poor cold-starter

[SvendH]

hello again,
My "new" super is not starting well after a night at 4-6 degrees Cent.The engine is on the starter for several revos. of the crank before before stumbling to life and emitting huge amounts of grey smoke.
She starts and runs fine when warmed up,no aparent blow-by or heavy breathing.Using cold start butten dosent help.
cylinder bores looking ok except for a bit of glazing.
had the fuelpump and injectors checked,
have tried various settings of injection timing ( besides 21 deg as per minimec)-still smoke-smoke smoke.The smoke is much reduced and darker when she warmes up.
Could it be the camshaft that is out af time somehow,its about the only thing iI havent checked yet.
she is not losing coolant or overheating so it cant be the head gasket.
Any Idears?

[mathias1]

probably bad compression -> worn pistonrings/head gasket. Or problems with the valves.
Did you check the valve settings ?

[oehrick]

While I've yet to have my pump & injectors serviced Sven I'd agree with Mathius, having honed my bores to break the glaze up and ground the valves in, I have still had to use a whiff of ether to cold start, even with the button pressed, and when warm or hot (before honing) I also had to use the button. After some work and with warmer days I have had several cold starts without ether and warm restarts without the button - I put this down to improved compression.

I presume there must be some fitting to press a test gauge plug into a vacated injector hole for compression testing but I don't recall ever seeing one - perhaps time to re read that section of the manual.

Before this work, when cold (say 10C and below), I used to heat up the fuel lines & unions on each injector with a small propane torch, annoying but it worked well

[SvendH]

I double checked valve clearences.and set them i bit loose for sure!
you all are probeley right about the compression,still isent it odd that she shows no sign of heavy breathing when worked hard?
At least she doesent require ether for starting at these tempertures,not like some

[AdrianNPMajor]

Our tractors are sixty years old.
Worn bores and reduced compression are inevitable.
Best, Adrian.

[shepp]

When you say you have had the pump and injectors checked, what exactly do you mean? - "checked" covers a multitude of sins!

Ironically if the cold start mechanism is stuck in the excess fuel position that will contribute to white smoke on start up and black smoke when warmed up, and even bad cold starting.

Take off the side cover so you can see the fuel rack and pumping elements. With a bit of throttle on depress the cold start button, listen for the locking "click", and observe if the rack moves to excess fuel position. Operate the stop lever and observe if the rack moves back and the excess fuel button pops back out. If not the mechanism is stuck.
The pump needs to be properly CALIBRATED UNDER LOAD on a proprietary testing machine to check if it is delivering the correct amount of fuel for cold start and for running settings. It also needs to be checked for proper PHASING on a proprietary machine so that the fuel to every cylinder is delivered at precisely the correct injection point. If the phasing is out for one or more cylinders you will get bad starting and SMOKE! These pumps are not like rotary pumps, every cylinder's pumping element has to be individually CALIBRATED AND PHASED!

Look at the experiences of dwol under "Knock in No1" posted by dwol on February 13 2008. His pump had been "overhauled" by an "expert"!! But we got to the bottom of the problem in the end.

[mathias1]

Bad valve stem seals can can be a problem also. When getting hot, the oil gets thin. The next day it's all on the pistons and the engine starts horrible with a lot of smoke.
If the smoke is getting darker, is it black or rather blue?

[Timeee]

Dear SvendH

Appears to me to be down to poor compression. Even though it is not "breathing", it only needs to be down a bit on compression and perhaps the starter/battery isn't whipping it over so fast and you will get no start and loads of smoke (unburnt fuel). Rather than warming up fuel lines with a blowtorch, try whipping off the big hose from the air filter to the inlet manifold. Direct a blow torch down the inlet manifold as you crank the engine (carefully) and you have a most effective manifold heater which will heat up the inlet charge of air and get your "tired" engine started a lot quicker on those cold mornings. Be aware that with the air filter disconnected, the tractor will rev higher on start up, so be ready to knock back the throttle. Connect the air hose as soon as it is running and remember that the manifold is alloy and will not appreciate too much heat from the blowtorch flame. In the end you need to diagnose the probable low compression problem with a compression test. It is most likely either tired rings and liners, or cylinder head valves.

Timeee

[shepp]

Poor valve stem seals as suggested by mathias could be an issue, but if they are bad enough to let oil down the stem you usually get oil blown out of the exhaust - this was an issue even when new with the very first production tractors that had "O" ring stem seals just on the inlet valves. The soon introduced modification of mushroom type seals fitted to both inlet and exhaust valves soon cured that problem.

If the engine was down on compression, as suggested by Timeee, resulting in wetting of the cylinders with fuel on cold start up, that amount of fuel would be soon burnt up when the engine started, probably within a minute or two, and the engine would run clean again. From the description it sounds like the cold engine runs with white smoke for some considerable time and this gradually changes to dark smoke when the engine is warm. This does not sound like a compression issue to me, I am still of the view that this is down to injection pump condition and calibration and phasing issues, or a possible stuck excess fuel mechanism. Also this is a minimec pump not a vacuum governed pump, so removal of the air cleaner pipe from the inlet manifold should not affect the engine speed. What removal of the pipe might show up is a blocked air cleaner if the engine starts better and runs clean with the pipe off.

[SvendH]

since I startet the thread, i have done the following to the engine:-
- changed the injectors,got a used set from another super which seemed to help the "harsh " running but not the smoke and "lumpy" starting.
-converted to vacume governor and put it to work mowing the meadows,several days of work!
- so having fiddled for hours with pump timing and govenor set-ups the starting is now instant on all four (as it should with a major) and with minimal smoke
Hard to say what helped the most, possibly the hard work? Still it will be interesting to see if she still behaves when winter comes round again

[shepp]

Well, that's a novel retro-modification fitting the earlier vacuum governed pump to a later engine! But it can be done, the engine block was changed at serial number 1613500 in August 1961 in readiness for the fitting of the minimec pump from about April 1962, so there were many Super Majors made in that period August 1961 to April 1962 that had the later block necessary for the minimec pump but which were actually factory fitted with the vacuum governed pump and the associated injection pipes and vacuum pipes. However the minimec pump cannot be fitted to engine blocks earlier than serial number 1613500.

Undoubtedly I would say that your almost instant improvement in starting and smoke emissions is entirely due to the fitting of an injection pump that must be in good condition and accurately calibrated and phased ( and that is probably down to luck!). The slight bore glazing that you described would not have so quickly gone in work, and as you said the engine did not breathe. The poor compression due to wear that other contributors kept attributing the problems to would not have somehow miraculously disappeared either! As I suspected, your problems lay with the injection pump, whoever "checked" it probably did not know what they were doing, which is the same experience "dwol" had.

[SvendH]

Yes the vacum job seems to be in good shape and is probably what saved the day, and good fun getting the nessary bits together to make it tic!

[shepp]

What people don't appreciate is that in the days when in-line pumps of any make - CAV, Simms etc. - were fitted to diesel engines it was a fairly routine matter to have the injection pump re-calibrated and the phasing checked and re-set. For example if the engine needed a top end overhaul the opportunity was usually taken to have the injection pump re-calibrated at the same time. As the pump camshaft and followers wear in use the effective stroke of the pump plungers reduces so the fuel delivery of each pumping element reduces over time. As the phasing spacers wear then the injection point of each element changes and individual cylinders get out of step. So you get reduced performance and cold starting ability and SMOKE! That is why each individual element in the pump has to be re-calibrated and the phasing set for that element.
Usually this was just a matter of setting up the pump correctly again on a proprietary machine, but eventually after several thousand hours the pump would need a full overhaul. In the early 1960's it cost about £5 to have a pump re-calibrated, and a full overhaul of a 4 cylinder in-line pump was about £25 to £30.