Tiny bubbles...

[MercFan]

No, not a Don Ho song this time...

... while under the hood today I noticed I have lots of very tiny bubbles in the clear filter while the car is running.... Is this an indication of a clogged tank screen or something else?! Is it a problem at all?! Car is running fine...

It means you have a leak. Check the rubber hose below the tank.

[MercFan]

Originally Posted by ForcedInduction

It means you have a leak.

I don't have a fuel leak, or I would see it on my garage floor... maybe I have a slow air leak somewhere in one of the fuel lines?! Does it have anything to do with a tank strainer?!

[Ryan Z]

Most likely an air leak. I would start by changing hose that goes to the clear filter. I had that problem last week.

[pawoSD]

Tiiiiny Bubbles.....innn the liiinee......makes me worrieddd......is my engine doing fiiine?



You have a leak downstream somewhere....

[Bob Albrecht]

The primary filter will trap dissolved gas from your tank. Fuel is cool and under slight pressure by design. This is ideal for dissolving gas. When the fuel gets up to your engine it heats up and de-gasses. The primary fuel filter is designed to trap gas. That is why the outlet is low. You should not see a continuous stream of bubbles coming into the filter, but even if you get rid of all of the gas in the filter it will come back eventually.

I have seen this myself and I am sure I don't have a fuel leak before the filter.

[diametricalbenz]

Originally Posted by pawoSD

Tiiiiny Bubbles.....innn the liiinee......makes me worrieddd......is my engine doing fiiine?

That's hilarious

[pawoSD]

Originally Posted by diametricalbenz

That's hilarious

Thank you. Thank you.

[MercFan]

Originally Posted by Bob Albrecht

You should not see a continuous stream of bubbles coming into the filter...

But that's exactly what I see when the engine is running.... I do believe it's something new that was not there before... the only other thing is that I recently cleaned the vent tube (looks like a little trumpet - under the car on the driver's side rear) that vents the tank to the atmosphere - took it apart and it acted like it may be a check valve - though not a strong one as I could overpower it with my breath... anyway - I wonder if I may have re-installed that part backwards!? Possible for these symptoms?!

[pawoSD]

Are all of the lines in good shape? Under the car? Check all hoses for age and metal lines for corrosion. There are rubber hoses back at the tank that are usually neglected too.

[MercFan]

Originally Posted by pawoSD

There are rubber hoses back at the tank that are usually neglected too.

You mean the two hoses under the tank?! They appear fairly aged but not destroyed - guess I could replace them. I need to put in Viton-lined lines anyway and maybe event clean out my tank. Some more questions related to that:

1) How difficult is it to clean the tank and then to purge the fuel lines of all the air?! I've seen a DIY article on it but never done it...

2) What size of hose clamps do I need for connecting the 5/16 ID fuel lines to the steel lines (both in the engine compartment and under the tank in the rear)?!

Thx in advance -

[C Sean Watts]

Originally Posted by pawoSD

Tiiiiny Bubbles.....innn the liiinee......makes me worrieddd......is my engine doing fiiine?



You have a leak downstream somewhere....

[Bob Albrecht]

Originally Posted by MercFan

But that's exactly what I see when the engine is running.... I do believe it's something new that was not there before... the only other thing is that I recently cleaned the vent tube (looks like a little trumpet - under the car on the driver's side rear) that vents the tank to the atmosphere - took it apart and it acted like it may be a check valve - though not a strong one as I could overpower it with my breath... anyway - I wonder if I may have re-installed that part backwards!? Possible for these symptoms?!

If the fuel is cold and the engine is hot it is possible that tiny bubbles could be de-gassing fuel, or, there could be a leak. I am not sure how a leak would not show up as dripping fuel.

BTW: About Viton

A few of the flexible OE fuel lines on my car have survived years of B100. They are
1) The flexible hose from the tank to the long stainless line.
2) The line from the long stainless line from the tank to the stainless line that goes to into the engine compartment.
3) The "cigar tube" that returns fuel to the tank.

I think the lines that connect the primary filter would have survived had my mechanic not changed them to some incompatible material. The return tubes from the injector eventually leaked, but it may not have been the B100.

The grommet around the fuel filler neck melted away immediately.

Depending on the year of your car, Viton may not be needed everywhere.

[Ryan Z]

Get a piece of hose and replace the hose in the engine compartment.
Then send Bob A. some Gas-X.


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1984 MB 300SD Turbo

[Toblin]

I thought this thread was going have something to do with Don Ho.