RPM loss on Volvo TAMD63L

[David435]

Hi All
I purchased a Princess motor cruiser in September 2019 and since then have only run the TAMD63L engines for a total of 30 hours . At the time of purchase we engaged Volspec to undertake an engine survey and the maximum rpm load while moored was port 3150 rpm and starboard 3350 rpm while on sea trial port was 2800 rpm and starboard 2900 rpm. In March 2020 the port injection pump was removed and serviced due to an oil leak together with the injectors. I always cruise at a maximum 2500 rpm and have never fully opened the throttles until last week. We were returning from Brighton to Chichester and as it was calm conditions decided to give the engines a good blast. The throttle levers went fully forward but the port engine just maintained 2500 rpm while the starboard engine went to 2900 rpm. My immediate thought was perhaps not enough fuel was getting to the port engine as the filters had never been changed but then slowed the boat down and fully opened the throttles again with the clutch engaged and got 3400 rpm on both engines. The cruiser was only returned to the water mid May after pressure washing, antifouling, new anodes fitted and propellors, shafts, P brackets and trim tabs burnished. I am quite comfortable to continue cruising at 15 - 17 knots from 2500 rpm but would like to know why the port engine is not producing the extra rpm while under load and whether there might be a simple explanation and possible fix.

 

[Portofino]

Was it not sea trialed back in May after the new stern gear ?
They demand more fuel under load , so the full revs / rpm in N is a pretty meaningless test .

I,am assuming you did a typo ^ with “ opened the throttles with the clutch engaged and got 3400 rpm with both engines “ ??
Did you mean disengaged , my N ?

Fuel restrictions would be the first port of call in your investigations , replace all the filters and if possible drain off a bit from the tank , if it’s got a drain cock,to check for debris / contamination etc .

Did you overwinter it with any diesel bug mitigation?

Failing all this refer back to the alleged injector pump service agents as they know the motor by now .

 

[David435]

Was it not sea trialed back in May after the new stern gear ?
They demand more fuel under load , so the full revs / rpm in N is a pretty meaningless test .

I,am assuming you did a typo ^ with “ opened the throttles with the clutch engaged and got 3400 rpm with both engines “ ??
Did you mean disengaged , my N ?

Fuel restrictions would be the first port of call in your investigations , replace all the filters and if possible drain off a bit from the tank , if it’s got a drain cock,to check for debris / contamination etc .

Did you overwinter it with any diesel bug mitigation?

Failing all this refer back to the alleged injector pump service agents as they know the motor by now .

Hi Portofino
The stern gear was only fully cleaned and polished so didn't warrant a sea trial.
I always use diesel bug mitigation whenever I refuel throughout the year.
You are right, I meant the clutch was disengaged but the equal full rpm confused me as I would have thought the port engine would have had less rpm than the starboard if it was fuel starvation.

 

[David435]

Hi All
I am still struggling with the problem of loss of revs on the port engine.
We have now changed the primary and engine filters and on a sea trial on Tuesday still only managed to achieve 2,500 rpm with the throttle wide open on the port engine. We checked the exhaust at this speed and there was no indication of any excess smoke of any colour, although we do get the normal black exhaust residue on the fibreglass near the exhaust outlets on both engines. The throttle cable has been checked on the berth and the injection lever travels to the stop when the throttle is pushed to maximum. As mentioned before, with the throttles in neutral, both engines achieve 3,400 rpm which suggests to me the problem is not fuel starvation. The port injectors and pump were serviced by Powerdrive in Portsmouth and I spoke to our local engineer who removed and refitted the injectors and pump and he confirmed no sea trial was conducted after installation. Could the problem now relate to the turbo charger? I am no engineer and would really appreciate any advice / suggestions as to the next step.

 

[markc]

If you have no black smoke that would suggest that the turbo is OK and you have a fuel supply issue. Revving in neutral consumes way less fuel than under load, so it's not a way to rule out fuel starvation.

 

[AllanG]

As the port fuel injection pump was overhauled in 2020, and the max revs problem on the port engine was noticed after the pump was refitted, it could be that the pump is not giving enough fuel to the engine, so I would be comparing the port pump settings against the starboard pump, to see if any differences are obvious.

 

[kashurst]

Testing on the dock only verifies the engine can mechanically rotate that fast. It is no indicator of available power as it requires very little effort to make an unloaded engine go that fast.

It does sound like a fuel restriction issue. Before pulling injectors/pumps/turbos apart I would be going through the fuel pipes and switching valves very carefully. Essentially I would take it all apart and rod it all through, you may have some foreign body stuck somewhere in the piping/valves. Any rubber fuel pipes I would replace. It's cheap and easy to do and will eliminate anything simple.

When you accelerate do both engines increase RPMs at about the same rate?
What kind of fuel filters do you have Racor or Separ?

 

[Portofino]

Get the pumps swapped over .To see if the problem migrates .If it does I refer you back what I said earlier - refer back to the pump refurb guys .

If it doesn’t then follow ^^^ Kashurst post - check out the supply for blockages .

 

[Portofino]

Just reviewing your original post this sprung out
You said “ renew ——-/———- and propellors, shafts, P brackets”

I will throw this out there , could a whole shed load of miss alignment of the above cause excess binding that limits it 2500 rpm in gear ?
Or when you say “ new propellors “ …..are they identical? - but no black smoke - Hmm. Unlikely that one .

First as said you really need to know if that pump works properly before tearing into other stuff .Swop it over .

 

[Portofino]

I mean if it’s not too much hassle why not swop over the Racors / Separs .That’s DIY .I mean the whole units not the cartridges.
Racors have a funny ball valve which might foul up .

 

[ElJames]

Go for the simple things first assume the the fuel injection is good it starts easy not much wrong with the engine it is revving not under load so the turbo will not be doing a lot you say it is not smoking a lot but exhaust outlet area is sooty when did you last clean (the most forgotten part of any engine servicing) the intercooler and air filters to change over the parts as mentioned before will be very time consuming and if the fault moves to that engine you still have to diagnose the problem

 

[oldgit]

It is perfectly possible that after five months you have sufficent growth on the bottom to slow the boat down considerably..
If you are using a hard anti foul your tootling about may not have eroded the surface of the anti foul much .
However a mucky bottom usually betrays itself with a just detectable trail of smoke (if you bother or know what to to look for.).
Really bad fouling usually results in coating of oily soot on the transom.
Sometimes just putting hand underneath the boat arounf the stern will suggest a coat of slime at best or even barnycules.
Would always check the simple easy stuff before anything else. ?
A couple of years ago it took barely 3 months from a May Jetwash and A/F to a August speed loss of about 5-6 knots.

 

[David435]

Thanks for your interest, I'll try and answer all the queries in one post:

AllanG - Can you check the settings between port and starboard injector pumps without removal from the engine?
kashurst: - Both engines accelerate at the same rate. Primary filters are Racor S3201T. Not sure if I could rod the fuel lines but would an air pump blowing back work?
Portofino: The propellors, shafts and P brackets were not removed only buffed up to remove all the dirt.
ElJames: The engines start immediately even when left cold for a long time. The air filters were changed late 2019 just before covid started and since then have done less than 50 hours running.
oldgit: The overall cruising speed of 15 - 17 knots at 2500 rpm was achieved last Tuesday with full water and fuel tanks. This is about right for this boat.

It would seem best to eliminate a fuel restriction issue before starting to dismantle the engine but having just filled the tanks with diesel this might not be as easy as it sounds. The fuel lines are all metal up to the primary filters with separate stop cocks for both tanks positioned in a locker on the aft deck which is situated higher than the tanks, the fuel lines from the stop cock to the tank are hidden behind the bulkheads, as far as I can tell these stop cocks would be the only inline access available. other than the inlet pipe on the primary filter. There is a rubber hose leading from the primary filter to the injection pump. Any other suggestions would be appreciated.
Thanks a lot.

 

[kashurst]

From your replies it does sound like a fuel blockage. If the turbos were suspect one engine would accelerate faster than the other. As they both behave the same up to 2500 I think they are probably both OK. There is a possibility the exhaust waste gate is sticking open but based on how the boat behaves again I think they are OK, by 2000+ rpm the turbos will be wizzing round.
If the fuel pump or injectors were off, the engines would again behave differently. So at the moment leave them alone.

In the past I had a piece of metal that was in the tank from when it was made, make its way all the way to the switch over valves and it limited the engine. I would still be looking at taking the fuel pipes all to bits, the valves and filter assemblies and rod them through with a stiff wire or that stuff people used to hang net curtains up with.
Blowing air might get a foreign body out, but you won't know if it has and I doubt it will work. You may just move it to a position in the pipework with more space and it will then move back again. It may not matter if the tanks are full, the pick up pipe usually comes out the top of the tank so if you undo that connection fuel will not pour out.
If something is stuck in the pipe work, most likely it will be at a joint or a tight bend or a valve where the diameters change. It is not unheard of for older rubber fuel pipes to delaminate and narrow internally either.

Also check that all the fuel valves completely open and close properly.
What boat is it?

 

[Mr Googler]

Does the throttle cable move the injection pump lever all the way to the stop.

always worth a check that one

 

[Machaseo]

Max Rpms for that engine is 2800, Definately shouldnt be getting anything higher, check the rpms with a laser tacho don’t rely on the gauges then get some meaningful data and go from there.
they are prone to boost leaks at the inlet manifold gasket and the silicone hose between the turbo and the aftercooler.

 

[oldgit]

P 435 ? ................ a lot of boat to be pushed by those engines !

 

[David435]

Hi All

kashurst: The boat is a 1990 Princess 415. When you mention the valves when using a rod, are you referring to the stop cocks and all filter fuel inlet and outlets?
Mr Googler: The throttle cables have all been changed and checked for maximum travel to the injection pump stop.
Machaseo: I think the gauges are fairly accurate although I haven't used a laser tacho. Once both engines are at 2500 rpm, there is a distinct change in power and noise when the starboard engine is pushed to WOT.
oldgit: The 435 related to my previous boat when I joined the forum. I now have a Princess 415 which hopefully will soon get a berth at RCC.

 

[Bandit]

I have had TAMD 63p's in two boats over 20 years, excellent engines providing you look after them and keep on top of them.

They are mechanically governed 2800 rpm engines I cruise mine at 2500 in an 18.5 ton Aquastar 48.

Your boat needs to be propped to run at 2800 max no more. Are your props in good condition , is the pitch the same, are they original are they mismatched?

Running them off load at over 3000 proves nothing.

By all means check your fuel system, clean it and blow back fuel lines to tank to clear obstructions and re prime. Any signs of fuel bug in the prefilters.

Then have boat lifted and the hull pressure washed so it is spotless.

Then run seatrials again with a spotless hull, and also run each engine alone and see if they accelerate and pick up revs /speed in the same way.

It sounds like your starboard engine is not propped correctly and the port one is taking all the load.

I assume your engines are circa 20 years old, how many hours and what weight is your boat?

I caught a tarpaulin once at sea and de pitched one prop, i did not know it had de pitched a prop the diver said props were fine, it showed the same as you are reporting one engine low on rpm and one max rpm, the good one was doing all the work. After re pitching by Clements marine again they were fine.

Also with elderly 63's the turbo's wear and the exhaust gas crud starts to block up the inlet manifold, mine were well gunked up after 19 years when we cleaned them and replaced the turbos as well as replacing injectors.

 

[volvopaul]

Get the pumps swapped over .To see if the problem migrates .If it does I refer you back what I said earlier - refer back to the pump refurb guys .

If it doesn’t then follow ^^^ Kashurst post - check out the supply for blockages .

Have you any idea in the Labour time involved in that ?