question Zetor 5211 sputters and dies after running under load for 90 minutes

Greetings,

Let me start off by saying that I am not a diesel mechanic, and I probably have not kept up with the maintenance on this tractor as it was supposed to be done. We acquired the tactor as part of our house/farm purchase about 7 years ago, and only use it periodically to mow the driveway and pasture.

This is a 1986 Zetor 5211. Today I took it out and mowed using a bushhog for about 90 minutes when it started to sputter and then it shut down. I let it sit for a minute, then it restarted and ran under load for about another 3-4 minutes before starting to sputter again. I disengaged the bush hog and the RPMs came back up. I re-engaged the bush hog and about 2 minutes later it sputtered and died again. I was able to restart it then and get it back into the barn.

A few years ago, I had a similar issue which was resolved by adding an electric fuel pump. I had also changed the fuel filters back then. We have recently replaced the electric fuel pump, and things were working fine until about a month ago when we had a problem with algae growing in our fuel tank. After that happened, I drained the fuel, cleaned the fuel tank, and filled it back up with new fuel. The fuel that is currently in the tractor is only a few weeks old.

I checked the fuel cap vent, and it is clear and working fine.

I have had friends ask if there was debris still in the line, if there is an air leak in the fuel line, or if there is water in the line. My question to those is why it would run perfectly for 90 minutes and then start to have problems? Wouldn't there be problems within the first minute or two if that was happening?

Any suggestions on what to check or if you have heard of this specific issue before would be greatly appreciated.

Craig

firerescuecapt said:

This is a 1986 Zetor 5211

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first series, bevore first face lift

firerescuecapt said:

Today I took it out and mowed using a bushhog for about 90 minutes when it started to sputter and then it shut down. I let it sit for a minute, then it restarted and ran under load for about another 3-4 minutes before starting to sputter again. I disengaged the bush hog and the RPMs came back up. I re-engaged the bush hog and about 2 minutes later it sputtered and died again. I was able to restart it then and get it back into the barn.

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Sounds like dirty diesel filters, quite simply. Clean the pre-filter (in the glass) and reinstall it with a new rubber seal (93-3221), making sure to tighten the knurled nut exactly in the middle under the glass.

Then replace the two diesel filters, making sure that there is a coarse filter and a fine filter and do not mix them up.
When installing, fill the bells with the new filters with fresh, clean diesel before attaching them, use a new rubber seal (93-1102) for each one and then bleed the system before attempting to start the engine for the first time.

firerescuecapt said:

I have had friends ask if there was debris still in the line, if there is an air leak in the fuel line, or if there is water in the line. My question to those is why it would run perfectly for 90 minutes and then start to have problems? Wouldn't there be problems within the first minute or two if that was happening?

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No, not necessarily - it depends on how big the leak is.

Diesel plague is a problem that doesn't just affect the tank. If you've had diesel plague, you have to clean the entire system and then at least the first few times you fill up your tank, you should use a high dose of anti-diesel plague.

You should also clean and treat all of your canisters/barrels and possibly your own diesel filling station.

What diesel do you fill up with?

In Germany, we often have problems with diesel with a biodiesel content when we don't use it much. That's why many people who have had problems here prefer to drive pure diesel without a biodiesel content.

There are also additives that make diesel last longer and are supposed to prevent diesel plague.

I had trouble like your before with a 8011. Everything was clean, no leaks, replaced everything and still for some reason, randomly it would start to die back and stop and was impossible to get running again. I used to pump it and it would go for a bit and stop again. It turned out to be in the tank, a broken diesel cap base in the tank floating around and every so often it would cover the outlet and stop the diesel flow.

At a Zetor 5211 the fuel tank is under the cab, so the fuel pipe is mounted from above - no chance that this hapend on this series tractor.

Joachim said:

At a Zetor 5211 the fuel tank is under the cab, so the fuel pipe is mounted from above - no chance that this hapend on this series tractor.

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Aw No your wrong. The tank can get blocked too. It has 2 pipes go down more than 3/4 way down inside the tank and stuff still gets stuck in the pipes. I know as I to remove the tank off my 10641 before when it start doing the same go for a bit and then conk out, it was possible to bleed it and would slowly re-start and run for a bit and conk out again

Joachim said:

What diesel do you fill up with?

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I use the standard Ultra-Low Sulfur Diesel from the local gas stations. It is pretty much all that is available here. I only buy 10 gallons at a time (2 x 5-gallon jugs) because I don't have an on-site tank to keep more.

diyfarmer said:

Aw No your wrong. The tank can get blocked too. It has 2 pipes go down more than 3/4 way down inside the tank and stuff still gets stuck in the pipes. I know as I to remove the tank off my 10641 before when it start doing the same go for a bit and then conk out, it was possible to bleed it and would slowly re-start and run for a bit and conk out again

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I just cleaned out the tank and inspected it, and there *should* be no debris in it.

Joachim said:

At a Zetor 5211 the fuel tank is under the cab, so the fuel pipe is mounted from above - no chance that this hapend on this series tractor.

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I had this happen before when there was a piece of the fill spout from a diesel jug that broke off and fell into the tank (I didn't know it was the problem until I drained and inspected the tank). The fuel pipe would "suck" it up and it would kill the fuel flow. When I recently had the algae problem, I physically removed the tank after draining it and inspected it for foreign debris and found none.

Also, I do not have any fuel leaking, but air coming into the fuel line could definitely be a possibility. What would be a good way to check for an air leak?

firerescuecapt said:

I just cleaned out the tank and inspected it, and there *should* be no debris in it.

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Did you make sure the 2 pipes inside the tank is clean?

Are you using modern road diesel in a tractor is 38 year old tractor? It was not designed for that stuff. Why don't you get tractor diesel for it?

diyfarmer said:

Aw No your wrong. The tank can get blocked too. It has 2 pipes go down more than 3/4 way down inside the tank and stuff still gets stuck in the pipes.

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I based my answer on your example of the broken tank cap metal part - that is almost impossible with the Zetor 5211. The pipes end 3 and 5 cm above the bottom of the tank. Apart from that, the tank cap of the Zetor 5211 has no metal part that can fall off, but is made entirely of plastic.
What can get into the pipes is straw or similar, relatively light material.

Either way - such a foreign body would be easy to find and he wrote that he had checked the tank.

ULSD Diesel:

ULSD runs in any engine designed for the ASTM D975 diesel fuel, however, it is known to cause some seals to shrink,[8] and may cause fuel pump failures

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Source: Ultra-low-sulfur diesel - Wikipedia - https://en.wikipedia.org/wiki/Ultra-low-sulfur_diesel
That sounds not so good for me.

firerescuecapt said:

Also, I do not have any fuel leaking, but air coming into the fuel line could definitely be a possibility. What would be a good way to check for an air leak?

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You hardly have a chance. The easiest thing to see straight away is if there is a lot of air in the sight glass, which can indicate a leak on the way to the tank.
In that case I would:
- replace the seal on the sight glass (93-3221)
- replace the suction line to the tank as a precaution (it's only 1m of hose) and maybe use one made of FPM. Make the new hose a little longer so that you can push it a little further onto the pipe socket and only use good hose clamps and not the cheap ones from the hardware store.

Anyone in Germany who has had problems with B7 diesel (max. 7% biodiesel content) usually prefers to drive with "premium diesel" like Aral Ultimate or Hoyer Premium Diesel afterwards, or do as I do and are lucky enough to live not far from a refinery (30 minutes drive) and get their diesel there and it is guaranteed to be biodiesel-free.

Many then also use products like Wagner Diesel Additive (Diesel-Additiv - https://www.classic-oil.com/diesel-additiv/272/) to prevent diesel plague from occurring again.


What is definitely noticeable (I work commercially in the Zetor spare parts trade) is that there has been a significant increase in defective diesel feed pumps in the last 2 years and even new ones, whether from Motorpal or replicas, often do not last very long.

The damage pattern is almost always the same - brown/black coating on metal parts and, in the final stage, wear marks on moving metal parts such as the working piston in the feed pump.
And this is almost exclusively the case with customers who say they tend to fill up with B7 diesel (75% biodiesel) and practically never with those who have only been driving premium diesel for a long time.

Since this also happened to me with my rarely driven Zetor 2011 and the repair will end up costing me almost 800 euros, the calculation is quite simple: the fewer hours I drive the machine, the more likely it is that a premium diesel will pay for itself in a relatively short time.

Do you still have a hand primer pump?

diyfarmer said:

Are you using modern road diesel in a tractor is 38 year old tractor? It was not designed for that stuff. Why don't you get tractor diesel for it?

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Honestly I am not sure where to buy that near me.

diyfarmer said:

Do you still have a hand primer pump?

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Yes, right above the glass bulb.

That's amazing you can't buy tractor diesel in America. I have 2 local petrol stations that sell tractor diesel in Ireland. I don't buy from them as they have a huge mark up on the price they sell it at, I buy it in bulk off a wholesaler, who deliver enough to do me for a year at a time. But if I was stuck I could pull up at a pump at my local petrol station and get a fill.

Thank you all for your help. So, it seems that three issues were causing this problem:
1. A large amount of foreign debris in the fuel filter. I changed it and replaced the gasket.
2. The screen in the sediment bowl had collapsed and was full of debris. The screen was replaced as well as the gasket.
3. Some of the hose clamps for the fuel lines had become loose. I went around and made sure all were tight.

Yesterday, I ran the tractor for two hours and then went out and mowed the pasture for another hour. It did not sputter or die.