Deutz 2011 Engine Lope/Hunt at Idle

[MarshallPowerGen]

Well, since my last thread on the Deere 4024 went so well, I figured I'd ask about the next headscratcher that came into the shop.

4840 Skidsteer with a Deutz F4M-2011 air cooled diesel, Hobbs shows 8800 hrs. Engine fires right up, and within the first few seconds starts to lope/hunt up to about half throttle, then smooths out. Does this until it warms up, then the lope goes away and runs like normal. It's identical to this thread (that was never finished).
https://www.heavyequipmentforums.com/threads/gehl-5640-engine-lope.68603/

Already found and replaced a clogged inline fuel filter and the water separator, checked fuel pressure which was around 8-9 PSI when loping, and smooths out when idled up and showing 11psi, so replaced the fuel lift pump since it was original (with no primer or screen cover plate) and not having a manual with the specs. Tested the oil thermostat in the filter housing and ran an overhead, but with no change.

Curious what the next spot to start looking would be, or any info on governor adjustment (or if anyone out there has a Workshop/Service manual for these engines). Not a lot of info online it seems...

Thanks in advance folks!

 

[mg2361]

Did you try placing a clear line in the fuel system return line to see if there is air in the fuel system?

 

[Nige]

Maybe a bit off the wall but what grade of engine oil has it got in it and/or when was the oil last changed..?

 

[mg2361]

I forgot to mention if you put a clear line on the return make sure you make a vertical loop in the line. Also Nige brings up a good point since I believe that engine is oil cooled and not air cooled it makes routine servicing all the more important. Unfortunately with that design an oil change does not change all the oil so maybe try changing, running and changing again.

 

[Nige]

Maybe if it has 15W/40 in it right now try some 10W/30..?

 

[funwithfuel]

I would check/replace the timing belt. Those little 4s have a timing belt that needs frequent adjustment and replacement. I believe it should be replaced @ 3k if memory serves correctly. PM me if you want the service manual in pdf.

 

[funwithfuel]

Maybe if it has 15W/40 in it right now try some 10W/30..?

Yep, manual calls for 20w20. I guess, that would be SAE20 for us non German speaking folks.

 

[Nige]

https://www.motorex.com/en-us/construction-line/motor-oil/extra-sae-20w20/
I think you're right that it's a mono-grade. Thinking aloud maybe multi-grades cause issues with the injector pump/governor until the engine warms up..?
If the manual specifies an SAE20 then maybe a 5W/20 multi-grade might work..?

 

[funwithfuel]

I think its gonna boil down to a weak governor spring and sloppy belt drive. Those little engines are so reliable and resilient.

 

[MarshallPowerGen]

Thanks for the responses folks! Like I said, I've had a few thrown at me recently; one with a blown head gasket blasting oil out of the exhaust, then the last one in a S-125 lift that started rolling coal at 3200hrs (checked turbo, overhead, timing belt (was at 60lbs, supposed to be 120lbs), oil thermostat and pop tested injectors, then found the cylinders were at 300/300/220/170 PSI) so I've been learning a hell of a lot on these in a short time (never ran into any in the generator world). Just dug up the 1011 and 2011 service manuals through the Gehl dealer portal yesterday (if anyone needs a book, let me know what you're looking for, I'm a service manual hoarder)

I'll definitely check the return side for air. Like I said, the inline filter was so full I have no idea how it was running up to that point, replaced that and the water separator and was watching fuel pressure. Just pulled the fuel line from the tank in case there was some garbage plugging up the fitting and ran it off a container with a mix of diesel/ATF/Powerservice so it can soak over the weekend.

We run diesel rated 10W30 synthetic in everything that comes through, and the fleet Deutz's seem to do fine with it, but don't know how old the oil is in this one off hand (customer equipment). I'll check the service record on Monday.

I'll pull the plugs and see if the timing pins both go in, and see if they have any idea when/if the timing belt was done.

Any adjustments or checks that can be done with the governor without tearing down the front cover of the engine?

 

[funwithfuel]

Is it a newer model with EGR? yes they managed to do something so foolish.

⁴

 

[MarshallPowerGen]

Luckily no EGR. I'm still yet to see one of those. One of the guys I spoke with at Memo about issues with another engine had asked about that as well.

 

[MarshallPowerGen]

Well, looks like this is going to be ann unfinished thread like the one I linked to.

Ran some clear tubing on the return side, and no air to be seen. Manager contacted the customer about digging deeper into it, but say they don't have to money for it now and will run it how it is. I was wrong on the meter though, it's only 880 hrs, not 8k so timing belt should be good as long as the hour meter is original.

Thanks for all the suggestions folks!

 

[heymccall]

I lost two cogs on timing belt with less than 1k hour on a 1011, but, it was 9 years old. Still ran fair.

 

[MarshallPowerGen]

I'll definitely keep that in mind in the future, don't know how many years sitting time this machine has had.