We love Autumn.  We love driving. We love driving with friends.  

We especially love Autumn driving with friends.

We did just that Sunday past.

Some of our favourite roads and a few squiggles we weren’t familiar with were thrown into Google maps, a last minute invite was posted onto Facebook and before you knew it a cruise was happening.  

It never fails to awe how a machine can bring people together as the automobile has managed to do, for over a 130 years.

Our unlikely cast came from all walks of lives.  Quite a few decades separated the youngest from the oldest .  Several of us have only known each other for a few weeks, and most only met that day.  Yet when you throw the love of cars and driving into the mix any differences quickly faded into the background and a bond instantly solidified.

It is perhaps ironic that in an age where there seems so much strife due to differing political, religious, and social values the attack on the automobile is at its height.  Maybe rather than attack car ownership we should celebrate it, and encourage driving events, and car club membership to bring unity and fellowship.

Okay so admittedly we’re romanticizing a bit and straying dangerously near politics but the point is, it’s pretty cool how a machine can bring folks together.  Heck, for all its importance to society you don’t hear about refrigerator clubs, or refrigerator meets do you?!

Enough words.  Here are some pretty pictures.

The route snaked up and down the Niagara Escarpment in southern Ontario between Burlington and Orangeville.  Whether weaving your way up, flying down, or approaching from a distance the escarpment provides a brilliant backdrop at this time of year. 

Despite the ‘seat of our pants’ planning that was employed in organizing the cruise at least some effort was expended in choosing the route.  Some roads were hit from the direction providing the best driving experience, while others were approached with the best view in mind.  

The route took us through a number of quaint towns and hamlets including Limehouse, Glen Williams, Terra Cotta, Cheltenham, Boston Mills, Inglewood, and Belfountain where we stopped for coffee and some treats.

A big thanks to everyone for making it out, it’s always more fun cruising with others, we appreciate the company. 

This coming Sunday October 28 Frontseat Driving will be hosting yet another cruise, this time in the Niagara Region.

Expect a great variety of rolling country roads, tight winding technical driving, riverside and lakeside views, several waterfalls, and along the entire route a beautiful autumn backdrop. We’ll stop for lunch and drop into a couple of wineries worth the stop even if you aren’t a wine drinker. We’ll roll through many small hamlets, and towns and stop to explore several unique neighbourhoods along the way.

A very special thanks to Larry Strung not only for all the car photos seen in this article, but also for the great company in the Fintail.  The best backseat driver Frontseat Driving has experienced yet!  You can reach Larry at Larry.strung@me.com

We’ll leave you with this beauty – perfectly curated with autumn themed paint and a rolling ribbon of asphalt behind it.

 

Repairing a W111 Mercedes Fintail Fuel Pump


Returning home to Frontseat Driving HQ in the daily driver, we were surprised to see a puddle under our Fintail Mercedes that had been sitting idle overnight.  The bigger surprise was that it turned out to be fuel not coolant.

It isn’t often a vehicle is generous enough to break down in the driveway.   Perhaps it was her way of thanking us for the fun, and doting she’s enjoyed so far.

Driving a vintage car can be a unique experience, maintaining one a challenge, and finding parts to repair one nearly impossible.  So far we’ve been shocked at the availability of parts for the Fintail.  In fact Mercedes Classics carries nearly every part we’ve inquired about – nearly every part.  

While our immediate assumption was that a line had ruptured it quickly became evident that the pump itself was leaking from the weep holes, a sure sign that the diaphragm was damaged.

In normal operation the fuel enters and leaves from the same side of the pump.  The holes worn through the diaphragm however were allowing the fuel to spill out the backside of the pump casing and out the weep holes and onto the hot engine clearly a dangerous situation.

The entire pump splits into three pieces.  The part circled in red remains bolted to the engine block.

The part circled in blue is still attached to the fuel lines and is left hanging in the engine bay.

The diaphragm that needs to be repaired is found but not shown in the section of the pump highlighted in yellow. 


Mercedes exploded diagram of the pump.


Weep holes on backside of pump body (yellow in above diagram).


Pump housing (yellow in above diagram) showing diaphragm.


A hole through both layers of the diaphragm proves to be the culprit.

Okay so the problem had been found, now came the time to find the replacement diaphragm.  Unfortunately unlike many fuel pump diaphragms our unit doesn’t disassemble any further than pictured, so the spring, seal, rod, and diaphragm must be replaced as an entire unit.  Not only is it not offered by Mercedes Classics, it doesn’t even appear on the exploded Mercedes fuel pump diagram.  

While a new replacement pump is available it isn’t cheap, and it’s shiny.  Ideally we want this car to retain as much of it’s dirty original parts and patina as possible. 

A couple years ago, before the Fintail was even purchased we came across a forum post claiming that Fiat part number 0009918453N was a suitable replacement and that factoid was filed away for future reference.  Going with that vague info, we found and ordered the part from C. Obert & Company in Santa Cruz, California.

The Fiat diaphragm is a more typical example of a replacement part in that it disassembles to it’s component parts which can be individually changed out.  That said, the Fiat part is by no means a suitable replacement as can be seen in the following photos.  


Here the similarities of the Fiat part, on the left are obvious.


Here the differences, again Fiat part on the left are obvious.


Length of the Mercedes pump rod vs…


…the Fiat pump rod.


Here the diameter of the Mercedes pump rod is compared to…


…the diameter of the Fiat pump rod.

Initially it occurred to us that perhaps with a bit of minor surgery we could adapt the Fiat pump rod to the Mercedes.  It quickly became clear that the required alterations would be much more than minor surgery.  For now the idea of altering the rod has been shelved while we investigate an easier approach.  

Our revised approach involves disassembling the Fiat part, and using the diaphragm material on the Fintail pump.  At this point you might be saying, “But wait, didn’t you say the Mercedes part didn’t disassemble?”

Yes we did.  


The Fiat diaphragm disassembled.


Socket used to carefully cut the diaphragm.


Fiat diaphragm with hole carefully cut.

While the diaphragm material looked to be about the same size and the bolt hole pattern the same, it really was tough to tell.  We took one of the layers of the Fiat diaphragm and using a hobby knife and an appropriate sized socket as a cutting guide we cut a hole in the material big enough for it to fit around the Mercedes’ spring.

Fitting the newly cut Fiat diaphragm over the spring and between the two layers of the Mercedes diaphragms it proved to be a near perfect match.

By now the secondary plan of attack is probably becoming clear.   While the new layer of diaphragm fit well, it alone wouldn’t be capable of preventing fuel from travelling to the other side of the pump because it isn’t sealed along the inner diameter.  The next step then was to try gluing the old diaphragm to the new diaphragm.  While the diaphragms looked like butyl rubber and smelled like it too, were they?  An experiment with a couple of scraps, seemed to confirm it.


Near perfect match.


Sticking together but will fuel dissolve the glue?

The result, as suspected that the glue did not hold up to the effects of gasoline.  Tomorrow, we will try a glue known to be gasoline resistant.  We will update this post as soon as we have results.  Rather than wait to post this blog entry until the project was completed (successfully or not) we thought we’d publish it now to solicit some input.  Perhaps with the above details you might imagine a good approach.  Maybe you have repaired one yourself, or better yet you have a lead on a replacement.  Feel free to comment below with any ideas, or questions, and stay tuned for the update!

 


This cement is fuel resistant, and currently curing.


Both surfaces were scored.


Glued and clamped

After a couple days of glue, clamp, and repeat the finicky job of gluing the two diaphragms together was complete.   It looks promising folks!  That said, we have a new mechanical pump in transit.  While we aren’t thrilled with the replacement (more on that when it shows up) we found it much cheaper than that we first sourced.  If nothing else the replacement will serve as good research. 

 

Time now to reassemble the OEM pump;  

 

  • the spring plate slips into the actuator lever.
  • the open spring end fits over a post in the pump body.
  • the pump seal is fit into place on the pump body.
  • the spring is compressed while the pump rod is extended.
  • the rod mates to the actuator simultaneously. 

 


From left to right the parts are assembled.


The yellow circle shows the placement of the spring.


In the center of the pump the fork of the actuator lever is visible.


This shows how the diaphragm rod mates to the actuator fork.