Hi. Took bus for a run....runs well apart from uphill it 'judders' sounds a bit like a tractor...and doesn't tick o er nicely, dies a bit. what could cause this??? Just done valves, plugs clean and gapped, new fuel filter, I've never cleaned the carb yet.
I think he means the cylinder isn't firing. If this is the case, there could be a number of causes. You would need to find which cylinder is causing the problem, usually I keep removing plugs leads until I hear no change, that means I just removed the lead on the misfiring cylinder, it's that one.
Youve only done a few things, so just double check your work...assuming that you know how to do the valve clearances, it's most likely to be a loose/ disconnected plug lead, which means one cylinder won't be firing.
.... and the "Osteopathic" observation is, just because you find one not firing doesn't mean there isn't another one not firing .... You saying "tractor" made me think that as the ones round hear sound like a two stroke even though they're not ......
Makes sense.....I've been having trouble with plug leads.... They feel a bit loose. I tried new ones but one of those kept jumping off. I put the old ones back on....much better but they feel 'loose on the plugs. I hear them clicking on.
Valves are the one thing I haven't plucked up courage to do...seen all the videos on YouTube...still not physically done it. That can be my New Year's resolution!
I think someone posted that the rubber bungs through the tinwear help keep everything in order...I always think they seem loose though.
Having one cylinder not firing can be either a loose ignition wire, broken sparkplug. A split manifold boot can be quite effective at killing cylinder power at low RPM and making it run hot and lean. I have personally also left a complete rocker assembly so loose it koosened itself a few days later but that was self-inflicted. A bus will do a top speed of 70mph ish on the flat with 4 cylinders, 50mph on the flat and struggle up hills on 3 cylinders, 10-15 mph on the flat on 2 cylinders. It might just move with one cylinder if it lost the rest while running and you dont stall it.. All tested when I lost a valve then blew out an inlet manifold gasket on the opposite side with backfiring .. If the rubber flanges on the leads are pushing the plug leads off pull them back a little. Dont try too hard to get them to seal, having them pop off is worse than a 1mm gap... Nightmare misfire causes are burnt valves, burnt piston with a hole causing no compression. Or a cylinder head to cylinder barrel seal leak. These are down to bad ignition timing and air leaks. So a compression test may be needed if all the ignition leads seem good
Yep, mine was firing on 3 and I was a recipient of the last 2 paragraphs recently. Bread and water for me this Christmas
Reminds me of this one from Quantas: Pilot's report: Number 3 engine missing. Engineer's report: Engine found on right wing after brief search.
I found that the HT lead coil to dizzy ( with acuspark on it! ) gave me a shock when I touched it. I put it as it was originally ( cabled tied to heater tube) and much better ...more power in 3rd. Now only slight juddering high revs 2nd and 4th. Could well be something g else simple.
