothing but a waste of money, but what about medium compression engines with a compression ratio ...
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What are these two rubber-ended attachments used for in a compression tester kit?

I'm looking to buy a compression tester kit and am a little puzzled by the purpose of the two rubber-ended attachments shown below. Am I right in assuming that these two attachments can be jammed ...
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How Many Times to Crank During a Compression Test

I've read a number of different recommendations on how many times to cranks the engine during a compression test. I've read those that say to crank until you reach a stable reading. In the book, ...
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Interpreting Cylinder Compression Readings

So I've been having some engine trouble with my 98 Mazda 626 GF 2L, specifically a low, rough idle and lack of power on acceleration. One of the things the WSM says to check for both these problems ...
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Do Compression Rings and Oil Ring Wear at the Same Rate?

Is it possible that the oil control rings might be worn to the point that you're burning significant amounts of oil, but the compression rings still be good? Or do they typically wear out together ...
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Is cylinder leak down test needed if compression test results are fine?

If I compression test my engine and the results are fine, could there ever be any need to leak-down test it as well? IOW, can a leak down test ever fail if the compression test is fine. RELATED: ...
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Converting Cylinder Compression Specs to Inches of Vacuum

If I have the specifications for cylinder compression can I convert that to how much intake vacuum the engine should be pulling? For example, if I have a 4 cylinder engine that is supposed to have ...
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Could this be the result of bad compression?

I've had a bunch of problems with my truck (2000 Ford Ranger) and I've been hoping to sell it. Most recently, I was driving it and the heater control valve snapped. I drove it home and replaced the ...
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Mondeo 04 TDCI bent conrod - worth fixing?

I have a 2004 Mondeo 2.0 TDCI which has issues when starting from cold: lots of white smoke and rough idling until it warms up. Had it tested at several garages, who both diagnosed low compression in ...
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How much Octane Fuel does Honda CBR 250R (India Version) needs? 91 or 93?

Honda CBR250R STD 2013 Model's manual state that fuel(petrol) used should be 91 or more. Seems like they have defined the minimum threshold of RON than stating the optimum RON for the given bike. ...
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Is it wise to use engine compression to help slow down a car to prolong brake life? [duplicate]

I have a 2010 Mercedes C-300 with six speed standard transmission. I'm wondering if it is wise to downshift to get engine compression to help slow down the vehicle when stopping to lessen brake wear? ...
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Low compression and will not ignite after broken camshaft pin and replaced head and gasket

My 95 Geo Metro Lsi 1.0L had a blown head gasket. I replaced the gasket and drove the car for approximately 120 miles before it started spitting and sputtering. Then it died just before I got home. I ...
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Corsa Sport (2007) low compression cylinders 2 & 4

I have been having trouble with my Corsa. It sometimes just cuts out or does not want to start at random times. I have had the car serviced, I have had the starter motor replaced & am now having ...
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What do these compression figures mean

This is a follow up question to What are the causes of fluctuating intake manifold vacuum I have a 2005 Honda CBR600 F4i which suffers from occasional hesitation at low rpm when accelerating. After ...
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Cylinder 1 and 4 has low compresion, after engine has been redone

I have a Opel Corsa 1999 B type. We had a mechanic redo the engine about 4 months ago, but this week it just does not want to start. Today had other mechanic look at the engine, and did a quick ...
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Typical Stock Boost Values

For an engine that is boosted out of the factory, what are typical maximum and average boost values? Are they conservative in the 5-6 PSI range or do they get more aggressive getting up to 10-15 PSI? ...
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Strokes during compression test?

Just wondering what the general consensus out there for the amount of times the vehicle turns over during a compression test? I have heard anywhere from 5-8, and personally crank 7. What is the ...
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Does a warped engine block affect compression test?

Check other questions, and did not see an answer. Backstory: Driving around, discovered pin hole in radiator. Chose to drive home, since I was at my exit, and I lived right there. Blew head gasket. ...
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Motorcycle 125cc question about PISTON condition and battery

Last year I bought a 125cc bike, Modenas brand, most likely unknown to you. It is a moped. http://www.modenas.com.my/v2motorcycle.asp?id=70 It can go as fast as 110 km/h enough for the city, ...
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Static vs. Effective compression: Why does higher effective compression not require higher octane gas?

Background I've been trying to do a lot of research on boost lately because I'm planning on running a moderate turbo setup on my daily/light-duty-autox car in the future. I'm trying to get into the ...