McCormick IH 434 starting problem

[Wisconsonian]

We're giving all kinds of different advice because we don't have much to go on. Can you answer the questions asked to give us some more information?

When it does "fire" is that just one pop from one cylinder? or does it run long enough to smooth out? or at least run on more than one cylinder for a few revolutions?

When you try to start it back up right away, does it produce white smoke like when you first try to start it, or no smoke at all until it sits a while and then still no smoke until it fires?

 

[Timbo]

Fuel is running back would be my thoughts

But he says under extended cranking it starts to white smoke more and more then eventually starts, but cuts out...

 

[darrylh]

Timbo has it exactly.

Pennine: Pump went on last, after timing wheels were set right. Camshaft came out during rebuild, and did not go back exactly as it was before, so timing wheels have (each?) gone round a revolution or 2 to line up. Then once happy, fuel pump went on (with wheel engaged with cross-pin). It could be either right or 180 wrong (but note your comments that it would not fire if 180 wrong). I was reluctant so far to move the inspection cover on the pump, as fuel started to flood out from it the instant I started to undo 1 screw, but I guess the only way to check is drain and re-bleed.

BTW, to answer other q's: when bleeding, the bottom bleed undone on the pump floods out when cranking, but i did not get more than a few drops out the top one.

I tried to start with heat-gun: firing took far less time, and we were able to re-fire several times and batteries are still good, but after say, 5 fire-ups, it would not run for more than 5 seconds, then cut out.

Thanks for all input, so far. Any further suggestions gratefully received.

 

[Mur Huwcun]

By this stage I would be giving it a whiff of drugs if it’s cranking fast enough and trying to keep it going with the easy start for a few second. That will confirm compression and correct valve/cam timing. As said pump will only fit one way on the gear due to the dowel but I have seen some bolted on without considering the dowel and the dowel just pushed flush into the gear. The fact that it nearly starts only points to being at most a tooth or two out.

Rocker cover off, no1 at TDC using the mark on front pulley with both valves closed will give TDC at compression. Plate off side of injector pump and it should line up with a letter. I would have to check book which one. Much easier than stripping front end again.

Another point to check first, are you sure your glow plugs are working? Do you get a draw on them? Easy way to test the 12v ones is remove bus bar connectors and use a wire to power them one by one, a spark will indicate that it’s drawing some current. Again try the blow lamp or heat gun approach, much easier on 276/434 as inlet manifold intake is not next to battery

 

[averageguy54]

Could it be a rubber fuel hose collapsing, when fuel is being pulled through. I've seen this happen before. engine starts and fuel pulls through the hose collapsing the inner walls. Leave for a while wall expand back and tractor starts again. Just a thought.

 

[Pennine Ploughing]

Have you bypassed the heater resistor on the dash when fitting the new type plugs ?
As they won't work properly if resistor is drawing power, needs to be full 12 volt to each plug, as direct from battery to plug as possible,
I still say its either not heating or timing,
White smoke is cold unburned fuel, ,
The cav dpa pump, will draw fuel itself, and if tank is 1/4 full fuel level is higher than cav pump, so running back is a no no, and yes the fuel filter is high up, but if running back from there, then it would never smoke on 2nd start up, as it won't bleed itself, and he made no comment of doing this,,
As for air cleaner, yes it is possible that during the rebuild, a cloth was placed at open points to keep muck out, and forgotten to be removed, this could prevent it from running once started, however a symptoms of this would show, by the fact that starving the engine of air, would make lighter work for starter motor, and the engine would spin over faster than normal, he has not said anything about this, so I assume its normal,,
These tractors fun on next to nothing fuel wise, and he says he is getting lots of fuel at bleed screw, so I doubt it will be any of the fuel lines or filter, yes a sealed tank would cause a vacuum, and starve the fuel, but this would take a lot more running as was posted,
Early in line pumps have a fuel pressure regulator valve in the fuel lines, on the return side to filter head,as the lift pump is on the side of the inline pump, and inline pumps need a pressure of fuel to work, where as a cav dpa does not need a pressure feed, infact a dpa pump can and will draw its own fuel, and a lift pump is only needed to bleed the air out of the system, they will run without a lift pump

 

[darrylh]

I put a gauge on plug 1 hole and got compression of 12 bar (did not do any others though).
I have been doubting the plugs but put a meter on plug 4 and get 12.7v. I have direct wire from term 5 on keyswitch to plug 4, then 4mm2 tails creating my busbar. Plug 1 is not ground to earth on block. These plugs were bought about a fortnight ago (supposedly for a Vauxhall Blitz 2.1D). I will run a wire direct from battery to each plug to make sure (may have burnt some due to continual cranking.

A couple of things for me to check that sound good to try.
1. Checking pump letter (should be E I gather). Am I right in thinking this must be checked when Cyl 1 is TDC.
2. Set TDC. So Rocker cover off and both valves need to be closed on Cyl 1. Is this right? Just to confirm: there is a mark to find on the pulley??? Where should this line up? 12 O'clock??

Many thanks

 

[darrylh]

BTW, I have not touched tappet clearances. They are set exactly as before. Is this crucial to set after a rebuild??

 

[Pennine Ploughing]

Good god, you have replaced the head and not checked the tappet clearance, it should be 20 thou on both inlet and exhaust valves,
On this model there should of been 2 wires from key switch to heater resistor,
Not sure on terminal numbers but at a guess it's terminals 3 and 5, as sure they were not together, you need one terminal to only power in the heat position on key, and the other to power when in start position on the key, if only connected to just 1 terminal it will heat in heat position but not start, or heat in start position but not heat in heat position on the key, that is if an original key switch,
And test volts to all 4 plugs, not just no4, as you need to know they are all getting heat, put a test light onto plug 1 before you try to start it, and watch the light to see its getting power all the time,
I went through all of this in a previous thread a couple of weeks ago

 

[Kidds]

BTW, I have not touched tappet clearances. They are set exactly as before. Is this crucial to set after a rebuild??

Don't know about crucial but shocked you haven't.

 

[darrylh]

Excuse my ignorance. Assume nothing. My tractor ownership in months can be counted on 1 hand, but I am grateful for your expert knowledge.

OK, I need to check clearances at 20 thou, which I will do.

Heater resistor has been binned/bypassed. In terms of the key switch, tractor came to me with a 2 position switch, which was no good and I replaced with a 4 position, 5 terminal one. I have only 1 wire coming from plug 4 and going to term 5 on the key switch (HTR on the paperwork). Starter motor is on term 3. Do I need a link from 3-5, or run another wire to term 3 (from plug 4 again presumably?).

 

[startinghandle]

BTW, I have not touched tappet clearances. They are set exactly as before. Is this crucial to set after a rebuild??

Before you do any more check valve
Clearance

 

[startinghandle]

Did you renew fuel filter?
12 bar sounds low after rebuild
Did you renew pistons and liners or just rings?
Could be bad seating valves?

 

[darrylh]

will be checking 20 thou on tappets.

Pistons and rings. Liners were good. Went 12 bar first, then 20 bar almost instantaneously (pop,pop).

 

[Wisconsonian]

Check the voltage at the glow plugs when activated. I'd expect a heavy duty relay, or heavy duty switch on the glow plugs, any replacement is suspect, it won't handle the amps the glow plugs draw.

I wouldn't worry about compression, it's going to be bad with new rings not seated, it will make starting hard until it's broken in, but once it fires it should run even with poor compression. Poor compression will not shut an engine off after a second, only fuel or air will do that, lack of fuel or air.

 

[Pennine Ploughing]

Heater resistor has been binned/bypassed. In terms of the key switch, tractor came to me with a 2 position switch, which was no good and I replaced with a 4 position, 5 terminal one. I have only 1 wire coming from plug 4 and going to term 5 on the key switch (HTR on the paperwork). Starter motor is on term 3. Do I need a link from 3-5, or run another wire to term 3 (from plug 4 again presumably?).

No need for 2 wires if its a new style 4 position switch, its only needed on the original type of switch

 

[Mur Huwcun]

Excuse my ignorance. Assume nothing. My tractor ownership in months can be counted on 1 hand, but I am grateful for your expert knowledge.

OK, I need to check clearances at 20 thou, which I will do.

Heater resistor has been binned/bypassed. In terms of the key switch, tractor came to me with a 2 position switch, which was no good and I replaced with a 4 position, 5 terminal one. I have only 1 wire coming from plug 4 and going to term 5 on the key switch (HTR on the paperwork). Starter motor is on term 3. Do I need a link from 3-5, or run another wire to term 3 (from plug 4 again presumably?).

First thing first, stick a probe on one if the heater plugs and make sure you know where to hold the key switch to power them. Then check all 4 independently (remove link wires) to make sure one is not burnt out then give it at least 15 seconds of heat assuming all 4 are working. You can check them in situ with a multimeter using the continuity setting. Google a youtube video if you’re not sure how to test glow plugs. You will have to remove your link wires though

 

[darrylh]

Just for the record, for those that find this thread after, I want to document a solution.

I thought it couldn't be the plugs, but checked anyway, all good. Thought the key switch was OK too but did the test and got current in pre-heat and start positions. Moved onto the CAV pump letters next and attempted to find TDC and corresponding mark in the pump. Of the methods suggested I found getting TDC only approximate and unsure. I was not happy with it and looked at some other resources concerning the flywheel, then found the TDC mark upon it and the lines on the casing with utter ease and simplicity, then lined the marks up and checked what the injector pump might be (letter B). Should be E (Pennine's info).

B is opposite E, I thought?

Things were making sense now. Flipped the pump timing wheel around (how did that happen, anyway?), gave key 5 seconds heat and it started in 1 second of turn. Sounded better than ever, no black smoke, kept going and the idling was as sweet as it possibly could be, so left those tappets be. Started it 10 times just for fun, never failed.

I have learnt a lot and will not forget it. Thanks for inputs.

Just for the record too: it is my son's tractor, he is 14 1/2. Long before he could drive he cut his teeth on Laptop's "Farming simulator".
Of course now a faulty tractor is a major problem to him. He is on my back about it, and every day he gets home from school and asks me if I have fixed the tractor. Now it is my chance for pay back - maybe I should not tell him it is working until the weekend!

Anyway, now we are fault free, we can add all those new parts he has bought for it - headlights, steering wheel (with IH Logo, of course), 2-tone seat, pressed number plate, etc, etc.

Regards
Darryl

 

[Pennine Ploughing]

Well you have sorted it, and it is also very good of you to give a full report of the problem and how it was fixed ,

I did say E but was a little unsure hoping someone would confirm this, as my books are in the workshop, not at home, and memory is not what it was,
So was it E or B in the end ? Just for anyone reading this at a later date

 

[Kidds]

Good to hear it is sorted.