Re: Compression

[Todd Tomason <jayscore@xxxxxxxxxxxxx>]

I ran the engine about five minutes prior to the compression test to warm it 
up.  So I'm thinking I'm a little on the low side.  The engine has a lot of 
vibration at idle, enough to shake the whole car side to side.  I'm thinking 
that might be a bad timing chain.  (I already replaced the motor mounts.)  
I'm also getting water in my oil.  Probably a bad head gasket.  The water 
pump started leaking last week.  

With 140,000 miles on the engine I'm thinking it's time to stop trying to 
patch it together and just do a full rebuild.

Todd

On Sunday 12 February 2006 11:23, farna@xxxxxxx wrote:
> "Normal" compression varies with the engine. A 1978 232 should have 140
> psi, a 258 150 psi... NEW. The 82 TSM states 120-150 for the 258. I believe
> that's pressure measured with the engine warmed up. Before you get scared,
> 95-100 psi is still good. Should be no more than 10 psi variance between
> adjacent cylinders, 30 psi from highest to lowest.
>
> If you read 85 psi across the board, you're probably still good, and likely
> measured cold. You can also put a squirt of oil in the plug hole and
> measure compression. That should increase it just about the same as if the
> engine is warm. As it warms up some oil gets to the rings and helps
> sealing, dry rings don't seal good.
>
> --
> Frank Swygert
> Publisher, "American Independent
> Magazine" (AIM)
> For all AMC enthusiasts
> http://farna.home.att.net/AIM.html
> (free download available!)
>
> original message----------------------------------------------
>
> Date: Sat, 11 Feb 2006 16:58:34 -0600
> From: Todd Tomason <jayscore@xxxxxxxxxxxxx>
> Subject: Compression
>
> What is normal for compression, anyway?  I did a compression test on my 258
> in my Spirit a while back, and it was about 95 lb. on each cylinder.  Is
> that normal or low?
>
> Todd