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Engine oil removal through diptube and others....

Engine oil removal through diptube and others....

Engine oil removal through diptube and others....

(OP)
Why?

A few newish European cars now have no sump plug and the oil is sucked out of the dip tube when changing it, I can't think of a more stupid idea, but there must be a reason for it, anyone any ideas?*

I like to look at how things are done on new cars when I get chance (incase there are things to be learned and applied to my own older car), but I just can't get my head around some of the weird things I see sometimes - I had a look at the intake manifold that was removed from a VW turbo diesel, the inlet was at one end, it ran along, did a U-turn, back the other way, another U-turn then went into the plenum, but why? Why make the air go further and round more flow losing U-bends? Noise reduction perhaps?

*It would be too easy to say it is to thwart any keen DIYers as hardly any 'normal' people get their hands dirty these days and for those that want to the tools to do the job are readily available....

Any additions or answers appreaciated.

RE: Engine oil removal through diptube and others....

I'd guess a sump plug costs around $3, and will cause a small but discernable number of oil leaks, and within the warranty life of the vehicle sucking oil out of the dipstick is acceptable.

So far as the manifold goes, all sorts of reasons are possible, noise is quite likely the main one.

 

Cheers

Greg Locock

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RE: Engine oil removal through diptube and others....

I suspect cost is the main factor as Greg stated above but ham fisted mechanics stripping the thread in an alloy sump will also be a consideration.
Had this happen with my car at an authorised dealership !

By the way this is not a new idea...I first saw it advertised at a national franchise car wash and vacuum clean distributorship in the late 1970's.

The idea being anyone who knew where the dipstick was could carry out an oil change.
Never tried it myself.

Pete.

RE: Engine oil removal through diptube and others....

Probably there is no sump plug for same reason automatic gearboxes don't usually have sump plugs - it can't come loose if there isn't one.  Car engines in boats have been having their oil changed by sucking it out for years.     

RE: Engine oil removal through diptube and others....

Many dipstick tubes do not extend to the bottom of the sump, leaving a considerable amount of oil remaining.  I took a look at my 5.0L Ford engine sitting on my stand and the tube is a full two inches from the bottom of the sump.  On a good day, it MIGHT vacuum the top inch, or about one quart of oil.

Franz

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RE: Engine oil removal through diptube and others....

Well, at least the cost of changing your oil would be lower! jester

RE: Engine oil removal through diptube and others....

cost was not the object to introduce engines without drainplug. the idea is to make maintenace easier - you don't have to crawl under the car to get to the drain plug, and the hot oil does not run up your sleeve when you get it out.

mercedes was the first manufacturer to introduce it way back in the 80-ties(after thorough testing), together with an oilfilter that was easily accessible from under the hood.

they took care to position the dipstick guide in such a way that the (rather wide) suction pipe reached the lowest part of the oil pan so only a minimal amount of oil remains in the engine when sucked empty this way. they also stipulated the use of only a view types of suction apparatus that are compatible with their design. basically these have a metal suction pipe and they work better then apparatus with a plastic pipe that may deform under the heat still in the engine.

RE: Engine oil removal through diptube and others....

A lot of new cars (particularly European, but probably others as well) have a plastic belly-pan underneath the engine, mostly for aerodynamic reasons, although it helps with keeping debris and dirt and direct water splash/spray out of the engine compartment, too. If you use a drain plug, the belly pan has to come off, typically with a lot of screws (my VW diesel is like this). It's less labour to suck it out from the top, and a lot of people do this with the VW diesels ... although I prefer to do it the old way, if nothing else but to have an excuse to look around underneath for signs of other fluid leaks, cracked CV boots, and the like. VW still puts a drain plug there.

I don't know why they don't just put a small access hole in the belly pan to allow the drain plug to be reached without taking the whole belly pan off. I've thought about doing that myself, but every time I'm doing an oil change I can't be bothered, so it's never gotten done.

RE: Engine oil removal through diptube and others....

Some late 80s onward Hondas and Toyotas had a plastic underbelly under the engine compartment. It had to be removed to change oil. After ten or so years of removal and replacement, the attachment points become so damaged that they cannot be refitted. An access hole for oil change would certainly improve that, however I expect the manufacturer has little interest in improving durability beyond 10 years.

Regards
Pat
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RE: Engine oil removal through diptube and others....

as mentioned above, they've had aftermarket kits for this for decades.  If you've got a good shot to the bottom of the pan, I don't see the harm in it.  That's how I draw oil samples for analysis.

If it really torques you off, then drop the pan, weld on a plate, drill and tap the plate, and install a removeable plug.
 

RE: Engine oil removal through diptube and others....

Personally I always like the kits that put a lockable ball valve in place of the drain plug.

I'd hate to suck steaming hot oil out of a car that just drove in (a la Jiffy Lube).   

RE: Engine oil removal through diptube and others....

If it helps, I don't think they use their mouths for the task.

My neighbor has one of those lockable quick-drain plugs.  The odd thing is that the only position it locks in is "open."  It's held closed by friction, gravity, a whole lot of luck, and a very small spring.

 

RE: Engine oil removal through diptube and others....

(OP)
Thanks very much for your thoughts gents, the plastic undertray is my favourite reason so far.
It has been suggested elsewhere that this could have been done for health & safety reasons, not only the danger of splashing hot oil, but also its potentially carcinogenic properties. However, it has to be said that any proper mechanic over the age of 13 should be able to drain the sump of oil without bathing in it, not only through experience and having the correct tools, but also from having some decent degree of manual dexterity.....  

RE: Engine oil removal through diptube and others....

In the 1980's a number of UK Petrol Stations had a "change your own oil through the dipstick service."  The sales pitch was a "clean and easy way of changing your oil".

RE: Engine oil removal through diptube and others....

that service was introduced in more european countries at that time, with little succes. both due to the public not really wanting it and the fact that they used all kinds of small diametre plastic tubing to suck the oil out - which did not work well with many cars, especially not when the oil was relatively cold.

nowadays the system is only used in workshops servicing cars and vans that are expresly designed to have the oil changed that way.

RE: Engine oil removal through diptube and others....

It would only take a small hole in the belly pan for drain plug access, but a bigger one for the filter (or top access) which presumably would affect the aero benefit of the pan proportionally.  Several interesting explanations here- may be a combination of all (including declining DIY oil changes in the market, especially under warranty) . . .

RE: Engine oil removal through diptube and others....

Another thought is perhaps fewer back yard mechanics changing their own oil means more of it will end up at recycling stations and not be disposed of improperly.

Pete.  

RE: Engine oil removal through diptube and others....

This not an uncommon way of changing oil with many small fixed marine engines.  The apparatus to perform this is available ready-made.  I have personally used two different ones on two different engines.

The kits I've used had a relatively stiff plastic pick-up tube of diameter small enough to slide inside the dipstick tube of the engine in question, even though the engine had the standard dipstick tube of around a quarter of an inch (6mm) ID.  Sliding the stiff pickup tube into the dipstick tube gave a better access to oil in the bottom of the oil pan.

The small diameter of the pickup tube made the oil change a bit slow if the oil was cold, but we all know that oil should be changed hot anyway.

 

old field guy

RE: Engine oil removal through diptube and others....

Honest question...

How does all that lovely sediment in the sump get sucked up?  

- Steve

RE: Engine oil removal through diptube and others....

I would be afraid of a ball valve. When I was working on a drill rig we installed a ball valvle to make changing the oil easier. What we didnt account for was the extra vibration because of the weight of the ball valve. About half way through the week the nipple going to the valve broke and we lost all the oil, if it wasnt for the operator watching the gauges so close we would have lost the motor. Granted it was a huge cummins with alot more vibration but I wouldnt trust it on my car, surely not if all I had was a dummy light for oil pressure.
As far as the funny shape of the intake I would venture to guess it would be to increase the available air charge to help the torque of the motor down low and let it breathe easier at high speeds. Like a common single plane intake versus a dual plane intake. Just my .02 cents.

RE: Engine oil removal through diptube and others....

How does all that lovely sediment in the sump get sucked up?  

same way it always does - the oil pump intake tube draws it in and the pump sends it to the filter, where the particles are trapped.  

another reason to change your oil while "hot" is that the particles are more likely to be suspended vs deposited.
 

RE: Engine oil removal through diptube and others....

Actually, Isaac, you have correctly stated the theory of the dip stick oil change.  I don't remember the first time I heard about this method, but I had a neighbor many years ago that had a small mechanical pump and changed his oil regularly with it.  Years later he wanted to upgrade to bigger, better, faster...whatever and he needed my advice on how to clean the "gunk" from the oil pan.  To my amazement, the sludge had built up to about a half inch and was hard enough we had to use a gasket scraper and sand blaster to get it cleaned out.  My guess, therefore, is that "...all that lovely sediment in the sump (does not always) get sucked up"!

Rod

RE: Engine oil removal through diptube and others....

perhaps I should clarify (although it may be clear from context) - I was referring to the engine oil pump, not an external oil change pump.

I would have said "what's the sludge matter, as long as it stays put" but I'm aware of at least one example where accumulated sludge (at the end of a crankshaft drilling) came loose and relocated to a less-benign position, resulting in engine failure.

That sounds like a pretty extreme case, Rod.  Do you think a modern commuter car with modern lubricants produces/accumulates that much "sludge?"  What's the "sludge" made out of, anyway?  Soot+oil?
 

RE: Engine oil removal through diptube and others....

"What's the sludge made of...."?

Good question, Isaac.  I don't really know.  If memory serves (and, of course it usually does not), the gunk was more like a thick layer of varnish.  Quite hard with a black, sludgy, gooey stuff on top.  

Rod

RE: Engine oil removal through diptube and others....

As far as crankcase deposits goes:-

I would call black lumpy deposits carbon. They build up on very hot surfaces like parts of pistons and where oil splashes on exhaust ports. I think they are oil decomposed to the point that they are pretty much carbon.

I would call golden to black thin shiny deposits varnish. this normally builds up in very tin areas that get hot, but due o space get worn and polished. I think this is a mixture of oil molecules that have cross linked and some small particles of carbon from decomposed oil. They are thin and shiny mainly due to polishing action. The cross linked oil is the result of enough heat to start some degradation, but not enough heat to fully degrade most of it to carbon.

I would call the grey pasty stuff that lays in corners and crevices and on the bottom of the sump sludge. I think this is a mixture of fine carbon, some degraded oil additives, some detergent, some fine metal and metal oxides and dust particles and some water.

I have seen the grey sticky toothpaste like deposits 1/2" thick on the bottom of a sump. I have seen it come loose and plug a gallery or pick up screen or both. This has always been on engines from cars that had owners not interested in cars and only use it for local shopping with  no highway or high speed long trip use and  were long overdue for an oil change.

The change to a new owner who changes the oil and drives longer and faster stirs the sludge up, wella, spun bearing.

Regards
Pat
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RE: Engine oil removal through diptube and others....

The classic grey sludge that is really nasty is in old cars that ran on leaded gas, with cool thermostats, and no PCV.

Talk to the kids at Jiffy Lube et al;  they all have burns from hot oil getting up their sleeves.  They are probably applauding this move.

RE: Engine oil removal through diptube and others....

Well if one wants to call technical things by technical names, CRC Manual no. 20 for rating engine Sequence Test parts has formal definitions for varnish & sludge.  In a nutshell, varnish deposits cannot be scraped off with a rubber spatula, and sludge deposits can.

By contrast, Shell Gasoline has apparently decided 'deposits' isn't alarming enough to attract consumer attention and so scrupulously refers to them in their marketing by the equally descriptive 'gunk'.

Sludge and varnish form from oxidized components of the oil.  Oxidation makes them more polar and hence less soluble in the oil.  Anti-oxidants are included in oil to prevent their formation, and dispersant ingredients are incorporated to prevent their precipitation.  I think sludge tends to have water present and so tends to form at lower temperatures, while varnish is more of a high T issue, but it's not unusual for them to be observed together.  I speculate there may be more cross-linked polymers in varnish, too.  But the definitions are practical rather than chemical.

RE: Engine oil removal through diptube and others....

Back to my question...

How much of all this stuff comes out of a sump drain compared with a sump suck?

- Steve

RE: Engine oil removal through diptube and others....

Tons of airplanes flying around with 'quick drains' installed, never heard of one failing causing oil loss. I would be afraid of such on a car, because of road debris maybe knocking it off. Fram marketed some quick drains for awhile that were pretty flush to the pan, but needed an adapter to drain the oil. ( something else to lose!)

RE: Engine oil removal through diptube and others....

Early in my career I worked as a mechanic on yachts, about 90% of those engines had their oil changed via the dipstick.  Based on that experience, engines that were properly maintained and operated did not appear to have excessive deposits in the sump when taken down for major repairs, even though the oil had been pulled from the dipstick for regular changes.

Engines that when torn down had lots of "gunk" in the bottom of the pan usually had irregluar maintenance, lots of idle time or used fuel from Mexico.

Never really saw where doing the oil change via the dipstick caused any additional problems as long as the right equipment was used and the oil was warm when pulled.  This experience is mostly based on high speed diesel engines from 35 to 1500 bhp that ran 100 to 2000 hours a year.

Hope that helps.  

RE: Engine oil removal through diptube and others....

The only point I can see is it is important where the oil is drawn from, not by which method it is drawn. Whether by drain plug or suction tube, what counts is how close that point is to the bottom of the sump and how much is left behind when the process is complete. That depends on pan design and drain point placement.

For pans I have made for my boats, I run a slight trough along the bottom of the pan getting deeper at the drain point end and tend to form the pan to direct oil to that trough. At the drain point I drill a hole in the side of the pan at the trough and insert a short steel tube into the hole so it is flush with the grove and weld or braze it in place. I attach a rubber hose to the tube and run it through the transom via a skin fitting. I install a ball valve along that hose in a protected position that is also easy to access. I remove the handle of the ball valve but keep it safely stored in the boat. I also install a plug in the tube so the plug is removed from outside the transom. the plug is a type that can be removed by hand, but will seal in oil if the ball valve is left open. That way I can easily drain oil to outside the boat while it is on the trailer. No risk of spillage or accidental release into the hull or the waterway. It drains to the last drop if the oil is hot.

Regards
Pat
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RE: Engine oil removal through diptube and others....

patprimmer said:

"Some late 80s onward Hondas and Toyotas had a plastic underbelly under the engine compartment. It had to be removed to change oil. After ten or so years of removal and replacement, the attachment points become so damaged that they cannot be refitted."

Ten years?  Here where they lay down lots of salt in the wintertime, the bolts usually snap off after one or two years, to be replaced by sheetmetal screws or cable ties, assuming the undertray isn't just discarded.

I assume the reason why they still continue to use 6mm thread bolts is because the issue is isolated to this region.  Vehicles that use 8mm thread bolts generally have no issue.

RE: Engine oil removal through diptube and others....

I look at the old oil in the drain can. I like to reassure myself that it has no lumps of metal in it or other signs of impending failure. If I was to suck up the oil through the dipstick tube, directly into a can, I couldn't do this and in any event, those lumps might still be in the sump pan.

I'm the sort who goes for lunch while the sump drains out; I don't like leaving even a drop of dirty oil in there and I take care to jack up the car so the sump plug is sitting at the low point. Hopefully, draining this way, the old oil pulls all the loose gunk and debris out with it.

PW

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