Erratic idle diesel
Erratic idle diesel
Hi. I have a 157k mile, 1991, 1905 Bx. Recently, I have noticed the when idling it sometimes seems to hunt between around 750 rpm to 1000 rpm and then often settles on an idling speed of around 1000 rpm. I have checked the throttle is returning properly (it seems to be fine). Anything else to check? I'm getting married on Saturday and going on honeymoon in it on Sunday and don't fancy breaking down in deepest darkest Wales!
Thanks in advance!
Rob.
Thanks in advance!
Rob.
19 TGD estate
17 TZD Turbo hatch
17 TZD Turbo hatch
- jonathan_dyane
- BXpert
- Posts: 975
- Joined: Sat Feb 09, 2008 7:15 pm
- Location: Liverpool
Has it just started doing this, and does the car have a Lucas pump? If so, an uneven idle can be caused by the bearings starting to break up, and clogging up the pressure relief valve and correspondingly causing the pressures to be all over the place and an uneven idle.
This is easy to check for, as the pressure release valve is within the banjo that attaches the diesel return pipe to the injector pump. I would recommend that you remove the banjo for inspection (removed you should be able to easily rattle it's ball bearing by shaking it, and there should obviously no sign of swarf within it).
Another (probably more likely) possibility, is the fuel heater on the back of the engine gone/going porous. This is a casting fitted to the rear of the water pump area, which is intended to heat the diesel in winter conditions. Sadly the heater is made out of a form of allow which is closely related to cheese, and they always go porous. I suggest that you check to see if the diesel feed still flows through the heater (access best from below IIRC) and if so bypass it with some suitable tubing. The car will not suffer any ill-effects from not having a fuel heater.
This is easy to check for, as the pressure release valve is within the banjo that attaches the diesel return pipe to the injector pump. I would recommend that you remove the banjo for inspection (removed you should be able to easily rattle it's ball bearing by shaking it, and there should obviously no sign of swarf within it).
Another (probably more likely) possibility, is the fuel heater on the back of the engine gone/going porous. This is a casting fitted to the rear of the water pump area, which is intended to heat the diesel in winter conditions. Sadly the heater is made out of a form of allow which is closely related to cheese, and they always go porous. I suggest that you check to see if the diesel feed still flows through the heater (access best from below IIRC) and if so bypass it with some suitable tubing. The car will not suffer any ill-effects from not having a fuel heater.
"Boring damned people. All over the earth. Propagating more boring damned people. What a horror show. The earth swarmed with them." -Charles Bukowski
Thanks for that Jonathan; very much appreciated.
The symptoms first showed themselves a few weeks ago. I noticed it once and didn't notice again until yesterday. Today, it's fine.
I haven't got any time this week - last minute wedding preparations but if needed, I can probably get the car to my local specialist. Are either fault likely to cause more problems or get rapidly worse if left for another 2000 miles (I am thinking I would rather not have to sort out anything car related until after my holiday in it)? I appreciate that it is a bit of a "how long is a piece of string question" but am I on borrowed time?
Thanks again,
Rob
The symptoms first showed themselves a few weeks ago. I noticed it once and didn't notice again until yesterday. Today, it's fine.
I haven't got any time this week - last minute wedding preparations but if needed, I can probably get the car to my local specialist. Are either fault likely to cause more problems or get rapidly worse if left for another 2000 miles (I am thinking I would rather not have to sort out anything car related until after my holiday in it)? I appreciate that it is a bit of a "how long is a piece of string question" but am I on borrowed time?
Thanks again,
Rob
19 TGD estate
17 TZD Turbo hatch
17 TZD Turbo hatch
- docchevron
- The Immoderate half of the admin team
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It's possible.
What make of injector cleaner was it mate?
They dont all do quite the same thing.
Equally, Lucas pumps do some eraatic stuff if any air gets in to the system, but quite sporadically sometimes..
What make of injector cleaner was it mate?
They dont all do quite the same thing.
Equally, Lucas pumps do some eraatic stuff if any air gets in to the system, but quite sporadically sometimes..
Smokes lots, because enough's enough already!
Far too many BX's, a bus, an ambulance a few trucks, not enough time and never enough cash...
Far too many BX's, a bus, an ambulance a few trucks, not enough time and never enough cash...
Hi Doc,
I an't remember what make it was, just the cheapest from halfrauds. I also filled up with the "super" diesel at a shell garage last tankful - I'd queued for ages in a line and realised that there was no normal diesel. Couldn't be arsed to queue again!
Thanks,
Rob
I an't remember what make it was, just the cheapest from halfrauds. I also filled up with the "super" diesel at a shell garage last tankful - I'd queued for ages in a line and realised that there was no normal diesel. Couldn't be arsed to queue again!
Thanks,
Rob
19 TGD estate
17 TZD Turbo hatch
17 TZD Turbo hatch
- mat_fenwick
- Moderator
- Posts: 7326
- Joined: Tue Sep 20, 2005 4:08 pm
- Location: North Wales
- x 19
Hi matt, thanks for the kind offer. I'm spending a week in a cottage near Lampeter (not sure I've spent the correctly!) then off to Llangollen for a night followed by a week on a narrowboat on the llangollen canal. We're hoping to to to Llangollen via Harlech. I love Wales, I only really discovered it a few years ago when my twin moved there (he's an outdoor instructor) but have had some great holidays over the last couple if years. Where's ffestinog?
Welsh place names scare me witless - I dread getting lost whenever I'm there!
Best wishes,
rob.
Welsh place names scare me witless - I dread getting lost whenever I'm there!
Best wishes,
rob.
19 TGD estate
17 TZD Turbo hatch
17 TZD Turbo hatch
- DLM
- Our Trim Guru
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- My Cars: Historically, lots of BX hatches/estates in the 90s/00s - 16/19i/17td/19d
Recent scruffy diesel n/a estate - "The Red Shed" - is no longer mine. - x 9
Another possibility is that the rubber diesel filter primer diaphragm is perishing away - but I'd expect that to show up at times other than idle. Air bubbles will be seen in any subbed-in clear tubing upstream of the pump, (a giveaway that it's happened before) and random minor surges and dead spots become an everyday occurrence - if you can get the thing started in the first place..
I'd also recommend not pushing away at the primer button in an attempt to provoke the problem ... as it almost certainly will provoke this problem. A spare diaphragm is a useful part to have salted away.
I'd also recommend not pushing away at the primer button in an attempt to provoke the problem ... as it almost certainly will provoke this problem. A spare diaphragm is a useful part to have salted away.
Back on two wheels and pedal power for the moment.
Interesting stuff... I have a Lucas on my A8A with a different problem. Sometimes, when driving at a steady speed, it suddenly starts to accelerate the car for a short while. Although the idling is always steady, I will suspect the pressure release valve.
The most problems I've had was with faulty wiring to the fuel cut-off valve, having a large resistance somewhere. Since I'm lazy I removed the valve and now stop the engine by popping the hood and push the stop lever.
The most problems I've had was with faulty wiring to the fuel cut-off valve, having a large resistance somewhere. Since I'm lazy I removed the valve and now stop the engine by popping the hood and push the stop lever.