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bobbybrown
09-06-2013, 11:14 AM
Hi all,
Got an engine query, it appears to be firing and combusting however the exhaust on the left side of the car doesn't get anywhere near as hot as the right one and the engine is down on power.
Quite seriously down on power, don't get me wrong it's been a long time since I've driven an old air cooled vw but they should "want" to drive :lmfao:

Not sure what to check first, it's got new plugs, points, cap, rotor, coil, condenser and tried two sets of leads.

Was leaning towards the carb on the left side or even a slight gap causing an air leak on the manifold for that side as it only seems to be the left side causing the issue.

Open to any and all suggestions, been a while since I've had a vw air cooled to work on, it's a 1641, so thought I would gather opinions and ideas from here first.

It will start and idle quite happily, just isn't quite right.

Cheers

jasoncambs
09-06-2013, 12:13 PM
I had this once , i remember taking off a rocker cover and having a tap about but then it decided to then be ok afterwards

If you have a spark yhen it gotta be fuel starvation



Check coil
Points (just open them with ignition on to see for spark )
Dizzy and rotor arm
Leads
Fuel ,

I would chuck a egg cup of fuel down the carbs prior to starting to see if cylinders come alive ,

bobbybrown
09-06-2013, 12:18 PM
Coil is brand new and have tried both new and old one, the points are sparking, dizzy and rotor are new, good amount of new fuel and new plugs. Tried swapping the leads but the issue seems to stay the same.

jasoncambs
09-06-2013, 12:21 PM
Just a thought ,
If it idles ok then you need to check the jet that squirts when you push the throttle , it may be blocked
While looking into the carb barrel with engine off ,give the acceleration lever a push and see if you get a sqirt of fuel from it ,

If not that may be blocked eith some bit og grit etc

jasoncambs
09-06-2013, 12:23 PM
The engine idles from one jet , and a pump from accelerator pushes a diaphram on the side of carb injecting a jet to give it responsiveness

KEITHCANFIXIT
09-06-2013, 04:57 PM
Just about to suggest same as Jason, sounds like blocked jet, filter off ,engine off ,press throttle while looking down barrel, should be nice decent squirt of petrol out of jet into throttle body , if not remove and blow through with compressed air.

MicksRedNova
09-06-2013, 06:41 PM
When mine was running hot one side a cold the other it turned out to be the leads the wrong way found.

Mick

Spacenut
09-06-2013, 09:14 PM
Mmm, yes, that's another one for the list Dan!

Unlike an inline 4-cylinder engine, the boxer has 180° between firing pulses and so a number of different firing sequences can be used, while still maintaining perfect balance, not just the standard 1-3-4-2 of the I4.

I believe for the Beetle engine the sequence is 1-4-3-2, but you might want to check because my Alfa boxer uses a different crank design and fires 1-3-2-4!

Distributor rotation is clockwise in each case.

Lauren

bobbybrown
09-06-2013, 09:22 PM
Thanks both, the leads have been checked, checked again and then a few more times when the engine originally was refusing to start.

Just posted an update in the "your cars" thread, if that doesn't solve it then I will again investigate the leads.

letterman7
11-06-2013, 04:49 PM
Hi Dan,
Firing order is printed on the riser on the oil fill under the generator. I think Lauren has it at 1-4-3-2, but it's been a bit since I looked at it personally. In any case, easy test - get the engine running, then pull one lead off the distributor cap at a time. See if the engine wants to choke as you pull each successive lead off. If one lead comes off and the engine doesn't change - that's your bad cylinder(s). Could be the lead or the spark plug. If you have a non-contact thermometer, aim it at each header connection at the head; low temp will also pinpoint the problem child. If it's both cylinders on one side, then it's definitely a carburetor issue, either a plugged jet or not tuned correctly.

R

Peter
11-06-2013, 08:15 PM
1 4 3 2 it is :thumbup:

jasoncambs
12-06-2013, 03:52 PM
Have you checked the plugs are of correct length , you havnt put short threads in by mistake !!!!!

bobbybrown
12-06-2013, 04:10 PM
No :crylol:
Update,
Compression test done, good compression on all cylinders and all the same sort of values so, moving on.

Changed the plugs and leads again for brand new ones, still the same.
The left sound of the engine sounds more rattley than the right and also if you rev it hard after a few seconds the left side "pops", almost like a backfire sound.

Smell of fuel on left side is present more than the right side.

What else could this be?

jasoncambs
12-06-2013, 04:25 PM
Worn lobes on distributer , ?!

Untill you swap the carbs now we need to eliminate the carbs

bushboy
12-06-2013, 04:40 PM
Check your dissy cap for cracks or other signs of arcing. You may find that the non firing bank may be due to corroded or burnt pickups in the dissy cap. Has it also got a centre carbon? or is the dissy shaft bent causing the points not to open correctly on those two cylinders? And the old favorite, have you got the plug leads on the correct plugs? I did this on the V6, it rans as smooth as silk, just no power & only one bank got hot!!!

Bushboy

bobbybrown
12-06-2013, 05:46 PM
Will swap the carbs over Sunday if I don't get chance before.
The dizzy cap is new Martin.

I'm 99% certain the leads are on correctly, followed both the haynes manual I have here and also reference from a VW website.

Anyone have the order of the leads so I can double check? May as well rule that out as well.

jasoncambs
12-06-2013, 05:57 PM
The lobes on dizzy shaft that open the points , check they open on the 2 lobes reference the non working cylinders

KEITHCANFIXIT
12-06-2013, 06:53 PM
Hi Dan

Cylinder orientation is as follows

Left side towards front of car cylinder 3, right side towards front of car cylinder 1, left side rear cylinder 4, right side rear cylinder 2.


Distributor

Standing at rear of car looking down on distributor ,right side upper cylinder 2, left side upper cylinder 3, right side lower cylinder 1, left side lower cylinder 4, or to put it another way, at 2o'clock 2, at 4 o'clock 1, at 8 o,clock 4 and at 10o'clock 3.

Still think you have bad air leak which would account for petrol smell

bobbybrown
12-06-2013, 07:01 PM
Jason, working as expected.
Keith, leads correct, thanks.

I'm leaning towards an air leak aswell. Will check it out ASAP.

KEITHCANFIXIT
12-06-2013, 07:27 PM
Try the wd40 trick, and have you checked the gaps on all of the rockers on that side.

MicksRedNova
12-06-2013, 08:53 PM
Try the wd40 trick, and have you checked the gaps on all of the rockers on that side.

My money is on the valve clearances being too big on one cylinder.

Mick

KEITHCANFIXIT
12-06-2013, 09:10 PM
Most likely no.4 cylinder, for some reason that is the one that always gives problems!!! :crossfinger:

bobbybrown
12-06-2013, 09:15 PM
That's another job for Sunday.
Valve clearances (lost my feeler gauges, had to order some more) so will do it Sunday.
Was hoping they would arrive today so I could have done it today but sods law!

First on the list will be the wd40 trick, valve clearances then finally swap the carbs and see what happens.

Bit of luck will see it sorted this weekend.

KEITHCANFIXIT
12-06-2013, 09:29 PM
Seem to remember clearance is .004 or the first three pages of war and peace.

bobbybrown
12-06-2013, 09:59 PM
Yes that sounds familiar.
From memory inlet and exhaust are both the same on the 1641 at .004

KEITHCANFIXIT
12-06-2013, 10:04 PM
Newer versions, that is to say 70/71 + went out to .006, change of casting from magnesium to aluminium

KEITHCANFIXIT
12-06-2013, 10:05 PM
What I cannot understand is did Steve not have this problem in ownership, how long has the engine been stood idle?

bobbybrown
12-06-2013, 10:15 PM
Around three years now Keith.

It's a 71 so could be .006

KEITHCANFIXIT
12-06-2013, 10:22 PM
If set to .006 and it sounds to tappety, just adjust to .004.

KEITHCANFIXIT
12-06-2013, 10:27 PM
.006 is the centre two pages of playboy circa 1965, but how would a Pope know such a thing hee hee :outahere:

letterman7
13-06-2013, 02:57 AM
.004 is too tight, even on older engines. Aim for .006 and all will be fine.

Peter
13-06-2013, 07:58 AM
Depends on the internals, if your running chrome moly push rods, bolt on rockers with swivel feet, double springs and lightweight lifters one can get away with .001 clearance. Guess who runs .002 :whistling: Box standard is OK IF if you are a set and forget type.
(In & EX, Pre '71 0.004. later 0.006)

bobbybrown
13-06-2013, 08:20 AM
Will do at .006 and see if its any better.
If I can't find an air leak and the valve clearances don't work then will swap carbs, if that still don't work I'm well and truly out of ideas!

Peter
13-06-2013, 10:19 AM
Just remember the basics of a 4 stroke,

Suck; are you getting fuel and air in?
Squeeze; are you getting compression?
Bang; are you getting ignition at the right time?
Blow; are you getting the exhaust gases out?

If yes to all four, it WILL run.

Amended, I should have said, "run PROPERLY"

bobbybrown
13-06-2013, 10:32 AM
Everything except bang!
Can't be certain of that one. That's the thing, it will run and it does. Just seems to be very cold on the left side as if that side isn't running properly.

We will sort it :) eventually :laugh:

Peter
13-06-2013, 12:55 PM
If it's cold then it isn't firing, simple as. Or if it is firing/sparking, then it's not producing power which = heat :@ which means nothing to go BANG! :shock: just a phut! :( so back to suck and squeeze
There is a very slight variation on cylinder temp on 3 running hotter due to the oil cooler blocking some of the airflow to it, even on doghouse versions, but to the untrained touch there is nothing in it, especially at the exhaust port all four should be the same-ish, never cold. If there is a spark confirmed on that cylinder (at the right time) and you have compression it HAS to be fuel related especially if the plug is dry, as in, no un-burnt fuel on it. :confused1:

KEITHCANFIXIT
13-06-2013, 10:15 PM
I know this sounds like a stupid question, but is the throttle linkage on that side actually working properly, have you tried opening the throttle by hand when engine is running???? Sill plates duh!!!!

jimcub
14-06-2013, 12:25 PM
I have had the same problem as Dan for a while now, not cured due to health and moving house. I get fuel in the 3/4 cylinders, ticks over great no problem, but number 4 is cool and number 3 is not much hotter compared to 1&2.

I can see fuel going into 3&4 but there is no power there even when driving on road, as Dan said 50 mph is tops. I have yet to try the wd40 test due to an empty tin, but that will be next when I sort my mates head out

Peter
14-06-2013, 02:02 PM
Def' a carb problem, as the dizzy, points, coils, etc. are common to all 4 you can forget those. so it has to be unique to # 3&4 and that's leads, caps, plugs or the carb. if your running a single carb, then it has to be the leads, caps plugs or valves. simple, no? If it's dual carbs then it is usually the carb'.
If you have dual carbs you really should have a sync' vacuum tool as it's impossible to get all 4 chokes the same and balanced without one..
Are the plugs dry or wet on the cold cylinders, if dry then there is your problem, no fuel, if wet, it's ignition.

I use one of these
http://img.photobucket.com/albums/v219/Ukhozi/KGrHqJogE8VbSV2hHBPUJpkcEw60_12_zpse2a95aa1.jpg

MicksRedNova
14-06-2013, 02:08 PM
Def' a carb problem, as the dizzy, points, coils, etc. are common to all 4 you can forget those. so it has to be unique to # 3&4 and that's leads, caps, plugs or the carb. if your running a single carb, then it has to be the leads, caps plugs or valves. simple, no?
Are the plugs dry or wet on the cold cylinders, if dry then there is your problem, no fuel, if wet, it's ignition.


Or Valve Clearances !!

Mick

bobbybrown
14-06-2013, 02:15 PM
Which is my next port of call. I will exhaust every other avenue before writing off the carb.
That said, I do need to get a balancer as shown by Peter.

jimcub
14-06-2013, 03:11 PM
I have one of these Peter, donated from a dying friend :( .
I have dual 34 ict webers, they have a single barrel.

Peter
14-06-2013, 05:47 PM
Def' a carb problem, as the dizzy, points, coils, etc. are common to all 4 you can forget those. so it has to be unique to # 3&4 and that's leads, caps, plugs or the carb. if your running a single carb, then it has to be the leads, caps plugs or valves. simple, no?
Are the plugs dry or wet on the cold cylinders, if dry then there is your problem, no fuel, if wet, it's ignition.


Or Valve Clearances !!

Mick

jasoncambs
14-06-2013, 08:20 PM
After all this , i would pull the leads off the hot cylinders , chuck a egg cup of fuel down the other carb , turn it over and see if it fires the fuel you dropped in :-)

bobbybrown
14-06-2013, 08:38 PM
Not a bad idea at all. Totally isolate the one side.

jimcub
14-06-2013, 08:45 PM
But what if you can see fuel squirting into that side, twin carbs only.

KEITHCANFIXIT
14-06-2013, 09:10 PM
Still think it is a massive air leak causing such high dilution of air to fuel meaning it is OK on tick over but as engine is revved the vortex effect is sucking far to much air in giving effect of fuel starvation causing lag and effecting the popping sensation every now and then. But what do I know, I am just the Pope according to Dan, maybe that's it, has car been christened, if not it is damned :tongue: for all eternity, the heathen :outahere:

bobbybrown
14-06-2013, 10:03 PM
Let's fix the car Keith not damn it :tongue:

KEITHCANFIXIT
14-06-2013, 10:15 PM
One other thing to check is the fuel line from the splitter ( tee) to that Carb, it maybe collapsing internally under throttle pressure causing fuel starvation under load. Right off to confessional to receive my penance for previous transgressions. :sorry:

MicksRedNova
17-06-2013, 04:22 PM
I think its fixed now (mentioned in another thread) so speculation can stop - it was the valve clearances I think.

Mick

bobbybrown
17-06-2013, 04:45 PM
Indeed, valve clearances were the issue.

It's at a local garage today and I will be collecting tomorrow, they are setting up and tuning the carbs and a couple of other little bits to get it running as it should.

Then tomorrow it's off to the bodyshop!

jasoncambs
17-06-2013, 08:03 PM
I think you should check the tyre pressures ,,,,,,,,,


:)

MicksRedNova
17-06-2013, 09:32 PM
Then tomorrow it's off to the bodyshop!

Only for painting I hope?

Mick

bobbybrown
17-06-2013, 09:46 PM
Yeah, the body is a little worse for wear in places from sitting outside for so long so that will be repaired and smooth out the small chips etc, then paint.