Yesterday's Tractor Co. Low Prices, Parts Ship Fast!
Click Here or call 800-853-2651 
   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver
 
Marketplace
Tractor Manuals
Tractor Parts
Classified Ads
Photo Ads

Community
Discussion Forums
Project Journals
Tractor Town
Your Stories
Show & Pull Guide
Events Calendar
Hauling Schedule

Galleries
Tractor Photos
Implement Photos
Vintage Photos
Help Identify
Parts & Pieces
Stuck & Troubled
Vintage Ads
Community Album
Photo Ad Archives

Research & Info
Articles
Tractor Registry
Tip of the Day
Safety Cartoons
Tractor Values
Serial Numbers
Tune-Up Guide
Paint Codes
List Prices
Production Nbrs
Tune-Up Specs
Torque Values
3-Point Specs
Glossary

Miscellaneous
Tractor Games
Just For Kids
Virtual Show
Museum Guide
Memorial Page
Feedback Form

Yesterday's Tractors Facebook Page

Related Sites
Tractor Shed
TractorLinks.com
Ford 8N/9N Club
Today's Tractors
Garden Tractors
Classic Trucks
Kountry Life
Enter your email address to receive our newsletter!

subscribe
unsubscribe
  
Harry Ferguson Tractors Discussion Forum
Show Parts for Model:

Re: Compression Testing...

[Show Entire Topic]  

Welcome Guest, Log in or Register
Author  [Modern View]
Ark68SS

03-05-2013 10:50:19
70.232.35.147



Report to Moderator


Tom in MO said: (quoted from post at 09:21:29 03/05/13) Is there a thread on this site, or on another website, or a book, that has detailed, step-by-step instructions for testing compression? (On a Ferguson TO-20, in my case.)

I"ve never done it, but I can read and follow instructions, and it doesn"t sound too difficult.

Are gauges usually available for rent/borrowing from auto parts stores? I have a local parts store, and an O"Reilly"s nearby.

Thanks.


1. Remove all spark plugs

2. Be sure fuel is shut off

3. Attach battery charger to battery (the test can be skewed by lower battery voltage, esp on the last cylinders you test)

4. Set throttle lever to full open

5. Screw the gauge in and crank the motor over

A compression test is more of a comparison test between cylinders rather than a pass/fail kind of deal. The maximum pressure is a determined by things like compression ratio, speed of the starter motor, ambient temperature, and other factors. You want to compare the readings of the cylinders to each other rather than looking for a specific number, although anything less than 90 psi does indicate a problem. A 10% or less variation between cylinders is ideal, but the motor will still be OK with anything less than 20%.

If you have two cylinders with lower compression that are side-by-side, that usually indicates a blown head gasket between those two cylinders.

If you have a much lower reading with a dry cylinder than a wet one, you probably have a ring seal problem.

You can use a two-gauge cylinder leak down tester for more meaningful results.
Remove the plug for the cylinder you're testing and bring the piston to the top of the compression stroke. Install the tester and shoot air into it. Don't put too much air in or the piston will be pushed down by the pressure, but get at least 50 psi. You may have to hold the crank nut to keep the piston up.
Compare the readings between the two gauges. One gauge will read the air pressure you're applying to the cylinder, the other gauge shows how much the cylinder is holding. I.E., if you're putting 50 psi in and the other gauge reads 40 psi, you have 20% leak down. Another benefit of this test is you can tell where the cylinder is leaking. If you feel air coming from the exhaust pipe, the exhaust valve isn't sealing. Same for an intake valve if you feel air coning out of the carb. Pull the dipstick and, if air's coming out of it, the ring seal is suspect. If the head gasket is bad, you can feel the air coming out of the adjacent spark plug hole if you pull the plug out of that cylinder. Sometimes you can find a cracked head using this tool. If the crack's large enough, you'll see air bubbles coming up in the coolant when you remove the radiator cap and look in the radiator.
Hope this helped,

BillL

EDIT: Jason types faster than me. :D Good info from him, too.
This post was edited by Ark68SS at 10:52:37 03/05/13.

[Log in to Reply]   [No Email]
Jerry/MT

03-05-2013 14:35:37
206.183.116.145



Report to Moderator
 Re: Compression Testing... in reply to Ark68SS, 03-05-2013 10:50:19  
I always disconnect the air cleaner at the carb so that a partially clogged air cleaner does not affect the results. I would also conduct the test with the engine at operating temperature and would also conduct the tests both dry nd "wet"(add several ounces of motor oil to each cylinder and repeat the test) recording both numbers.

Very low compression readings are generally indicative of a stuck open or burned valve. Low pressures that don"t improve from dry to wet are generally indicative of leaking valves.

[Log in to Reply]  [No Email]
[Show Entire Topic]     [Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:

TRACTOR   PARTS TRACTOR   MANUALS
Same-Day Shipping! Most of our stocked parts ship the same day you order (M-F).  Expedited shipping available, just call!  Most prices for parts and manuals are below our competitors.  Compare our super low shipping rates!  We have the parts you need to repair your tractor.  We are a Company you can trust and have generous return policies!   Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ More Info ]

Home  |  Forums


Copyright © 1997-2014 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters