Levanter Posted July 21, 2013 Share Posted July 21, 2013 I am sripping down and cleaning a sticky OS 48FS Surpass and everything was going well until I tried to get the wrist pin out. The liner came out easily and the little plastic end cap on the wrist pin was also a doddle. The wrist pin refuses to move. I tried some gentle heat and I tried inserting a close fitting dowel and then wetting the end to make it swell. This gave me a lot of grip but still nothing. The engine is back in the white spirit overnight and maybe this will help. Why oh why did they not put a thread in this pin? That would have been a nice solution. The engine is in good condition so worth the effort. Any ideas anyone? Quote Link to comment Share on other sites More sharing options...
001 Posted July 21, 2013 Share Posted July 21, 2013 I would try cleaning it and putting it in a very hot oven. Stand it on its side on something like an old cup and the pin will probably slide out on its own. Quote Link to comment Share on other sites More sharing options...
Doug Ireland Posted July 21, 2013 Share Posted July 21, 2013 I've stripped a couple of Surpass engines before and can't recall having this problem. As I recall, once the liner is out you extract the small-end pin through a hole in the back of the cylinder barrel. A small wood screw in the hole of the nylon cap usually does it but if not there should be enough room inside the cylinder barrel (with the liner out) to allow you to get the big-end off the crank pin. A simple soak in boiling water of the piston and con rod assembly should be enough to get your recalcitrant small-end out. Once you get the pin out you may want to consider gluing the nylon pad back onto it as this is what stops the pin from scoring the inside of the liner. Edited By Doug Ireland on 21/07/2013 21:24:43 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 21, 2013 Share Posted July 21, 2013 I believe the pads are PTFE which is unlikely to be glued successfully by any common adhesive - but why would you recommend this Doug? It isn't possible for them to come out in operation... Edited By Martin Harris on 21/07/2013 22:28:17 Quote Link to comment Share on other sites More sharing options...
Levanter Posted July 22, 2013 Author Share Posted July 22, 2013 The wrist pin is still stuck fast exept that it has now moved inwards a bit following an attempt to get a screw to bite. I have a suspicion that following the soaking and cleaning with solvent it has worked its way in and is baked hard. The crank will not turn at all now. There is not enough play to slide the connecting rod off the crank pin and now I have a siezed engine in bits! What about the boiling water? What if I put some detergent or something in with the water? I have an idea to make up an aluminum pin with something to grip on and try to get it to fit after a spell in the freezer would be a very close fit. When at normal temperature it might grip enough. Maybe I could glue something in place. There is finally a solution but it would mean cutting through the connecting rod to release the piston. It might come to that if I could be sure of obtaining a replacement. Any more ideas please! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 22, 2013 Share Posted July 22, 2013 Spray Fairy Power Spray liberally under the piston and around the gudgeon pin (or wrist pin if you hail from the far side of the Atlantic!) and let it soak for 20 minutes or so - then wash it thoroughly with hot water. If it still won't come out, pop the assembly into the oven and bake at 200 degrees for 10 minutes. Using some stout heat resistant gloves, have another go. If those methods don't work them you have got real trouble!!! You might just be able to wriggle the con rod off the crankpin at some point (probably around bottom dead centre but try all around) so that you can get access to drive it out but leave that as a lest resort. Quote Link to comment Share on other sites More sharing options...
Doug Ireland Posted July 22, 2013 Share Posted July 22, 2013 Hi Martin, I'm sure the Teflon pad is only on one end of the pin as the piston is not drilled all the way through? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 22, 2013 Share Posted July 22, 2013 Not certain Doug - an older stripped pre-Surpass 61 that I have at hand has a through bored hole and 2 pads but I think some engines I've stripped may have had a shoulder - although I think you could still drift the gudgeon pin out from that end. Hopefully it won't get to that stage! Helpfully, the OS website doesn't show or list any pads for the 48... Edited By Martin Harris on 22/07/2013 23:07:35 Quote Link to comment Share on other sites More sharing options...
001 Posted July 23, 2013 Share Posted July 23, 2013 Gents, this is what is shown on the O.S. discontinued engines site for the O.S. 48 Surpass, so I guess its all one assembly, one pin, two pads. Part No. 45806000. I doubt if there are none available at all! Edited By Chris P. Bacon on 23/07/2013 01:28:29 Edited By Chris P. Bacon on 23/07/2013 01:36:41 Quote Link to comment Share on other sites More sharing options...
001 Posted July 23, 2013 Share Posted July 23, 2013 There is a source on Ebay USA at........ **LINK** If you need one! Quote Link to comment Share on other sites More sharing options...
Glyn R Posted July 23, 2013 Share Posted July 23, 2013 Posted by Chris P. Bacon on 23/07/2013 01:35:18: There is a source on Ebay USA at........ **LINK** If you need one! I have used this company for other parts the service is very good. Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted July 24, 2013 Share Posted July 24, 2013 Percevere with a small self tapping screw and plenty of heat and it will pull out. Worst case scenario is a new piston so give it a go . I have heard of soaking stubborn parts in a mix of petrol and auto trans fluid . it seems to get everywhere and loosens things off. Quote Link to comment Share on other sites More sharing options...
Levanter Posted July 24, 2013 Author Share Posted July 24, 2013 Thank you Engine Doctor. I will keep up my search for the right sized screw that will get a good grip. The frustrating thing is that once this is out everything else is plain sailing. Except that is for the left hand camshaft bearing! But I haven't threatened that yet. Maybe I should have a go at the two, as you say with the engine hot. Quote Link to comment Share on other sites More sharing options...
PatMc Posted July 24, 2013 Share Posted July 24, 2013 Have you tried a small taper tap instead of a self tapping screw ? Fitted in a T wrench it would provide a convenient handle once the tap got a decent grip. Quote Link to comment Share on other sites More sharing options...
Levanter Posted July 24, 2013 Author Share Posted July 24, 2013 PatMc. That is a very good idea. I suppose a really small stud extractor would be similar. I havven,t got either so I must have a look around. Quote Link to comment Share on other sites More sharing options...
Shaunie Posted July 24, 2013 Share Posted July 24, 2013 The trouble with self tapping screws and stud extractors is that the gudgeon pin is fully hardened so they are unlikely to bite in the hole. Another possibility is to heat some thin oil (ATF would be good) as hot as you dare and lower the engine in. The hot oil is very thin and will penetrate very quickly, on top of this the thermal shock is quite pronounced. The hot oil is much less likely to cause damage than uncontrolled heating by other methods. All the usual safety warnings apply, boiling oil on body parts is a bad thing! Shaunie Quote Link to comment Share on other sites More sharing options...
Doug Ireland Posted July 24, 2013 Share Posted July 24, 2013 Posted by Levanter3 on 24/07/2013 14:42:26: Thank you Engine Doctor. I will keep up my search for the right sized screw that will get a good grip. The frustrating thing is that once this is out everything else is plain sailing. Except that is for the left hand camshaft bearing! But I haven't threatened that yet. Maybe I should have a go at the two, as you say with the engine hot. You could try the hydraulic method to extract that bearing. Fill the bearing with something like EP2 grease, place the Camshaft over the opening in the the bearing then give the other end a smack and the grease should force the bearing out. Quote Link to comment Share on other sites More sharing options...
stevejet66 Posted July 24, 2013 Share Posted July 24, 2013 What you need to do is put the thing in the freezer over night for the pin to shrink, Heat will only expand things! lubricants etc never penertrate like everyone thinks, deep freeze tap out. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.