Well sorry to disappoint there chief but you'll have to go back and reread what was said and try again!

I was responding to Barry's discounting of 602 and 603 owners and being facetious in doing so. The 603 and 602 engines from the factory enjoy those increases in fuel economy over the 615/6/7 engines from the factory. No where in my post was it stated or implied that some modification to any of these diesel engines from their original configuration would result in any significant fuel economy increases; quite the contrary, I’m of the opinion that there are a number of threads populated with such mental masturbation over imagined problems and imagines fixes!

To which I respond in jestful boast:

The context of a simple test has occured to me. Takes three individuals. If you burn vo I would not pass this by.

Have one individual keep an eye on the temp gauge. Warm car up and read the milli volts present at any glow plug. Glow plug harness is the easiest point to read from. Have another individual take a piece of cardboard and blanket the rad. Have the guy inside call out the temperatures. Continiously read the milli volts and record temp and milli volts. Take the car to 195 degrees should be safe enough.

If milli volts are increasing with temperature we are on the right track. Efficiency is increasing. Put the results on this thread. It is well known a hotter engine is more efficient than a colder one.

The limitation on this design has been the cooling capacity perhaps. With the evans waterless very high temp anti freeze produced since these cars where introduced. We might be able to raise the block operation temperature higher than stock. Getting hopefully more power or mpg.

We should be able to extrapolate some information by reading the milli volts at say 100 degrees, 125 degrees, and 160 degrees to plot a curve we might figure out how to use. The milli volts of an engine at say 100 degrees should be less than at 160 degrees I suspect.

Once again for vegatable oil burners the improvement by speeding up the flame front in combination with getting more btus out should be most notable. The driving force to complete this is less unburnt fuel down the piston walls into the ring area and contamination of the base oil would be less. The diesel fuel burners efficiency possibly increased only by the more rapid hotter burn providing more energy for the same amount of fuel.

A hotter engine is considered more efficient. Time and experimental testing will tell. The temperature gauge is fed off the head. 160 degrees if you think about it is pretty low. May be limiting efficiency.

Here's a couple chunks of info on the subject:

Personally, I switched from the 80C to the 85C on my OM606 and saw about a 1.5 MPG increase.

Now, here's a good bit of detailed info on the subject from Bob Riley, a well respected member of the Diesel aftermarket community with a solid reputation. He had custom thermostats made to fit the later Powerstroke Ford trucks.

Read here:

http://www.dieselsite.com/index.asp?PageAction=VIEWPROD&ProdID=186

And here:

http://www.dieselsite.com/pdffiles/higherenginetemps.pdf

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Barry on my 240D I had tried several thermostats . I found they where opening high and the engine was running at 100c plus. There is a screw on the bottom that is set and the outer portion is crushed. I unscrewed it slightly and it dropped the temps opening the thermostat earlier. Not sure if it was the autozone or the napa one.

Turning it in may in fact increase the temps. I'm not sure on that I just wanted mine lower and the screw worked in that case.

I tested this on my outdoor grill with a metal coffee can full of water and a thermometer. After installing it the 240 stayed at 80c continuous.

Maybe some one else can say if that is the purpose of that screw.

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

Soothhappens, what good information if there are still adjustable thermostats out there. We need to identify a source and brand. Our Canadian parts outlets are somewhat different than yours.

I guess it amounts to someone having a look in the aftermarket thermostat boxes to acertain if one brand has a screw adjustment. I have never seen or noticed one. But then again never had a reason to critically examine a thermostat before. Do now I suppose.

A good working cooling system in conjunction with increases efficiency might allow a two hundred degree or close to that thermostat. Still using our current anti freeze.

I still would do the engine drag tests at each elevated temperature. Slowly increasing and checking fuel milage and piston drag as The temperature increased. Any indication of the slightest hot drag increase and backwards I would go.

My son in law dropped by this morning. He thinks there is basically free milage to obtain here as well. Power as well. I was thinking originally on diesel fuel a couple of miles per gallon at 200 degrees and somewhat more on vo. No proof but just intuition.

He thinks I might be estimating on the low side. With the last post I now wonder as well. A 90C degree thermostat compared to an 80C as a trial might show increased fuel milage. I cannot see any substantial risk in attempting this. Also an engine running at higher than 80C in theory should develop less internal wear over time as long as those pistons are happy.

I wonder what exact operating temperature the original designers had in mind. Have a hard time believing they designed for a block at 160 degrees. The effects of a higher operating temperature were well established even back then. Around two hundred became the norm as the anti freeze and water boiling point was the limitation. They used the pressure system to get a little higher temperature reserve eventually.

You do not suppose the missing five miles per gallon between certain 240ds could be this thermostat issue? Soothhappens indicates that out of the box thermostats where higher than the 80C ones they replaced.

The discrepency sounds about right milage wise. We need temperature scans of the higher milage 240s versus the lower milage ones that are on the road now.

I am almost certain someone out there should have picked this up before. Soothappens description indicates they might not have in many or any cases though. Well life throws some pretty strange curves so it should be checked out.

Imagine a senario of the milage you get on your 240 being dependant on a luck of the draw on the replacement thermostat in the engine. An almost impossible senario.

Okay I have really mulled this over. I am not sure why mercedes decided on this substandard block operating temperature of 80c. For one thing the engine will wear at an abnormal rate. Compared to what is possible.

The drop in efficiency would normally be substantial as well. Fuel was cheap by anyones standards when these cars where built as well so overall miles per gallon where irrelavent perhaps as long as in a reasonable range. The people buying these cars new where not particularily concerned. What they did not know would not hurt them possibly was a corporate view.

This may be why this basically rugged design will not go 500k miles without needing an engine rebuild. Thinking about it I cannot remember another well designed engine actually operating at this known substandard higher wear temperature. Where is the design deficiency otherwise that made them go there?

Again after a days applied though it just seem inconcievable that they would intentionally limit the engines lifespan. Still it is a possibility. We will hopefully be able to undo this issue and get the efficiency increased to where it should have been soon.

Again the more I consider this the more concerned I become. It makes no sense I can think of yet. Other than a fight between mercedes car marketing arm and the engines designers. This area needs input from many members perspectives to get a handle on it.

Some members are only getting less than mid 20 miles per gallon average. That to me is terrible efficiency for even indirectly injected diesels..