8N White Smoke - Low Compression - What Next?

First off, AMAZING forum! I"ve been following suggestions, now I"m just not sure what to do, please help!

I have a 1951 (I think) Ford 8N. It runs okay, I"ve had it for a few months and don"t run it too much. The other day I was mowing and running it harder than usual (1st gear, high throttle). White smoke started coming out of the oil fill and the exhaust. After sitting for a few days, the white smoke was gone, until after i warmed it back up, did compression tests, and then ran it for a few more minutes afterwards. I noticed it was also low on oil, so I added a couple quarts (still low though, all I had at the house). I did notice some oil leaks underneath (nothing too alarming), and the fuel cut off did not seem to work (ran fine with it closed for a few minutes, not sure how quick it would run out of gas, but then leaked some during compression tests, not sure if thats normal). Following instructions on the forum, below are the compression results, #1 is closest to front of tractor. The first number is what it registered on the first crank, the second is where it ended. It got from beginning to end pretty quick, few revolutions.

1 - 45/60
2 - 60/90
3 - 60/90
4 - 60/85

Obviously #1 has issues. Additionally, the top of #3 had some type of fluid on it as if it was leaking, not much but you could see a color shift in the dust layer on the engine. As far as the plugs, #4 was black and fuzzy, #3 was oily, #2 seemed okay a little dry slightly rusty looking, #1 had a little black but not heavily blackened like #4. I added the heaviest weight oil I had (only 10w30) to #1 and tested a few more times, no improvement.

It seems I could have more than one problem. Any tips on the best way to fix, whether its just a complete rebuild, or step by step troubleshooting for each issue would be greatly appreciated. And if I"m missing any required details, please tell me.

Thanks in advance!

From the plug description and the commpression numbers,Your engine is worn out.There is no quick easy 'fix'.Time for a major overhaul.

Run the SNOT out of it... pull the heck out of it for a couple of hours, THEN re-check the compression.

Is this a working tractor, a trailer queen, or a parade tractor?

Do NOT condemn it/lay out a lot of money for an OH "til you run it like it was designed to be run!

White smoke says you have coolant getting in to the cylinders. Good chance you have a couple of problems.
#1 blown head gasket and also
#2 stuck rings and or heavy carbon build up. I would pull the head and check the head gasket and head and also pour in say 1/4 cup ATF in each cylinder and let it sit over night with the ATF.

You can also dump some ATF in the gas and run the crap out of it. That will help get rid of any carbon build up you may have, however, white smoke smells like a head gasket or worse. If you are going to work her I think you are going to end up pulling the head for starters and who knows what you may find. Sorry.

The first puff needs to be half of the final puff or rings are suspect. It doesn't mean the engine is bad. White smoke out the exhaust may not be what immediately comes to mind. Does it smell sweet? If so, then coolant is finding it's way in the combustion chamber. If it's not, it may just be condensation on a cold day.
You're compression readings are consistently low. Make sure you had sufficient cranking speed, throttle wide open, fuel off, disabled ignition, all plugs out and a clear (or removed) air cleaner. Gerard

My understanding is the flathead in a Ford N series is 115 PSI when brand new. 90 PSI isn't that bad for a tractor with some hours. There's a lot of worn out Ns that "run good" with only 70-75 psi.

I'd pull the head and plan on having it planed and and a new gasket and check the valves for wear.

Thanks everyone, certainly appreciated. Im thinking I just need to open her up and take a look at the wear. She"s likely just old and worn out, and I think the last time I may have just ran her hard enough to blow a gasket. I might try the atf trick prior to dismantling, but think I just need to bite the bullet and turn this into a winter time project.

Old (or anyone)

On the atf trick, I need some addtl help, pretend I dont know much (which isnt really pretending)! Both you and Dunk on another post say roughly the same thing, pasted below. My question is around 'spinning it over'. Does this mean to crank the engine, or to physically flip the engine upside down to drain (if thats the case, could I siphon the atf out instead of physically flipping it)?

Thanks!



The best advise I would give you is to take the plugs out, and pour in an ounce or 2 of ATF (automatic transmission fluid), and let it set over night.
Then the next day spin it over, without the plugs in to make sure that you clear all the liquid, and don't liquid lock it.
Then put the plugs back in and see if it will start.
That should help loosen any stuck rings, and help to lube up any sticking valves.
If that doesn't help post back that you tried that, and are still having problems.
If it starts, remember to change your oil soon after this treatment.

The term spin it over is to have the plugs out and crank the engine like you where trying to start it but of course with the plugs out it will not start. That pumps the excess ATF out of the cylinders. By the way do this where you do not mind making a mess or lay something under it to absorb the ATF

Alright - Results of the ATF trick (thanks again for the advice!)

Let it soak for 1.5 days. Went out this morning and ATF had leaked out of the engine, around the first cylinder (closest to radiator)in the area around where the exhaust connects (couldn"t pin point it, but that area).

The engine turned fine by hand. When I gave her a spin, the only cylinders that blew out any ATF were cylinders 2 & 4 (cylinder 1 was the cylinder I had low pressure with).

My questions are, are there any additional tests I should performed prior to taking this girl apart? Any thoughts about what might be wrong with the additional info above, things to look for, how deep to dig, etc?


Thanks & Happy Thanksgiving!

Hi Guys

No one responded to my post on 11/28, not sure I am replying in the right spot. Anyway, that question still stands. I did remove the head and manifold but have not pulled out valves yet. Just nervous to dig too deep if not needed. Based on last post and pictures below, what would you do next. I am thinking maybe bad gasket and carbon build up could be the cause (wishful thinking perhaps). Any insight is appreciatd. Thanks!

Hopefully the pics load

I would pull the valve guide cover sand make sure you have a gap at all the valves as per the manual. Add a couple 0.00? to each when cold so when hot they will still have a close to correct gap. Also check each valve seat for carbon build up etc. Clean the head up real good and the block deck before you put the head back on. I'll send you another e-mail with info as to how to get hold of me direct so it that helps

I have a similar problem with my 8N. Low compression on all cylinders. I took mine apart and discovered that the rings were stuck from too much carbon deposits. I believe this was made worse by the rings being gapped wrong. I measured 0.052" when it was supposed to be 0.012 - 0.017". This engine was purported to have been previously rebuilt. All the bearings are within tolerance, but the rings were stuck and it needed the valves lapped.

While you are determined to tear the tractor apart. It"s running just fine and does everything you ask of it. It"s mostly carboned up and full of moisture from sitting around and light usage. You will sink more $$$ into it than it"s worth. Change the plugs, set the carb and run the soot out of it.

Sorry this is late (haven't been to this area for awhile) but there is a very useful tool you can make for trouble shooting these kind of issues. Take an old spark plug and knock off the center electrode and the top ceramic so all you have is the hollow metal part. Braze or weld a male QD that will fit your air hose for your compressor. Bring the piston on the cylinder to test up to TDC on Compression stroke (not that important to get it right at TDC) screw in the tool, connect the air hose and start to apply some air pressure to it (about 10-20 psi).
Bubbles in the radiator= head gasket, cracked head or block
Roar in the crankcase= rings, damaged piston
Roar in intake= leaky intake valve
Roar in exhaust= leaky exhaust valve
Thanks to a high school auto mech teacher (great teacher!)