Blue smoke and loud engine knock after head reconditioning.

[tophat47]

As a project I decided to recondition the head on an 1956 Fordson Major as the head gasket was blowing out exhaust gas and oil at the no.1 cylinder. The engine was fully rebuilt in the 1970’s and it did a lot of work afterwards.
All valves and guides replaced, head skimmed & pressure tested in an engine re-manufacture machine shop.
Injectors reconditioned (including new needle valves) and tested in a diesel repair shop, but I didn’t go near the diesel pump.
Cleaned piston crowns etc and took the wire mesh air filter apart and cleaned it out.
I set the tappets. One of the inlet valves had a very large gap when I reassembled the rockers before I set then, but I put this down to a new valve. I ran the engine initially for a few minutes initially and then rechecked and reset all the tappets
On second strating , idling sounded OK but with a little blue smoke (from a new exhaust!) but when I drive it in fourth, there’s a fair bit of wispy light blue smoke. Drove it for around five minutes and just as I was parking it, I revved it up a bit.... then a heavy loud knocking from the engine: I had to shut it down .
So I’m wondering on these two issues:
1)The heavy knock
2)The blue smoke.
Are these two connected in any way?
Is the heavy knocking from a possible troublesome big end which is now been shown up with the reconditioned head or a misbehaving valve with a piston slapping into it or something else?
(The exhaust gas was more black but not as wispy blue before I did the head work.)
Any ideas ??
 

[d beatty]

You say that you had a major over haul in 1970 thats 41 years ago and did a lot of work with it. With that many years and worked a lot it may be ready for a major overhaul. With the head re done that puts more stress on old rings and pistons. You didn't say if the injector pump had ever been rebuilt.
 

[David G]

I would expect an injector or diesel pump issue. I do not think the additional stress on the bottom end would create a failure that quickly.

You had a good indicator of the ring where when you had the head off. The outer edges of the pistons should have been washed clean if oil was seeping past.

Make sure you have good oil pressure, and that you put oil back in if you changed it.
 

[d beatty]

tophat you say you had the head skimmed. i have never heard the word skimmed used before. Is it like milling the head or like polishing it? If they milled it did they mill to much off of the head? Did you check the number 1 piston & cylinder when the head was off?
 

[tophat47]

Thanks to everyone & replying from the top down:
1) Diesel pump was reconditioned in the 1970's also.
2) Will check oil pressure: what oil pressure would be expected on this vintage of machine ?
3) Piston crowns were uniform black across their surfaces, no cleaned edges.
4) "Skimming the head" is the term we use here this side of the pond! (I'm in Ireland). I could see very fine cutter marks on the head see the attached photo. I don't know how much they removed. I didn't see anything untoward with No. 1 piston.
 

[cdmn]

I have a 1956 Fordson which was shut down for a bad knock, and the seller told me to not start it because a rod was about to let go. I believed him, because I"ve seen Fordson engines in the salvage yard with No 1 rod out the side. (Also an NAA, and a 801, but No 4.) I took the pan off and found the rods good and tight. Noise came from front, so took the engine apart and found that the timing gear had broken its hub. Fordson changed the design shortly after.

It is also conceivable that the compression relief can cause pistons to hit valves.

There were several attempts to solve a headgasket problem. Involves protrusions on sleeves and different materials and thicknesses of head gaskets. Have to be careful with what you have. Wrong set up and piston could hit head. Might be a function of how warm the engine has gotten. Pistons and rods get longer, and oil films get thinner.
 

[dwol]

I have a similar issue, that I have not resolved in 3 years. But I think mine is related to the head. To eliminate mechanical from fuel issues. Run the engine, then untighten the fuel lines (just a bit) to the injectors one by one. If it is an injector problem, the noise will go away when you do this. If it is mechanical, the noise will continue.
 

[David Farris]

If you have a lot of hours on the motor itself, you should do a major overhaul. the block should be deck clearenced and honed,and the crankshaft journals and main bearing webs checked for proper clearance. a good machine shop can do the grinding and prep work at a fair price.then after the job is completed and the motor is reassembled you should have a fresh start with your tractor.good luck.