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muz666
01-05-2008, 10:47 AM
Hi all,

My girlfriend has a 1972 1300 beetle.
There seems to be excessive fuel consumption, just calced it and we are getting around 11.5 miles per gallon, which is pretty shocking, I know they arn't the most economic vehicle, but i thought they should be in the 30 mpg region.

I've not really worked on beetles so could do with some pointers or suggestions.

Thanks

Murray.

kenney
01-05-2008, 11:25 AM
Hi That was not very many mpg.For a start you should check your oil to see if it is excessive.If your girl friend has a lot of short journeys,this does not help with petrol consumption,with the type of choke these engines have,Is there much black smoke from the exhaust?You need to look at the heat hose running from the exhaust to the air filter,if this is not in place you will get icing on the carb.and excessive fuel consumption.

muz666
01-05-2008, 12:16 PM
no its pretty shocking! it doesn't seem to go thru much oil. journeys are varied, but she said she used to get 200+ miles out of a tank, now its 80 ish.
No black smoke, overall runs pretty good, passed emmisions on the mot 2 weeks ago, so i'm scratching my head as why its so bad. Also there doesn't seem to be any fuel leaks either. I'll check that hose you mentioned. thanks.

kenney
01-05-2008, 12:42 PM
When i said check the oil i did not mean oil consumption what i meant was, that there was not too much oil.What happens is, when the hose i mentioned is not in place, or if one has many short journeys the engine does not reach a high enough temp,unburned fuel runs into the oil and dilutes it.You can smell this on the dip stick.

Crasher
01-05-2008, 12:52 PM
Also needle valves tend to become poor at seating and allow excessive fuel flow. Often the best solution is to fit a new carb from GSF, they are copies of the original but pretty good. I think the one for the 1300 is made by Bocar and I have used them to good effect. Another cause of carb icing can be the runners under the inlet manifold becoming blocked BUT DO NOT TOUCH THESE WITH THE ENGINE RUNNING as if they are working, you will burn yourself badly.

muz666
03-05-2008, 10:18 AM
Thanks for the pointers guys, gonna take a look today.

A new carb seems pretty reasonable too from gsf.

One final thing, i have heard thats post 68 beetles can run on unleaded with no mods, is this true? reason i ask is at present the beetle is run on lrp, and i personally think it is rubbish fuel.

Crasher
04-05-2008, 06:29 PM
Theoretically all air cooled VW engines have hardened valve seats and quite strong valves but officially only heads made after 1976 are strong enough (I am being intentionally simplistic hear, I don’t want to baffle you). The other problem is most engines have been rebuilt and you cannot vouch for the quality of the parts used. The way to find out is the use unleaded and see what happens, if it burns a seat, fit a pair of new complete heads which will be unleaded suitable. Other than that, run it with an approved lead substitute additive such as from Red Line. I rebuilt my Bugs engine a few years ago and fitted a pair of brand new heads and stainless valves although I haven’t run it yet.

muz666
01-06-2008, 11:03 AM
There is a noticible smell of petrol in the oil, the carb itself look quite new, its a solex one. I believe that the GF's dad put a new carb on it a while ago.
Checked the air pipe from exhaust to air filter, it is present and connected. I also noticed the bit that looks like cool air or hot air selector valve is loose, well the mech is.
The 2 pipes that go to the top of the air filter had perished at the ends, so i have trimmed them back and one of the pipes was blocked.

I am not sure what is meant by the intake runners, so a couple more pointers would be great.

We have put unleaded in, the car actually runs better, doesn't hesitate and the idle seems good.

Crasher
01-06-2008, 02:50 PM
Petrol dilution of the oil can be caused by over fuelling which on that engine can have many causes and severe dilution can indicate that the fuel pump diaphragm is leaking which allows fuel to enter the crankcase directly but this is quite rare. The manifold runners are pipes that come from the exhaust to the inlet manifold and the set up varies according to the engine. If you can post a good picture of the engine bay I will point them out to you.

muz666
01-06-2008, 08:01 PM
Thanks for that, i dont have anywhere to upload images thou.

Crasher
01-06-2008, 09:11 PM
email sent.

Crasher
02-06-2008, 09:49 AM
The red arrows point towards the inlet manifold pre heat pipes, these must get very hot when the engine is running but DO NOT TOUCH THEM with your fingers, I did that once about 25 years go and took the skin of four of my fingers. I use an infrared heat gun but a wet cloth dabbed onto the pipe will tell you how hot they are.

The fuel pump is a Brosol and they are known for over enthusiastic pumping and diaphragm leakage but the proper Pierburg units are now obsolete and so are genuine VW supplied parts.

I suggest you remove that fuel filter from the fuel pump to carb fuel line as they should not be used there due to the possibility of bursting, more than a few bugs have gone up in flames because of this. A fuel filter should only be installed on the suction line under the car and even then should be correctly secured so as not to rub on the drive shaft or the heat exchanger.

That carburettor is a Bocar and they are reasonably OK so I suspect your problem is fuel pump over pressurisation. It probably won’t be inlet manifold icing even if the heater pipes are blocked as just below the carburettor is a little electric blanket called an IMDU (Inlet Manifold De-icing Unit) which is made in Nottingham by a friend of ours from years ago and it is designed to heat the manifold to stop it icing. When we have had this problem, we have fitted an in-line fuel pressure regulating unit to the fuel line after the carb, in the same sort of position that the filter is on this car but not tucked away like that as there isn’t room.

On top of the air cleaner, there is a valve with two pipes going to it, this is more than likely faulty but is still available from VW under the part number 113 129 828 A for £38.16 and it would make sense to change it as a precaution, it helps prevent carb icing, something the IMDU cannot do, that prevents manifold icing.

If I can be of any further help, please don’t hesitate to ask.

muz666
07-07-2008, 12:23 PM
I have fitted a new fuel pump to the car and also checked the entire fuel lines for leaks. The beetle had the fuel line done about 5 yrs ago and the person that did it fitted a flexible all the way along the underside of the car. There were no leaks from this. I also went and checked all the clips and clamps from filler cap to carb, tightened them up where needed. The tank is in good condition and no leaks.
Fuel consuption is still rubbish so I'm still scratching my head as to the cause, my next idea is to do the needle valves on the carb. I have the original one in the garage so thinking of overhauling it and refitting it. Is this the best action or should i be looking elsewhere for the problem?

kenney
07-07-2008, 01:03 PM
Hi A couple of things we used to do,which usualy helped for petrol consumption.The first, adjust the choke element off as far as you can without the engine being difficult to start when cold.There is a membran on the front of the carb which pulls the choke off when you apply the throttle,see if this is working.There is a small pipe on the top of the carb which injects fuel when you apply the throttle,and the amount of injection,you can adjust.You can try with a smaller main jet,when on that subject i have seen these loosen.We have lowered the fuel level in the carb housing,by placing a thicker washer under the needle valve.One last thing,if you remove the tailpipes,in the center of one of the outlets you will see a pipe this should be in the center,if not then you can adjust it, then measure the distance from the end of the pipe to the end of the outlet on the silencer and mark the same distance +1cm on the tail pipe. The marking should be at the edge of the outlet when you assemble the tail pipe

muz666
07-07-2008, 04:12 PM
I don't totally follow what you are saying about the tail pipes, but will have a look and see if it makes more sense with the engine infront of me.

I am thinking of installing a fuel regulator, but would like to exhaust other possibilities before bolting more bits on.

Albie1
17-07-2008, 01:14 PM
An air -cooled beetle shoulld deliver 30 - 35 mpg if properly tuned on a good engine. Dip-stick levels will be high if you are losing fuel into the oil.
If engine has done 150 000 + miles a good reconditioned one will be in the range of £500. A new one for £800+ [ plus carb etc...]
Reconditioned ones should have Heads that will run on unleaded fuel.;)

muz666
17-07-2008, 02:12 PM
The oil still smells of fuel, oil consumption seems to be about the same as it has always been.

The Engine has done in the region of 250-300k, had a new carb fitted 6yrs ago, I am thinking of a recon, but would like to see if its the set up causing the problem.

Would the distributor have much effect over fuel economy?

The other thing I have noticed is that the idle speed fluctuates quite a bit, weather conditions seem to affect it, its a bit strange, i can understand you get better performance on a cold day as cold air is denser.
Also the drivability is also affected, some days, you get good acceleration and response other times the car trys to swallow its back end.
This is leading me onto whether there maybe an issue with the dizzy. it has a bosch vac advance unit on it, and I have been looking into the 009 ones.

Crasher
17-07-2008, 03:46 PM
I would suggest VW Heritage for one of their brand new Mex units if they have some or possibly a Remetc unit if finances are tight but they use align bored cases and I don’t like them. I have been building (mainly AB 1300 and AD/AS 1600) air cooled engines for over 25 years and I will only re-use a case if it is standard on the mains and in perfect condition, otherwise I buy a new case. I only tend to build semi auto engines now as they have some differences Remtec and Vege (another good reman company) don’t cover.

Personally I don’t like 009 dizzy’s, they cause a lot of running problems such as flat spots or high engine temps due to dialling out the flat spot with advance. I prefer to have the original dizzy re-coned and fit a Magnetronic electronic ignition module to replace the points.

Albie1
20-07-2008, 11:28 PM
250.000 + miles on an air-cooled engine! Time for a rebuild or new/recon engine I think. I bought one from Stateside Tuning fitted a single Weber progressive carb 009 dizzy and new fuel pump. What a difference - better mpg and I can go up hills in 4th gear. Not a cheap deal though.
If the manifold pipes are blocked/iced that can cause rough running. I find the 009 fine and I use contact points.
All depends what you use your motor for - you can tinker with the carb etc..
and still get around, however if you want reliability/distance best to think recon.