TAMD41B sudden power loss

Zetec7 · 08-12-2023, 12:06 AM

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

Choices · 08-12-2023, 01:14 PM

Check fuel filters first. Could be several things separately.

DavidM · 08-12-2023, 01:43 PM

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

twistedtree · 08-12-2023, 01:46 PM

Failing, now seized turbo?

Zetec7 · 08-12-2023, 05:04 PM

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….

Jeff F · 08-12-2023, 05:56 PM

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

kchace · 08-12-2023, 07:26 PM

Symptoms seem to be classic clogged filter.

Ken

Pete Meisinger · 08-12-2023, 07:37 PM

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

SteveK · 08-12-2023, 07:58 PM

Quote:

Originally Posted by kchace

Symptoms seem to be classic clogged filter.

Ken

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

Zetec7 · 08-12-2023, 08:08 PM

Jeff F - Nope - no smoke at all, of any color

twistedtree · 08-12-2023, 08:21 PM

Quote:

Originally Posted by SteveK

+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.

Zetec7 · 08-12-2023, 09:39 PM

Quote:

Originally Posted by SteveK

+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…

DavidM · 08-12-2023, 10:03 PM

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

Zetec7 · 08-12-2023, 10:46 PM

Quote:

Originally Posted by DavidM

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.

Zetec7 · 08-12-2023, 10:58 PM

Of course, at only 2 microns as the primary filter, it’s maybe not surprising if it clogged quickly….?

SteveK · 08-13-2023, 12:20 AM

Quote:

Originally Posted by twistedtree

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.

Datenight · 08-13-2023, 11:34 AM

[QUOTE=Pete Meisinger;1188470]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

rgano · 08-13-2023, 12:26 PM

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.

Zetec7 · 08-13-2023, 03:52 PM

Quote:

Originally Posted by rgano

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).

Zetec7 · 08-13-2023, 03:58 PM

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….