Aircooled VW South Africa

Test as I've mentioned below. Valves not opening can cause this. Just remove rocker covers and crank motor over to observe if rockers have full throw.

sean wrote: ↑Sun Aug 16, 2020 12:11 pm
2nd. Lifter / camshaft issue. A compression test may show compression 100%, but a failed lifter or lobe on a camshaft could cause this. If your compression is 100%, start motor with tappet covers off and inspect movement on the rockers. They should all have equal movement. If one rocker is not travelling the full distance, you may have a badly failed hydraulic lifter (but you should be able to hear this) or a lobe on the camshaft that has worn away (you cant hear this).

Another nice method I like to use other than a compression test is to measure the exhaust temperature of each manifold pipe. They should all more or less be equal in heat, a drastic temperature difference in one will point to the suspect.

Tony I hear what you say, but this is not an set up issue, as it progressively went from perfect to bad without interference.

Dawie, I have the same feeling as you have that it is some bad fuel, or a mistake of maybe a bit of diesel.

Only thing it was not instant, I am sure it would have mixed within the 1st few Km.

BUT it could have deposited carbon, which is giving the pre-ignition.

Something I did notice during my thinking look,

was that the plugs of 1 & 3 where black soothed and the plugs for 2 & 4 not so much(actual had some brown to then)

But when you look at my high rise manifolds the balance pipes are into the head side of the # 1 & # 3 pistons intake.Which makes me think that we have an issue with either 1 or 3 or even both 1&3 chambers.

Will take out engine in the morning, and see if I can start it up on the bench, maybe even close off the balance pipe and block it off just to see if the backfire stays in one or the other or stays in both carbs.

Herman

sean wrote: ↑Thu Aug 20, 2020 3:02 pm Test as I've mentioned below. Valves not opening....

Thanks Sean,

Will do on the bench but have full compression in all chambers, and the backfire will be from open valves rather then not opening valves.

Have reset valves before with no difference, yes it may be lifters but will have to wait till engine is out.

Herman

Oh ! and yes before pulling plugs, I did spray all joints with quick start but no difference in engine speed.

Will be testing on the bench with new type 4 electronic distributor and a new coil, with new Plugs and plug leads, new dizzy cap and rotor.

This will eliminate all ignition issues and then the rest will follow.

Herman

retrovan wrote: ↑Thu Aug 20, 2020 5:37 pm
was that the plugs of 1 & 3 where black soothed and the plugs for 2 & 4 not so much(actual had some brown to then)

But when you look at my high rise manifolds the balance pipes are into the head side of the # 1 & # 3 pistons intake.Which makes me think that we have an issue with either 1 or 3 or even both 1&3 chambers.

that is to be expected with carbs like the ICTs and one of the reasons I dont like them.
By design, they cannot distribute the fuel evenly between the cylinders, which is why you are seeing differences between the two that each carb feeds.
Also note that the first cylinder firing that the carb feeds is lean, while the second cylinder is rich... this is happening on both sides of your engine.

Have 5 sets now, and they all work fine, if you remove the plugs they all burn the same, its just now that the engine is giving that I notice difference between plugs.

Normally when checking plugs they all the same colour.

No its not the carbs its some thing to do with ignition system or pre-ignition.

Herman

retrovan wrote: ↑Thu Aug 20, 2020 5:43 pm

sean wrote: ↑Thu Aug 20, 2020 3:02 pm Test as I've mentioned below. Valves not opening....

Thanks Sean,

Will do on the bench but have full compression in all chambers, and the backfire will be from open valves rather then not opening valves.

Have reset valves before with no difference, yes it may be lifters but will have to wait till engine is out.

Herman

Negative, I am saying this because I have experienced this myself. Valves not opening will still give you a high compression reading.

I had a 2l motor that had 1 lobe On the camshaft that had completely worn away. Most strange issue as all the other lobes were still fine. It had good compression and idled well. As soon as under load, it started the popping out the carbs.

I’ve also had a failed lifter (which caused almost no movement on the rocker) and the symptom was also popping out the carburetor.

Not saying it is this, but checking the movement of the rockers can help you diagnose before replacing parts.

Thanks yes I will be looking at all these points, when I have sorted out all the possibles outside the engine, will take off the covers and look for tappet movement than I will start to look at the heads, lifters and cam.

Will remove the lifters and machine a extended teflon lifter to insert and measure the lobes on the cam. rockers and rods will also be measured, as Once I have the engine out I may as well do it all.

Will even remove the hydraulic lifters and give them the once over.

I personally feel its an internal issue, but others that know the type 4 better then me think its external.

So will have to look at both options.

Have been wanting to fit a Type 4 electronic dizzy for a long time, as I am not happy with my current dizzy.

so replacement was on the cards for a long time, just now doing it.

Herman

This engine and carbs... were in your Brasilia before, and later in the 72 when you went to KKK?

A few years ago heard a story from a cam-regrinder as well as... i think Alert Engine parts.
Apparently there were some replacement type 4 lifters, made from incompatible metallurgy. These were sold locally at the time, causing fast wear/wiped cam lobes.

As said, I think its inside as you say, but hope-ping its not.

Yes thats the same motor and it ran very well.

The thing that eats me is the fact that its progressive and not instant.

so can very likely be the cam.......

Herman

very possible, especially as 1&3 share the same lobes
Why not just check it while it is still in the car? Take tappet covers off and measure how much the valves open while turning over the engine. Turn it 15deg at a time - its pretty damn easy
but then again, if it is the cam, you'll need a rebuild to fix it anyway

Herman,.....don't keep me suspense any longer,........what was the verdict on this issue? Or have you not dug any further yet ?
Regards Nick

Hi Haans,

sorry been on site with a factory build, and working 16 hours a day to complete.

But yes the engine problem has been identified and repaired.........



So when the engine did its thing, and I spoke to the engine guy, he was persistent it was and external issue, and I insisted it was an internal issue.

So as the less wise, I did all tests as told and found no problem.

Carb's where blamed by all sides, and knowing that there are two, they would not both go bad at the same time and speed.

Also did the dizzy swap and plug and coil swap as insisted on, but still thinking its the piston / valve timing that is too blame as it ides fine but gets progressively bad as the RPM picks up.

As the engine had to come out, and it being easier to start, stop, look and compare when on the bench with all tin's off,

I waited to test and measure the tappet movement.

Low and behold, the exhaust tappets on 1 & 3 barely moved where the inlet valves opened full

Also the exhaust on 2 & 4 had less movement then there respective inlet valves.

On stripping the engine, it was found the cam lobe on 1 & 3 Exhaust was gone, down to less then a few mm movement and 2 & 4 Exhaust lobe was half gone.

Inlets where still fine and the lifters where worn to match the respective lobes on the cam.

So knowing this, it makes sense that the full load of fuel when into the chamber, fired, could not get out the exhaust, but with the pressure went flying out the carb's when next the inlet opened.

This then mixed with the new fuel, and with bad fuel /air ratio, burnt everything black.

It was amazing how much soot got into the rest of the engine.

On confirmation of this issue, it was verified as per Dawie's post that there where a lot of lifters that would kill the cams over time.

this apparently lead to a few law suits and claims.

So with that said, the engine was measured, inspected, new Oettinger cam fitted and re-assembled.

(why fit an Oettinger can, well just because I can, and why not... )

Engine should be back next week, as it was done by engine guy, seeing my time was fully consumed by my work.

SO...

Will change bell-housing, and refit engine next week hopefully.

Will let you know how she runs.

Thanks to ALL for your participation, as I am sure it would have helped not only me, but all that have read these posts.

Thanks Guys

Herman

is he using new lifters, matched to the cam or just old ones?
What oil is he using?

Wrong lifters or wrong oil will kill that new cam...
Good luck, hope it works well

Tony Z wrote: ↑Fri Sep 11, 2020 1:23 pm is he using new lifters, matched to the cam or just old ones?
What oil is he using?

Wrong lifters or wrong oil will kill that new cam...
Good luck, hope it works well

Brand new lifters, and will do a oil/ run-in myself just to make sure.....

Do we get a API SL grade run-in oil in SA ??
Or an additive to add to the normal oil.??
Which additives have ZDDP zinc additives, (brand names) ???

Herman