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GrahamSop

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  1. Hi all, Over the weekend I installed an R&D type flexible coupling, and to do it I had to remove the split half-coupling from my propshaft anyway, in order to get the old bolts off it. After installing the new R&D flex and reclamping the half-coupling onto the shaft, doing the pinch bolts alternately, I'm happy to say my alignment is now much better 😊 I think the reclamping of the half-coupling was what made the biggest difference, as now there is <0.05mm movement on the shaft, but there is also barely any angular misalignment, judging from the red bolt system on the R&D coupling with feeler gauges. But I'm happy to have the flexi coupling installed now as well - all runs much more smoothly and no engine oscillating around in the mounts any more. Thanks for all the helpful replies!
  2. In an ideal world that would be nice. But this would definitely need a shorter propshaft and the boat out of the water. Maybe one day. There are plenty of boats without a thrust block, and my mounts are in pretty good condition so I think for now I'll make do with how it is. Interesting suggestion, I might try loosening and re-tightening to check this, thanks!
  3. Thanks Mike, glad to have a second person suggesting either the shaft is bent or the coupling is not running true. Thanks Tony, it is a split half coupling with the clamp bolts either side of the shaft. I will have a look more closely, I am not sure if it has a key or not. I don't have a torque wrench but I do have large socket set with breaker bars etc. I'll try again putting the shaft in the V block and try to determine if it is the shaft that is bent or the coupling. Regardless, I think I will get a flexible coupling for now, as I'd be happier taking some of the vibrations out of the gearbox flange. It seems a sensible addition to have in the drivechain anyway. I have plenty of room between rudder and prop to push back the 3cm or so to get the flexi coupling in. But is it a bad idea to have this length of shaft sticking out the other end of my cutlass bearing, between the end of the bearing and the prop? I have no plans to take the boat out of the water until next year, so shortening the shaft/getting a shorter one is not going to happen at the moment.
  4. Thanks Tony, Yesterday I spent a few hours trying to get the alignment as perfect as possible using feeler gauges between the two flanges (gearbox flange and my split half-coupling on the propshaft). Unfortunately after bolting everything back up it is only very slightly improved, and the shaft still moves about 0.3mm when it is turned. However, I think I discovered a bigger problem: After aligning as best as I could, I mounted the base of the dial indicator to the engine itself, not the hull. First I measured the radial displacement of gearbox flange. this was zero. Then the flange on the half-coupling, this was also fine, <0.05mm. Then I measured the propshaft to have a significant displacement. The further I measured from the coupling, the bigger the displacement. So it seems my propshaft is clamped at a slight angle in the half-coupling, or it is bent. I think this is the main cause of my vibrations and it explains why I can't align the engine better. I am pretty reluctant to loosen the half coupling as I think it'll be the start of other problems like not getting it tight enough again, or making the alignment even worse! I could possibly fit a flexible coupling between the flanges but I feel it's really covering over the problem rather than sorting it out. What are your thoughts?
  5. Do you often take pictures of someone else's boat then upload them to discuss the problems on here? Wow.
  6. I can disconnect the propshaft. But even without disconnecting it, as Tony says you can put a dial indicator with the base fixed to the hull and the needle on the propshaft. Turning it by hand will still show if the propshaft is oscillating in an ellipse or not. I initially attached the indicator base to the engine block and registered no misalignment...only to realise this was because the whole engine was moving 😑 (although this is a nice check to see if the shaft is bent or not)
  7. Hi, I know this is a fairly well-covered topic on here, but I'm after tips in aligning my engine better. It's an Isuzu 35, with a solid coupling between the flange of my PRM120 gearbox to the propshaft, and the shaft goes through a Vetus cutlass bearing stern gland. With a dial gauge and turning the shaft by hand I have around 0.4-0.5mm radial misalignment. The whole engine moves in a small ellipse when in gear, and starts to vibrate quite badly above 1000rpm. I've read lots about doing the alignment: http://www.canaline-engines.co.uk/wp-content/uploads/2017/06/Canaline-Operators-Handbook-CE-Version-3870T.pdf https://www.yachtsurvey.com/Alignment2.htm But with a cutlass bearing, when you disconnect the prop shaft it just sags down, so you can't align the engine to it. When connecting the two flanges together, they seem to fit very nicely with no obvious angular mismatch. I admit I haven't actually checked this with feeler gauges, but I don't see the point if the propshaft is free to flop around anyway? I've tried one thing by keeping the propshaft connected, and making small adjustments to the engine mounts, re checking the eccentricity, re-adjust, and so on. After an hour I had improved it slightly to about 0.3mm, but surely it can be better? I've also heard the propshaft can be supported in place when disconnected with a bit of wood with a V notch, or similar. But in this case how do you know the shaft is in the correct place? What do you have other than 'feeling' when it's in the centre of the cutlass bearing, and how to you know it's sitting at the right angle? Any tips greatly appreciated!
  8. Hi Mike, Apologies for the lack of conclusion to my thread! Nice to hear (or not nice actually) somebody with very similar issues. I removed my gearbox back then for a separate reason (I was replacing my driveplate), it just happened to coincide with me investigating the knocking noise, so it was handy being able to rule out the gearbox/driveplate from the knocking problem. I know the first thing you did was adjust the valve clearances, but I checked mine as thoroughly as possible last night and I can definitely say it reduced my engine knocking noise a lot. It is still there slightly, but for sure it has made a big difference. Graham
  9. Apologies for never following up this thread...😔 Back in April I tried the injector cleaner which seemed to improve the knocking after I put a slosh in the fuel filter itself, but it came back a few minutes later. After a fresh tank of diesel, there was no difference here either. The knocking remained the same until yesterday when I rechecked the valve clearances after being advised on Isuzu engines they can easily create a knock even if one is slightly mis-adjusted. Last night I took my time setting the clearances as accurately as I possibly could. When I started up the knocking was reduced significantly. It is still there slightly, but it is definitely not as bad. I guess a perfect valve adjustment would have the knocking all but gone.
  10. I added some injector cleaner at the weekend, including a slosh in the fuel filter, and for about 20mins after starting it sounded better. But the knock returned soon after. This makes me think maybe it is just stale/funny diesel, and it was happier running on the cleaner-diesel mix for a bit? I'll fill up soon with new diesel and see if this helps. At least based on this hopefully it is fuel related and not mechanical.
  11. Thanks catweasel, I guess it's possible it is related to my current diesel. It's also quite old now as I haven't been cruising much since christmas. I'll fill up with new diesel soon anyway so it'll be interesting to see if this changes anything. At the moment the gearbox and also driveplate aren't even mounted on the engine so alignment can be ruled out.
  12. For what it's worth, the oil light goes out about 2.5 seconds after pressing the stop button. Maybe the recording doesn't capture it very well above the normal running noise, but 100% it is there and it never used to be. I can try to get a better recording over the weekend. Is it worth trying a bit of injector cleaning additive in the diesel, if only to see if it changes the knock? Or would I be better going straight to taking them out and having them overhauled? My engine is currently my only source of hot water (other than the kettle!) so I don't really want to have to send the injectors off for a few days, at least not if I don't have to.
  13. Thanks bizzard, I have a warning light. Not sure if I understand you correctly: Run engine up to temp Stop engine time how long it takes for the oil light to come back on If it's faster than 3 seconds, is this good or bad?
  14. I don't think so - it was my first time doing them, but if anything they are all set slightly loose, I made sure none were too tight. Supposed to be 0.4mm so I used a 0.43mm feeler just to be on the safe side. But I will check them now in case.
  15. Yes it is. And when I last checked the valve clearances I cleaned the air inlet 'mesh' on the rocker cover because it was covered in gunk. So this is definitely possible, except it seems to be getting worse not better.
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