Ivan Posted February 24, 2006 Share Posted February 24, 2006 Not for me but a chap who works at my wifes place, who's Discovery broke down whilst on holiday. Symptoms are as follows :- He says, driving at speed down motorway no probs, slowed down for toll booth and got a knocking sound. When pulled away and sped up - fine. Up mountain and slower - knocking sound. Then motor cut out. Next day started, but still got knocking sound. Next day wouldn't start. He'd experimented a bit and says the knocking sound was only at low revs. It was taken to a local dealer, in France I think, and they could not find the problem (now there's a surprise!) so it came home on a flat bed. It's an M reg so 1993/1994 300Tdi. Had a recon engine when he bought (supplied by Turner Engineering and fitted by garage). I did point him to the alarm spider post but what confuses me is the knocking at low revs. Ivan Quote Link to comment Share on other sites More sharing options...
Les Henson Posted February 24, 2006 Share Posted February 24, 2006 Turners are excellent engine builders, so it's unlikely to be a mechanical problem. Not diesel knock is it? Also known as detonation, which is a timing or possibly fuel problem. The best people to talk to about this would be Turners themselves. http://www.turner-engineering.co.uk/ Les. Quote Link to comment Share on other sites More sharing options...
imspanners Posted February 25, 2006 Share Posted February 25, 2006 Wrong fuel in it? Particularly common in foreign countries. Alternatively slipped timing belt, but I'd have thought that would cause a rattle at high revs. Quote Link to comment Share on other sites More sharing options...
minivin Posted February 25, 2006 Share Posted February 25, 2006 knocking is a bit of a wide one on engines, does it actually turn over on trying to start or has it locked-up? that would narrow down the possible symptoms, also is it a load knocking or a gentle knocking? Quote Link to comment Share on other sites More sharing options...
BogMonster Posted February 25, 2006 Share Posted February 25, 2006 Is it an auto? If it is it could be the torque converter drive plate. I saw one about five years ago which did something similar to this, the drive plate is a slightly flexible bit of (bluddy expensive) metal coupling the nose of the crank to the torque converter, looks a bit like the lid out of an old metal 5 gallon drum though! What happens to make a horrific knock at low revs is that the plate fractures around the crankshaft boss (there is an adaptor which bolts between the end of the crank and the plate), and a crack gradually spreads around the edge of the boss. With the engine running, and because the TC provides much of the "flywheel" effect on the auto, the natural oscillations of the engine revs at low speed make the crack open up and close again. It sounds awful, a bit like a gnome is trying to get out of the bell housing with a small ball-pein hammer, worst at idle and IIRC disappears by about 1500-1800rpm as the engine revs even out at higher speeds. Eventually I assume it will break completely which is probably going to make it a non-runner due to there effectively being no flywheel on the engine (not to mention a lack of drive!) though the one I saw had the TC just hanging on by about 1/2" of metal it just made the most awful noise.... Possible causes include the fact that they sometimes just break anyway but more commonly the fact that there are selectable shims that go either between the crank and the boss, or the boss and the drive plate (can't remember which) to set the position of the TC, and if you get those wrong it'll put a permanent load on the flex plate which will cause it to fail quite quickly I think. Given that the engine has been changed, I guess it is possible that whoever did it, didn't sort out the shims properly, but that is just a guess - worth checking anyway. IIRC the Tdi engines use 2 drive plates one for the TC and one for the starter ring so it might still turn over but not run - a V8 just uses the one plate which has the starter ring bolted around the edge. If it is a manual then none of this applies, unless the flywheel has fallen off but I've not heard of that being a problem! Quote Link to comment Share on other sites More sharing options...
Ivan Posted February 26, 2006 Author Share Posted February 26, 2006 Thanks very much for all of the replies. Apparantly the vehicle is still on it's way back and the owner has booked it into Rogers Of Bedford. To be honest I suspect the LR Dealer in France just took a quick and couldn't be bothered carrying out proper checks. I would have thought an LR dealer would be able to spot any fuel issues quite easily. I think even I could check if fuel was getting to the injectors and, if not, try and track back to the point where the fuel stop getting through. Being an M reg I don't think it will have the Electronic Fuel Distribution. So IMHO the only reason it won't start (provided it's turning over) is because the fuel solenoid is not working or the fuel pump or lift pump are shot. As for the knocking we will have to wait and see. My brother in law is also having starting problems with his 96 Discovery. Basically some times it will turn over and other times it won't. We have provided a separate earth to the starter motor solenoid relay (which bypasses the alarm spider) and so far it's started every time. Cheers Ivan Quote Link to comment Share on other sites More sharing options...
Ivan Posted March 1, 2006 Author Share Posted March 1, 2006 Quick update. The car has arrived back to Rogers of Bedford and they say that the "Flywheel has sheared". So it's an engine out job at least. So I assume that, although the starter was turning over, the flywheel was not connected to the crank so the actual engine wasn't turning over. What I think may have happened is that when the garage he bought it from fitted the new engine they didn't loctite the flywheel bolts and so the bolts have worked loose. I have told him to contact Rogers and get them to take pictures when they take it apart and, to check for signs of loctite on the flywheel bolts. Ivan Quote Link to comment Share on other sites More sharing options...
Shaun D Posted March 2, 2006 Share Posted March 2, 2006 Hi Ivan, Just a word of warning Be careful when wiring direct to the starter motor to defeat the spider, if you leave the original wire connected you may get the starter motor "hanging up" and not releasing when you let the key back, if you don't you may find the glow plugs stay on all the time the engine is running, causing a flat battery and killing the plugs (the cranking signal goes to the glow plug timer relay). If you feel it has confirmed a faulty spider bite the bullet and whip it out (easier said than done, I know, I've done tons of them). Pop it open, inspect the circuit board with a magnifying glass and resolder any joints with cracks round them, they will be the ones on the relays (if you are not too handy with a soldering iron find someone who is). Put it all back together, job done. I've not had one too badly damaged to repair yet. Just off to read the spider thread now, what I've just written is probably in there already HTH Shaun. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted March 2, 2006 Share Posted March 2, 2006 what I've just written is probably in there already I hope so Quote Link to comment Share on other sites More sharing options...
Ivan Posted March 3, 2006 Author Share Posted March 3, 2006 As I said earlier the car is now at Rogers Of Bedford and apparantly the flywheel has sheared off. Nothing to to with bolts not being loctited etc. I have no idea how this could have happened, and Rogers say the same as they have never heard of this happening before either. BTW it is a manual so it's not the flexplate problem that Stev (Bogmonster) mentioned. Ivan Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 3, 2006 Share Posted March 3, 2006 Blimey, it would take some force to shear all the crank bolts like that. I wonder if the crank can be salvaged. I suppose if the remains of the bolts can be removed and the threads are still ok, then there's a chance. Lucky the bell housing survived as a spinning flywheel can do a lot of damage. Les. Quote Link to comment Share on other sites More sharing options...
Ivan Posted March 5, 2006 Author Share Posted March 5, 2006 OK I got some duff info. I was at Rogers Of Bedford yesterday picking up some bits. Apparantly it is an auto and the problem is exactly what Steve (Bogmonster) described. So top marks to Steve. It's amazing that someone on this forum who has not even seen the vehicle can diagnose the problem. But, the LR dealer couldn't!!! The chap at Rogers did say they have had a couple like this befoe but not very often. Ivan Quote Link to comment Share on other sites More sharing options...
BogMonster Posted March 5, 2006 Share Posted March 5, 2006 The bill will be in the post Glad the problem has been cracked anyway Quote Link to comment Share on other sites More sharing options...
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