forbs Posted July 23, 2016 Share Posted July 23, 2016 Hey up chaps as I'm pretty "novice" in terms of nitro I'm having a few teething problems with my revo 2.5 1st there seems to be a small leak by the flywheel whilst running. I returned the needles to factory settings but the car seems to be running hot. Not too bad whilst idling. But gun the motor and it cuts out for a few minutes cools down a bit then re starts. There is also a lot of due by the fuel tank/battery box and a arms so I think the fuel tank may have a little leak but can't find it. The only thing I could find wrong was the servo was not opening the throttle fully. And there is quite a bit of oil coming out of the exhaust. This to me would indicate a rich running engine, but wouldn't the engine run cooler? Anyway any advice would be helpful. Thanks very much. Dave Quote Link to comment Share on other sites More sharing options...
HellaFlush Posted July 23, 2016 Share Posted July 23, 2016 What fuel are you using? % and brand. Have you ever played around with any of the head shims? 1 Quote Link to comment Share on other sites More sharing options...
forbs Posted July 23, 2016 Author Share Posted July 23, 2016 I'm using 20% serpent fuel which I think is rebranded model technics. I've not touched any shims mate Dave Quote Link to comment Share on other sites More sharing options...
Nitroholic Posted July 23, 2016 Share Posted July 23, 2016 Fuel choice explains the oil.... The cooking brand ModelTEchnics fuel uses a very high % of oil, so will make things a bit messy. Something like Byrons or Opti race blend use around 9-10% oil. Something like MT Duraglo is 16% oil.....which is smokey and messy. Doesn't mean it's running rich though. If your tank has a leak, then that would result in lean running as it won;t hold pressure like it should. Will also screw up any tune you might try to find. Easiest way to find a leak in a fuel tank is to use a bowl of water. Empty out the fuel, and block up both pipes ( connect them together). Then hold the tank underwater and look for bubbles. Any split seams will show up...and that means buy a new tank. Check that out first...as it would lead to fuel starvation exactly as you describe 2 Quote Link to comment Share on other sites More sharing options...
forbs Posted July 23, 2016 Author Share Posted July 23, 2016 Thanks nitro. The fuel tank seal has gone. Iv tried replace it off a donor tank but it's just too thick. I'm now trying to think of something I can rob one from hmmm I'm wondering if a plumber seal will work. Quote Link to comment Share on other sites More sharing options...
spannermonkey Posted July 23, 2016 Share Posted July 23, 2016 Common problem with the Revo. Part number is 5362 and they are about £3 for two. Check your crank bearings too, my first 3.3 had a similar leak from the flywheel area and the inner bearing failed in under a tank of fuel. The cutting out when hot could also be signs of a worn piston and sleeve. If you have a broken seal then have where you need to start. 1 Quote Link to comment Share on other sites More sharing options...
forbs Posted July 23, 2016 Author Share Posted July 23, 2016 13 minutes ago, spannermonkey said: Common problem with the Revo. Part number is 5362 and they are about £3 for two. Check your crank bearings too, my first 3.3 had a similar leak from the flywheel area and the inner bearing failed in under a tank of fuel. The cutting out when hot could also be signs of a worn piston and sleeve. If you have a broken seal then have where you need to start. Thanks mate. Is the crank baring an easy fix ? I will do the seal first thanks for the part number. I don't know how old this engine is I'm thinking it might be worth me upgrading to the 3.3 Quote Link to comment Share on other sites More sharing options...
spannermonkey Posted July 24, 2016 Share Posted July 24, 2016 If you are mechanically minded as most of hobbyist's are then the bearing is fairly simple. The problem comes from the cost, if pinch is poor and the bearings worn then the rebuild costs will be close to if not more than a new engine. Saying that, let's not put the cart before the horse. Fix the tank seal and do a leak check then try again before condemning the engine. Quote Link to comment Share on other sites More sharing options...
NOFX Posted July 24, 2016 Share Posted July 24, 2016 Google nitro sleeve pinch trick. If you get the sleeve really hot & tighten a jubilee clip onto the top of the sleave it can fix the slackness. 1 Quote Link to comment Share on other sites More sharing options...
spannermonkey Posted July 25, 2016 Share Posted July 25, 2016 I've watched that a few times but never tried it. I'm afraid I can't see it working too well. I'm a mechanic by trade and understand the idea but also know the limitation of a hose clip and can't see it being perfectly round afterwards. Just my opinion though. 1 Quote Link to comment Share on other sites More sharing options...
Burridge Posted July 25, 2016 Share Posted July 25, 2016 I've watched that a few times but never tried it. I'm afraid I can't see it working too well. I'm a mechanic by trade and understand the idea but also know the limitation of a hose clip and can't see it being perfectly round afterwards. Just my opinion though. Agreed, if you were planning on buying a new engine anyway and had nothing to lose then there's no harm in trying it but my other worry would be that it would no longer be a snug fit in the engine casing 1 Quote Link to comment Share on other sites More sharing options...
Nitroholic Posted July 26, 2016 Share Posted July 26, 2016 After a pinch, you 'sort of' break the motor in again, but it's never going to make the motor like new, it just lets it run for a few more litres of fuel. There is also no guarantee of success....but as it's done on motors which are no longer servicable, failure costs nothing..and if you can keep it going for a bit longer, it buys you the time to save up for a new engine! It's not something I have ever done, or would ever really want to. If you have a good quality engine, then bearing replacement is a good way of keeping it running. On cheapo RTR engines, there is usually so many other things worn out, replacement of the engine makes more sense. If you are going to do it often...invest in a bearing puller. 1 Quote Link to comment Share on other sites More sharing options...
forbs Posted July 26, 2016 Author Share Posted July 26, 2016 Thanks guys I'll look at all these suggestions. As it is at the moment within 1 minute of the engine being on its running red hot. And the front bearing us leaking so I think it's past fudged ! I will try another fuel tank first but I think even pinching the engine is not going to fix all the problems. So my options are to either Buy a replacement engine in 3.3 format or A big block conversion A new 3.3 is going to cost around 140 but will drop directly in. A conversion is going to cost 50 and I have a spare hyper 7 21 engine that's has seen less then half a gallon hmmm Quote Link to comment Share on other sites More sharing options...
Nitroholic Posted July 27, 2016 Share Posted July 27, 2016 I'm not a fan of TRX motors. If it was me, I would fit just about any engine that wasn't a 3.3 I had a Revo with a Picco .26, and that was a great motor. Quote Link to comment Share on other sites More sharing options...
spannermonkey Posted July 27, 2016 Share Posted July 27, 2016 The 3.3 is OK but not worth the price tag. When all said and done it's only a .19 So a good .18 will have similar power. If you have the hyper engine then for me its an easy decision, pop the hyper motor in and get out and enjoy some tx time. Quote Link to comment Share on other sites More sharing options...
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