Ok this is the 3rd hydro this has happened on in the last 5 years. But on this job we have a much better timeline as to when it happened. We are finding purple grainuals in the oil tank that are about twice the size of coffee grounds and will clog up the intake screens enough to starve the car for oil. We had a Dover relay controller (dry unit) with a bad I2 valve. The tank was pumped down and cleaned out. We replaced the valve established working pressure with weights set bypass.And then proceeded to run the car up to temperature to make sure all adjustment held. After about 3 hours of run time the unit started starving for oil. We pumped it back down and the tank was full of the purple grainuals we had seen before!!!! Mind you we pumped the veg oil out of the tank and right back in without adding any outside oil except for what may have been in the filter pump.Back in the day when these units were converted to Vegetable oil I know they would just pump the tank down and fill them up. No draining of oil lines or emptying of the jack. Any ideas what could be our problem here????

I believe its crystallization from the oil heating then slowly cooling back down. I don't remember where I read it. But Google may have a better time with memory retention then me.

TKE was using vegetable oil about 10 years ago and had all sorts of problems with leveling due to the fact that the veggie oil did not respond well to temperature change and also the jack seals did not react well to the oil either which caused a lot of friction causing poor ride quality. Every TK unit we had with the early vegetable oil we at some point ended up pumping out and using standard AW32 and changed the jack seals. There was strict instructions on the tanks that you were NOT to mix the veggie with any other oil.

Since then they started using a new biodegradable oil called Enviromax which I guess is a lot better.

My suggestion in your situation would be to get rid of the veggie oil and go the good old tried and true AW32.

Sounds like a broken down muffler. I have seen it look like coffee grounds and also like little rubber granuals that clump. The mufflers Kone used in the 90's have been the worst but they are not the only ones.

Interesting topic. I have three MCE cars that Millar put in maybe 15 years ago or so. They too used an early version of the bio D vegetable oil (VEG2?)which #1 stinks something fierce, and #2, the reservoir tanks on the inside ribbing supports and tops of motors looks like thick layer of fine back silt. I believe this oil has a short life and is breaking down, hence the stench and silt. No known valve issues yet, but the customer has paid to have a different type of biodegradable oil replaced in one unit as it was inside the building and the tennents could smell it. This vegetableqw oil was a seemingly good environmental selling point then, but now...I don't know for sure.

I haven't herd of Millar in a long time.. weren't they based in ohio?

I don't know for sure. Seems to my recollection they were bought out by Schindler about that same time.