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Bad News Bears Compression
Just had a compression test done today.
Came out 175/175/175/125 I'm flipping out on that last cylinder. I was planning on getting an install next week. Now I am going to seafoam the car, then get a leak down + another compression and see what the deal is. Shit sucks. |
ouch...that's low. Still think you don't need a re-route and a dual feed fuel rail?
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Originally Posted by Zabac
(Post 293121)
ouch...that's low. Still think you don't need a re-route and a dual feed fuel rail?
How many miles on the engine? |
Originally Posted by Saml01
(Post 293123)
His car is stock and produced those numbers. Somethings gotta be wrong.
How many miles on the engine? I've been thinking about it, and the car has been relatively well maintained and there is no reason the compression should be this low. Thats why I am going to seafoam it and get "another" opinion. My car doesnt feel low on power, and seems to get MPG in the 27-28mpg range. I'm wondering if maybe they got word I was turbo'ing the car and tried to get me to buy the full deal rebuild or something. If so, I'm going to be pissed. edit: also the number are pretty fishy too. All 175 and exactly 50psi lower on the last cylinder. |
My compression went out on #3 #4 on stock power too. At 130K, religious oil changes etc. Never revved when cold...still went out.
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Boost it and blow it up, then swap in a new motor.
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If you think it's fishy, repeat the test yourself. The cost of the tester is likely less than the cost of having someone else test it once!
Here's hoping it's just a stuck valve or something though.. |
Sorry to hijack, but is there anyway to know if you have lost some compression on a cylinder without a tool. Meaning driving every day, can you feel the difference between 125 and 175? I can imagine enough loss and it will just run like shit.
And can someone walk me through this tool for me. http://www.amazon.com/Actron-CP7828-.../dp/B00020BM28 The spark plug adapter is bolted into the engine and then the line is fished into the spark plug hole to mate to it?
Originally Posted by kotomile
(Post 293137)
If you think it's fishy, repeat the test yourself. The cost of the tester is likely less than the cost of having someone else test it once!
Here's hoping it's just a stuck valve or something though.. |
Originally Posted by Saml01
(Post 293139)
The spark plug adapter is bolted into the engine and then the line is fished into the spark plug hole to mate to it?
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Originally Posted by Saml01
(Post 293139)
Sorry to hijack, but is there anyway to know if you have lost some compression on a cylinder without a tool. Meaning driving every day, can you feel the difference between 125 and 175? I can imagine enough loss and it will just run like shit.
And can someone walk me through this tool for me. http://www.amazon.com/Actron-CP7828-.../dp/B00020BM28 The spark plug adapter is bolted into the engine and then the line is fished into the spark plug hole to mate to it? It will have some slight hesitation, but not everyone can feel a 10% power loss on a 100hp car. The tool is pretty self explanatory once you have in in your hands. Just put the adapter on the end, pull the spark plugs, and stick the tube where the spark plug was. |
http://custompistols.com/cars/articles/compression.htm
http://www.imperialclub.com/Repair/Engine/tests.htm or Remove all spark plugs so the engine can rotate easily. Block open the throttle plate (I usually just hold the pedal to the floor while cranking... This prevents restricted air flow into the engine. Disable the ignition system to prevent sparks from arcing out of the disconnected spark plug wires or burning up coils. Unplug coils Disable fuel injection, it should also be disabled to prevent fuel from spraying into the engine. Pull fuse Check the manufacturer’s manual for specific directions on the tester. Screw the compression gauge into one of the spark plug holes. Crank the engine and let the engine rotate for about four to six compression strokes (compression gauge needle moves four to six times). Write down the gauge readings for each cylinder and compare them to the manufacturer’s specifications. While holding pedal to floor Wet add 1 tbsp of oil to cylinder and repeat... (add the oil to ea cylinder as you test it, otherwise you'll get sprayed on :) and if your battery is weak, you may need a charger on it... |
just boost it. i didn't even do a compresion test before or after the turbo on my car.
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From a 92 Workshop Manual:
INSPECTION, PAGE B-10 STANDARD: 1,324 kPa ( 13.5 kgflcm2, 192 psi 1-300 rpm MINIMUM: 932 kPa (9.5 kgflcm2, 135 psi)-30~rpm INSPECTION 1. Check that the battery is fully charged. Recharge it if necessary. (Refer to Section G.) 2. Warm up the engine to the normal operating temperature. 3. Turn the engine OFF. 4. Remove all spark plugs. 5. Disconnect the ignition coil connector. 6. Connect a compression gauge to the No.1 spark plug hole. 7. Fully depress the accelerator pedal and crank the engine. 8. Record the maximum gauge reading. 9. Check each cylinder. Compression: 1,324 kPa ( 13.5 kgf/cm2, 192 psi)-300 rpm Minimum: 932 kPa (9.5 kgf/cm2, 135 psi)-300 rpm Differential limit between cylinders: 196 kPa (2.0 kgf/cm2, 28 psi) 10. If the compression in one or more cylinders is low, pour a small amount of engine oil into the cylinder and recheck . the compression. (1) If the compression increases, the piston, piston rings, or cylinder wall may be worn. (2) If the compression stays low, the valve may be stuck or seating improperly. (3) If the compression in adjacent cylinders stays low, the cylinder head gasket may be defective or the cylinder head distorted. 11. Connect the ignition coil connector. |
Originally Posted by bryantaylor
(Post 293181)
just boost it. i didn't even do a compresion test before or after the turbo on my car.
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Originally Posted by bryantaylor
(Post 293181)
just boost it. i didn't even do a compresion test before or after the turbo on my car.
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Originally Posted by bryantaylor
(Post 293181)
just boost it. i didn't even do a compresion test before or after the turbo on my car.
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Originally Posted by naarleven
(Post 293130)
Thats why I am going to seafoam it and get "another" opinion.
Originally Posted by naarleven
(Post 293130)
My car doesnt feel low on power, and seems to get MPG in the 27-28mpg range.
Originally Posted by naarleven
(Post 293130)
I'm wondering if maybe they got word I was turbo'ing the car and tried to get me to buy the full deal rebuild or something. If so, I'm going to be pissed.
Overall, 1) this is not terribly uncommon. some BPs have been pampered and they suck. others have been used and abused and still blow good numbers. 2) fuck these goddam compression tests. they are useless. you need useful data, like those which could be procured from a leakdown test. 3) did you outsource this compression test? if so, then I'd have to ask: "why?" Based on that answer, I might suggest that turbocharging your car may lead to a lot of challenges. |
Originally Posted by chucker
(Post 293304)
Overall, 1) this is not terribly uncommon. some BPs have been pampered and they suck. others have been used and abused and still blow good numbers. 2) fuck these goddam compression tests. they are useless. you need useful data, like those which could be procured from a leakdown test. 3) did you outsource this compression test? if so, then I'd have to ask: "why?" based on that answer, I might suggest that turbocharging your car may lead to a lot of challenges. and I outsourced my test, because as is, I have a lack of experience, a shortage of time, and a surplus of money. |
A shop that does a LOT of engine work may also have a borescope. The combination of a leakdown test and a borescope is pretty good in diagnosing engine problems.
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my guess is the battery was going a little low when they got to number 4
do the test again but this time start on number 4 I would boost it and worry later put it this way if it is "down" you can lean all about tuning and so on on an engine that is not perfect - so if it blows up you were already "expecting" and budgeting for it the next engine will be even more awesome think of the internals you can add for the "surplus" of money or you can just paypal to me |
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