CAT 3208 TA's Smoking

375HP. About 1000 hours each. Boat is 1994 Ocean Alexander 46.

A fair amount of greyish white smoke above 2100 rpm, just a little in the high teens. None at lower rpms.

Both engines smoke the same, both start fine, run fine with WOT rpm around 2600-ish. I suspect the rpm is lower than 2800 due to the props, but not certain.

Rpm was the same on the purchase survey, but I'm pretty sure they weren't smoking then (early 2024).

I mostly drive around the bay at 1000-1200 RPM, occasional short, faster runs.

The fuel is from last summer, 50% left with stabilizer added. I just don't burn that much cruising around the bay at sunset.

Need to get the aftercoolers checked, but an oil sample two years ago was normal, no Sodium (my tech forgot to do the last oil sample).

I took it out and ran it hard for about 30 minutes today, did seem to improve a little after that.

I don't have any diesel experience other than owning this boat for a couple years. Any idea what might cause the smoke? Looking for a sanity check before I get a pro involved.

Routine service (fluids & filters) only in the two years I've owned it, neither the surveyor nor management company seemed concerned. I haven't discussed the smoke yet, trying to get an idea what the issue might be and whether I should find a cat-specific tech (hard to get service onsite at my marina due to their insurance rules, limited options).

One engine had an injector pump rebuilt about three years ago.

Hull and gear should be clean, I have routine diver service and he's good about sending me pics if he finds anything amiss. Hauled, soda-blasted and painted less than two years ago, props were tuned up too.

Potential over-prop is something I've learned about since it was hauled, it's my first boat aside from a seadoo and years of submarines in the Navy. So diesel is what's new to me, I was on the nuke side in that Navy.

Usually do afternoon sunset cruises for a couple hours at 1000-1200, with maybe 5-10 minutes at higher rpm on average, but not usually above 2000rpm.

Thanks guys. I checked, the CAT dealer is on the list so that's good. I actually worked for them years ago, probably still know some folks.

Filters and fluids have been done annually since I owned the boat, most recently in Dec 25. The only thing that's changed in the last two years is that the PO went to Catalina and Mexico on a regular basis, while we've only been trolling around the Bay. So maybe it's just the low speed ops, I'll give it another good hard run for 30 minutes, see if that helps any.

It's on my list to get the aftercoolers (and turbos) serviced, but I don't know how long it's been and am concerned that if the collars break coming off I'd need new cores, which is of course expensive. Maybe I'll do one and see how it goes so I can stagger them out. I understand I should ensure that brass collars are installed vice aluminum. Again the last oil analysis didn't show any sodium, so they probably weren't leaking two years ago.

The tech didn't get an oil sample in Dec (miscommunication), how many hours should I run before getting a sample that will be valid? I might be doing 5 hours/month.

For prop spec, do I need it hauled so a pro can evaluate what's on there? Or if my diver took pictures would that provide enough info?

All good info, thanks. Definitely will figure out the props and service the AC's.

Cooling system is maintained regularly, temps look normal. Hull is cleaned every 3-4 weeks.

Boat is lightly loaded, not a live-aboard.

The engines just got fluids and filters, so the oil level was at the top. I may not have run the engines hard with the oil all the way full before. Would they tend to burn oil at the top of the dipstick normal range?