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Old 26th July 2010, 14:31   #1
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Default Diesel as an Engine Flush!!??

I saw this last week at a petrol pump that I frequently visit. While I was waiting for my bill, I saw one of the attendents tending to a motorcycle. He was changing the engine oil - after draining the old oil, he poured a liquid into it from a pet bottle - the liquid looked like diesel. since the plug was open, all the diesel flowed down. After pouring through about a fourth of a liter, he losed the plug and poured another around 250 ml. he then proceeded to gently kick the starter pedal!!
By now I was intrigued and wanted to know if it was diesel and he confirmed yes. He went on to add that this was the cheapest way to flush the engine off all old oil. What he did next blew me off - he kicked hard, let the engine fire and run for about half a minute before killing it and draining the oil mixed diesel. When I pointed out to him that this could harm the engine as diesel would get into pockets from where it can't be drianed he said "Saar no problem. that will be just a few tens of ml of diesel and if that mixes with a can of new oil nothing will happen

Gurus, is this right? Isn't what he did likely to harm the engine?

@Mods: Not sure if this is the right place for this thread. If not please move it to the right one.
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Old 26th July 2010, 15:13   #2
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Well, if cleaning is the intention, they could use petrol because, petrol cleanses as well as evapurates leaving no stains; however Diesel leaves stains & doesn't evapurate & that's probably the reason he cranked the engine without the engine oil.

IMO, no need to clean up the engine between oil changes unless the engine oil is in worst condition & hasn't been changed for years.

BTW - would like to know what motorcycle was being experimented at the fuel station? Hope it wasn't Shell either.
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Old 26th July 2010, 16:19   #3
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It was engine flush that caught my attention, a friend has bought an esteem done just 36000 kms, it runs really coarse, had thought of suggesting to go for an engine flush. Nulon and Abro are two makes that i see in the market. But as its not suggested what could be a remedy ?

The car stalls in the first gear for less than 1200 rpm. Is it because its a BS3 esteem or clutch problem. Only 1st and reverse there is an issue.

Please suggest or advice.
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Old 26th July 2010, 16:20   #4
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Quote:
Originally Posted by cnaganathan View Post
I saw this last week at a petrol pump that I frequently visit. While I was waiting for my bill, I saw one of the attendents tending to a motorcycle. He was changing the engine oil - after draining the old oil, he poured a liquid into it from a pet bottle - the liquid looked like diesel. since the plug was open, all the diesel flowed down. After pouring through about a fourth of a liter, he losed the plug and poured another around 250 ml. he then proceeded to gently kick the starter pedal!!
By now I was intrigued and wanted to know if it was diesel and he confirmed yes. He went on to add that this was the cheapest way to flush the engine off all old oil. What he did next blew me off - he kicked hard, let the engine fire and run for about half a minute before killing it and draining the oil mixed diesel. When I pointed out to him that this could harm the engine as diesel would get into pockets from where it can't be drianed he said "Saar no problem. that will be just a few tens of ml of diesel and if that mixes with a can of new oil nothing will happen

Gurus, is this right? Isn't what he did likely to harm the engine?

@Mods: Not sure if this is the right place for this thread. If not please move it to the right one.
Ideally they should be using only Petrol to clean engines. This is first time I am hearing of diesel being used as a cleansing agent, since a diesel/air mixture has to be compressed much more than a petrol/air mixture so the engines are built differently from each other.
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Old 26th July 2010, 16:43   #5
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Originally Posted by aargee View Post
Well, if cleaning is the intention, they could use petrol because, petrol cleanses as well as evapurates leaving no stains; however Diesel leaves stains & doesn't evapurate & that's probably the reason he cranked the engine without the engine oil.

IMO, no need to clean up the engine between oil changes unless the engine oil is in worst condition & hasn't been changed for years.

BTW - would like to know what motorcycle was being experimented at the fuel station? Hope it wasn't Shell either.
Station - BP
bike - Hero Honda (IIRC)
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Old 26th July 2010, 17:05   #6
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Quote:
Originally Posted by Aarman_008 View Post
Ideally they should be using only Petrol to clean engines. This is first time I am hearing of diesel being used as a cleansing agent, since a diesel/air mixture has to be compressed much more than a petrol/air mixture so the engines are built differently from each other.
No petrol can not be used to flush engine it may ignite and burn down the bike ,
Diesel wont ignite as it need high compression ratio.

I don't know what harm it may cause but flush is basically a mild solvant oil which does not burn and dissolves the sludge and so is diesel in this case
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Old 26th July 2010, 18:22   #7
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Hi all, I have used Diesel as engine flush in old Diesel engines as follows
1) drain the old engine oil when the engine is hot or after a long drive preferably
2) let the engine cool down
3) fill up diesel only up to 2/3's of oil capacity
4) run the engine at Idle for 30 seconds max.
5) drain the diesel completly. ( keep it like this for at least half a day,so that diesel drains completly )
6) change oil filter & fill oil when the engine is cool.
this is a time consuming process.
( many times I have used this before overhauls of engines to get rid of the black carbon sooth, gives good results)

This is Not to be done frequently

I have never used this for petrol engines
May be I will use this method as last resort ( Suppose vehicle gets submerged & water /dirt gets in ) & when opening the engine to cleanup is not possible
This may be used to clean old & unused engines without opening them .
I dont think diesel does much harm .( the distributer pump uses diesel as its own lubricant in diesel vehicle ) but using petrol only ( without small amount of oil sounds risky.
Anyways I will not use Kerosine for such purpose anytime.

Draining oil after long drives is a best Idea

Yours Sudarshan
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Old 26th July 2010, 18:37   #8
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My mech used about half a liter of kerosene to clean my Jeep's engine valve system before the oil change. He said it will drain itself out in a few minutes and indeed I felt a definite improvement... must be in my head!!
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Old 26th July 2010, 18:48   #9
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Hi

I have tried flushing the engine with diesel before changing the oil at shell petrol pump once, as the old oil was very muddy i felt the need to flush it. My engine is running fine with out any problems, i guess its fine to flush the engine with diesel incase its really needed.
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Old 26th July 2010, 19:30   #10
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The diesel, though not as good as a solvent as petrol, can be used as a solvent for flushing engines. The benefit of using diesel over petrol is that petrol posses a higher risk of catching fire if used as engine flush, as all engines need be operated at-least half a minute for the flush to be effective.

But IMO, the correct way of doing an engine oil flush is to use respective fluids available in the market. When I had switched from normal to synthetic oil in my bike, the mechanic used some 'engine flush fluid', but then I don't remember the details.
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Old 26th July 2010, 19:52   #11
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Quote:
Originally Posted by challa View Post
Hi

I have tried flushing the engine with diesel before changing the oil at shell petrol pump once, as the old oil was very muddy i felt the need to flush it. My engine is running fine with out any problems, i guess its fine to flush the engine with diesel incase its really needed.
Yes, you are right.

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The diesel, though not as good as a solvent as petrol, can be used as a solvent for flushing engines. The benefit of using diesel over petrol is that petrol posses a higher risk of catching fire if used as engine flush, as all engines need be operated at-least half a minute for the flush to be effective.

But IMO, the correct way of doing an engine oil flush is to use respective fluids available in the market. When I had switched from normal to synthetic oil in my bike, the mechanic used some 'engine flush fluid', but then I don't remember the details.
We cannot use petrol, a main reason being. Petrol hardly has any lubricating properties, and there is a huge risk in blowing off all your engine gaskets.

While Diesel has lot of oil content, its a good lubricant and also a good flushing agent. But this method is not recommended, but most of the flushing agent you get has the similar characteristics and is derived out of Diesel

I use 250 ml abro to flush out old oils, but on the other hand, if you cultivate the habit of changing the engine oil every 5000 kms, you dont even need to use flushing agents. I do it so every 25000 kms i flush the engine, be it petrol or Diesel engine.
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Old 26th July 2010, 20:23   #12
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Quote:
Originally Posted by PAVAN KADAM View Post
We cannot use petrol, a main reason being. Petrol hardly has any lubricating properties, and there is a huge risk in blowing off all your engine gaskets.
Pardon me for my ignorance, but if at all we use petrol to flush, other than the risk of catching fire, will the engine overheat and gaskets blow off in a short interval of about 30 seconds?
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Old 26th July 2010, 20:24   #13
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flushing an engine with diesel or any engine flush has both pros and cons.

We might think that carbon accumulation in the engine is bad. but it is a real essential for any engine to run in full efficiency.
the carbon actually acts as a seal and sets the piston rings to the cylinders geometry and thus full compression is achieved. and as all of us would know, this is what happens during the running in period.
diesel or in this case any engine flush would act as a detergent that dissolves this carbon and takes it away making the rings to lose its tight fit causing decompression in the cylinder.
now the same thing happens when we switch from normal engine oil to synthetic oil after running the engine in normal oil for anything above 30,000kms. the synthetic oil has a detergent property that creates a similar problem.

Now, the pros
If engine flush is carried out frequently from new or if synthetic oil is used in early stages then you'll have a nice clean engine that is almost like new.

what i think is NEVER FLUSH AN OLD ENGINE.
by old i mean by mileage an engine with 2000kms and 5 years old is still a virgin engine.

my point here is if you are thinking of flushing your engine because the existing oil is very old, i suggest you buy two types of oil. one cheap one and another regular oil that you want to use. after draining your old oil, pour in the cheap oil. run the engine for about 30 MINUTES and then drain it. now you have clean engine but with all the essential carbon in it. after this you can proceed with your normal oil and filter.
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Old 26th July 2010, 20:34   #14
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Quote:
Originally Posted by PAVAN KADAM View Post
We cannot use petrol, a main reason being. Petrol hardly has any lubricating properties, and there is a huge risk in blowing off all your engine gaskets
Does this happen even when the flush is done when engine is cold? Also could you explain how a petrol could blow the gaskets? Appreciate to shed some knowledge on this. Tks.
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Old 26th July 2010, 20:44   #15
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Quote:
Originally Posted by dhanushs View Post
Pardon me for my ignorance, but if at all we use petrol to flush, other than the risk of catching fire, will the engine overheat and gaskets blow off in a short interval of about 30 seconds?
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Originally Posted by aargee View Post
Does this happen even when the flush is done when engine is cold? Also could you explain how a petrol could blow the gaskets? Appreciate to shed some knowledge on this. Tks.
All i know, with my limited knowledge acquired over all these years with overhauling engines is, Petrol should never be used to flush engine oil, i dont use petrol even while cleaning overhauled engines, my mechanics always use diesel to clean the engine. Simple reason, Diesel cleans as well as lubricates.

There is no risk of fire as such, but your bore and pistons would get damaged due to loss of lubrication. Rubber gaskets tend to expand in contact with petrol, thus loosing its properties.
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