348 Camshaft Plugs

As I was removing the cam covers to paint them, I found that one of the rear camshaft plugs had come out and it was sitting at the bottom of the housing. Luckily it did not find its way down into the crankcase. Do these plugs hold oil pressure or are they for decoration only?

I had good oil pressure before the find and no strange cam noises. One thing I noticed was that the tappets on the affected head were just very slightly noisier than on the other but it was nothing worrying, almost normal. There are no signs of wear on the cams or the bearings. I would appreciate some info on this.
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Thanks Bruce.

 

Thanks for the replies. Another related puzzling thing: the plugs on the other camshafts are in place but not sitting fully in (I haven't checked them for tightness) and have 2-3 threads outside. If you look at the fallen-out plug, 2-3 threads on it were also not engaged (brown colour). The staking mark is clearly visible on the fallen-out plug, on the plug outer face. If 2-3 threads are not engaged, then the staking at the plug face does nothing to stop it from coming out.

Is this normal installation of the cam plugs or should they be threaded fully in until the plug face is flush with (or even slightly into) the camshaft end then staked. If this is correct, then my plugs were either incorrectly installed or the two that are still in are on their way out.

Please advise.
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Thanks, that explains everything. The plug I found fallen out is indeed tapered, probably Metric Taper Pipe thread but it could also be NPT or BSPT. It is surprising that the plug came out, my engine has only done 12,600 miles (possibly due to threadlock applied on threads not fully degreased). It was well tightened as I can see fairly deep indentations made by the allen key in the tightening direction (only). Anyhow, I have ordered new plugs and will tighten them as advised.

 

And the saga continues. This is now the third plug that has come out of the left intake cam. Recognised it when I heard a (now very familiar) slight rattle from the left cam cover during engine warm-up. I have done only some 5k miles between the first and the third plug coming out.
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What about the wasp? - She was just checking whether the camshaft is suitable for her nest.

Here are the three plugs - factory, 2nd and 3rd.
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The staking on the factory plug was very small and did not provide any grip as it was only on the part of the thread that was not engaged (protruding out). I staked the second one much deeper, used blue threadlock, but it didn't hold long. The third plug - used red threadlock (high temp) and staked/punched it lower down inside the hex, on two opposite sides, hoping to jam the threads that were engaged in the camshaft but no joy. One thing I noticed is that the threadlock was wiped-off clean from the plug thread during installation, i.e. pushed to the threads that actually sit outside the cam threads. Perhaps I made a mistake by applying the threadlock only on the plug threads. This time I'll try with threadlock on both, the plug and the cam threads.

 

The problem with my cam plug continues. The fourth plug has also come out after small mileage:
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For the forth plug, I have degreased the threads in the camshaft very well, applied red high temp threadlock on both threads and tightened it so much that the allen key almost spun. Didn't stake it as the previous stakes did nothing (the "chisel" stakes deform only the threads that are not engaged, anyway).

As I do not wish to continue trying with the genuine Ferrari plugs, I am thinking of using something different (the thread is M18 x 1.5):

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The left brass plug is similar to the original plug but it is just slightly tapered and it can be screwed fully in without much resistance. Of course, I would install it with red threadlock and also stake it. The stake will have effect as the plug's outer face will be a few mm inside the camshaft threads.

The right plug is the second option I am considering - screwed-in with red threadlock and tightened against the camshaft end.

The third option would be to use a plug like the left one but made of carbon steel. This would go in with just red threadlock as it cannot really be staked. The advantage would be that a steel plug will have the same heat expansion/contraction as the camshaft and less chance of loosening due to expansion/contraction cycles.

I would appreciate any thoughts/experience/advice as to my consideration of using one of these three options.

 

Thanks for the suggestions, Mark and Brian.

For the last (4th) plug, I degreased the camshaft threads very well - screwed in tight a "cigar" of tissue paper and kept it for a week to absorb the oil; before installing the plug, I screwed in and out a number of rolls of tissue soaked in degreasing (Zippo lighter) fluid and applied red threadlock on both threads; counter held the camshaft with a spanner at the sprocket bolt and tightened the plug until the allen key almost stripped, see pic:

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And the plug still came out. This is why I am now thinking of an alternative.

Mark, I noticed what looks like stripped initial threads in the cam but I thought it was just some aluminium deposit left by the factory plug. This is where the plug is jamming the most during tightening. Anyhow, I will now inspect the threads carefully with a strong magnifying glass. There might be something wrong there but a soft aluminium plug could not have caused any cam thread stripping. Or, perhaps, the threads were faulty from the time of cam manufacturing and this could have been the reason for the factory plug to come out.

Otherwise, I have tried the brass plug (the one with allen socket) and it starts jamming when it is in flush with the camshaft end. I have not turned it further but it looks like it will go in until it is below the cam end where it can be staked. I am still waiting for the same shape steel plugs which I will also try-fit and see if they will jam a bit stronger than the brass ones.

 

Not teflon, just light reflection. I have not used Loctite 277 but other similar red threadlockers (high strength, high temperature). I cannot remember which threadlocker exactly but it was one of the following that I currently have: Loctite 266 or Hardex 6262 or Permatex 27240 or Loctite 2620 (paste). Will get the 277 and go with it on the next plug. Otherwise, there is no excessive gap between the plug and the threads in the cam; the plug progressively gets tighter and tighter (as it should) and, when the allen key comes to almost stripping the hex, the last couple of plug threads are not engaged. It actually looks to me that the tapered threads tighten-up a bit too early - I would prefer if the plug could get deeper in, at least flush with the camshaft end

Before I install the next plug, I will inspect the threads in the cam in detail to see whether, perhaps, there is something wrong there.

 

I checked the threads in the cam, following the comment by Mark, and found that there is, indeed, some damage on a section of the second thread but nothing significant:

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It actually looks like a manufacturing defect. In any case, it could not have been made by a soft aluminium plug. The brown staff further inside is the residue of the threadlocker I used on the last plug which I will clean-out.

As this small thread defect should not be the cause of my plugs, as well as the original factory one, being "spat out" by the camshaft, I am more inclined to now try either brass or a steel plug. I did a "dry run" with a brass plug today (not to the full tightness) and it looks like it will go in until its face is some 2-3 mm inside the camshaft. This will provide for some staking. Otherwise, this plug has the same height as the factory one (only gentler tapered) so it will sit deeper into the cam and possibly beyond the defective second thread.

Brian, thanks for the info on the factory "staking" of the cam plug. I see that it is indeed another cam timing mark for quick reference, not at all for the plug retention as I wrongly thought.

With regard to the Zippo lighter fluid that I used to degrease the threads, this fluid is actually Naphtha (also called ""white gas"). It is a very good degreaser and leaves no residue after it has evaporated.