Ongoing TAMD41A under power/ low WOT..ideas?

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petrolhead63

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An update on working through the lack of WOT on our twin shaft TAMD41A engine. About 1100 hours only.

Clean bottom, no barnacles etc. Engines max out low from previous, port unit seems a bit low on power so could be dragging down the starboard revs by overloading prop. If port can only get to 2900 I guess the starboard will struggle to get more than a few hundred more.
No undue smoke, both start and run lovely as far as they go. Should WOT at 3800rpm but we only ever got 3600rpm ish but put down to load/bottom/age etc and was acceptable.
Max offload revs P 4100 and S 4400
Set one engine on 1000 and WOT the other P 2500 S 2700
WOT both P 2900 S 3100

so there is a constant discrepancy on port. I have not yet used photo tacho to check gauges but similar story on upper helm so likely accurate.

I also notice the port stick is moving further forward at similar revs as far as they go and having achieved revs cant back off like the starboard one and maintain them.

As background after buying it we had very clogged primary filters following a rough passage and lost power to similar levels...2800/2900 ish. This lack of revs currently is similar to back then...lack of power/revs like fuel starvation. Tanks cleaned, new filters through out, Lift pump strainers already missing so not blocked.
I have looked at turbos which seem ok...though I am no expert.
Has new exhaust hoses already.
Has new flexi fuel hoses already.
Have blown back through fuel lift pipes in tank in case blocked partially.
Air filters not very old and look ok.

Injectors never serviced but no obvious issues..smooth and not smoky.

I am starting to struggle where to look, could it be a weak lift pump? I have no idea if they work or don't work or can have an in between state causing fuel starvation! I could switch port to starboard.
 
Hi,

With all you have done so far I would surely try to switch the fuel pump. That should immediately give you the answer whether this part is to be blamed or not.
I notice that you say that the injectors never have been serviced... Not exactly sure about your engine though but I hear from many that injectors should be serviced every 1000 hours (or 5 years) but since you have no smoke I believe you are fine.
Hope you find a solution soon.
 
Hi, thanks for your interest. The injectors I think should be serviced by now, I even hear stories of nozzles falling into engines! ouch...but we run smooth, even and not unduly smoky which normally means injectors ok. also injectors tend to overfuel when duff from experience.
much of the other works has been planned maintenance since getting her but this lack of oomph is now puzzling. It did go well so should again!
Does anybody know if lift pumps can be lazy or simply just stop? A new type sealed unit is not mega bucks either, if they are known to wear both could be tired so perhaps I should try a new one and if it does not do anything simply put it down to a useful spare in the box we carry?
 
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Can't add much, but have you checked that when the throttle levers are fully forward, the levers on the injector pumps are at full travel? Engines don't need to be started for this check of course. Just another quick and simple thing to eliminate.

Www.solocoastalsailing.co.uk
 
Hi, yes good idea re the stops, and I have checked that...both hit the stops and I do not believe it needs adjusting other than minor because the boat ran better previously and they have not been messed with.
It has crossed my mind I am unsure if this engine has a stop solenoid that could be lazy and not fully open?
 
In all my years working on Volvo and various other makes I can honestly say that injectors play a massive part in the performance of any Volvo engine , why I don’t know but they do.

Get the injectors pulled out and tested by a pump shop that knows marine Volvo not a car or truck place , over the years I e taken some units to a normal Bosch dealer , they have reported nothing much wrong and charged for lapping in nozzles.
A total waste of time , have new ones fitted. The opening pressure plays a big part as well because it alters the timing when the springs go weak.
Looking at your data are you saying the bad engine is 200 rpm down at full throttle but will only pull 1000 on its own?
 
Hi, many thanks indeed for your interest. sorry if I was not clear, no, on a load test if I set one engine to 1000rpm in gear and WOT the other the port engine is about 200rpm down on what starboard can achieve. 2500/2700
The port engine is also 200rpm down at both WOT getting 2900/3100 and non load test port is 300 down on starboard though starboard is technically a little high 4100/4400
Neither engine starts to cook on the single engine load test which I watch closely as it is overloaded really in this test.
I have photos of the turbos both sides...I am not too experienced with them but they look good to me!
I will add that when we first got it perhaps the early signs were there. They should pull WOT 3800 and being a storebro I know it would new have been correct, but we were getting about 3500/3600 perhaps marginally more but port was always a little less.
Also, when new, the Storebro papers show the non load test with the starboard engine marginally lower than the port one by 100rpm and the governor stops are still factory sealed so never messed with. In other words off load some 28 years on for what is worth the port engine which did run faster is now slower WOT! not sure that tells us much ;0)
 
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I wouldn't bet that Storebro set them up as well as you think - I've owned a Storebro for the last 16 years, and I recall talking to someone outside at RK Marine many years ago who was involved in importing them. He reckoned they often were delivered in an over-propped state.

The last time I tried, I think I got ours up to 3,600 under load, but the engines are old, and I'm in no hurry, so it's not something I try often. The hardest I ever run them is 3,200 these days, and that's quite infrequent.
 
Hi, yes our last Storebro was a 31 Baltic owned 16 years...proper semi displacement I preferred. She would pull 3600, the rated max with her TMD40A engines, though as you say only done maybe once a year as a test after hwer antifoul/work etc.
Our 340 biscay of three years is a planer though...although barely, its hull is almost a cross between semi displacement and planing. It has no noticable horrendous period coming over the hump and the fuel consumption/rpm chart is almost linear without the huge drop in the middle so typical of planing craft as it bods in the water.....fuel consumption not vastly different at any speed.
I was happy with the 3600 max this got against the 3800 spec and like you suspect they are often a little over propped if only because they were set up without cruising gear/family/spares/junk etc aboard!
Also a dinghy on the bathing platform with a planing boat is dead weight just where its not wanted!
We noticed with our 31 even weedy late in the year and lots of kit aboard the performance was affected little because it did not plane.
I also personally feel 200HP engines in a 34 feet 7 tonne boat is a little on the small side but having the hull shape she has it performs well and economically at the 13-15 knot range and very understressed...when it works right!
 
petrolhead63 said:
Hi, many thanks indeed for your interest. sorry if I was not clear, no, on a load test if I set one engine to 1000rpm in gear and WOT the other the port engine is about 200rpm down on what starboard can achieve. 2500/2700
The port engine is also 200rpm down at both WOT getting 2900/3100 and non load test port is 300 down on starboard though starboard is technically a little high 4100/4400
Neither engine starts to cook on the single engine load test which I watch closely as it is overloaded really in this test.
I have photos of the turbos both sides...I am not too experienced with them but they look good to me!
I will add that when we first got it perhaps the early signs were there. They should pull WOT 3800 and being a storebro I know it would new have been correct, but we were getting about 3500/3600 perhaps marginally more but port was always a little less.
Also, when new, the Storebro papers show the non load test with the starboard engine marginally lower than the port one by 100rpm and the governor stops are still factory sealed so never messed with. In other words off load some 28 years on for what is worth the port engine which did run faster is now slower WOT! not sure that tells us much ;0)
Click to expand...

Where is this boat located .?

Test like this .
One engine in neutral , other full throttle record attained rpm.
Do same for other.
Both in gear at idle ; full throttle then watch rev counters , they should rise together, if they don’t it’s more likely a turbo issue , check the o rings on the air inlet pipe and clamp from turbo to intercooler, check rear part of intercooler for corrosion .
If possible do a boost pressure test on both engines , bring back data .
This is a heavy boat I’ve never seen one make 3800/3900 rpm
 
Hi, ok next time out which may at this time of year be a little while I will test with one in neutral...I was taught years ago to test with one nailed at about 1000rpm.
The revs do rise equally as you acceplerate, although I think ultimately the port stick is further forward or cant be backed of after reaching say 2600 like the starboard can...and to cruise at its current near max the port stick is further forward the starboard one can back off a bit as usual.
Intercoolers were stripped out, cleaned, new style plastic tops 2 years ago...no signs of leaks on joints.
both turbos spin fee and look good to me...vanes do not look worn/corroded etc. Have photos if i can make smaller to post.
To sum up if behaves and feels just like when we badly clogged primary filters in rough seas soon after purchase with black gunge...and it was then the port one that was really grim and starboard less so.
 
Could have a blockage at the tank pickup end, how about making an adaptor for the filter vent screw that can take a rubber pipe and attach a pela type oil sucker and see how fast it can flow out and compare both sides.
I have non-return bleed valves (designed for brake calipers) on both my engine filters and it makes bleeding the system an absolute doddle with a pela pump, I have been plagued by rust in the filters all this year so now have new stainless tanks en-route but has meant a lot of bleeding this year.
 
Hi,

In addition to the earlier good replies ...

Have you checked the engine to fully open the lever when your control device is full trhotles.

Another idea of ​​your pre fuel filters in the engines and the raw fuel filter, may be the difference between dirt and flow.

Third is a turbo, can be carbon or bearing wear, you can watsh, remove airfilters system from the front of the turbo.

The fourth is your gearbox and shaft where there may be a difference that causes the rmp difference.

NBs
 
I thought it time to update on this thread and perhaps get ideas on where to go next! I have improved matters and things still point to issues following the bad gunge stir up in tanks blocking filters.
As a reminder, port engine is down a bit but runs fine up to about 3000rpm now, however I now know it seems the stick is always further forward and it uses less fuel (unless by coincidence the fuel gauge/sender has gone duff too on that side!).
It behaves just like when we had badly blocked filters after stirring all the dirt in the tank up from 27 years little use.
I took apart the racors as suggested by Snowbird i think and indeed found lots of black goo blocking the spinners/ball bearing valves that was invisible unless on the bench and since then it has improved but not back to where it was.
This too seems to suggest we still have blocked fuel flow?
Those following will know we have worked through many other checks, filters, hoses, turbo checks, intercoolers, pipes, throttle stops, etc etc and I still feel it is a syptom like fuel starvation as supported by stick further forward and using less diesel. No black smoke either.
The boat runs spot on to about 3000rpm but i know it used to exceed 3600 on both. currently it has improved to max 3100-3200 on port with Starboard achieving about 200 more...probably held back by port being underperforming.
Naturally i have not tested it too much, we tend to cruise at about 2700 anyway.
I have not changed the lift pump yet...I bought one from Volvo Paul but it is later and needs different pipes so it could be better to switch them over port to starboard.
Also although I have blown back on both pick up pipes to the tanks and they seem fine I wonder if they may have a gauze strainer part blocked restricting high flow? Whether I can get the pipe out without breaking anything is another matter:eek:
I hear differing stories on the lift pumps..I thought it would work or not work but i am told some people have restored maximum revs with a new pump, though mine look fine inside.
Finally, yes...it has a clean botty and props!
 
As well as commending Volvo Paul’s advice as sound.....I might also add that the traditional tachometer gauge can be far from accurate. Surprisingly far. Normally you can tell if the engines are in sync by ear. Hard to explain but entirely possible
 
Hi, thanks for your thought. The lower and upper helm tacho's give similar stories so if it is under reading on port it can only be the alternator output signal.
The lack of power at the top end can be felt..without needing the tacho's, though I agree the rpm readings may not be exact! I did switch the port and starboard tachos over downstairs anyway because i had one rebuilt/serviced after failure so it has been calibrated and is therefore on the under powered engine.
I do have at home a digital tacho used with reflective tape I use on cars, I had intended checking the accuracy of the boat gauges with this but am certain it is not running the revs it should.
I just cant help but think the port engine is a bit down following the seriously filthy tanks stirring up and making a mess of the pre filters. The port one as it happens was a lot worse than the starboard one.
I will add, the tanks have been cleaned out and even after some lumpy trips this year on holiday the pre filter bowls are lovely and clean as are the filter elements.
Having found the black jelly goo still in the spinner/ball valve part of the racor though still makes me think it could be somewhere else?
Does anybody more expert than me know if it can defeat the Racor pre filter, the fuel lift pump (which were clean inside even when the pre filters were totally gunged up) and also the engine main filter to actually reach the diesel pump?
 
Hi, off the wall possibility-------have you had the sea water pump overhauled on the problem engine, if yes, it is possible that the pump shaft is protruding further out of the pump than originally before the rebuild. If this has occurred the shaft "end loads" the fuel injection pump drive gear and will cause poor performance.

If no ignore this drivel.

Best wishes

springer
 
Hi, thats a great idea and no drivel....it will be files in my memory banks in case its needed in future. Sadly though, not that simple....raw water pump has not been removed.
 
Given all the black gunge you’ve been finding, have you used/do you use diesel bug treatment in the tank? Sounds like you’ve got a nasty infection!
 
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