TAMD41B sudden power loss

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Zetec7

Veteran Member
Joined
Sep 17, 2020
Messages
52
Location
Canada
We have a 1991 Cooper Yachts 28’ Prowler with a Volvo Penta TAMD41B mated to a VP 290DP leg. About 875 hours on it since new.

Boat’s been running beautifully - up to 28.2 knots an a smooth 23.5 cruise at 3750 RPM. Gets out of the hole and up on a plane quickly as soon as the turbo spools up.

Recently it’s started losing oil, about 1 litre per hour at cruising speed. No smoke except a tiny amount at idle when cold. A little of it ends up in the bilge, but most of it disappears. Dye tracers haven’t revealed any leaks at all.

A couple of mechanics have suggested a leaking seal in the turbo could be the culprit, burning the oil so completely that there’s no smoke. As there are no mechanics available before October I’ve just been topping up the oil as needed and checking it often. We’re leaving the country for 8-9 months, long before we could get a mechanic to look at it.

Yesterday we did a long cruise at 23 Knots, and as we neared our destination the engine suddenly started slowing dow, losing speed and coming down off the plane (down to 14 knots). Temperature had gone up about 3-4 degrees above the normal 173 degrees F.

As soon we stopped the boat (engine at close to idle) the temperature immediately dropped to normal idle temp (about 165F).

When I throttled up again, it was back to 23 Knots….but only for about 3 minutes, and then the process repeated. Eventually it was slowing down to 10 knots. Turbo gauge was reading 14 PSI boost (don’t know if that means normal atmospheric pressure of 14psi or 14 psi of boost above atmospheric, but I suspect the former…although at idle the gauge always reads zero…), which was full throttle at 10 knots.

When I run it again Tuesday morning I’ll get my wife to watch the turbo gauge (only at the lower helm station, and I always drive from the upper station for visibility - thousands of logs in these waters) and see what happens when it does it’s slow down thing. It kind of reminds me of a blockage in the muffler on my Mustang, choking off the exhaust - same loss of powe, exhaust got really hot, coolant temp started to rise.

I’ve checked the usual things available without disassembly, and all looks normal.

Hoping someone can offer some advice. We’re a long way from home with no mechanical assistance available…i
 
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Fuel supply is the usual cause of sudden power drop. But your oil loss is another question. Could the power and oil loss be related?

David
 
I wish I knew! I have a 500 series Racor 2 micron filter ahead of the engine mounted spin on filter. No visible water or anything in the Racor, although there are some particles on the shelf below the filter element (bits filtered & dropped from the element, maybe?). I’ve ordered a new element for it.

I, too, suspect the turbo. I wonder if it’s possible that a worn seal is causing oil consumption & enough sooting to cause drag in the turbo?? Or clogging up its bearings, maybe? If so I’m hoping a clean up & new seals might fix it. It’s strange - the turbo was professionally (and completely) rebuilt less than 100 hours ago….
 
Did you see black smoke out the exhaust? It'd be hard to miss at high loads if the turbo failed.

Sent from my moto g play (2021) using Trawler Forum mobile app
 
Symptoms seem to be classic clogged filter.

Ken
 
I agree with those who suspect a fuel delivery problem. Check the filters and connections.

On the off chance that it is turbo related BE READY for a runaway. By that I mean have something handy which will stop all air from entering the turbo. You will need to think and act fast, you wont have much time before the engine blows. You will know the engine runaway as soon as it happens. It will not respond to the throttle controls or the kill switch. The usual air stoppers are a plank of lightly padded board over the air intake. Some have had even large rags sucked into the engine.

pete
 
+1. I just had the same symptoms, once the primary filter was replaced all normal.
The oil loss not related, another matter


The two problems may be unrelated, but also a tough coincidence to ignore. But of course, check filters. Easy to do, and no harm.
 
+1. I just had the same symptoms, once the primary filter was replaced all normal.
The oil loss not related, another matter

I’m desperately hoping this will be the source of my power loss! I guess the Racor would be first in line for replacement & I’ve ordered one. My favourite marine diesel mechanic has told me not to worry about the spin-on filter as the 2 micron Racor will remove everything before it gets to the spin-on.

We’ll see…..

Sure like to know where all that oil is going though…
 
This issue has been debated at least a hundred times on this forum, but I believe that the Racor should be 10 microns and the on engine filter 2 microns. This balances the load between the two filters and they will last longer.

David
 
This issue has been debated at least a hundred times on this forum, but I believe that the Racor should be 10 microns and the us on engine filter 2 microns. This balances the load between the two filters and they will last longer.

David

I’ve seen that in the posts - the filter element listed for this Racor 500MA is Racor part number 2010SM (replacement part number is printed right on the filter housing), which is sold on Amazon as a 2 micron filter. I would have thought it would be coarser than that - not much point in having it the same as the spin-on, really. Could be it’s listed wrong on Amazon.
 
Of course, at only 2 microns as the primary filter, it’s maybe not surprising if it clogged quickly….?
 
The two problems may be unrelated, but also a tough coincidence to ignore. But of course, check filters. Easy to do, and no harm.

Suppose the OP stops adding oil but continues to monitor the dipstick. Will it settle at a level? That is another thing I have found on engines, no explanation why it is the way it is.
Started with my new Harley kept adding pint until I ran out, checked and found no further movement.

Same with my previous Lehmans, one wanted to be lower than either dipstick so I let it be, did not move after that.

Now with my Hino, PO said I add a litre every so often to Port. I noted the location on dipstick and have not added any oil, year later still the same.

Maybe we think the dipstick is right and add oil for no reason.
 
I agree with those who suspect a fuel delivery problem. Check the filters and connections.
Some have had even large rags sucked into the engine.



Many years ago a neighbor had a diesel Peugot sedan. One day it was smoking badly and could barely make it up the hill. He changed the filters but no luck. He started the engine with the hood up. I noticed the rubber air intake was collapsed. A rag he kept in the engine compartment for checking the oil had been sucked into the intake. Removed the rag and all was well.

Since this is an intermittent problem it's probably not that but wort a check.

Rob
 
Is there a vacuum gauge on that Racor? Do you have only one Racor?

Because I have uses 2-micron elements in my Racors for a few decades, I have a vacuum gauge at the helm and change elements any time vac begins to rise. Never change spin-ons.

From what I can see here, you may have only one Racor 500 - why? Two with appropriate valves to allow one to be idle gives the redundancy to allow switching them on the fly in bad conditions if stirred up sediment clogs one plus troubleshooting capability for situations like this.
 
Is there a vacuum gauge on that Racor? Do you have only one Racor?

Because I have uses 2-micron elements in my Racors for a few decades, I have a vacuum gauge at the helm and change elements any time vac begins to rise. Never change spin-ons.

From what I can see here, you may have only one Racor 500 - why? Two with appropriate valves to allow one to be idle gives the redundancy to allow switching them on the fly in bad conditions if stirred up sediment clogs one plus troubleshooting capability for situations like this.

When I bought the boat 23 years ago it had the original spin-on Volvo Penta filter, and the Racor had been fitted as an extra for redundancy.

I had never thought of adding a 3rd filter, though your idea sounds great, and it’s an option I need to investigate. Not a lot of room in that area of my engine room, but I think it’s doable. It sure would have prevented the problems I’m going through (assuming a clogged filter is my issue, and it’s sure looking that way at the moment).
 
I forgot to reply about the vacuum gauge issue - nope, don’t have one, and I’m not sure it’s possible with the TAMD41B - there’s no intake manifold to speak of to tap into - the air cleaner housing is mounted directly to the turbo. Maybe through the lid of the air cleaner, but I’m not sure if it would give meaningful information. I haven’t seen a vacuum tap shown on the engine schematics. It sure would be useful, even if it was just in the engine room….
 
I forgot to reply about the vacuum gauge issue - nope, don’t have one, and I’m not sure it’s possible with the TAMD41B - there’s no intake manifold to speak of to tap into - the air cleaner housing is mounted directly to the turbo. Maybe through the lid of the air cleaner, but I’m not sure if it would give meaningful information. I haven’t seen a vacuum tap shown on the engine schematics. It sure would be useful, even if it was just in the engine room….



I think he’s talking about a vacuum gauge on the Racor filter assembly that will show when there is a restriction in the filter.
 
On checking Google, I see there is an “engine vacuum valve ki” for my engine - not sure if that’s what is required, but I’ll look into it further….
 
I think he’s talking about a vacuum gauge on the Racor filter assembly that will show when there is a restriction in the filter.

Ahhh, okay. Never seen one of those - should be a fairly generic part, I would think…
 
I see there’s a specific kit for newer Racor 500’s (replaces the T-handle on the top - couldn’t be easier thuan that, right?). Unfortunately it doesn’t fit older units like mine, but I’ll keep looking…

Wow, getting a LOT of help from you wonderful folks here!!!
 
Agree with all who suspect a fuel system issue. In that case, always begin with the filters. Two Racors with an isolation valve to switch between them is good practice, along with a couple of extra cartridges on board.

A sooted-up or failing turbo ought to be exhausting visible black smoke. If you're not seeing anything when tached-up, that's probably not the issue.
 
I think he’s talking about a vacuum gauge on the Racor filter assembly that will show when there is a restriction in the filter.

I have a gauge on one of my Racor filter bodies, the one usually in use, but I ALSO have teed into the fuel line between the Racors and the engine-mounted spin-on filter to run a vacuum line up the the vacuum gauge I mounted at the helm. That second gauge is the one I use to determine there is an issue with clogging, at which time I can examine the gauge at the in-use Racor before flipping the valve to bring the second Racor online in PARALLEL with the first one. I sympathize with the shortage of space, but as you can see, I had little to spare either when I was considering adding another Racor. I moved the original Racor from an inconvenient location and mounted it on an aluminum plate to the stringer outboard from the engine.
 

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Wow, that’s quite a setup!! Very tidy! I really like the parallel filter idea. Even as an emergency measure I could plumb in a manual bypass for the Racor, so the 2 micron spin-on could pick up the load temporarily. I do carry a spare spin-on aboard.
 
If not in the filter, the vacuum gauge goes between the primary filter and the lift pump.
If you have a fuel manifold, then it goes there.
I have a dual Racor primary setup. One is on line and one is waiting. I flip a couple valves and the other filter takes over. They are 2 micron.

My Detroits pump about 70 gallons an hour, returning about 60. I change them once a season or 500 hours. At that point the vacuum gauge shows about 4"hg. In 500 hours 35,000 gallons has been thru the filter.

On diesel engines I have worked on, a sudden loss of power isn't a fuel delivery problem. It's usually an air problem. Either intake air is restricted or air entering the fuel lines. It also could be a problem in the injector pump. If both engines are using the same fuel source, then it's not a fuel quality problem.
 
Well, I was in a fix (60 miles from home, serious need to get home, and a major wind storm to transit through), so I decided to take the chance that the primary filter was the issue. I managed to find the right filter (10 micron for the Racor), so I bought two.

I installed the filter (the old one was quite clogged up) and sealed everything back up. I was kind of rolling the dice because once I left the protection of the marina I was going to be right in the teeth of the gale. Other boaters coming in (several in 45-50’ trawlers) were white as sheets as it was very rough out there. Even right inside the protected marina it was blowing 30+ knots with 40 knot gusts. Saw a LOT of close calls with skippers trying to moor, get up to the fuel dock, etc.

Left the marina and was immediately int a northwester that was creating 3-4’ swells, opposing the heavy southeasterly tide & currents. Ugly, ugly seas (although clear skies & hot temps).

The filter did the trick. She spooled up nicely, and I had good power again. This was good, because I had to transit Dodd’s Narrows (with a 9 knot roiling tidal current, whirlpools, lots of drying rocks, etc.). Made it through safely (not without tense moments though) & later was able to get back up to my normal 22-23 knot cruise speeds again.

THANK YOU to all who replied, & offered such great advice!!! I am in your debt, as you helped me get safely home with my family and vessel.
 
Glad you fixed the problem but I hope you learned from this experience. When you are in a safe harbor and the weather is that bad don’t go out for any reason. You could rent a car or Uber to where you need to be. It certainly could have turned out badly for you.
 

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