compression test? - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 09-20-2002, 08:51 PM Thread Starter
 
Join Date: Mar 2002
Posts: 48
Thanks: 0
Thanked 0 Times in 0 Posts
 
compression test?

Okay, I think I have asked about every possible engine conversion for a cj-7. However, I have finally accepted the fact that I'm a poor broke college student and have no means to finance an engine conversion in the near future. However, the 4.0 head conversion looks affordable and promising for me.
My question is if there is a compression test that can be done that can distinguish between leaking rings and leaking valves. Also, can it be done cheaply by a shop?
If the rings are good, then it seems like it should be fairly straight forward swap.
Thanks
bellotti is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 09-20-2002, 09:52 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: compression test?

Don't waste your money haveing a shop do it. A compression tester is only about $20 and most come with instructions. To find if rings or valves are the weak link test all cylinders and record the results, then pore a little oil in the cylinder and retest. If the compression stays the same then valves are at fault. If however compression increases significently the the rings are bad.

bandhmo
post #3 of (permalink) Old 09-21-2002, 12:12 PM
 
Join Date: Nov 2000
Posts: 2,687
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: compression test?

I know this isn't exactly what you asked, but do you get a lot of blowby? As in the crankcase spewing out exhaust gas under pressure from seals and pcv filter at the air filter, covering the air filter with oil? This is also an indication of poor sealing rings, as the pressure from above the pistons is leaking into the crankcase and escaping from the crank everywhich way it can, usually carrying oil with it.

Definately do the compression test on each cylinder. Also consider a leakdown test, which involves pressuring each cylinder one at a time with compressed air and seeing how well it seals. You will hear where the air is leaking out, intake, exhaust, etc if it's a bad valve.

It's not that time consuming to remove the head to remedy the problem if it is a valve or a head swap. You can do it in an afternoon.
TiminMb is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 09-21-2002, 06:54 PM Thread Starter
 
Join Date: Mar 2002
Posts: 48
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: compression test?

Thanks for the input. This board's always helpful!
bellotti is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome