Exhaust valve pics/question

Strecker25

Well-Known Member
SILVER Sponsor
Nov 20, 2014
4,905
Rochester, NY
Boat Info
2002 410DA
Engines
Caterpillar 350HP 3126
I had to pull the port exhaust from both motors in the fall to allow me to get to the remote oil hoses for replacement. I had taken pictures of the exhaust valves and one of them has what I would assume is oil on the valve and a little on the stem. I know the exhaust stem seals can be trohblesoon on these motors. They’re 5.7efi’s with about 750 hours on them. No issues running, but I will get a hint of smoke at startup if they’ve been sitting for a while. This pic was taken about 36 hours after the last run (which was on muffs with the fogging cocktail run through.

Opinions? I don’t plan on necessarily doing anything about it now but I’m wondering if there’s some PM I should think about. Compression was outstanding on all 16 cyclinders when we bought her 3 years ago

The first two are of what I would consider “normal” looking at the last one is the valve in question. Also, neither engine burns any oil and entire exhaust was replaced when I bought it

680BCAE3-0784-4965-AB04-87CC8D4F0F4A.jpeg
C6C2297E-CD58-49C0-8F2F-794BB89BB617.jpeg
EE374A8E-AC6A-4CC1-A07C-913C08A24B27.jpeg
 
The wet residue looks like it came out of the cylinder. Is it the lowest on that bank? Probably your fogging cocktail. If you had "a problem" with seals you should see build up on the stems. Looks good for 750 hrs in my opinion. Some engine don't even use seals on their exhaust valves.
 
The wet residue looks like it came out of the cylinder. Is it the lowest on that bank? Probably your fogging cocktail. If you had "a problem" with seals you should see build up on the stems. Looks good for 750 hrs in my opinion. Some engine don't even use seals on their exhaust valves.
Thanks, to be honest I don’t remember what cylinder that was but based on the order of pics on my phone I do believe it was the furthest aft cylinder. I still have the one manifold off so I’ll take another look this weekend. Was also going to pull the plugs and get a quick look at those as well since I haven’t looked at them in about 160 hours of use since their replacement.
 
Change your valve seals, valve guide has probably got more clearance than it should.
 
Most likely valve seals as they will dry out over several years. As long as you are not burning excessive oil and spark plugs look good I wouldn't worry about it.
 
Thanks all. I won't do them this year as we have a little one on the way and the season is about to get underway (hopefully)

Since it runs fine I'll just keep an eye on the oil as usual and if I feel motivated over next winter I'll replace the seals. I found a bunch of info on how people do them with the heads still on. One guy said there is an air compressor attachment for the plug hole to keep the valves from dropping and that napa has a tool to compress the springs with the head still on.
 
Thanks all. I won't do them this year as we have a little one on the way and the season is about to get underway (hopefully)

Since it runs fine I'll just keep an eye on the oil as usual and if I feel motivated over next winter I'll replace the seals. I found a bunch of info on how people do them with the heads still on. One guy said there is an air compressor attachment for the plug hole to keep the valves from dropping and that napa has a tool to compress the springs with the head still on.

I'm sure you tube has several videos on how to do the valve seals. Been many years since I've done a set but I could do them tomorrow if needed. Still have the tools in my box.
 
This port is the outlet of the cylinder and is pressurised for the most part. Warn exhaust guides and bad seals will deposit oil on the stem and downstream. You said it does not use oil. The oil dampness you see is your pics is from unburnt fogging. I would be happy with it and wouldn't waste any concern if it was mine.
 
"Hint of smoke at startup" Valve seals are shot

No doubt. Judgement call as to whether or not to replace. If oil consumption is normal and plugs look good I would wait until such time as engine requires some other work. In Rochester NY the boat is most likely raw water cooled running in fresh water. Engines have a long life expectancy but may need some disassembly in the future anyway.
 
"Hint of smoke at startup" Valve seals are shot

or he might be running an engine oil that is too thin but most likely worn valve seals are the problem....

cliff
 
Quicksilver 25w-40, changed annually (typically about 60 hours), RWC, no oil consumption during the season, no issues with performance or any other engine related problems for the past 3 years.

I'm going to pull the plugs for a close inspection and evaluate from there.
 
I expect you will decide to leave well enough alone.
 
I think I would leave well enough alone, not likely that at 750hrs your valve guides/seals are worn to the point of leaking oil into the cylinders. Me, I would do nothing at this point, it's not using oil and running fine and can you be sure the hint of smoke on startup is oil or a rich fuel mixture? I personally think the oil you are seeing is from the fogging oil. If it really bothered me, I would pull the manifold again in another 25hrs, not after fogging and have a look.

I know we are all boat/motor geeks, (I have "fixed" too many things that didn't need fixing) but I would really try to resist any temptation to start tearing into a perfectly good running motor.
 

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