Head Nuts - Haflinger the Gift that Keeps on Giving - Pain

[AustHaflinger]

It has been quite a while since my Haflinger has had a decent service so I have been doing the brakes, changed the oils and now onto the engine side of things. Tappets, timing, spark plugs, carb tune etc

When I last did the tappets I had the heads off as part of the last engine rebuild. I torqued the heads up to 19 lbs ft but have not touched them since when I should have checked them a while later but was too lazy.

So doing the right hand side today, the tappets were a little loose which was good as mine normally tighten up so came to checking the torque on the heads - set the wrench at 18 - top left OK, bottom right OK, top right OK, bottom left - no resistance at all (holy crap) . The nut was just spinning. My immediate thought was have I over torqued but the setting was slightly less than required and the others were ok.

So removed the nut and washer to check the barrel head stud - seemed OK - I then used the Dremel to slot the end of the stud and tried to turn it with a screw driver and all was good. Then I noticed that the threads near the head seemed to be damaged/stripped however on closer inspection there seemed to be metal between the studs threads - hmm - looking at the head nut I could see that its threads had stripped out but the threads on the stud were actually OK. I ran a M8 1.25 die over the stud and it cleaned up fine and pulled the nut metal out of the threads.

So I got a nice new shiny hi tensile nut out of the tool box and as a precaution put an additional thick washer on so some unused threads would now be used.

Now I could not have over torqued the nut this time around, and when I did it a few years back all four head studs were tightened up Ok but maybe there was an issue with this nut - torqued up but with the engine operating has failed.

So tappets now set back to .2mm and head studs at 18 lbs ft (2.5mkp) and fingers crossed all is OK and there are no oil leaks when I put the rocker cover back on.

Garry

[heinkeljb]

What luck!

Good job you had a spare nut.... I have known nuts shear the threads inside after apparently going tight. Obviously, the metal on the threads was in the "pastercine" stage of deformation when you stopped tightening the first time.

I need to do that on the engine in Lurch, but the weather is not conducive to working outside, so it will have to wait until I can rustle up the courage to deal with both the weather and the Haf!

John

[AustHaflinger]

the weather is not conducive to working outside, so it will have to wait until I can rustle up the courage to deal with both the weather and the Haf!

John

I know what you mean - the sun is burning me to a crisp and for the last 10 days the temp has been over 35 degrees but today was a delightful 26 so was able to get outside.

The nut is nothing special just a M8 1.25 Hi tensile that I have in my nut and bolt box. Yes I agree with you there must have been something wrong with that particular nut as all the others went up OK previously.

garry

[AustHaflinger]

Did the left hand side of the engine - no real issues other than wrecking the rocker cover gasket and the rubber seal on the end oil return tube. Had to use my last rubber seal and make a new rocker cover gasket.

Changed the spark plugs and had a look at the timing. I have one of those timing lights that you just read off the timing from the light. So if you use the recommended 0-2mm to the left of the timing mark then that is actually 2° BTDC - I also have marks at 4°, 6° and 8° BTDC - with the timing light I have I do not to use these. I had my setting at 8° BTDC and have now set it at 9° BTDC - based on other engines with lower comp ratio this should still be OK on 91 octane fuel but I would not go any higher.

Now to clean up the carb and reset the idle mixture.

Garry

[AustHaflinger]

Ok sorting the carb did not go well. I did not remove the carb but just blew compressed air through all the jets and cleaned the tips of the mixture screws. I figured that would be Ok as when I did my work on the fuel tank it was all clean, the old fuel filter was clear and the water trap bowl only had some very fine particles at the bottom. So the fuel system is clean.

Anyway I screwed in the mixture screws all the way and then backed them off half a turn as the book says. I restarted the engine but the engine would not run at a constant speed so I could adjust the mixture screws - I would get the revs to sit on about 900 and just when I would go to adjust them the revs would shoot up with no input from the accelerator and then drop back down. This carb has always has issues with not idling well - drives great just wont idle.

So I pulled the carb off - the bowls are perfect with no corrosion or dirt in them, the floats all look OK. Tomorrow I will go and get another can of carb cleaner and then one by one remove the jets and give then a clean and a blast of compressed air and hopefully on reassembly I can get the engine to run at a fast idle so I can set the idle mixture.

Or maybe I should just take it to a carb mechanic to fix for me

Garry

[heinkeljb]

Sounds like you have an air leak some where. If you screwed the idle jets in too hard at some point, you could have changed the ring area that is used to provide the seal / air metering surface. Have a good look at the two tips of your idle jets and see if they have a good ring on the tapper from where it touches the jet at the bottom of the hole.
The other place is the Main jets / idle jets can have holes that are no longer the same size / shape. Think Grand Canyon on a smaller scale - everything wears!

John

[AustHaflinger]

Have a good look at the two tips of your idle jets and see if they have a good ring on the tapper from where it touches the jet at the bottom of the hole.
John

Thanks John - there are no marks on the tips of idle mixture screws.

[AustHaflinger]

Well I disassembled the carb and cleaned everything up with carb cleaner and compressed air - all good and I cannot see if there is any where air might be getting in.

Issue still remains with unstable idle - and revs changing from 900 to about 2400 and back and doing it again over and over again with no input from the accelerator.

Here is a vid https://www.youtube.com/watch?v=fDgyuyURAVk

The same Zenith NDIX carb is used on the Pinzgauer and some Mogs so I have also asked on the Real 4x4 forum to hopefully pick advice from owners of those other vehicles on what the issue might be.

Garry

[Ole]

Not sure what the problem is Garry, but a tip if you suspect any vacuum/false air getting in somewhere is to by a small can of propane (like a spray bottle) attach a "straw" to it so you can direct the flow of propane to an exact point. Work your way around the flanges and throttle plate shaft and listen for changes in rpm. It is very obvious/instant when you blast the propane at a leaky spot. Engine will run slower and smoother as it sucks in the propane.

[AustHaflinger]

Thanks Ole - yes I know of that but haven't tried it yet - I will give it a go today.

Cheers

Garry

[AustHaflinger]

Ok - a different day and it would seem the problem has diminished. Still hunting around a bit but on 100 rpm or so - the only difference is a different day. I sprayed around the engine and car and there are no air leaks. Changing the idle screws really made no difference whether in or out so I have them set on one full turn out from right in. When playing around with the carb I had the ignition timing back at standard at 2mm BTDC (or about 2 degrees). When I was finished and had the engine idling at about 800rpm, I reset the timing back to my usual 8 degrees BTDC and revs jumped by 100 rpm so the engine likes a bit more advance in the timing.

So all back together and is running OK - also put the low fuel sensor back into the tank so now as well as the VDO fuel gauge I now have a low fuel light.

Now to clean up all the mess in the garage.

Garry

[Ole]

This is why if encountering a hard problem one should sleep on it. Sometimes all that is needed is a new day:)

[AustHaflinger]

Yes I agree, but I didn't do anything -

[AustHaflinger]

Ok went for a drive today after my tinkering - only getting about 2/3 power - I had reconnected the oil bath air filter but as suspected it does rob a bit of power - the air intake side is so small compared to the carb inlet so it has to rob some power. I removed it but still down on power.

Engine dies if you floor the accelerator - is not a flat spot caused by lack of fuel from the accelerator pump - is more like a governor kicking in but I do not have a governor.

I think I will try a mechanic next week.

I should have just done the plugs, filters, oil and tappets and not touched anything else as it was running Ok before.

Garry

[heinkeljb]

I hate to say this Gary, but you might have to check the tappers again. Do you have a compression tester? Try that first.
Might also be worth taking the whole points unit out and checking things like the heel to make sure it does not have a strange edge that is causing ignition timing issues.
Might also need re-timing, but if you remove the points then re-timing is part of putting them back.
Still think your “hunting” is down to an air leak. How sealed is the exhaust side?
Could be something obscure like a pin prick hole in the heat exchanger junction under the carb due to hot gas corrosion.
Hope it’s not that, but it’s a possibility.

John

[AustHaflinger]

Thanks John - yes rechecking the tappets is one of the first things I intend to do as it could be the issue. Likewise I will pull the spark plugs and reinstall - from past bad experience I no longer do the spark plugs up tight but just firm so I will double check them to ensure there is a seal.

I no longer run points and have a Pertronix module fitted - is working fine and when the timing light is on the timing is nice and steady and advances with increasing revs so the dizzy seems fine.

It now idles well, though adjusting the idle mixture screws did not seem to change revs much. I sprayed carb cleaner all around the inlet system and carb with no change in revs so externally there is no air leak - maybe there is an internal issue in the carb that is allowing air internally into an area it shouldn't be.

On aspect that I did confirm is that oil bath filter strangles performance quite a bit as the inlet size is far smaller than the inlet to the paper filter and the carb - I noticed it a few years back and took it off but decided to try it again last night with the same result. With a modern paper air filter in the main filter chamber, the oil filter is really not needed.

Busy next week on other matters so the haf will have to wait for a while.

Garry

[AustHaflinger]

Ok went for a drive today after my tinkering - only getting about 2/3 power.

Engine dies if you floor the accelerator - is not a flat spot caused by lack of fuel from the accelerator pump - is more like a governor kicking in but I do not have a governor.

Well I have had this problem since I thinkered with it back in January. (note to self "stop tinkering") Would drive satisfactorily but was lacking in power and would die if the accelerator was floored.

Subsequent to this I had my charging issue which was a simple blown fuse and then last week I had my ignition issues which turned out to be a failed rotor arm.

Well I went for my first drive with the new rotor arm and serviceable ignition and guess what - all the issues I had with engine performance in this thread since January are gone - the engine does not die and no longer feels like it has a flat spot.

So this rotor arm has been breaking down for a long time - breaking down under load. I have had rotor arms fail but normally they just go no slowly fade away.

Now the engine is running pretty good and developing power but needs a little more fine tuning but is pretty OK as it is.

Garry