DDR valve seats

[iannima]

We have repeatedly mentioned this known problem: valve seats breaking loose The catalogue of horrors as a result is infinite. One can be lucky and just lose compression or the seats can break up into pieces, which are then sucked into the bores scoring the sides The bottom line is a major rebuild of the engine, with the associated problems.



The problem is routinely mentioned on the German GAZ-69 forum, and it may easily count as one of the most common faults But the question that I could never answer was why the issue was practically unknown for ex Soviet; ex Polish; ex Tczeckoslowack vehicles... Only ex NVA ones like mine
...until now...

[iannima]

A recent post on the German forum, which I have had confirmed by our dear friend Dirk Schneider , has now answered the question...

The Soviets did produce replacement valve seats, but these were in extremely hard metal which had to be cut to size before fitting them into the block. For some reasons, that I still find difficult to fathom, the NVA workshops did not have the machinery for such an operation. So what they did was to replace the seats with locally produced SOFT metal ones. The result is what we see

[iannima]

As always, for one question answered, there are a number that remain open...

The first one is why did they bother to replace all these valve seats? Because it certainly isn't a routine operation that would have to be done all the time, and only after very heavy usage would it be necessary. I have asked this question many times, of many German friends and I have received varied replies... One was that DDR TV was not very good, so people had to find something else Another -more plausible- is that in the military, one has to find something to keep the soldiers busy, even if it is totally unnecessary or useless, so to keep the workshops going, this is what they did
The one reason that can be ruled out and had been suggested by some is to cope with unleaded petrol. There was no such petrol -to the best of my knowledge- in the DDR. Besides unleaded petrol is a product of the environment-conscious West. The DDR was spectacularly unconcerned by such matters. And in any case, for unleaded petrol one needs hardened valve seats, not soft ones...

The second question is why did the NVA itself not find that these soft valve seats they were fitting, were a problem, causing so many engine failures? And this is where the post I mentioned in the German forum may provide an explanation. Apparently petrol was rationed in the NVA, and therefore certain vehicles were not driven around that much. So all in all the problem might not have manifested itself during DDR times, but it certainly did, once the said vehicles found their way into the hands of their current, civilian owners who proceeded to drive them around a lot...

One possible interpretation can rely on the very speculative reconstruction of GAZ-69 usage in the NVA. Whilst there were some around all the time since the 1950s, it's noticeable that for much of the 60s the NVA relied heavily on the locally produced P2M and P3. By 1967 or so, it became clear that the P3 was going to stop being produced. It is definitely then that the bulk of NVA GAZ-69 seem to have been produced and imported into the DDR. But by the 1980s or so, fresh imports of UAZ-469 were making their way in bulks. It is probably at this stage that the GAZ-69 were taken off active service and brought into some kind of reserve. That was common practice in the Soviet Army, which kept entire divisions equipped with mothballed older stuff to be manned by (older) reservists, if the balloon went up. It is at the stage of mothballing the vehicles, that a major engine overhaul makes some sort of sense. And then obviously as the vehicles are mothballed, one never finds the problems out... Pure speculation on my part of course, but it's the best I can come up with.

[iannima]

But the bottom line remains the same one:

If you have a DDR vehicle, you will be well advised to take the head off and check what the valve seats are like...

I know that Yurgen had such a problem

[Kozchik1]

A more plausible reason could be the horrible spare parts supply of factory to fellow warschaupact countries.
I my self work in aviation and remember the stories of soviet build airliners sometimes waiting for 7+ months for spares from factory.

This horrible supply of spares did not only apply to soviet airlines and aviation. But als to the military.
This forced many a warschaupact member to “produce” spare parts themselves rather than waiting for months.

And sometimes using ....not so good materials.
In warchaupact countries therefor it sometimes rained aircraft from the sky....( bad bad bad safety records) the airlines simply could not wait with half there fleet on the ground they got inventive ..... with horrible results

[iannima]

This horrible supply of spares did not only apply to soviet airlines and aviation. But als to the military.
This forced many a warschaupact member to “produce” spare parts themselves rather than waiting for months.

True but some did it better than others. I understand that CZ produced pistons and rings are better than the original Soviet ones. So it still begs the question why the NVA did the valve seats so badly...

[iannima]

This photograph (again from the German forum) shows a major disaster The head of the outlet valve has parted company with the stem, jammed itself vertically, driven a hole into the cylinder head and then fused itself to the piston head



It is on the outlet valve, and therefore where the valve seats are. The vehicle is definitely ex NVA. But I am not clear whether this spectacular disaster can be at all connected to a loose valve seat. It seems rather extraordinary that the valve should be decapitated this way Is it just a coincidence that it is on the outlet valve?

[Kozchik1]

Looks like it got a clean separation from the stem.
The stem top look so clean that it almost looks like the valve head never was bond to the stem. If you zoom in you cant see any tears or cracks. It looks like the top of the stem was smoothend over.

If you ask my opinion i would rather see the valve as the culprit.

[iannima]

So you reckon “just” a bad valve?

[Kozchik1]

As in not the valve seat that is . Bad batch , low grade.
At least the piston does not leak this way