TRACTOR PARTS Allis Chalmers Case & David Brown Farmall & International Ferguson Ford & New Holland John Deere Massey Ferguson Massey Harris Minneapolis Moline Oliver & Cockshutt Kubota / Yanmar

TRACTOR MANUALS

Allis Chalmers	Case	Farmall IH	Ford 8N,9N,2N	Ford
Ferguson	John Deere	Massey Ferguson	Minn. Moline	Oliver

Ford 9N, 2N & 8N Discussion Forum

Compression Test

Welcome Guest, Log in or Register

Author

Brian S, NE

08-30-2004 21:07:52

Report to Moderator

OK, did compression tests this evening. I think I even did it right: (almost)

Cold motor, dry - 75 75 80 75

Cold motor, wet - 90 85 95 ?

Couldn't get her to turn over enough for the last cyl wet. Grumble, ran down the battery. Will do again tomorrow after I get a chance to charge her up.

I did notice the very middle head bolt (couldn't find any reference to a number) had oil around it. I couldn't see any easy way to get at it to tighten it down. Couldn't get socket past the tube which carries the spark plug wires. Is there a "correct" way to get at it? I may just wait 'till this winter when I have her apart to paint etc. and replace the head gasket.

From what I have read, I'll likely add some MMO to each cyl and let her sit a couple of days and then redo the test.

The motor doesn't smoke at all, haven't run it enough to know if I have any power issues, but doesn't seem like it. Only messed around with the blade on the rock lane for a short time.

Any thoughts?

Brian
'48 8N 60986

[Log in to Reply] [No Email]

Brian S, NE

08-31-2004 15:55:43

Report to Moderator

Re: Compression Test in reply to Brian S, NE, 08-30-2004 21:07:52

Thanks guys. I didn't think I had it completely right. Gonna do it again this weekend.

Brian
'48 8N 60896

[Log in to Reply] [No Email]

Dan

08-31-2004 07:51:17

Report to Moderator

Re: Compression Test in reply to Brian S, NE, 08-30-2004 21:07:52

A few points on the test. First - it should be done on a warmed up engine, meaning run it for about 5 minutes or so before the test (also charges up the battery some)it doesn't need to be hot, just warmed up. Cold engines do not take into account the natural sealing properties of engine oil as it gets worked back into the piston walls from setting all night, and also makes your motor spin faster to reduce strain on your battery. I'm guessing the variance between your dry and wet numbers will be reduced after this. Second - open your throttle ALLLL the way open and make sure there is no choke on. If it is only partially open, you are not allowing it the most possible amount of air intake. Third - make sure the compression tester connection is screwed down tight to the spark plug hole, so you aren't loosing any compression by leaking through the threads. It is hard to get to that with the hood on, and sometimes it is hard to screw it in tightly.

On a good note, your numbers are close to each other, and that is a very good thing!

Good luck,
Dan

[Log in to Reply] [No Email]

Spudds

08-31-2004 20:21:46

Report to Moderator

Re: Compression Test in reply to Dan, 08-31-2004 07:51:17

I"m not having compression problems currently, but in case I do I"d like to know more about this "compression tester", and how to use it. Where can I buy one and how much should I expect to pay for it. Thanks

[Log in to Reply] [No Email]

Rob

08-31-2004 04:38:24

Report to Moderator

Re: Compression Test in reply to Brian S, NE, 08-30-2004 21:07:52

Brian, I'm with Dell and go with the 7 or 8 puffs or 10 or whatever it takes to max out the pressure. You may be right with those pressures and not having any problems but it's only a matter of time. Cold weather hits then low compression makes it harder to start. Guys live with lower compression than you are seeing but they probably don't have to start their tractor when it's under 20-degrees either.
That dang plug wire conduit gets in the way for sure. I have crowfoots for my 3/8"-drive ratchet. If you want to torque all the bolts on the N, especially the older model, you need a set. I seem to remember I got it at Sears for less than $15, maybe more like $20...either way, it's not too bad. Thing is...after installing the head, all torqued up nice and proper...I ended up pulling a couple-three headbolts down harder than the torque spec to stop leaks. 1/8-turn at a time with a boxend wrench and run it for a few hours and check again. At some point I would back off and redo something but I have a little experience to fall back on to make that judgment, I think. That's not recommended by anyone and you got to figure that at some point you break a bolt but I bet I'm not the only guy that 'final torques' a couple headbolts with a boxend wrench. One day I might learn the hard way to not do that anymore but so far so good. I'll be really ticked off at myself if I break a bolt.

[Log in to Reply] [No Email]

Russ in SoCal

08-31-2004 09:14:07

Report to Moderator

Re: Compression Test in reply to Rob, 08-31-2004 04:38:24

Rob,
Ya" got one thing goin" for ya"; at least ya" can SPELL "judgment."
Russ

[Log in to Reply] [No Email]

Rob

08-31-2004 10:14:13

Report to Moderator

Is that good for any points? in reply to Russ in SoCal, 08-31-2004 09:14:07

I could use some extra points.

[Log in to Reply] [No Email]

Dell (WA)

08-30-2004 22:21:34

Report to Moderator

Re: Compression Test in reply to Brian S, NE, 08-30-2004 21:07:52

Brian..... .....N-Ford compression specifications: 90 psi min (dry) Yer numbers ain't good, but they don't suppport yer report of plenty of power, and non-oilburning. The wet compression increases of 10-15 psi is consistant with good used engine, NOT a tired and wornout engine which is indicative of 75 psi compression. Cold engine can contribute to semi-sticky rings and low compression, but the wet compression increase does NOT support a sticky ring hypothesis. Make certain you're taking compression correctly. Throttle wide open. 5-puffs min. I usually crank until the pressure stops building, about 7-8 puffs..... ....Dell

[Log in to Reply] [No Email]

[Options] [Printer Friendly] [Posting Help] [Return to Forum] [Log in to Reply]

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]

Home | Forums

Copyright © 1997-2023 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

Website Accessibility Policy