DG will not idle with refurbished Pierburg 2E

[handsmann]

Apologies for re-using text that I posted on the Facebook group, but this was hard enough to describe once:

A couple of weeks ago, club members were kind enough to respond to my request for help after I bolted my Bromyard-refurbed
Pierburg 2E back onto the DG and warmed the engine up very satisfactorily. I then reconnected the throttle cable, electric
choke heater, air cleaner, vacuum hoses and crankcase breather hose and the engine could barely idle, even when fully warm.
Today I made up some new vacuum hoses for carb-to-air cleaner and air cleaner-to-warm air flap, though the ones on there
looked fine. The engine started fine - I gently revved it after 10-20 seconds and the idle speed dropped. I let the engine
run for another 5 minutes and revved it slightly once more and the idle speed dropped again. So far so good. The third
time I revved it gently, the idle dropped almost to a stall and stayed there even after the engine was at normal working
temperature. The gauge was in the centre - I don't think the fan cut in so maybe I have a thermostat issue to look at too.
I tested the following:
* Removed the breather hose to see if this affected engine speed or note - no
* Removed the vacuum hose from the distributor - idle slowed even more
* Removed the vacuum hose from the air cleaner - the idle speed increased but was still lumpy
* Stopped the engine, disconnected the wire from the choke, and restarted - idle was still very slow
* Disconnected the vacuum hose from the air cleaner and held the end of that hose and the hose from the warm air flap
together to test the flap operation. The idle speed initially rose but fell as soon as the ends of the two vacuum hoses
were in contact (which I think means the warm air flap is working). I should say that the idle speed during this test
didn't drop any more than it did by just connecting the vacuum hose back to the air cleaner
I changed the coolant when I refitted the carb and I'm confident that the cooling system is fully bled and working
properly, with the possible exception of the thermostat for the fan.
I don't want to start adjusting the mixture and idle screws, but it looks like I have to. I also should say that the
exhaust still has a tang when the engine has been running for 25 minutes, which suggests that the engine is running rich
even though the mixture was set to produce 0.75% CO2 at Bromyard. Would a failure to draw in cool air to the carburettor
have that effect?

Any Pierburg experts out there who can help please?

Thanks,

Chris

[Smiffo]

Can't help with the Pierburg issues, I have some Pierburg problems of my own too

I would say don't worry about the fan not kicking in.
It would have to go past half way on the gauge ( about 2/3 on mine ) before the fan kicks in...

[Mocki]

I'm watching with interest .......

[itchyfeet]

checked ignition timing and vac unit on dizzy? a tested carb is tested with a good engine.
hot air flap not required normally in uk, bung up a short piece of pipe at carb.

[handsmann]

checked ignition timing and vac unit on dizzy? a tested carb is tested with a good engine.
hot air flap not required normally in uk, bung up a short piece of pipe at carb.

A reply I just had on Facebook suggested that a properly set up carb may have a stronger vacuum and affect timing - so I get that totally. Someone else told me they had disconnected the vacuum hose from the air cleaner, so I'll go that way now I've heard it from you, itchy

Many thanks,
Chris

[ajsimmo]

Every engine is different so your carb will need adjusting to suit, especially idle speed. If your engine has lower compression than Bromyard's test engine, or an inlet manifold/brake servo hose air leak, for example, then it will have less "draw" or manifold vacuum at idle. You will need to screw the idle screw in slightly to compensate and set the the idle rpm correctly (don't touch the mixture screw at this stage, and not without a gas analyser). It would be a good idea to test with an old school vacuum gauge - a very useful diagnostic tool that not many seem to use these days. This would give info on the state of your engine, and maybe point towards any faults.

Sent from my SM-T210 using Tapatalk

[ajsimmo]

Btw have you called Roger at Bromyard to ask his advice?

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[jamesakers]

The Bromyard fitting instructions say the same as Andrew so that's probably the solution.

"It has been set to run at the correct idle speed and with the correct mixture control on a test engine of 114k miles and will possibly, therefore, require adjustment of mixture and idle speed of engines that vary and subject to the degree of wear."

[kevtherev]

Yep just increase the idle speed.
and check timing is ok.


I would not be fiddling with mixtures, not without a gas analyser

[handsmann]

I'd like to reply to the last few posts in a single message.

First - thank you all for taking the time to read my very long post and for giving me the benefits of your experience

The timing was professionally set when a new distributor was fitted just over a year ago - the van has run very little since then. I have emailed Roger at Bromyard since refitting the carburettor - I thought calling him would be a bit intrusive but if I can't resolve the idle issue ultimately, I will call him. It's probably fair at this point to say that I don't question Roger's work for a second - his reputation and the evidence of my own eyes convince me we have spent money wisely. His fitting notes are always on my desk - I've read them umpteen times

If the timing does need adjusting, I suspect it won't be by much because pickup when warm is good and starting is surprisingly good even after the van has stood for 2-3 weeks.

I'll warm the engine now and adjust the idle a mite. Mixture I will leave alone. I have a gas analyser but those who know better tell me it's a pile of junk!

I will report back when this is sorted.

Thanks again,
Chris

[handsmann]

Oh dear, with the engine up to temperature I turned the idle screw 1.25 turns to get a smooth-ish idle.

Now I have coolant dripping from where the choke housing meets the carburettor body.

Time to call Bromyard, I think!

[kevtherev]

Oh dear, with the engine up to temperature I turned the idle screw 1.25 turns to get a smooth-ish idle.

Now I have coolant dripping from where the choke housing meets the carburettor body.

Time to call Bromyard, I think!

loose clips or split hose

[handsmann]

loose clips or split hose

After I posted my last comment, I found a related post on the forum - I'm glad to know the solution could be a simple one. Ironically, I removed the hose clips that were in place before I sent the carb away and replaced them with 'better' ones. If it ain't broke...

Many thanks for your advice.

Chris

[handsmann]

It's Sunday - I should be putting the tree up and present-wrapping but...

I have changed the battered old hose from the 'pancake' to the air cleaner for what appears to be a new one (£15 - good price).

I thoroughly cleaned the pancake to remove a major buildup of oil and crud - God knows how long that had been there - and I don't believe it was helping matters.

I put the 'old' coolant hose clips back on the choke housing but checked the hoses and cleaned everything first. One of the spigots is badly pitted and next year might see some JB Weld on there, but for now moving the clips a couple of mm further out from the carb and tightening them properly seems to have done the trick.

I've let the old fella run for 25+ mins to go through all 3 warm up stages and he idles better than at any time since we have owned him. Smoother, quieter, responding well when I snap the throttle shut quickly and really a pleasure to listen to. I did not need to adjust the idle screw after my initial 1.25 turns clockwise (above).

Feeling very chuffed, starting to feel Christmassy and VERY grateful for the help I've received from you all.

Merry Christmas and Happy New Year!


Chris