Carb Heater(s)

Hi guys,

I have fitted a weber to my golf 1.8 clipper. I am having problems with what I expect to be carb icing. Itll run fine until I put my foot down (driving me crazy as Ive done loads of work to the car and have no idea if the thing is any quicker) after Ive given into temptation the car will only run on the second choke. i.e. you wouldnt be able to just cruse at one speed its all or nothing really. It judders violently trying to drive normally.

Pete and maximo advised me to check my air box and flap thing. Now I just want to be sure that my heater(s) are working. Am I right in thinking you can check the one under the carb by turning the ignition on and feeling for heat under the inlet manifold? Ive also heard talk of a second heater in front of the carb. Is this something I should have remover from my old carb and fitted to the weber? No idea what this second heater is ( if it exists) or what it looks like.

Thanks for any help guys

 

dont think they get that hot tbh. the best what to check if they are working is check they are getting 12v then they will likely be working. Did you take the front heater off the 2e2 and put it on the weber>?

 

Yes mate, if you turn the ignition to the last position before cranking, and grope around under the rear of the inlet manifold, you should feel it start to warm up within a minute if all is well with the manifold heater. Obviously, it's got a lot of metal to warm up, so don't expect instant warmth. I'll check this on mine at lunchtime, just to make sure it does work with engine not running, and maybe I can give you a better idea of how warm, how fast.

The second heater is a little cylindrical dude about 16mm diameter by about 20mm long, with a single black wire emerging from it. Item 37 on here: http://www.gowerlee.dircon.co.uk/2E2type.html

On the Pierburg carbs it mounts low down at the front and directly warms the idle fuel outlet area. You can probably find one at a scrappie if you have disposed of the old carb. It's held on by a little sprung bracket and a single M4 screw. Not sure where or how it fits on the Weber, someone'll be along shortly to advise, I'm sure.

I'm running a very unprofitable business in refurbishing these little dudes for free, if you find one that looks dodgy/broken wire etc. PM me as reqd.

I'm not 100% sure this is your problem btw, but it can't hurt to find/fit one.

 

The 2nd heater is exactly where EZ Pete said. It the same on the weber and pierburg.
I noticed I had carb icing without the heater, my carb doesnt seem to suffer from it now I have fitted it.

 

Here it is in position on a weber, black cylinder low down on front. It screws to a bracket that is screwed to the weber baseplate.
You can feel both heaters with just the ignition turned, the engine doesn't need to be running.

 

Teehee, bloody typical. Just went out to see how warm it (manifold heater) gets, how quick - and... not a hint of heat!

I've got a feeling I need to check the relevant relay...once I've found which one it is.

Anyone know which number/posn on a post-'90 fusebox?

[:^(]

Edit: Found the relay but it seems fine...maybe my thermoswitch? (Pardon the hijack please Nathan!)
Out with the voltmeter after work I feel...

 

hey guys

thanks for all your help (again) still have my old carb so will swap the heater over tonight. Thanks for the offer pete. I'll let you know if my one's broken.

Thanks again - i'll let you know how i get on and if it makes a difference.

 

If the wire looks OK where it comes out of the cylinder, just make sure the brass end/face that pushes up against the carb/baseplate is nice and clean. Also clean the bit it will press on, this physical contact is the (only) earth return connection for the heater element.

Oh, and if you can get the connector on the far end of the wire out of its plastic housing and give that a clean, all the better. There's a little metal tab that needs to be pushed in with a tiny screwdriver to release the connector from the housing IIRC.

 

Cheers John, really good to see you back on the carb forum.

It's an odd one, 'cos before I took off t'intake manifold the hedgehog was in exactly the same state as it is now - has 12V feed, manifold is well earthed, but when I measure the current going to the hog (cold engine) it's less than a tenth of an amp. Should be massively more, fused at 20A iirc.

After I 'fiddled' with it and tested it on the bench while the manifold was off, it worked well, drawing enough current to pull down the voltage of the beefiest bench power supply I could find (10Amp o/p), and getting hot quick into the bargain.
When manifold went back on I still could feel it heating the manifold from cold with just ignition on (to avoid confusion with exhaust manifold heating). Assumed it was fine ever since, until now...

Checked the thermoswitch, and the relay (and the fuse!), but the fact that the hedgehog's feed wire has 12V exonerates these anyway, unless I'm being daft .

Anyway, a kind member on here is sending me an unwanted hog to (non-destructively) dismantle and see what else could be going on inside the thing. May be a struggle, as once you've got into the cover (drill out three rivets) there's a tricky looking internal circlip, without any bits to grab, but I'll find a way .

 

The manifold heater relay is in position 12 - bottom right - and numbered 1 on late models with CE2 fusebox. When fitting the Weber kit you keep the hedgehog heater in the manifold but not the one on the front of the carb. Can't do any harm to fit one but mine hasn't got one and once I'd got the hot air feed working properly the carb icing became a thing of the past.

Barkstar

I will finish a Weber DMTL FAQ soon honest

 

Hi Barkstar, as it happens I've just spent a merry hour or so staring at Haynes wiring diagrams and rubjonny's fusebox FAQ, with some success (comprehension). There doesn't seem to be a fuse in the hedgehog feed, contrary to what I thought before.

I have a vague theory that could explain my problem... At the very top of the CE2 rear wiring info rubjonny says "30-30b - red- bridged on GTI models (Fuel pump relay) "

but on Haynes (1081) page 12.47 diagram 53, 30 & 30B are shown linked on the carb models too, to power the hedgehog via its relay. I'm wondering if I have a dodgy connection here (high impedance, not completely disconnected), so that when the hedgehog relay is energised, I see 12V at the hog's feed wire, but 'cos of the high impedance/bad contact of the dodgy link, no significant current can flow...

This suggests that I hallucinated the hedgehog having worked after the manifold went back on, but I wouldn't put that past me.

Another mad theory from EZ_Pete... Well, hopefully, come daylight I'll know.

 

First of all, apologies to Nathan for the hijack to his thread, hope your trouble was solved.

Well, I thought I'd cracked it for a second there... Got the fusebox exposed and found the 30-30B link-wire (it actually went Y2-30B, but I'm pretty sure that's same difference). The 30B end had significant signs of corrosion! I guess that wonderful bonnet-release cable water-leak thing. Anyway, cleaned up the two halves of the connection and replaced; ignition on.........and still no bloody warmth out of the hedgehog .

I'd actually pretty much convinced myself that this bad contact on the 'live' side of things couldn't be it, 'cos I'd not be measuring 12V at the feed wire (with it connected), it would be much less, so the trouble must be internal to the hog [:^(] . Ah well, at least I know how to get to the back of my fusebox now.

Edit: just had another look at the Bentley picture, and it's Y3-30B that my link does, not Y2. Pretty sure all the Y's are circuit 30 so should be fine.

 

Y has a 6mm red wire going to Y4 (bottom rh corner when fusebox is rotated down) Y3 is next to it one tag to the left.

Haven't tried pulling the relay and measuring at the contacts, but I will now... Nowt to lose . Ta.

Reckon I might have edited my '3's to 'Y3's while you were typing, sorry.

 

Measured:
6/30 = permanent live
8/86 = live from thermoswitch (ig on)
3/85 = earth
4/87 = well, nothing, 'cos the relay's out.

If I push the relay into position with ignition on I can hear and feel it switching on.

Slightly confused by the interchanging of live/earth on 85 and 86 (contradicts Haynes), but I know there's no diode inside the relay cos I had a good look at it's internals/contacts the other day, so shouldn't make any odds.

Hoping my spare hog'll turn up with the post.

 

all good stuff, if you're planning to leave the ignition at the "run" position for any length of time (whilst testing the various heaters) then you should remove the power to the coil to avoid burning the coil out

 

I would not have thought of that, cheers Drew. Note to self: Must learn about ignition coils soon.

Just had a 5W test lamp lit on the end of the red/white hedgehog feed wire, lit up nice and bright, now looking around for something that'll take a few amps to really prove the supply side...

Also gonna try putting the meter on 10A range direct from batt+ to hedgehog feed wire. If the hedgehog's OK I should blow the fuse in the meter

Edit: Disappointed...meter still works.... registered 70mA of current, that's hardly gonna burn anyone!

Meanwhile, the Postman's just been, delivered my spare hog, and had a fun chat about how good Golf's are, he has a mk3 apparently. lol.