pierburg to weber

Big lumps of metals and spanners. Including servicing and fluids.

Moderators: User administrators, Moderators

Post Reply
Betty boop 1
Registered user
Posts: 54
Joined: 13 Feb 2017, 18:41
80-90 Mem No: 0

pierburg to weber

Post by Betty boop 1 »

so we have just changed bettys carb on her 1.9dg from the original pierburg to a weber DMTL 32/36 and she is driving really well so far the carb fitting work was carried out by our local garage that looks after her and know her.... but their is a niggle... that little voice your head thats screaming something doesnt look right..... and try as i might it wont shut up so here's the voice 1: the original manifold coolant pipes for the peirburg have been joined.....is this right
2: the fuel return has just been blanked off ???????????? is it there for a reason
3: she has started running REALLY hot..hotter than usual is this because the coolant pipes have been joined
were going to the netherlands in just over a weeks time so any help would be great as that little voice is getting louder as is the bosses paranoia

User avatar
937carrera
Registered user
Posts: 3599
Joined: 05 Apr 2015, 19:29
80-90 Mem No: 16333
Location: N Yorks.

Re: pierburg to weber

Post by 937carrera »

Some quick thoughts

1. New carb probably doesn't use the coolant pipes to prevent carb icing
2. Carbs don't need a return,
3. If the engine is running hot I would be concerned that the carb mixture was running lean

You should really ask the questions of the garage that fitted the carb, especially on question 3

I have a Weber DAT on my WBX, and I'm happy enough with it
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

Betty boop 1
Registered user
Posts: 54
Joined: 13 Feb 2017, 18:41
80-90 Mem No: 0

Re: pierburg to weber

Post by Betty boop 1 »

cool thanks for that.... so is the return pipe a quirk to the peirburg ?....coolant pipes make sense as they are bypassed on my mini :ok and with out sounding like a putts how would you test for lean running.... would that be with an emissions test :?

User avatar
CJH
Registered user
Posts: 3018
Joined: 15 Jul 2013, 06:51
80-90 Mem No: 12576
Location: Nottingham

Re: pierburg to weber

Post by CJH »

The coolant pipes to the Pierburg are for the automatic choke - the heating of the coolant indicates that the engine is warmed up so the choke comes off.

The fuel return on the Pierburg allows a constant flow of fuel through the carb, which I've read helps to ensure that the fuel in the carb stays cool. Having said that, I ran for a while with a slightly larger Pierburg (from a 2.4 VW LT), and that didn't have a return. The float valve should shut off the fuel inflow, so the return isn't needed.

The hot running won't be due to the coolant pipes being joined - they were effectively joined when they were connected to the Pierburg choke anyway. Possible mixture adjustment issue? Too lean perhaps?*

*E D I T: Oops - I see that was already suggested.
"I'm a man of means, by no means....King of the Road!"

1983 Viking Xplorer, 2.1DJ

User avatar
937carrera
Registered user
Posts: 3599
Joined: 05 Apr 2015, 19:29
80-90 Mem No: 16333
Location: N Yorks.

Re: pierburg to weber

Post by 937carrera »

Betty boop 1 wrote:cool thanks for that.... so is the return pipe a quirk to the peirburg ?....coolant pipes make sense as they are bypassed on my mini :ok and with out sounding like a putts how would you test for lean running.... would that be with an emissions test :?

An emissions test doesn't test under load, the best way to do this would be an exhaust analyser in conjunction with a rolling road. However, your garage should really have the experience to set the carb up on idle and with the correct jets so the mixture stays in the right range through the rev and load range.

Alternatively, something else may have happened at the same time the carb was fitted, which is why you need to let the garage look at it and fix it.

CJH is right by the way on the choke aspect of the coolant pipes and the return pipe allowing the fuel in the carb to remain cooler. I went to type choke and carb icing came out :oops:
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

User avatar
Ian Hulley
Registered user
Posts: 12659
Joined: 11 Oct 2005, 08:08
80-90 Mem No: 1323
Location: Wirksworth, Derbyshire ... or at t'mill

Re: pierburg to weber

Post by Ian Hulley »

Buy a new Pierburg, forget the Weber, they are $hite.
The Hulley's Bus
1989 2.1DJ Trampspotter
LPG courtesy of Steve @ Gasure

Post Reply