Hi, again, my friends. I thought I'd update you on the work-up and diagnosis of the Volvo TMD22 rpm problem I've had on "Kristy" SM243. Thanks again to all of you who responded.
The engine was tested on Lake Texoma during the survey, and was deemed to be working satisfactorily. Unfortunately, there is no mention of how high the rpms got during the sea trial or under no-load. The Auto-prop was clean and the blades spun freely on the hub. Since she had been sitting for 6 years with only an occasional run on the lake, I had the fuel polished before leaving Galveston, but noted that the fuel was drawn from the fuel line going from the tank to the engine, and that no effort was made to check the bottom of the tank or clean it. I was told that only a small amount of sediment was recovered during the "polishing". Not knowing any better, I thought I was in good shape. The tachometer/hour meter was replaced due to the hour meter not working. I was told that the engine had only ~2000 hours after four years of cruising the Med, Caribbean, and northern S.America ???. The Onan had only 800 hours on its meter. The Volvo was clean and looked nearly new. The oil was changed and new Racors and secondary filter were fitted.
On the way to Ft. Lauderdale we noted that the engine purred like a kitten up to 1600 rpm, but started smoking a little from 1600 to 1800 rpm and wouldn't go any faster than that. At 1600 rpm the boat made a comfortable 6-6.5 kts. It started without problems. In Ft. Lauderdale, I left her in the hands of Ray Eaton, who checked the throttle linkage, changed the Racors and secondary filter again, removed the turbo and had it refurbished. He said that the turbo people told him that "the part that opens" wasn't working properly and had been repaired (?wastegate?). When he replaced the turbo, he was convinced that would solve the problem but didn't do a sea trial. When I moved Kristy from where she was docked to the city marina, I found that she still wouldn't get up over 1850rpm. Ray called in a favor from his best diesel mechanic, and at last minute notice he came out to look at the boat while Ray was there. He noted a significant exhaust leak where the turbo was attached to the engine and acquired new gaskets. He also felt that the engine was running faster than the tach indicated, and checked with his hand-held tach. Yep, the tach hadn't been calibrated. The paperwork for the new tach wasn't on the boat and it took him considerable time to run down the calibration technique. He came back the next day, the turbo was reinstalled using some high-heat sealant on the gaskets, the tach was calibrated and we sea trialed her only to find that she was actually topping out at 2400 rpm. The speedometer was reading 6.5 kts, but the gps was reading 8 kts in both directions (up and down stream at nearly slack tide). He felt the engine was working fine and that it was a problem with the prop. We dove on the Auto-Prop and it had only a couple small barnacles on each blade, the blades spun freely on the hub. The barnacles were cleaned off and the hull was noted to be free of any growth. Another sea trial and no difference was noted in performance.
We went on to the Bahamas for two weeks, motored for a total of 44 hours in light winds, and had no new problems. Downwind on the run from Abaco to Charleston there was a fairly strong exhaust odor noted. When we got to Charleston the port side from the exhaust outlet aft was significantly soot-stained. I waited in Charleston for a week for a storm to pass and couldn't get Superior Diesel (the local Volvo dealer) to return my calls, much less send a technician out to have a look. I finally got another mechanic (Aaron "Oil in a Day's Work") to take a look the next week. He found another smaller exhaust leak at the turbo/engine connection. He removed the turbo, cleaned the waste-gate (but noted significant pitting at the waste-gate seal), and replaced it with new gaskets. He checked to make sure that the injectors were all getting fuel. No change. Next he removed the turbo and took it to the Volvo people who told him it was "shot" and not repairable due to the pitting at the wastegate seal. New turbo installed. No change except that now there was no smoke at all when throttled up to 2400…now thinking a fuel problem. He brought another diesel mechanic friend of his to the boat the next weekend (I'm now commuting to and from Charleston every weekend trying to get this figured out). He checked the injector pump and found it "like new". This guy honed in immediately on the gauge at the Racors reading -11 cm pressure. I'm a dunce (but learning), but it's amazing to me that not one of the other 3 mechanics who looked at her noticed that. We changed the Racors again, there was no debris in the trap, and the secondary filter, and the pressure dropped to 0. She revved up to 4000+ rpms under no load, but when we sea-trialed again the max was now 2600 rpm. Damn!
Next weekend I met Aaron and a diving buddy of his (very professional ex-Navy diver who just retired and is starting his business in Charleston…Eric of "The Dive, LLC"). He was knowledgeable about the AutoProp and had an underwater camera that he used to show me what he found…very cool. I was amazed to see only a few small barnacles on each blade and on the shaft that he said would make a significant difference in performance. We sea-trialed again and this time got 3200 rpm under load, but by the time we got out where we could run her hard, the gauge at the Racors was reading -5 cm again.
I'm having the tank cleaned now, all lines from tank to engine checked, fuel polished (again), and am convinced I have the problem solved!
In summary: Turbo shot (not recognized in Ft. Lauderdale), fuel dirty (in spite of having it "polished" in Galveston, and neither of the mechanics in Ft. Lauderdale recognizing the high vacuum at the Racors), and AutoProp fouled (despite my checking and cleaning it up in the Bahamas…albeit obviously not adequately). Multiple problems all combining to cause the same symptom of inadequate rpm under load. Total bill: $3950!!!
So you see…almost all of you were correct in telling me what to look for. Thanks again.
Lesson learned: Take a marine diesel course, get my hands dirty, take your advice, only call a diesel mechanic after I've done what you tell me to do. These guys charge from $75-100 an hour and are so busy they don't act like they care if they get your business or not. Aaron of "Oil in a Day's Work" is an exception to that rule. He's a couple of years into his own business after learning in the Navy and working for Superior Diesel for a few years. He really took an interest in my boat and my problem and found the people to help him figure it all out.