Causes of low compression
08-12-2017, 02:35 AM
#1
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Causes of low compression
I need a straight foward answer. I've been rebuilding my engine for a while now and i finally had it in my car for the 4th time. My engine wouldn't turn and i had no clue what was wrong. Called over a specialist and he told me the car had really low compression so he advised me to take it apart again. I see no possible issues other than my side seals were stuck. Do you guys believe that is my only problem and that it should work now? I have the engine fully assembled and i just wanna know the community's opinion because i would hate to put my engine in and back out for the 6th time
Any ideas or opinions will help.
Any ideas or opinions will help.
08-12-2017, 06:22 PM
#4
Often when you go to start a rebuild the plugs get fouled with the assembly lube (often Vaseline)
If you flooded it it can be difficult to start. Before the seals are bedded in a bit the compression is often not great
If you are sure you put it together properly...and it should be good to start...often a quick pull start will get it going
There are so many assembly/install problems that could cause this as well....so you need to start with the basics...fuel, spark and making sure the wiring is hooked up properly
Good luck
If you flooded it it can be difficult to start. Before the seals are bedded in a bit the compression is often not great
If you are sure you put it together properly...and it should be good to start...often a quick pull start will get it going
There are so many assembly/install problems that could cause this as well....so you need to start with the basics...fuel, spark and making sure the wiring is hooked up properly
Good luck
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gwilliams6 (08-17-2017)
08-18-2017, 09:46 PM
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I currently have the engine in and as before it's not starting its trying to though. Any thoughts? Im totaly lost here. Mechanic is out of the question not enough funds for that
08-18-2017, 10:21 PM
#6
40th anniversary Edition
https://www.rx8club.com/series-i-tro...t-here-222584/
Starting the Engine
• Starter
• Battery
• Engine Compression
• Grounding Wires
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Fuel Pump
• Fuel Injectors
Starting the Engine
• Starter
• Battery
• Engine Compression
• Grounding Wires
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Fuel Pump
• Fuel Injectors
08-18-2017, 10:26 PM
#7
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Starter,battery,ignition coils,spark plugs,and spark plug wires are new. Engine compression im not sure i don't have a tester. I previously had one done and i had really low compression and fixed the only problem i saw and well almost the same thing. Fuel pump and injectors should be good their condition is ok im pretty sure i grounded everything correctly.
08-19-2017, 12:06 PM
#11
40th anniversary Edition
did you read the whole starting issues thread ? Please do and then diagnose your issues. maybe a fuel pump or injector issue, especially if the pump and injectors are original, worn out and/or clogged.
If all main things you need for combustion, fuel, air, spark are properly working, then it may still be a compression issue with the car. It can also be a front O2 sensor,Maf sensor or ssv problem .
If all main things you need for combustion, fuel, air, spark are properly working, then it may still be a compression issue with the car. It can also be a front O2 sensor,Maf sensor or ssv problem .
Last edited by gwilliams6; 08-19-2017 at 12:10 PM.
08-19-2017, 03:33 PM
#12
If you are sure you have everything back in correctly...I would assume it is flooded.
Pull the plugs...are they wet with Gas? If they are it is likely flooded.
If it is a MT I personally would tow it and try and start it that way. It sounds like you have a crappy starter and the pull starting will allow the motor to turn over faster and negate the slow starter. If it is flooded it should start with a huge smokeshow...if it is something else it won't start.
If it is an AT car..the whole deflooding thing is a lot harder to deal with.
Pull the plugs...are they wet with Gas? If they are it is likely flooded.
If it is a MT I personally would tow it and try and start it that way. It sounds like you have a crappy starter and the pull starting will allow the motor to turn over faster and negate the slow starter. If it is flooded it should start with a huge smokeshow...if it is something else it won't start.
If it is an AT car..the whole deflooding thing is a lot harder to deal with.
08-19-2017, 04:08 PM
#13
You gonna eat that?
iTrader: (1)
I've flooded 3 times, ( I can tell when it's flooded and have never checked my plugs first) and this method always worked for me;
Be sure battery is fully charged, battery terminals are clean and tight ON THE POSTS.
The bolts can bottom out and it seems tight, but they will stretch over time.
I've used post caps or shims instead of replacing the cable clamps.
If you don't have a charger, first be sure your battery is good, (if you're not sure, have it tested) then hook the charger or another battery as a jumper, in or out of another car.
BE SURE YOU DON'T SWAP POS. & NEG!
Pull your small fuel pump fuse in the box under the hood.
Crank your engine for 10-15 seconds, then wait a few minutes as to not burn up your starter.
Do this several times then replace the fuse and attempt to start normally.
If it doesn't start right away but sounds like it might start, it could flood again, and start over, maybe trying a few extra turns.
If it still just spins without any signs of starting, then you'll have to do a proper troubleshooting method.
08-19-2017, 04:12 PM
#14
You gonna eat that?
iTrader: (1)
Did you try pulling the engine fuse?
I've flooded 3 times, ( I can tell when it's flooded and have never checked my plugs first) and this method always worked for me;
Be sure battery is fully charged, battery terminals are clean and tight ON THE POSTS.
The bolts can bottom out and it seems tight, but they will stretch over time.
I've used post caps or shims instead of replacing the cable clamps.
If you don't have a charger, first be sure your battery is good, (if you're not sure, have it tested) then hook the charger or another battery as a jumper, in or out of another car.
BE SURE YOU DON'T SWAP POS. & NEG!
Pull your small fuel pump fuse in the box under the hood.
Crank your engine for 10-15 seconds, then wait a few minutes as to not burn up your starter.
Do this several times then replace the fuse and attempt to start normally.
If it doesn't start right away but sounds like it might start, it could flood again, and start over, maybe trying a few extra turns.
If it still just spins without any signs of starting, then you'll have to do a proper troubleshooting method.
I've flooded 3 times, ( I can tell when it's flooded and have never checked my plugs first) and this method always worked for me;
Be sure battery is fully charged, battery terminals are clean and tight ON THE POSTS.
The bolts can bottom out and it seems tight, but they will stretch over time.
I've used post caps or shims instead of replacing the cable clamps.
If you don't have a charger, first be sure your battery is good, (if you're not sure, have it tested) then hook the charger or another battery as a jumper, in or out of another car.
BE SURE YOU DON'T SWAP POS. & NEG!
Pull your small fuel pump fuse in the box under the hood.
Crank your engine for 10-15 seconds, then wait a few minutes as to not burn up your starter.
Do this several times then replace the fuse and attempt to start normally.
If it doesn't start right away but sounds like it might start, it could flood again, and start over, maybe trying a few extra turns.
If it still just spins without any signs of starting, then you'll have to do a proper troubleshooting method.
08-20-2017, 01:36 PM
#15
40th anniversary Edition
yes sometimes serious seeming issues have just been flooding. Try the deflooding first.
Though if your engine is right and all parts of the ignition system are in top condition, you should never flood, even if you turn off engine before fully warmed. .
I have never flooded, not even once, in nine years of driving my 2008 RX8.
Though if your engine is right and all parts of the ignition system are in top condition, you should never flood, even if you turn off engine before fully warmed. .
I have never flooded, not even once, in nine years of driving my 2008 RX8.
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