90 corolla diesel engine flush yay or nay
 

Good morning,

i bought a 1990 toyota corolla 1.8 diesel idi. It has 290,000 km. Perhaps an engine flush would loosen the crud and sludge in the engine and make better fuel mileage. I have been getting around 70 km/g around 44 mpg. I have heard about engine flush with automatic transmission fluid, kerosene, or diedel. I am a little apprehensive to flush such an old engine, because i have heard that the after engine flushes some old engines begin to leak and i would not like this.

Cheers

Jorge

If it starts leaking after a flush, the seals and gaskets are the problem. When it comes to which fluid to use for flushing, I have seen it done mostly with kerosene, and it can be done at different stages.

Where will the crud go once it's loosened? That would be my concern.

Hopefully into the oil filter but may end up in the pan, either is ideal. It's when it goes floating about that it causes damage

I would only "flush" if you have an immediate and serious issue that may be resolved. Otherwise just add a small amount of ATF, MMO, Seafoam, etc.

Flushing the engine would be akin to surgery or chemotherapy. Make sure the treatment matches the ailment.

Been wanting to add: flushing was fatal to the #1 crank rod bearing in a s10 I bought for my son. It died 50 miles later.

May not have been the actual cause but definitely a contributing factor

The closest thing I've done to a flush was a couple very low mileage oil changes and it seemed to work. I would try that instead. Not even close to as risky either.
Try like 1500-3000 mile changes with syn.

If you flush, do not replace the entire oil with something other than motor oil.
Option 1:
Frequent oil changes with cheap oil, about once every tank of gas untill the engine is sufficiently clean.
Option 2:
Get the oil up to temperature, shut the engine down, add 0,5L diesel to the crankcase, let the engine idle for 15 min, shut it down and drain the hot oil quickly.

Under no circumstance replace the entire engine oil with diesel/ATF/whatever that isn't motor oil.
That will likely cause bearing damage.

Even the flush with kerosene that I remember was done by adding a small amount of kerosene to the oil, allowing it to circulate between oil changes which were done at a shorter interval while the engine was undergoing a flush.

You're not supposed to drive the car with the diesel/kerosene added to the oil.
Only let it idle for a few minutes and then drain it.
Otherwise the oil might be too thinn and your bearings might suffer.