geoffbeaumont Posted October 31, 2006 Share Posted October 31, 2006 Finally put the 3.5 V8 in the Range Rover back together, hopefully ready for a bit of laning this weekend. The hotwire injection isn't too happy unless the AFM is unplugged to force it into limp home mode, so I guess I've buggered a wire or sensor somewhere - not that fussed as it'll be on gas as soon as it's warmed up anyway, and that's fine. However... Once the engine starts to warm up there's a whistling noise from the V - seems to come from down below the throttle position sensor. Idle's on the lumpy side, too, which makes me think vacuum leak, but I can't find it. I've checked all the pipe connections, stripped the top end back down to the inlet manifold and reassembled it just in case, but no change. Tried venting propane around the area with an unlit blow torch but that didn't seem to have any effect. Ideas? I used a compound valley gasket (this engine originally had tin). Bad idea? Would have thought it would be less likely to leak than tin. And no I haven't supercharged it Quote Link to comment Share on other sites More sharing options...
Fatboy Posted November 1, 2006 Share Posted November 1, 2006 Geoff, I guess you have elimnated the belts / water pump / alternator ? - Just to be doubly sure, I'd lightly spray the belts and pump with water while the engine is running and see if there is a difference. What is the theory behind the propane? You could always try spraying a bit of WD-40 around the manifold to see if you can change the tone - At least WD won't fight with the oil if a bit gets into the engine (unlike water ). Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 1, 2006 Share Posted November 1, 2006 Carb cleaner works for leak finding too. A mate uses a garden sprayer full of petrol, but no-one will stand near him when he does Quote Link to comment Share on other sites More sharing options...
Fatboy Posted November 1, 2006 Share Posted November 1, 2006 Ah - Got it. However, the assumption is that the inlet manifold has a leak and is drawing air in therefore engine revs rise as it gets more "fuel". Has propane got enough "beans" to make a difference or is it better to use a quick evaporating, more potent fuel ? But the valley gasket also seals from the crankcase which is positive pressure so, it may be blowing out through a little leak... I suppose its easily eliminated though by removing the oil filler cap to reduce the positive pressure.... Whos gonna lend me a coat ? Quote Link to comment Share on other sites More sharing options...
istruggle2gate11 Posted November 1, 2006 Share Posted November 1, 2006 I had similar symptoms when a injector 'o' ring failed, although it was loud and quite pronounced. Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted November 1, 2006 Author Share Posted November 1, 2006 I had similar symptoms when a injector 'o' ring failed, although it was loud and quite pronounced. It's a possibility - the injectors have been out, and this is quite loud. Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted November 1, 2006 Author Share Posted November 1, 2006 Ah - Got it. However, the assumption is that the inlet manifold has a leak and is drawing air in therefore engine revs rise as it gets more "fuel". Has propane got enough "beans" to make a difference or is it better to use a quick evaporating, more potent fuel ? Going round the inlet assemblies with an unlit lighter was a suggestion on here some time ago when I was having trouble tracing a vacuum leak before. It does seem to work to some degree. Not sure about the relative merits of different 'tracer' fuels. But the valley gasket also seals from the crankcase which is positive pressure so, it may be blowing out through a little leak... I suppose its easily eliminated though by removing the oil filler cap to reduce the positive pressure.... I wouldn't have though it would generate enough of a leak to make this noise, but I'll try that anyway - if nothing else it will eliminate it as a cause. Quote Link to comment Share on other sites More sharing options...
Orange Posted November 1, 2006 Share Posted November 1, 2006 If it's definitely around the valley then this is a silly suggestion, but have you touched the spark plugs? We had a bit of an issue with one not seating quite right and even though it tightened up well enough there was something in the way and it produced quite a nice little whistling sound! As I said, probably a silly point, but worth mentioning, I think! Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted November 1, 2006 Author Share Posted November 1, 2006 If it's definitely around the valley then this is a silly suggestion, but have you touched the spark plugs? We had a bit of an issue with one not seating quite right and even though it tightened up well enough there was something in the way and it produced quite a nice little whistling sound!As I said, probably a silly point, but worth mentioning, I think! Pretty certain this is coming from the valley not the side of the block. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted November 1, 2006 Share Posted November 1, 2006 What is the theory behind the propane? When you find a leak it produces a colossal #kin bang and opens up the leak to several feet across thus enabling it to be easily identified Quote Link to comment Share on other sites More sharing options...
geoffbeaumont Posted November 2, 2006 Author Share Posted November 2, 2006 When you find a leak it produces a colossal #kin bang and opens up the leak to several feet across thus enabling it to be easily identified Venturi LPG kit + dodgy ignition is great for scaring pedestrians ...provided you don't mind pulling over shortly afterwards to tape your air intake back together... Quote Link to comment Share on other sites More sharing options...
was a nice truck? Posted November 2, 2006 Share Posted November 2, 2006 I have used easy start(other products are availiable) to trace leaks on intercoolers at tichkover and dont see why it shouldnt work on a petrol motor DW Quote Link to comment Share on other sites More sharing options...
Fatboy Posted November 2, 2006 Share Posted November 2, 2006 Venturi LPG kit + dodgy ignition is great for scaring pedestrians ...provided you don't mind pulling over shortly afterwards to tape your air intake back together... Mine has a flapper valve on the chamber and has blown the tube off the washer and removed most of the soundrproofing On the day of the worst "Bang", I was passing a colleagues house when it backfired. He was in the garden, and ducked !! Next day asked me if I knew what the sonic boom came from. His neighbour had also come out of the house to check out the sky for a rapidly descending plane. Problem stopped when I replaced the camshaft. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted November 2, 2006 Share Posted November 2, 2006 so Rog - your ring whistles when its under a lot of pressure? hmm Quote Link to comment Share on other sites More sharing options...
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