"Benz" Diesel filters???

[Bacchus]

Some time ago we had this topic and I think John Young gave me a link ( or pics ) of the mercedes benz diesel filter. This is apparently the filter to use. I currently fly with the " innocent looking filter" with no problems at all. Just clean it every now and then. At least I can see the dirt when it gets there. Firstly who else believe in these filters ( the glass ones )?

Secondly. I want to get the merc filters, but is diesel fuel not a lot thicker than petrol and therefore it would not be such a fine filter.? Letting more dirt through to the carbs etc? And every how often do you replace them. 50 hours?

[Morph]

The problem with those glass filters is they are too fine, .1mm instead of about .3mm mesh. As a result they are prone to suddenly clogging which leads to an engine out. This happened to me and the electric fuel pump saved my bacon.

The diesel/merc ones are available as diesel fuel filters at Midas or at any Merc spares place as well as from Aviation Engines. I used to replace them every 25 hours, but I have heard of people going to 200 hours. They are so cheap I buy a whole bunch at a time

[GR8-DAD]

Agree use the Benz ones. About R15 each and replace every 25 hrs.

[Bacchus]

Thanks guys.
Will go for the benz ones.
Ek was net bang n diesel filter is nie reg vir petrol nie, maar ek is oortuig.

[Mogas]

I use the glass filters with the .3mm mesh. Always have and never had a problem, I suppose it comes from the days in Zim when you could not just drive round to Autozone and buy some new throwaway ones, being able to service them is a plus. I must add that my fuel sustem design has 2 of these filters installed, 1 for each carb.
viewtopic.php?t=3587&highlight=fuel+system
I like the fact that I can properly eyeball the filter on every pre-flight.

[KFA]

I use a GUD. BC 68 which is the replacement for the merc filter also been using them for 300+ hr's with no problem.

[skybound®]

Have had 3 of those glass filters starting to leak at the seals. I think the glass ones are made more for gas (LPG) as opposed to two stroke.

After the third incident, switched to the benz filter and never looked back again.

[Duck Rogers]

...... Firstly who else believe in these filters ( the glass ones )?

Ai yai yai........here we go again!
I believe in them! I DO NOT believe that the mesh is too fine.
I took off/out my bakkie's petrol tank some time ago to clean it out (22 years of rubbish in there) The pick-up inside the tank has a plastic/nylon type filter attached to the end. Believe me, that thing is so fine, you can't even see the mesh! It looks like a nylon cloth!
Now, how come my vehicle does not run out of fuel or clog up this filter? It's 100 times finer than the mesh in the glass filters.

And no, the glass filter was not made for LP gas either.

Please note, I'm not telling anyone that they HAVE to have a glass filter. You can put on whatever makes you happy. I'm happy with a glass filter and as far as I'm concerned, there's nothing wrong with them.

[John Young]

Hey Quack-up - please send some of those mind altering substances down this way - I think that you trying "to pull our chains" and hope someone takes the bait - you rascal Hehehehe

I believe in them!

Alright guys and dolls....listen up and pay attention.

After reading John's last post regarding the glass type fuel filter, I thought I had better obtain some unbiased opinion. After consulting with my friends in the USA, who, by the way are some of the most well known and well respected Rotax servicemen over there, I have come to the conclusion that even though some, or most of us, have never had a problem with the glass type fuel filter, we better take note of the fact that there is definitely something not too lekker with these things.

Here is what Mark Smith had to say:

"There is always something different that attracts some folks attention.

The Pteradactyl was once said to fly really bad, and it did so with full personal knowledge.

But some folks love it even though they may admit, or not, that it does
indeed fly badly.

Same with this glass filter.......It sounds good, replaceable element, cleanable, etc,

but it is bad news in my opinion.

A friend bought a used Rans S9, nice little thing but a bit underpowered with a 503.....

His first attempt at flight could have been a total of the plane as the
engine quit at a most inopportune time.........
he made it down in a sloped field across the road........

The filter was fully plugged and I tested it with a can of fuel and
gravity flow.....very small trickle at best.

I have seen other examples of this filter where they have come apart
inside and leaked, etc,

the best is a cheap, 2 dollars or so, paper filter to be replaced every
100 hours......it is clear to see major crud, and it will also show water if it gets that far,

my Quicksilver types have a loop of fuel line and two low points that connect with it, this traps any water for the most part,

I have removed many of the glass fliters from customer's planes and have a good reputation for continued good performance using the small paper pastic filters......

hope this helps...."

AND

This is what Brian McCallen had to say:

"Never heard of any problems with the Rotax engines on aircraft here in the states but I have heard of problems on snowmobiles. The problem was not that the filters were so fine that any they would clog up easy. The problem was the filter screen was so fine and the fuel consumption so high the filters would restrict the fuel flow. That may be the reason some of the microlighters are able to restart the engine after they successfully do their dead stick landing.
Now we have had problems with the paper type filters also restricting fuel flow when there is water in the fuel the paper will swell up and restrict fuel flow.
Now I noticed some of the microlighters say they have never had a problem. It could be in the way the fuel system is installed on that particular aircraft. If the fuel pump is located much higher than the fuel tank this may not allow the fuel pump to draw enough fuel through the filter to keep up with the engine demand because it is already working hard to just draw the fuel from the tank. Maybe their fuel pump does not need to work as hard to supply the required fuel at the higher RPM's because of where it is located in the system.
Just my opinion."

So, there you have it.......you can draw your own conclusions from the above.

Let it be known that the Duck has moved closer to the John Young camp of thought but will reserve judgement until further investigation........
_________________
.......Duck Rogers.......
---------------------------
Stop fiddling......just fly man!

Duck my mate

After 11 instances in the good old SA telling how bad these glass filters are you still disbelieve us untill you read two similar instances in the US where there have been problems. Now obviously there is credibility to this case and you have changed your mind. Why didn't you believe the original 11 experienced pilots here.

Take your chances, I am one of those who had in my entire 180 hours flying 1 bad instance and it was related to that damn filter. They say a 2 stroke engine is unreliable, not so, it's the fuel filter.
_________________
http://microlighters.co.za/viewtopic.php?t=3341
Building a Bush Baby Explorer

[Mogas]

This is my other transport, turbo diesel. Think I'll put a couple of those glass thingies in there to make it more reliable too

[Duck Rogers]

Not yanking anyone's chain.....
Note, I also said "Let it be known that the Duck has moved closer to the John Young camp of thought but will reserve judgement until further investigation........"
So, further investigation has lead me to believe that no-one has PROVED that it is because of a too fine mesh that we have engine outs.
Prove it, and I'll believe.........otherwise don't speculate.
I still believe they're ok. Like everything else, install it properly, in the correct configuration and look after it properly and it should do just fine.

Now, just for the record, I wil never again answer another post on this topic or get drawn into the glass filter debate again.

[Morph]

My experience and others I know of is the following

The mesh size is very small 0.1mm. The total surface area of the mesh is very small compared to other filters where the wavy shape of the mesh adds more surface area.

In my case, I had cleaned my filter within the previous 5 hours. Somehow I picked up some very fine yellowish fibres (I am talking about less than 1mm long and who knows wide)

At my preflight the filter was checked and appeared clean. I took off and within 20 minutes over Blouberg the engine lost RPM. It came back up again and then lost rpm again. I immediately switched the electric fuel pump on and after one or two coughs the engine came back to life. I climbed as high as possible to give me the option of choosing a better landing spot and managed to make it back to Morning Star

On inspection the bottom 5-8mm of the filter mesh was clogged with these fine fibres. The upper 35mm was clear but the filter would not allow fuel though. It had blocked solid. The Electric fuel pump had enough pressure to force fuel though the filter but without it there was no fuel.

Now a filter of a different design has much more surface area and would not have blocked solid that easily. A filter should block gradually and IMHO 20minutes from clean to completely blocked is too dangerous.

[Big-D]

There are glass filters (Good ones) and there are glass filters (Not so good ones).

P & M have their own Glass filter and it seems to work well, my Gemini has 2 of them, one for main fuel line and one for backup electric fuel pump. The GT450 also comes standard with this fuel filter.

Even though I trust the glass filters (Kinda), I am lazy and ask myself - What is less trouble?

1. Cleaning the glass filters every 25 hours (Takes 15 minutes)
2. Replacing with a Mercedes filter every 25 hours and chucking old one away

This sunday I will be changing to disposables - Will be less trouble in my opinion and we KNOW it works.


Another-John-Young-convert

[lamercyfly]

Hi Guys.

Have only ever used the diesel filters at La Mercy.

About 9000 hours of flips and 6 000 hours of training over the 9 years we operated, and NO fuel filter related problems.

We did the maintenance on all the aircraft at the field and can vouch that in many cases the filters would only get cleaned (NOT CHANGED) at about 100hour intervals.

It's all about putting clean fuel into the tank, and cleaning the tank out periodically. Yep, quite easy, remove the tank, put some fuel in, slosh it around, and pour the fuel out

Also about flying regularly. Fuels 'Varnish', and even little bits can eventually cause clogging. Backwashing a filter will NOT remove this varnish. So, if you do not fly regularly, then adjust your filter renewing times accordingly.........

Later,

[Aerosan]

Well well guys it seems everyone inside here actually agrees without even knowing it I do not think the fight is about the filters or the mesh as such but it should be regarding the surface area! The mesh cannot be too fine, if it is it suggests that some k@kas smaller than .03 mm will be let through. After reading Mrph`s post I can now see why Ill too stick to normal benz filters. All that needs to happen is a little bit of gunk has to be picked up by suction and if it is enough it will clogg the glass filter, no because of mesh but because of available surface area. This is the way it looks like to me!! So for safety1s sake maybe run 2 or 3 in paralell? or 1 benz filter