DC350

What are some symptoms of loss of or low compression?

I've been reading up on it.....

Thanks guys

dr0x

Low power, hard start. Im sure there are A LOT more. If you are worried about it just do a compression tester. I bought one at Autozone for 30$, removed the coupling w/ the valve that holds the compression in the gauge. It works like a dream.

zelgadiss-san

yeah, my rear housing is on the verge of low compression, and it's showing. won't idle in gear with the ac on...

DC350

damn, my car is REALLY hard to start

Icemark

hey... why don't you just do a compression check... instead of guessing. As drox says a cheap one is only $20-$30 bucks

dr0x

I was going to say it should die if you just put it in gear and arent moving, but I am going to guess its an auto

Snufelupogus

iTrader: (2)

Yo... I just bought a compression tester from my local parts store and did a compression test on my car. Its a screw in type, so I put it in as far as I could so that it wouldnt turn anymore.
Now heres the thing... I got 70psi on the front rotor and 80psi on the rear as my highest compression on each rotor! I DONT GET IT!!!
Its a rebuilt engine with 5000km on it! The car has been sitting for around a month in the cold weather and I went and hit the key and it started first try without any problems. I let it run till it was up to temp, then I turned it off and did the test and those were the results that I got! Im soooooooo confused!
I tested my 1/4 with a g-tech jigger and got 16s flat with this engine!

I DONT GET IT!!!

Someone help me!

StarionX

I am so far from being an expert, it's not funny... but, I have seen Kevin (hypntyz7) say that rebuilt engines will have low compression for awhile until they have been properly broken in. I know you have done 5000kms... it's just a thought. The other thing is that maybe since the car hasn't been running for a month, the seals have dried up a tad, which I believe would lead to low compression. You might need to run it a lot more before doing a test.
Off course, being the mechanical genius that I am (I tried for an hour to replace a window wiper ), you might get more intelligent responses from my ***.

sexyrexy

How's your battery? I've read that a low battery will give low compression numbers.

silverrotor

iTrader: (1)

Your Charging System has to be optimum In order to attain true Compression Numbers.

Snufelupogus

iTrader: (2)

yeah the battery can give you low numbers if it doesnt have enough power to turn the engine over fast enough... but the engine started up first try (held the key for 2 seconds and it turned on) and it had been in the cold for a month without use...
Id say the battery is good if it can do that

That died up seals maybe a reason...

CanadianRX7

could have low compression or no compression when your idle is irratic

Project84

You gotta run the engine up to normal temp, then shut it off and do your compression test.