M2 Freightliner Ambulance Conversion Project. 2007 Crew Cab

There's might be something dragging your economy down but it's hard to compare because you were driving faster than I can in my truck (with the same engine). In my 13-14 tonne 4x2 I get 8.5 mpg in mixed driving, and more like 11.5 mpg in flat terrain on the limiter at 55 mph. Charlie gets 9 mpg out of his 12 tonne unimog with the same engine, presumably driving at no more than 55 mph.

The OM906la is definitely a different engine to the Cummins 6bt, less agricultural, but also less fun.


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Yep this is definitely different to the Cummins. I am getting to like it more though. Even with a couple of quirks it did pull us back across the country at an average of 55 mph. Not too be sneezed at. I think a good baseline needs to be set and then work out if there are any issues before I can definitively comment on it.

One of the issues I need to rectify before chasing squirrels (looking for other problems/performance issues) is to get the battery voltages to a stable good reading. The ambulance monitor seems to be reading lower than the ECU is. I will be swapping the batteries out with a new set I have here and we will see what happens from there. Add to this a good check of all the earthing. I have found in the past that these electronically controlled engines can do weird stuff on low or variable voltages.

Then its off to the parts store for a couple of AMU (air modulation units) because on this model all the stuff is on a canbus and instead of replacing a $7 pressure switch I need to change out about $200 of modules. But its like eating an elephant, just one little bite at a time and we will get there.


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An Aussie redneck and a plasma cutter. Where could it possibly go wrong.

If I could swing a trip to your place I would take you up on the offer. The problems are twofold. Time to do it and I need to install the axles, turn the rims to match the MPT bead as well as trim the body. But the missus has threatened me with a very painful form of castration if I just sawzall this one and don't finish it off properly.
Hey, Oz! I do love that white lightning bolt racing strip on the side... I just showed that off to Kara. Very nice, with the red.

As far as the lettering goes, I have two words for you. Whizzy Wheel! Get a couple and they'll take those letters/decals off without damaging the paint at all. Pretty impressive.

The front tires look like they'll be an easy fit, but you're right about the rear being a challenge. On our rigs (mine and your green one), there was enough room between the boxes to tuck the tires in there, with some cutting. That, though, looks like you've got less fore-aft room between the boxes. It's gonna take some box frame, hinge, and door modification. Can you install the new axle a few inches aft, so you only have to alter one box? And, it would help the departure angle. Or is that a suspension problem? I'll be curious to see how yours differs from our older ones. On mine, it looks like it would be pretty easy to do.

We're getting ready for snow tonight. But, when it's nice here again you're welcome to come back up for a welding day.


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OK just ordered a couple of Whizzy Wheels. Luckily the county guys did a fairly clean job especially compared to the gorilla's who did the Yella rig.

I may be able to play with the axle placement a bit. Also it will be going up in the air at least 6" (rear axle will be under the spring/beam instead of on top and front axle is now a straight axle instead of a drop axle). I will need at least that to get a drive shaft to the front axle. So playing with the placement should not be that much of a bother.

The instant need is to get some tires onto one of the new axles and just take some measurements. Problem is I don't have anyway of moving/lifting 1700# axles. Also the rims need to be machined to match the MPT bead profile.


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I suspect there may of been someone from the county or affiliated with someone in the shop wanting this rig. The first clue was the tires that had been replaced and never left the lot. Also the care they took on getting the signage off, hardly a scratch. New batteries in June. But the latest clue was the low voltage warning and a couple of the sensors reading funny on the V-MUX system. I started chasing earths as I have the painful experiences to tell me these can cause a lot of funny problems. I found there were loose earths at all the battery post, the main connection points on the V-MUX controllers and the main earth at the electrical board. Now 1 or 2 I would just suspect shoddy work practice and maintenance but with this many I have to lean towards something deliberate. When I am talking loose I mean just finger tight. No load only had a small voltage drop (less than .5v) but as soon as they went under load it set the warning buzzers off.

So now all I need to chase down is the power supply for the low oxygen pressure switch and replace the AMU for the low air alarm. Happy days!!

Realistically I should be putting my time into cleaning the Yella beast up ready for sale but its so much more fun working on new toys.
What do these big ambulances get used for? In the UK ambulances are almost always based on the heavy van chassis', usually the 4.5 and 5.5 tonne Merc Sprinter. What's the GVW of this Freghtliner? Looks to be at least 20k lb?

Most ambulances in the UK are just designed to keep a patient alive until they get to hospital, do these big units have more treatment equipment on board?