Fordson Dexta oil in exhaust manifold

[tudor64]

A couple of months ago I purchased a 1961 Fordson Dexta (957E 76896) and the problem is that it spits oil or could be excess diesel from the exhaust/exhaust manifold. This tractor has been resprayed but now looks a real mess, If you drive the tractor you get oil spots all over your face and clothes. Now this engine had been done up just before I bought it, basically restored by an enthusiast. The list of things done to the engine include head Valves Re Ground, new Liners/Piston Rings, Crankshaft Re ground, Injectors Re Furbished and new Water Pump. The valve guides were not replaced as the person doing the head valves said that these were ok. Previous owner sold as soon as he finished doing up the tractor,

I have read a few reports on this forum suggesting that this problem could be due to lack of work but I'm finding it difficult to buy into this idea. The tractor starts and drives well and does not smoke (only a little bit as you would expect on revving). Does anyone have any idea what could be causing this oily discharge from the exhaust and can anyone suggest a methodical approach to identify the problem and fix. Could it be that the wrong type of rings were fitted or could they have not been fitted properly in the first place? Could it be the valve guides? It's not a problem for me to have to replace anything but I don't want to be barking up the wrong tree. The other thing is that every now and again you hear a slightly different engine note, lasts about a second and is accompanied by a puff of smoke, happens every 15 seconds or so, could it be that an injector is not shutting off properly and letting in too much fuel?

I'm not in a position of being able to 'work' the tractor and will only use it now and again on my smallholding for short periods of time. Does anyone know of any experts in my part of the world, Abergele, North Wales?

Many thanks in advance.

[Brian]

You have the answer.

The problem is due to rings not bedded in and the only way you can do this is by hard work. All diesel engines will slobber oil if they are used for light work or do a lot of slow running. The problem is suffered by all makes of tractor and, if the tractor is not worked, the liners will glaze and it will needed stripping and the liners honed.

If you are not using a straight HD30 engine oil the problem will be exacerbated, some of the modern oils contain brake anti-squark additives which plate the bores and also cause glazing.

If you have a local dealership with a dynamometer a couple of hours on there will sort her out but the problem will come back if you do all light work.

[Mathijs]

So letting her work hard at max PTO rpm for a while will at least partially solve this issue (I got the same problem)?

[tudor64]

Thank you for the replies, I will check to see what oil was put in the tractor. Would it help with bedding in the rings if I just let her run in situ for a while at a fairly high rpm? I wouldn't like to drive her for too long on the road as I would end up covered in oil spots!

[Brian]

Leaving the tractor running on high revs will not work at all, you need to put her under load at about 1600/1800 rpm and make her work without allowing the revs to drop or go much above that. Keep that up for between 2 and 8 hours and your engine will really benefit, then change the oil and see if you can plan your yearly work to get some heavy work in at times during the year, ploughing, cultivating and baling. Driving on the road with no load is not the answer either. However if you were carting grain, muck or soil in a 3 ton trailer on a regular basis that would be great.

I have just given my Nuffield a good workout ploughing some game cover on very heavy land for a local gamekeeper. The first plot caused the smoke to pour out of the pipe but now she runs clean. That was the first heavy work she has done for a year.

Just put a set of rings on my petrol Dexta and she has been on the cultivator and topper working hard from the first.

[tudor64]

You have the answer.

The problem is due to rings not bedded in and the only way you can do this is by hard work. All diesel engines will slobber oil if they are used for light work or do a lot of slow running. The problem is suffered by all makes of tractor and, if the tractor is not worked, the liners will glaze and it will needed stripping and the liners honed.

If you are not using a straight HD30 engine oil the problem will be exacerbated, some of the modern oils contain brake anti-squark additives which plate the bores and also cause glazing.

If you have a local dealership with a dynamometer a couple of hours on there will sort her out but the problem will come back if you do all light work.

Hi Brian, the tractor has Rock Oil Universal 20/30 In The Engine Gear Box & Back Axle - is this right?

[Brian]

The Rock Oil specifications I have found for Universal oils all contain the brake additives so may give glazing problems in a lightly used old style engine. May be looking at the wrong oil, I would check with your supplier and see if they have a "straight" 20/30W or 30W plain engine oil rather than a Universal.

The Universal will be great in the gearbox and rear axle but, if you decided to change, the "straight" 30W could also be used in both transmission and hydraulics.

[Jan 59]

Worked some years on International tractors . Some were used with a vacuumpump for milking in the field , so hours of idling in stead of working.
This sort of tractors came in the workshop with lots of oil blowing from the exhaust.
We run these with Shell Ensis SAE 20 for about 3 to 4 hours under heavy load with good results. Ensis is a anti corrosion oil with low anti-wear properties.