Diesel leak dripping off sump - the investigation
 

Hi folks I would appreciate opinions on this problem, been reading around but still not there yet...

At start up from cold for about 30 seconds we get a lot of what looks and smells like diesel dripping off the sump right next to the air con pump but none of it gets anywhere near the belts or pullys thankfully, its been going on a while by looks of it as there is a nice patch on the drive thats been present "a while" but i swear it was there before just not so moist as my last few vehicles where bit leaky :shrug:.

still investigating the source of the leak, it all looks dry from up top. Cant see anything even moist looking in engine bay so if it is HP pump related must be well hidden on engine side. Got to do drive belt and tensioners soon so an opportunity to do exploratory surgery around the HP pump area approaches. Also havent yet found where the hose to return the fuel back to the tank is routed but surely that would leak constant if it was the culprit?

This ZTT hs done 160K now its a great drive my first MG (we named him Nigel as didnt seem to like a Girls name). Has no under tray resulting in sump and surrounding areabeing moist most of the time, its hard to tell under there at present where it might be coming from to drip down off the sump like it does but the HP pump is above the area as an obvious candidate. I drove another ZT recently with leaking HP pump obvious from above fuel was bubbling out of various seals and it stank of burning off diesel but Nigel doesnt stink like that, though he does run cool till i get the inline thermostat ordered in next week.

Dont think the leak is anything other than diesel though have not touched the gear box oil its on the immediate to do list along with a reverse clutch bleed, just assembling the bits needed followed by the will to do it.

Had this car two years and done 30K in that time, enjoyed most of them miles tbf its always been a little resistant to go into first or reverse from standing and previous owner said he had clutch done. Been a large man i just persuade it when its a tough day and it seems happy never had clutch issue show itself. All other levels of fluid seem ok and not had any related problems rear up (yet).

Any ideas what area might leak diesel badly for 30 seconds from bottom of the sump and then stop? Ive watched it the last few days on start up and it looks scary bad at first then stops to a drip and then nothing. When out and about i have started looking under Nigel but its usually dry with no sign of owt bad leaking at all. :shrug: Once done the clutch bleed and gear box oil maybe I will have to live with it?


Today i put a tray under the sump to collect the leaking "diesel", its very yellow isnt it and smells pretty diesel like but it stops as quickly as it starts! Thats a 500ml bottle btw so reckon about 30ml or so in there on toadys start up.

https://www.the75andztclub.co.uk/for...dd1a65b6b2.jpg
https://www.the75andztclub.co.uk/for...mg&imgid=28279

It would be a good idea to take the engine cover off then have a look in the dark with a bright led torch as you can see more in the dark using a torch.
It's an odd one is it possible that the fuel is constantly leaking a little while you are driving then it runs and pools somewhere the gets disturbed when you start the engine . Could just be a leak off pipe dripping ?

Could be hp seals...maybe expanding once heated up / pressured up enough to stem constant leak?

Thanks for reply.


Sorry didnt mention the engine cover is off and have been shining a torch about looking for it but not in the dark maybe i will try it. Had to clean up engine a bit yday especially around HP pump as bit grimey but still cant see anything leaking. Have some return line somewhere at back of beyond so might just change what can be got at on top, did note a bit of return line on injector one looked bit moist on edge but only slightly will sort that all tomorrow one piece at a time style.

Thanks for reply, I could go with that it does seem like it. Thinking about getting a seal kit and hp pump tool and having a go at it in one mega weekend see whats what when do the aux belts and pulleys as all about overdue. I shall continue to chant silently in my head "if it aint bust dont fix it".

Hi great idea :} a few days ago i nearly sht me pants when i put a large piece of card under and started the car up from cold it was first time i witnessed what i shall now call the "start up leak off". Actually switched engine off after few seconds as it saturated the card badly n looked like it wasnt stopping see photo below. On restart it went drip drip for a half minute, then drip every minute for a few minutes to practically nothing. It starts as a massive dribble somewhere in middle of sump right on the edge and spreads out a bit along the sump bottom.


https://www.the75andztclub.co.uk/for...dfb82f04bc.jpg

It may well be the regulator seals leaking, but with that sort of a leak you would think that the engine would have trouble starting and maybe a running issue?

Does the car start ok and run ok no loss of power or misfire? if it does turn out to be the regulator seals then here is link below.

https://www.ebay.co.uk/itm/BMW-530d-...1/333540124490

Thank you Arctic, am I right in thinking thats the item on the end of the rail? I noticed to today that on starting from cold the leak takes about 15 seconds to get going so its defo coming down from high lol.


The car starts and runs fine, just been out in it to collect some gear box oil from town down the road and doing that after dinner. When i was out parked up for 20 minutes whilst in shop there was one small spot under the car about size of 2p coin and on starting up no torrent like it does from cold when we suspect some pressure is building to seal things up.

No that's the HP sensor. The regulator sits on the back of the engine driven HP fuel pump. The front shaft seal can also leak on the high pressure pump, but you won't find that leaking to ground, it just fills up the sump. :}