Author Topic: Blocked Breather Tube  (Read 3597 times)

Garry

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Blocked Breather Tube
« on: May 11, 2012, 04:50:24 »
I have been waiting to start my engine work but have been messed around by the mechanic so have pulled the car back from him after he had it for 2 1/2 months with out starting and asking for another two months.  Was good some years ago but time has wearied him.

Meanwhile back to the engine. when I left it there it was pushing oil out of the dipstick and the compression test showed 120-125 across all cylinders.  Not blowing any smoke though.

It's been suggested to me that I may care to check several things before pulling the engine to pieces, firstly that I have the correct dipstick and secondly that the breather tube is not blocked.  What is the best way to check for a blocked tube?

I have it in a shed but have limited tools etc to do work at the moment.

Garry

Garry Marks
Melbourne/ Kyneton, Brisbane. Australia
1969 MB 280SL 5 speed RHD SOLD.
1965 MB 230SL Auto RHD Lt Blue 334G, Top 350H, Tourist Delivery.
1972 MB 280CE Auto RHD 906G
2005 MB A200
2006 MB B200
2019 Izuzu DMax 4x4 Slide-on camper.
2022 Volvo XC40 Electric
2024 Volvo EX30 Electric

jacovdw

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Re: Blocked Breather Tube
« Reply #1 on: May 11, 2012, 08:13:40 »
Garry,

I seem to remember that this particular pagoda has the 2 piece metal breather line which is correct for your August 1965 built date.

The only way to check is to remove the entire assembly from the engine.
To remove the hollow bolt and banjo fitting on the valve cover, you need a 24mm hex socket or spanner.

Once removed and the two pipes separated from the rubber joining hose, you can blow through the pipes with your mouth.
That is about the simplest test you can perform.

Most of the time, these lines tend to rust from the inside out and get blocked even though they appear fine from the outside (think atherosclerosis...  ;) )
Rather replace than to try and unblock.

I had a similar problem and ended up taking both metal lines to a pipe/hydraulic shop. What they did was to bend new pipe using the old ones as a template
and they then soldered the old banjo fitting back on.

Garry

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Re: Blocked Breather Tube
« Reply #2 on: May 11, 2012, 08:28:17 »
Thanks Jaco,

Yes it is a two piece pipe with the bolt on it as distinct from the later rubber units. 

What i want to do is to see if the pressure is being forced down into the sump because of a blocked breather before i drive it the 200km to the new workshop or if the breather was not blocked shouldn't the pressure be relieved through the top breather rather than the dip stick.  In other words that may be the primary problem rather than just rings failing or a ring stuck.

Garry
Garry Marks
Melbourne/ Kyneton, Brisbane. Australia
1969 MB 280SL 5 speed RHD SOLD.
1965 MB 230SL Auto RHD Lt Blue 334G, Top 350H, Tourist Delivery.
1972 MB 280CE Auto RHD 906G
2005 MB A200
2006 MB B200
2019 Izuzu DMax 4x4 Slide-on camper.
2022 Volvo XC40 Electric
2024 Volvo EX30 Electric

jacovdw

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Re: Blocked Breather Tube
« Reply #3 on: May 11, 2012, 14:12:52 »
Garry,

Forgot to mention, you need to check the part of the breather that connects to the throttle body as well.
There is a steel insert (the bit that the L-shaped rubber hose connects to) in the aluminum throttle body that is prone to rusting as well.

If the breather is operating as designed, then you would not have the issue of oil being forced out of the dipstick tube.

My recommendation would be to change it anyway.

The information that I have is that the dipstick was changed and the vent filter removed in 1965.
I believe the respective engine number cut-offs are as of engines 981 10/20 0010787 and 12/22 002991.

The breather line was also changed at the same time as the dipstick to a single plastic pipe (as well as the fitting on the valve cover).

Garry

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Re: Blocked Breather Tube
« Reply #4 on: May 11, 2012, 22:35:00 »
Thanks Jaco,

I will pull it all off and check it before driving it.  As Joe Alexander often say's start with the simple and cheaper possibilities and work up to the big expensive ones.

Garry

Garry Marks
Melbourne/ Kyneton, Brisbane. Australia
1969 MB 280SL 5 speed RHD SOLD.
1965 MB 230SL Auto RHD Lt Blue 334G, Top 350H, Tourist Delivery.
1972 MB 280CE Auto RHD 906G
2005 MB A200
2006 MB B200
2019 Izuzu DMax 4x4 Slide-on camper.
2022 Volvo XC40 Electric
2024 Volvo EX30 Electric