Mower update - more trouble :(

[Lee Nowell]

Hi All,

Following on from my previous thread...

Firstly the good news.... I have just fitted a new diaphragm and head gasket to the mower and it runs= much better than before. No hunting and seems to running "quicker" than b= efore. I haven't tried it under load yet though...

Now the bad news....

1. Although it runs OKish, now and again it does a "cough"
2. On starting, it still pumps out a cloud of black smoke although after th= is one blast, smoke is colourless
3. When I refitted the head, one of the bolts snapped so it is currently on= e down!
4. I cleaned all the engine etc. and whilst at it, thought I would clean th= e exhaust. Stupidly, I hadn't realised it had baffles (or similar) in it s= o poured some petrol in to clean it. Petrol disappeared (assume it got abs= orbed by the stuff in the exhaust!).

Only other info I can think of which might be relevant is that I regapped t= he plug to 0.030" which I got from the B+S website...

Any ideas? I think I am ready to throw in the towel :(

thanks

Lee.

[ss]

much better than before. No hunting and seems to running "quicker" than before. I haven't tried it under load yet though...

one blast, smoke is colourless

exhaust. Stupidly, I hadn't realised it had baffles (or similar) in it so poured some petrol in to clean it. Petrol disappeared (assume it got absorbed by the stuff in the exhaust!).

plug to 0.030" which I got from the B+S website...

You really need to get the snapped bolt sorted before looking at anything else. Did you use a torque wrench for tightening? generally people with no `engine` experience will over tighten bolts. It is possible to to get the snapped bolt out DIY but if you are not sure or confident then almost any motorbike repair shop will do it.

[MM]

Well, the engine's buggered, then. You can't just ignore a cylinder head minus one bolt! Also, the head will warp - maybe it has already.

MM

[Brian Gaff]

It depends very much on where the bolt is that snapped. I'm worried about the snapping on fitting, if it snapped on extraction then its probably worth getting it sorted, but overtighteneing on fitting is not a good idea at all as all the bolts will now be suspect if not tightened to the right factory settings. I've seen the results of this sort of thing back when I was young, cracked heads, damaged blocks and warped parts that no gasket can fix.

Brian

[ss]

Based on the fact the engine is actually running I would attempt a fix on the bolt. Yip the head could be warped etc but if you can get it running and cutting grass what the hell give it a bash.

[Weatherlawyer]

ns much better than before. =A0No hunting and seems to running "quicker" th= an before. I haven't tried it under load yet though...

this one blast, smoke is colourless

the exhaust. =A0Stupidly, I hadn't realised it had baffles (or similar) in = it so poured some petrol in to clean it. =A0Petrol disappeared (assume it g= ot absorbed by the stuff in the exhaust!).

the plug to 0.030" which I got from the B+S website...

What manufacturer would put a bolt that easily clapped on his engines?

You might want to tell them someone has been flogging them china.

[Brian Gaff]

Yes, fine but I'm also a bit alarmed at pouring petrol into exhausts. I mean it went somewhere obviously not the intended outcome. also smoke at start tends to suggest there still is somewhere where the muck persists. I guess its the old right said fred syndrome of fixing things. No real excuse now we have the Internet. I know someone who trashes generators by doing daft things like wrong oil and tweaking.. shudder.

Brian

[Lee Nowell]

I guess the question is where it is coming from. Having completely cleaned everything when i took the engine apart, the only thing that hasnt been cleaned is the exhaust. Well least i tried tooooooo :)

Anyone any thoughts on the coughing? Could this be an issue with the exhaust being 'blocked'?

Thanks

Lee.

[The Natural Philosopher]

everything when i took the engine apart, the only thing that hasnt been cleaned is the exhaust. Well least i tried tooooooo :)

being 'blocked'?

usually a sign of weak mixture/sticking valve/advanced ignition...

If the head is held down by less screws then it may be warped causing te valve to jam.

[Tim]

Unlikely I would have thought as most lawn mower engines are side-valve.

Tim

[The Natural Philosopher]

can still warp the cylinder.

But I am fairly sure my B & S says OHV on it somewhere.

[Lee Nowell]

The valves on mine are next to the piston. All moving from front to back.