Blue smoke and loud engine knock after head reconditioning.

[tophat]

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 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 ??

[Brian]

Have you rechecked the valves? Could a valve cotter come out and dropped a valve onto the piston?

Injector failure? this would cause a knock and blue smoke.

Piston failure and big end failure are the things you really do not want to hear but are possible.

[tophat]

Thanks Brian,
I've a few things to check out.
I also found this nugget from "Cooling & Diesel System" document from your website:
"After prolonged service it is not unusual for the ends of an injector pipe to close up slightly giving rise to a heavy knock
on the cvlinder concerned".
Have you ever seen this ?

[Roadless63]

Bent pushrod could be responsible for larger gap, which has now bent further and allowed rocker to jump out of pushrod? had this happen to me before and made a racket.

[1962 model]

Hello,
probably not your problem ( I hope ) it is criticle when refitting a cylinder head that the injector bleed off line has all of it's soft solder joints in tact and that the banjo fittings have newcopper washers both sides or they often leak.

The problem with leakage is that diesel dilutes the oil and destroys the bearings, I have seen this several times and even have an engine here that has started to destroy it's big ends from this.

Another problem that can occur is that after several head resurfacing jobs if the valve seats are not recut deeper to match, the valves actually become higher, and there is not alot of room to clear the pistons.

And lastly the 1965 heads had a different rocker ratio and the head was cast with more clearance to allow for the push rods to clear the head internal casting.
If rockers are swapped between different heads problems can occurr.

Hope none of these are your problem?

Mike

[tophat]

Hi 1962 model:
one of the banjo fittings was broken: i resoldered it in place but there is no diesel as yet bleeding back from the port hole on the head. Was probably like this for a while as there is no pipe going back to the tank from the head anyway and it was dry with no diesel weeping onto the head & block, sounds like diesel and engine oil are a bad combination for the main/big end bearings....

[BearCreek Majors]

Tophat, your problem could be the air cleaner. This summer I took the air cleaner assembly off of the Super six and cleaned it out really good in the parts washer (mineral spirits). I reinstalled, started the tractor, topped off the power steering fluid and a checked a few other things, I then hopped on it and took off down the road. As I got moving and cracked the throttle all kinds of bad things started to happen, lots of smoke, missing and rattling, and running like crap, the mineral spirits from the parts washer was still hanging in the wire mesh of the air filter and as soon as I cracked the throttle it sucked it into the engine. It didn’t hurt anything, I just slowly increased the engine speed until it dried out the air cleaner.

Pat

[1962 model]

Hi 1962 model:
one of the banjo fittings was broken: i resoldered it in place but there is no diesel as yet bleeding back from the port hole on the head. Was probably like this for a while as there is no pipe going back to the tank from the head anyway and it was dry with no diesel weeping onto the head & block, sounds like diesel and engine oil are a bad combination for the main/big end bearings....

Yes Tophat diesel leakage into the sump often destroys these engines, if you have no fuel coming out of the return pipe you have a problem as it means all the fuel being pumped by the injection pump is being injected into the cylinders and this is not supposed to happen.
As you have resoldered your banjo fitting it is possible that the solder has blocked off the pipe, you may need to remove the whole return line and check it thouroughly ( always use NEW copper washers either side of the banjo fittings when refitting )
My return line is in need of repair externally and floods the outside of the engine in Diesel each time I use it.
( must fix it soon )
Usually little diesel will flow at idle and as the revs increase the excess fuel not required by the cylinders will increse and return to the tank, you need to check your return line for a blockage, but remember you MUST replace the copper washers either side of the banjo fittings or they will leak diesel into your engine.

The only other suggestion I can make is that one of your injectors may have had the tip break off ( not uncommon ) this will likely use all the excess fuel on the cylinder concerned and possibly cause a knock.
If you are going to remove your return line to check for a blockage it would be best to remove your injectors and check they are intact ( how long since they were serviced? )
I think Agrilline has new internal fuel return lines, this would be a good option as these lines are subject to cracking.

Hope this helps, Mike

[1962 model]

Tophat, your problem could be the air cleaner. This summer I took the air cleaner assembly off of the Super six and cleaned it out really good in the parts washer (mineral spirits). I reinstalled, started the tractor, topped off the power steering fluid and a checked a few other things, I then hopped on it and took off down the road. As I got moving and cracked the throttle all kinds of bad things started to happen, lots of smoke, missing and rattling, and running like crap, the mineral spirits from the parts washer was still hanging in the wire mesh of the air filter and as soon as I cracked the throttle it sucked it into the engine. It didn’t hurt anything, I just slowly increased the engine speed until it dried out the air cleaner.

Pat

That is the reason that it is not recomended practice to wash air cleaners in petrol or other volatile solvents, or at least if there is little option they must be thoroughly dried before using.
Tractor handbooks will likely state that this can damage your engine and it can also lead to a situation where the engine may over rev and not be possible to shut down.

Mike

[Dandy Dave]

I use laquer thinner to wash out old air cleaners. It cuts the dirt and grime better, and evaporates rather quickly. I then blow it out thoroughly with the air compressor and blow gum. I never put anything "wet" back on an engine. Dandy Dave!