Simon_CSK Posted October 14, 2019 Share Posted October 14, 2019 I have now replaced this seal twice with no difference. What am I doing wrong? Having stripped it down I put grease on the seal on the seating surface and the outside before I refitted it. Replaced the bottom pulley wheel with a know one and carefully replaced it on to the shaft. Started the engine and all was well. Gave it a little gas and it started to dribble oil. Given that it seals initially I suspect that there are no cracks in the casing. Help required I am so close to getting my car road worthy it is so frustrating. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 14, 2019 Share Posted October 14, 2019 Is it possibly leaking around the outside of the seal? Quote Link to comment Share on other sites More sharing options...
Simon_CSK Posted October 14, 2019 Author Share Posted October 14, 2019 Just now, Bowie69 said: Is it possibly leaking around the outside of the seal? A tight and snug fit with grease for ease of fitting Quote Link to comment Share on other sites More sharing options...
JohnnoK Posted October 15, 2019 Share Posted October 15, 2019 Did you lube the inner surface of the seal with engine oil before fitting the pulley? If it is dry, the seal will generate heat and fail, causing it to leak, but in all fairness, it shouldn't be immediately when you rev it. Quote Link to comment Share on other sites More sharing options...
lo-fi Posted October 15, 2019 Share Posted October 15, 2019 A few more thoughts... Is the surface it's running on smooth and ridge free? A rough, grooved surface can quickly destroy a brand new seal. Have you seated it in the correct position? I can't remember what design that one is, but occasionally it's possible to seat a seal way too far in as there's no stop and you're supposed to use a special press tool with a raised ridge and a stop to seat it. I think there's a keyway slot in the crank nose? Been a while since I had one apart. Are there any burrs or sharp edges? Is the crank straight? What brand seal are you using? Quote Link to comment Share on other sites More sharing options...
Tanuki Posted October 15, 2019 Share Posted October 15, 2019 Apart from seal-fitment issues, check that there's nothing pressurising the crankcase. Under normal operation the crankcase should always be at atmospheric-pressure or negative-pressure. If breather-issues mean the crankcase gets to positive-pressure it will inevitably cause seals/gaskets to leak. As a test, let your engine idle, then take the oil-filler cap off and put your hand over the hole. You should feel gentle pulsations and maybe a bit of a 'suck'. Then rev the engine until it hits the rev-limiter - the pulsations should fade away and the 'suck' should continue. If you feel any signs that your hand's being blown away from the filler you have crankcase-pressurisation issues which need to be investigated. Quote Link to comment Share on other sites More sharing options...
Simon_CSK Posted October 15, 2019 Author Share Posted October 15, 2019 14 hours ago, JohnnoK said: Did you lube the inner surface of the seal with engine oil before fitting the pulley? If it is dry, the seal will generate heat and fail, causing it to leak, but in all fairness, it shouldn't be immediately when you rev it. Yes I lubbed the seal. I used grease. 13 hours ago, lo-fi said: Is the surface it's running on smooth and ridge free? A rough, grooved surface can quickly destroy a brand new seal. Have you seated it in the correct position? I can't remember what design that one is, but occasionally it's possible to seat a seal way too far in as there's no stop and you're supposed to use a special press tool with a raised ridge and a stop to seat it. I think there's a keyway slot in the crank nose? Been a while since I had one apart. Are there any burrs or sharp edges? Is the crank straight? What brand seal are you using? I used a pulley that I know for a fact is good. Not sure of the brand. 1 hour ago, Tanuki said: Apart from seal-fitment issues, check that there's nothing pressurising the crankcase. Under normal operation the crankcase should always be at atmospheric-pressure or negative-pressure. If breather-issues mean the crankcase gets to positive-pressure it will inevitably cause seals/gaskets to leak. As a test, let your engine idle, then take the oil-filler cap off and put your hand over the hole. You should feel gentle pulsations and maybe a bit of a 'suck'. Then rev the engine until it hits the rev-limiter - the pulsations should fade away and the 'suck' should continue. If you feel any signs that your hand's being blown away from the filler you have crankcase-pressurisation issues which need to be investigated. Will check for pressurisation tomorrow. Going to have a good close look with an endoscopic camera as well. Quote Link to comment Share on other sites More sharing options...
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