2840 conversion from CAV to Roosamaster injection pump

It was one of many issues that Deere suspected with starting problems with 40-series tractors. On a few it was true, with most it had nothing to do with the problem.

You can buy brand new starters for around $150. Direct drive and gear reduction. Keep in mind that gear reduction starters will usually crank better in cold weather and can do it with a smaller electric motor - so the motor amp-draw is not always a good figure to use. Deere originally used 700 amp and 900 amp ratings on direct-drive starters. When they started getting rated in watts or kilowatts instead of amps, it kind of lost me. My 7.3 diesel in my Ford truck has a 3000 watt starter and works great. My 6.2 diesels have 2700 watt and 3500 watt GR starters - going by their ratings - and all work fine.

Try DB Electrical - that's where I've been buying.
They are in Tenessee and you can call if you want specs. 1-800-753-2242 Link

A>Link new gear-reduction starter - Nippondenso style OSGR 2.7 kW, 12 Volt, CW, 13-Tooth Pinion is $140.

A new direct-drive Bosch/Delco syle is $150 new.

It fits the following and more:
John Deere Tractor - 820VU, 1020, 1030, 1040, 1065, 1068, 1075, 1085, 1120, 1130, 1140, 1520, 1530, 1630, 1640, 1830, 1840, 2020, 2030, 2040, 2120, 2130, 2140, 2150, 2155, 2240, 2440, 2510, 2520, 2550, 2555, 2750, 2755, 2840, 2855N, 2440, 2550, 2555, 2750, 2755, 2840, 2855N, 2940, 2950, 2955, 3040, 3055, 3120, 3130, 3140, 3150, 3155, 3255, 6100, 6200, 6300, 6400, 830, 920, 925, 930, 932, 935, 940, 942, 945, 952, 955, 965, 986, 975, 5200, 5300, 5400, 5500

Also, if somehow your hydraulic system in in perfect condtion - with not even the smallest internal leak - destroking the pump does not make much of a difference in anything.

Does your tractor crank as it should?

Also what is the history of the tractor? Did it start well when you first got it, or has it been a p*ss-poor starter forever?

As I already told you, all the 40 series tractors were known for very bad cold starting, skipping and smoking, etc. The final - and only real fix from Deere Company was special pistons to make up for the bad machining tolerances that were used when the tractor was put together new. If it later got rebuilt again, and standard pistons got put back in, it would again - start lousy.

In regard to the lack of blow-by, good compression, full power on the dyno - it all means nothing. We had rows of the tractors - brand new - that started awful - but tested perfect with a compression gauge and on the dyno.
In fact, I've had tractors with all the top piston rings broken that tested fine on the dyno.

You are dreaming if you think that somehow, a Stanadyne pump will make it start better. Now, a GOOD Stanadyne pump replacing a BAD CAV will make a difference - just as fixing the CAV will as well. And, the CAV is a better built pump.

You need to do the basics first. Have you advanced the static pump timing? If so, any difference? Have you tried turning up the fuel delivery a little bit ? (takes 10 minutes on a CAV). Have you checked the valve-lash adjustment?
Those are the most simple things to check. Once past that, it's time to check the pump delivery - or - pull the head and look closely at the pistons and cylinder walls. And also, to measure the depth of the valve-heads in the head. That is critical. If someone did a valve regrind - by resurfacing the valves and regrinding the seats, they will sit too deep in the head. Result is - good compression, good running, but lousy starting.

A $5 manual pump destroker will often work wonders and sometimes do more than oversized batteries and a higher-torque starter.

With some tractors, adding a destroker acts like doubling the battery and starter capacity.

Granted, the more batteries, the higher the cranking voltage. Just a jump from 9 volts to 10 volts at cranking makes a huge difference.

Stanadyne/Roosmaster was the original and is the first rotary pump used by Deere ca. 1960 on 1010s and 2010s. CAV and Bosch purchased rights from Stanadyne to copy it with some improvements and use it only overseas. Later, some of those aggreements changed a bit.

Any of the pumps are designed to inject a certain amount of fuel at cranking speed - and it makes absolutley no difference if it's a Stanadyne or CAV. What is the difference is which one wears first and gives problems. A cared for CAV will outlast the Stanadyne.

Now, 2840s nad 2940s were some of the worst starting diesels Deere ever sold - we sold them new and had enless problems with them. Some old 4020s started at 10 degrees F with no heat or ether. We had new 2940s that wouldn' start at 40 degrees F. Deere had a long check-list to things to do to them - when new - in an effort to make them start as good as an older 2010s, 2020s, 4020s 4030s, etc.

I can guarantee you that your tractor has had many things done to it since it was sold. Some of the original "fixes" that rarely worked were - new transfer-pump blades in the CAV injection pump, advance the static timing 2 degrees, thinner head gasket, plane cylinder head to get valve-in-head depth .025" and .040", hydraulic pump destroker, and new graded pistons with higher top rings.

Kind of hard to tell what the story is now with your tractor - but I guarantee you the make of pump has absolutely noting to do with it - and anyone that told you that is clueless. Some of the best starting tractors we ever sold were the 50 and 55 series with CAV pumps. But, the improvement was not because of those pumps, it was due to closer assembly and machining tolerances. I will also mention - that at the same time of the starting problems with the 40 series ag tractors, we had the same cold starting problems with industrial stuff - like 350C and 450C crawlers - and they ALL had Stanadyne pumps.