Titan IOX-340 valve interference with rocker cover

[Langt]

I have a Titan IOX-340 with about 50 total hours, for which I am in the middle of a condition inspection. Compressions were all good (all 77/80 or better). However, boroscope of exhaust valves was not so good -- #4 exhaust valve shows some uneven heating. I took off the rocker cover, and it appears that the valve spring retainer (is that the rotator?) is wearing against the stamped rocker cover.

This wear is enough that it has a groove that can be felt by fingernail, worn maybe 1/3 through cover. Although clearly the valve operates, I am thinking that if the cover pushes the valve to the side, it might not rotate or settle properly.

I am hoping to be able to lap the valve in place. Sealing area "looks" ok. Has anybody else had this issue, or advice?

Thanks
Ted

 

[gfb]

Titan/Continental has excellent support, reach out to them and I’m sure they will sort this out with you.

 

[lr172]

I don't believe the spring retainer on a PV engine is anywhere near close enough to wear into the cover. More likely that plastic end cap on the rocker arm rod is missing and the edge of that rod is eating into the cover. You MUST have the plastic end caps installed, otherwise the rod is not fully supported in one of the outer bushings. Never seen an AV engine, so that may be different if that is what you have. Please post pic of the cyl from the top so we can see the rocker arrangement.

That looks like a hot spot on the valve that needs to be dealt with ASAP before the valve warps. Though it is hard to say as I only see the shadow marking and not signs of excessive heat inside of it.

 

[hgerhardt]

That wear in the valve cover is definitely not from the rocker shaft. It's from the exhaust valve retainer, as OP says. Look at the pic below. The exhaust valve is on the RH side. OP's pic shows the diagonal lower RH corner of the valve cover. Look at the stamped letter on the RH edge of the photo to orient yourself on the valve cover.

That interference is probably hindering normal valve rotation, as the retainer is being pushed to one side with every valve opening. And that's why the valve head is showing some temperature distress.

I'd dent the valve cover to create some clearance and then run the engine for a few hours to see if the valve coloration fixes itself. If it doesn't improve, can still lap it then.

 

[lr172]

That wear in the valve cover is definitely not from the rocker shaft. It's from the exhaust valve retainer, as OP says. Look at the pic below. The exhaust valve is on the RH side. OP's pic shows the diagonal lower RH corner of the valve cover. Look at the stamped letter on the RH edge of the photo to orient yourself on the valve cover.

That interference is probably hindering normal valve rotation, as the retainer is being pushed to one side with every valve opening. And that's why the valve head is showing some temperature distress.

I'd dent the valve cover to create some clearance and then run the engine for a few hours to see if the valve coloration fixes itself. If it doesn't improve, can still lap it then.

View attachment 45513

I see that now. Something must be way off in that head or cover though. Still a decent amount of clearance and there are 1000's of those cylinders out there that don't have this problem. I can't see how this could happen when all of the parts are manufactured and machined correctly. Maybe the holes punched in the stamping were offset during mfg.

 

[Langt]

Thanks for the replies. When I looked at the seat/valve sealing surface I didn't see any difference in color or width of sealing surface. I will look a little harder, although its tough to manipulate the boroscope just right to see all around and under the opened valve.

None of the covers show ANY sign of external impact or abuse. As to extent of condition, cylinders #1 and #2 show contact with the cover in the same area, though slight -- more of a mar with no wear groove as on #4. (#3 looks ok). The boroscope also looks ok for exhaust valves 1, 2, and 3 coloring.

One of my friends pointed out that possibly the edge of my Van's cooling baffles may tend to push the covers a bit off center, but those thin baffle edges, at most, really touch the gaskets, not the covers. Also, if the Vans cooling baffles do anything, they are pushing the covers downward with respect to play between the screw and screw holes, which would be beneficial. In fact, a little downward pressure during installation of the covers would improve things a bit and that will be part of my future installation method.

*** 8-18-23 update *** I have picked up used Lycoming valve covers on Ebay. I put varying thickness of tape on the inside of the valve covers to gage the clearance between the valve and the covers. With the Lycoming covers, I can have up to about 0.05" of tape before it interferes with the exhaust valves when the covers are centered with respect to the play in the cover mounting screw holes. With no tape, the Lycoming covers don't touch the valves at all regardless of whether the covers are pushed up or down with respect to mounting screw play. On the other hand, the Titan covers really don't fit with 0.05" of tape-- it pushes the screw holes way off center to clear the valves. The titan covers rub the valves with the screws visually centered in the screw holes, and no tape.

So, my Titan Engine will be wearing very old Lycoming covers that fit. Not really what you expect when you buy a new engine.

 

[Langt]

Just to provide closure on this issue:

I did in fact contact continental about this issue. They expressed that they had not seen this before, and were skeptical until they saw my photos. I told them the seats looked good and the compression was very good, so I intended to resolve the valve-cover interference and just run the engine for 5-10 hours to see whether the valve "indication" cleared up. They seemed to agree with that approach, and sent me newer valve / rocker covers in case there was a bad run, unseen damage, or adverse tolerance stack up, or just to satisfy me. The new covers arrived and were a slightly different stamping (different embossed lettering) but they probably had not intentionally been modified for better clearance. Anyhow, even the new continental Titan covers had less clearance than the used Lycoming covers I had gotten from Ebay. So i used the Lycoming ones and ran the engine as planned through the Fall. Less than 10 hours.

i removed the top spark plugs today to install desiccant plugs for winterizing, and looked at my valves while the plugs were out. All valves looked perfect to me! So whatever the indication was, it seems resolved.

Ultimately, the valve asymmetric coloring could have been due to:

Possibility 1) the valve hitting the rocker cover and not rotating properly due to side load, which is my best theory. Providing clearance restored proper operation in time.

Possibility 2) transient foreign material under the valve causing temporary asymmetric heating of the valve (but I did not see anything on the seat).

Possibility 3) unknown transient cause of asymmetric valve heating or faulty borescope interpretation.

But whatever the issue for #4 valve, it was rubbing on the cover. So, having best clearance, the Lycoming covers are staying on. I will check clearance in that area whenever i have valve covers off any of these engines in the future since there is less clearance than you would think.

Ted

 

[DanH]

Ted, thanks for the follow-up post. Good to hear the rest of the story.