Champion mower stopped & now unable to start

[Burnerman]

No, I don’t think so, side valve engines don’t normally need a decompressor.
I think your issue is with the valve spring retainers.....they should both be the same but do give us a pic please.
John

 

[ipbr21054]

Ok
It’s back together but I can advise.

Small valve.
1 Spring.
1 Valve retainer.
This valve retainer has two sized holes in it.
With spring compressed & passing through the valve retainer you then press it away from you & that’s it.
It then locates on the valve & holds it all together.

The larger valve is exactly the same BUT the extra piece is like a 1/2 pence piece with a hole in it.
This piece sits in top the spring before you put spring retainer on.
That’s it.

 

[Burnerman]

Yep, the smaller exhaust valve has the ‘keyhole ‘ retainer, common enough and there are other designs.
For the life of me, I can’t see why they are different!
Has the clicking stopped?
Do the valves lift by the same amount?
Always turn the engine over in the normal direction of rotation when you test this!
John

 

[ipbr21054]

Clicking still there every other cycle on the smaller valve.

Yes turning flywheel by hand valves move the same as before.
I don’t see anything broke & it turns / rotates with no resistance.
With the larger valve having that extra piece fitted you would expect it to open more than the other ?

I’ve been using this mower 2/3 years & this is what I’ve found when taking it apart so can only assume that’s how it is.

With regards no compression can head gasket be possible with regards the oil being low.
Maybe got warm & head gasket went ?

 

[Burnerman]

The valve lift is determined only by the camshaft profile, that opens the valve courtesy of a cam follower that the camshaft bears on to.
This is designed to rotate in its housing to minimise wear, and therefore the 'extra piece' plays no part here. The valve lift is the same.
If the oil is critically low, the piston starts to seize in it's bore and the engine will slow. On cooling down, all will be good again for a short while, although some damage must occur. Oil accounts for a significant amount of engine cooling!
Head gasket on these is shown as a burnt or scorched section on it's profile.....it's a laminated alloy gasket with a filler in the middle - on occasion the filler gets burnt away but this is noticeable.
Truthfully, how low was the oil level when the problems started?
John

 

[ipbr21054]

Dip stick didn’t show anything.

 

[Burnerman]

Oh hell.....that's critically low. Your engine was trying to seize up!
With luck you'll have got away with it, but there's a lesson in there somewhere!
John

 

[ipbr21054]

I agree my own fault.

So back to one question.
No compression.
Where is the fault ?

Head gasket as others seem all fine.

 

[Harry Bloomfield]

No compression.

Compression nil, or very low - a valve issue. Some compression - piston, bore, ring issues.

To be fair, I would be taking the cylinder off, to have proper look by now, just to confirm the condition of it.

 

[ipbr21054]

Ok cheers

 

[Burnerman]

I imagine the cylinder and crankcase are integral.....if you can be bothered, remove the two big end bolts and the piston comes out of the top.
Notice the valve timing usually has two centre punch marks that should line up.
John

 

[ipbr21054]

I think I’m running out of time with this one.
I will fit gasket hopefully when it arrives tomorrow & see what happens.

Otherwise will pick up another mower Saturday

 

[lostinthelight]

When you get the head back on and if it doesn't start stick some engine oil down the plughole,pull it over and if compression increases suspect ring/bore wear..I tend to do this before tearing things apart through.

 

[ipbr21054]

Ok thanks.

Learning curve for me.
With regards head torque, I don’t have a torque wrench so I can’t do anything but to do them up by hand & then a little tweak in a cross cross pattern as I go.

 

[Harry Bloomfield]

With regards head torque, I don’t have a torque wrench so I can’t do anything but to do them up by hand & then a little tweak in a cross cross pattern as I go.

You'll be fine, just use an appropriate length of spanner to tighten them - that's how we managed before torque wrenches.