560SEC fuel leak

When I last used my 560SEC before Xmas, I noticed a rather large puddle of petrol underneath it.   I’ve not driven the car since as it is rather dangerous to drive with such a leak.   I had assumed it was probably fuel hoses.  Many cars run on E10 rot their hoses.  I purchased a few of the relevant hoses so I would only have to do the job once.  In addition, I had previously acquired a filter for the car and keep a spare K-jet fuel pump just in case.

Here in Sydney it has been mostly mid 30s C and 80% humidity for the last two weeks, so I have not been particularly motivated to work on the car.   We finally got a break in that weather so I went down and had a look.

On removing the cover, I found the main leak coming from one of the two fuel pumps.   I also found the fuel hose from the filter to the hard line that supplies the engine had been poorly modified for the wrong fuel filter.  It didn’t look like it was in great condition either.

560SEC fuel leakThe picture above shows the replaced pump (the one furthest from the camera) and the replaced filter (above the front pump).   The hose in the foreground is the one that looked bad, it had been cut and a different hose spliced in to attach to a different type of fuel filter.     A pump and filter change on these cars is simple, but a little fiddly.    Unlike the 300SE, the fuel that came out of the filter was not dirty.

While I was able to get the pump and filter changed readily, I was not able to disconnect the fuel hose from the hard line.   The hard line is up behind the differential and drive shaft, and my 17 and 14mm spanners were too large to get up there.   I tried for a while, but not wanting to break the hard line, I decided to give up and have somebody else look at this.   Luckily there is a European mechanic 20m away from my little workshop.   I’ve never used them before, but this is a good opportunity to push the car down and see if they can get this sorted out for me.   They seem to mostly cater to BMWs, but I’ve seen a 560SL there before.    With the pump, filter and this hose changed, it should cure my 560SEC fuel leak.

In the future, I wouldn’t mind changing the hose from the tank to the fuel pumps, as it looks a bit older.   I don’t have one of these hoses to hand and the tank would need to be drained, so better to wait until its mostly empty.

Before I started this job, I noticed another issue.   I had pushed the car back into place because of its leaking fuel pump and not moved it for a few weeks.   Pushing it back out I noticed a massive pool of ATF on the ground.

560SEC ATF leak

Strangely enough, while I was using the car daily, I hadn’t seen a leak.   The car did come to me quite low on fluid. There is obviously a leak that seems more based on time than use.  Looking under the car, it seems to be on the plastic attachment with the two lines coming out of it.   Possibly there is some kind of O-ring that has broken there?

ATF leak



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