TAMD41a woes

[Seastoke]

A compression test may well show which cylinders are causing the problem but if I am going to strip down the engine anyway I am certainly going to pull all the pistons to inspect condition and measure wear. I have never seen an engine (particularly a diesel) where one cylinder has broken or siezed rings and the rest are in perfect condition. It is false economy to just recondition one pot and leave the rest. Even if they are not the cause of the problem they will get the same attention.
As for stuffing it full of abrasive........... Er No..........

surely a comression test would help with info so as you are stripping you know you are heading the right direction ,

 

[boatmike]

surely a comression test would help with info so as you are stripping you know you are heading the right direction ,

I have not said I would not do a compression test but unless it were to show all cylinders to be OK (which is highly unlikely) the very least I need to do is take the head off to ensure that it isn't something amiss with the top end. In fact low compression could be due to anything (burnt valve, head gasket etc) but sub piston crankcase pressure is very likely piston blow-by so having got that far it's a no brainer that all pistons should be pulled to inspect. In fact in all my many years of reconditioning automotive engines (not many marine admittedly) I have come to the conclusion that doing the bare minimum to solve a problem comes back and bites you in the bum later on when you wish you had done the job properly in the first place.

 

[DaineB]

What happened with this in the end? Did you do a compression test? What were the results? What conclusion did you come to and how did you resolve it? Mine is doing the same but no post ever states how they fixed it in the end.

 

[boatmike]

What happened with this in the end? Did you do a compression test? What were the results? What conclusion did you come to and how did you resolve it? Mine is doing the same but no post ever states how they fixed it in the end.

Just seen this post. Its going back a bit now. The original post was 2002. However to answer your question, I stripped both the engines in the end and found that as suspected the bores were glazed to hell and the piston rings were very worn. However the good news was that the bores, apart from being glazed were within a thousandth of an inch of original size. Hardly worn at all in fact so I honed the bores, cleaned the pistons, fitted new rings and that basically solved the problem. While the engines were down I fitted new bearing shells as well although it didn't need it. The only other significant fault was that the exhaust elbows were completely clagged up with carbon which I was able to clear out OK and the exhaust dampers (only found on the 41a models) were sticking. Its worth checking these before stripping down the engine as it could be causing some of the problems. Frankly I took mine off and removed the butterfly choke from the exhaust entirely. The glazing however was the major problem on mine caused I think by the boat having been used extensively on the Dutch canals and never really "worked."
Good news is that both engines now run and start easily, achieve full power at 3800 RPM and don't smoke at all apart from an initial puff on start up. This was all completed in 2013 apart from the exhaust elbows that were done last year.
Hope this helps. They are great engines if properly used and maintained and still going strong in 2024! Good luck with yours. I hope this helps.

 

[DaineB]

Just seen this post. Its going back a bit now. The original post was 2002. However to answer your question, I stripped both the engines in the end and found that as suspected the bores were glazed to hell and the piston rings were very worn. However the good news was that the bores, apart from being glazed were within a thousandth of an inch of original size. Hardly worn at all in fact so I honed the bores, cleaned the pistons, fitted new rings and that basically solved the problem. While the engines were down I fitted new bearing shells as well although it didn't need it. The only other significant fault was that the exhaust elbows were completely clagged up with carbon which I was able to clear out OK and the exhaust dampers (only found on the 41a models) were sticking. Its worth checking these before stripping down the engine as it could be causing some of the problems. Frankly I took mine off and removed the butterfly choke from the exhaust entirely. The glazing however was the major problem on mine caused I think by the boat having been used extensively on the Dutch canals and never really "worked."
Good news is that both engines now run and start easily, achieve full power at 3800 RPM and don't smoke at all apart from an initial puff on start up. This was all completed in 2013 apart from the exhaust elbows that were done last year.
Hope this helps. They are great engines if properly used and maintained and still going strong in 2024! Good luck with yours. I hope this helps.

I ended up fitting a breather relocation kit that blocks the rear filter hole and comes with the updated rocker cover with breather up there. Tested the boat at WOT for around 20 mins and no oil in the bilge. I suspect I may have a little amount of glazing and worn rings as compression is down a little but it starts and runs fine and gets 3700rpm with my current prop setup so I'm just going to run it hard for a while and see how it goes. I just get a little steam from both engines due to the wet exhaust but no soot on the back anymore. The filter relo and Italian tune up has improved mine significantly. Just a reminder that these engines need to work and to never let them idle without load on them I guess.

 

[Redsdog]

I have done a lot of work on my two TMD41a engines which are now fitted with new ZF gearboxes, shafts and props. I have also had both turbos professionally reconditioned, cleaned out both fuel tanks and fitted new filters. The Stbd engine runs fine and gets up to 3600RPM with 1 bar positive manifold pressure. The Port engine is down on power and only gets up to 3200RPM with about 0.7 bar positive manifold pressure. It also blows quite a significant amount of oil out of the crankcase breather. I am assuming that having got everything else right that the extra manifold pressure and higher revs has now exposed a more fundamental problem with the engine and thought at first that it must be busted piston rings. However it dawned on me that a head gasket failure could be the cause also blowing between a cylinder and an oil passage. In fact possibly more likely as there is a lot of oil blowing out indicating a crankcase pressure that is quite high when running at high revs when the turbo cuts in but not at less than 2000RPM . Does anyone on the forum have experience of a similar failure with this series of engine?? Looking at the workshop manual the oil passages are very near the cylinder and I am wondering if its a common problem? ps They are TMD41a not TAMD41a but I can't seem to edit title.

Had that problem b4 had cracks in the top of 2 pistons