I am new to this Forum.

I have a Hymer Motor Home based on a 307D 1982 vintage.

The engine is sweet and starts first time however the engine revs hunt up and down at idle. Though there is no rev counter I suspect they are going up and down between 500 and 900. Increasing the engine speed still has the revs hunting up and down until the revs are quite high. Setting off from stand still can now be an interesting experience. Out on the open road it runs well and is smooth. I'm a good petrol engine mechanic but diesels are a bit of a mystery.

Best wishes to all.

What engine is in it? Hoe many miles or km?

Have you replaced all the filters, performed a valve lash adjustment, performed a "diesel purge"?

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

It's the 616. It's not a problem that I have ever seen described on this forum.
There was a recent suggestion that there might be a spring in the IP that might fail.
I'd check the accelerator linkage first. You should be able to remove the doghouse and look at the linkage while you drive to see if the linkage itself is moving or if it's something internal to the IP.
By the way, I'm jealous. A Mercedes diesel Hymer is a very nice motorhome. I hope to own one someday in Europe.

Am I correct that you are in Australia? If so, if you're ever interested in a motorhome swap let me know. I've got a Bluebird Wanderlodge here in the US and I'd like to swap someday with an Australian.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Thanks for the suggestion [love the phrase doghouse, from this day forward it will be always known like that]. I have also been advised that water in the diesel filter might also cause this. Going to try and find the time today to check all these things out.

My Hymer lives with us in The Charente Maritime, France so a long way from you.

Paul

Gee, mine lives in the Tarn, although it's based on a 1981 309D (617 engine). You on French plates?.
If your French is up to it, a good source of merc truck info can be found chex mercotribe (http://merco.aceboard.fr/) if you didn't know that already...

Giles

Hi Giles, my French is not bad, we have been out here for two and a half years. I'll have a look at that site, thanks. Just bled everything, cleaned out the fuel filter and the air filter, no change. I presume oil is put in the air filter up to the red line, looks right.

cheers

Paul

That does sound like a broken or weak governor spring.

Does that particular 616 use the type of injection pump which has it's own sump amd isn't lubricated by the engine's lube oil? If so you should also confirm that it has the proper level of oil...the oil level in the IP in my ol 115 tends to creep up over time (I suspect that it's getting diesel in it) and it seems to idle strangely when overfull.

__________________
Never a dull moment at Berry Hill Farm.

As i said earlier Good with petrol engines not so good with diesels. The injector pump has a red plastic cap on it that unscrews. Taking it out while the engine is running makes not diference so its not on the fuel side. It seems to have breather holes in it. Is this where oil should go??? is so how much is the correct level??

Giles and Paul:
Are both of you guys residents of France, or are you just there motorhoming?
I'd like to know how your dealing with the plates/registration issues if your not a resident.
I used to own a 307d motorhome over there.(one off British construction) I had it registered in the UK because that's where I bought it and I have relatives there but the yearly MOT was a pain in the neck. I understand that Irish registration does not require a yearly MOT.
My 307d was an 85 and I never checked the oil in the IP or remember any directions indicating that it was necessary. That's not to say your may not be of the oil checking kind since my air filter also did not require oil. In fact, now that I think about it, if you have an air filter that requires oil, it's quite likely that you have an IP with a separate pump since when MB put the sumpless IP's in the cars (starting with 123's???), they also started putting in dry air filter.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

If it has the red cap, it sounds like it is an IP with a separate oil supply. There is a plug (looks like a bolt) on the side of the IP where you check the oil level.

I'll take some photos of mine and post here. And, see if I can find the procedure for checking the oil level.

Does it look like this?

Attached Thumbnails

 

__________________
Never a dull moment at Berry Hill Farm.

Kerry, yes I am resident in France and now quite an expert with vehicle registration here so if you need any advice just ask.

R Leo, it looks exactky like the picture, the red cap unscrews. Is that where I fill it with oil?? and to what level??

Thanks to all

Unfortunately, the FSM's instructions are somewhat ambiguous. I'll repeat them here:

07.1.4-220/6
Check oil level of injection pump and correct, if required. For this purpose, unscrew check plug (1). If the oil level is too high, loosen governor cover and raise it slightly so that the fuel-oil mixture can flow out. When the engine oil level is too low, unscrew filter, (2) and add engine oil up to check bore.


The check plug is a bolt head that's located on the side of the IP, just behind the priming pump (to the right of it, facing the IP while standing at the left fender). The filter is the red cap. I have been unable to decide what exactly is the governor cover. I'm guessing that the check bore is a ring inside the IP where the red cap screws in.

It appears from the FSM that the governor can be serviced while the IP is on the vehicle. If it is a broken or weak governor spring at least you won't have to pull the IP.

Sorry if this is sketchy; I'll read the FSM more and see what else I can find out.

Attached Thumbnails

 

__________________
Never a dull moment at Berry Hill Farm.

It's occurred to me that your issue could be an external problem with the governor. These engines have pneumatic governor that functions, somehow, using a choke like flap in the intake manifold which is connected via linkages to the IP. Thank Dog I've never had to do anything to it on my 115 but, if I ever do pull service on the governor, it should be entertaining. Somewhere here on the forum, there is a hilarious translation from German of the adjustment procedure. It starts with "Pull off at a shady place and open a beverage."

I will try to find the procedure in the FSM and somehow post it.

__________________
Never a dull moment at Berry Hill Farm.

Here are some links to keep you occupied:

Pneumatic Governor Questions
Curious: What's that OTHER cap on the back of my 240D injection pump?

__________________
Never a dull moment at Berry Hill Farm.

This mornings project is to check the oil level in the injector pump. Thanks so far, hope this works.