XUD Turbo Return to Idle Shaking

[Ian_Fearn]

Hi there, i'm a long term XUD owner but until recently have rarely need to touch one other than basic servicing.

I own a Talbot Express camper that I fitted a 306 D Turbo engine (1998 car) into a couple of months back. I swapped over to the old fully mechanical bosch pump complete with injectors etc and have ran it for about 3000 miles over the last few months. Generally it runs really well, starts well, as much power as you could expect etc and it idles well. The issue I have is the engine shaking badly for a couple of seconds as it returns to idle after any given period at speed.

The engine mounts look fine.

Any ideas?

[red_dwarfers]

Welcome to the forum Ian

Interesting one that. Are there any particular noises (missing for example) when it comes back down to idle?
Does the issue still exist or change if you
- Bring the car gradually down to idle from a high rev
- Come off the throttle suddenly from a high rev

[Ian_Fearn]

Thanks for the reply.

If you bring it down gently or if its been travelling at very low revs it doesn't do it to any noticeable degree.

No obvious missing. I don't know what the idle speed is but i'd guess at 800ish rpm (nice and steady at idle) but it feels like the idle speed drops to say 500ish rpm for a second or so.

I know theres a throttle damper on the pump which 'seems' to be working but i've no idea what its supposed to do exactly so i'm only guessing. Could the damping on this device be worn out perhaps?

[red_dwarfers]

The throttle damper is removed on most of my XUDs, shouldn't affect the return to idle issue you have.

Is there any way you're able to upload a video from a phone or something to YouTube and post a link here?

I guess if it was an air leak in the fuel line, the engine would have issues at idle too. An interesting one!

Sent from my GT-I8190N using Tapatalk

[Ian_Fearn]

I'm totally unable to capture it on film with any equipment I have. You can't replicate it when stationary and revving the engine. The engine needs to have been at 'high' speed for a period of time.

Additionally, when the engine is on fast idle setting when cold, it doesnt do it either.

Its a transient issue returning to idle where it appears to undershoot for a brief period before immediately recovering.

What it does mean is that when approaching an island say at the end of a dual carriageway, its difficult to make a quick gear selection as the movement means the linkages are all out of alignment and occasionally it does stall.

When i put the engine in, i had a trouble with whitesmoke and poor starting but advancing the timing sorted it and to prevent it always cutting out after a run i increased the idle speed a little.

I've never known an old diesel engine to have anything other than a rock solid idle.

[MikeT]

I know theres a throttle damper on the pump which 'seems' to be working but i've no idea what its supposed to do exactly so i'm only guessing. Could the damping on this device be worn out perhaps?

If you've altered the pump's settings and the idle is now off, I would try and reset the idle as per Haynes. As far as I recall, there is both a throttle damper (to smooth out acceleration) at the front and idle damper (to smooth out return to idle) at the rear. Don't confuse the two.

[Peter.N.]

On the old Lucas DPA pumps there was an adjustment that you could use to adjust the rate of deceleration, I don't know if there is anything similar on yours or if that's why the damper was fitted, most of them don't work anyway.

Peter

[Ian_Fearn]

The Bosch pump just has the return to idle damper. Its the Lucas pump with the damper on the front. All my other XUD Turbos have been Lucas.

I've been googling around the 306 forums and there is a very good guide to setting the timing and idle. It suggests the Haynes method is nigh on impossible to follow. Haynes suggests finding a setting position with a DTI. There just simply isn't the room.

[MikeT]

The Bosch pump just has the return to idle damper. Its the Lucas pump with the damper on the front. All my other XUD Turbos have been Lucas.

I've been googling around the 306 forums and there is a very good guide to setting the timing and idle. It suggests the Haynes method is nigh on impossible to follow. Haynes suggests finding a setting position with a DTI. There just simply isn't the room.

Interesting. I've only owned two xantia TD's and they both had Bosch pumps with the front mini "damper" and rear saucer-shaped idle damper/plunger. If the OP has Lucas, just ignore my ramblings.

[Ian_Fearn]

Check out the link below. Theres no damper on the front of those with the Bosch pump. Mine is Bosch.

http://www.vegetableoildiesel.co.uk/myb ... ?tid=33418" onclick="window.open(this.href);return false;

I had a 1995 Golf though with a damper on the front.

[Pug_XUD_KeenAmateur]

I recently replaced the N/S engine mount on my n/a XUD 405, which was 'clonking', especially in reverse. I initially 'ruled it out' as the source of the clonk as it seemed fine to view and I couldn't get any play out of it, levering it with a small jemmy. I un-necessarily replaced the Suspension D Bush on that side instead.

t' was only a fiver for a new mount from a popular online auction site. I didn't check how much the bottom and O/S mounts but likely a similar sum.

As you've quite recently disturbed the mounts, and they're quite simple to do, might well be worth your while replacing them to rule out the possibility. Am guessing they'll be the same or similar as mine (1995 405XUD). Also seems a bit 'wrong' that you say the engine 'shakes' at all.