Petro diesel through a heat exchanger = rough idle

[otto huber]

Hey guys,

Looking for some advice on a single tank SVO system. I'm currently running a blend of 30% petro diesel and 70% veggie oil through a Kayori heat exchanger in a 240D. In the summer I replace the petro with biodiesel.
My problem is rough idle with the petro diesel. The car idles fine until it hits operating temp. This leads me to assume that the hot diesel is causing the idle problems. That, and the fact that it idles well without petro.
Is the hot diesel causing damage to the engine at a 30/70 mix? Should I bypass the heat exchanger for the rest of the winter and run a petro/biodiesel blend? I live in Northern California. Thanks,

Otto

[Jeremy5848]

You may not need the heat exchanger at the temps normally seen in Alameda in the winter. Why it would cause rough idle I don't know...how hot does the fuel get? Maybe it is getting too hot. You could experiment by disconnecting the heat exchanger, see what happens.

Jeremy

[TWeatherford]

Diesel has very little lubricity as it is, and what little it has goes way down when it is heated. For this reason, most would recommend NEVER heating diesel beyond what the stock fuel system heats it up (of course in arctic climates they do a little but you don't live there or you'd never start up on a 30/70 blend). I know that we have IPs that are lubricated by motor oil, not by fuel, but I would still stay away from hot diesel. It may also be evaporating inside of there - not good.

Petrodiesel should not be allowed to pass 160*f.