The Mower Bench

[GardenKit]

LEAKDOWN TESTING

Who does it?

What tool do you use?Technique?

How can you find TDC on a mower to ensure valves are closed without removing the head?

 

Do you focus more on what the dial says or what you can hear coming from the mower?

 

Would this technique flag up a failing crank shaft oil seal? Before the oil starts to leak.

 

Don't want to push my luck with Barrie but he sure makes a good vid tutorial.

 

Sent from my GT-N7000 using Arbtalk mobile app

 

Firstly Mike, no vid. Have you any idea of the production costs of one of my vids?

Script writers, editors, producers, voice over celebrities, camera crew, sound crew etc. An astronomical amount. So, NO VID!!

 

Secondly, The Leak Down Test. This is to test the sealing capability of the compression components, including Rings,Bore, Piston, Valves, Head, Head gasket, Valve seats.

 

A regulated amount of pressurised air is used to pressure up the combustion chamber, and a gauge is used to show air loss in comparison with air input.

 

The magnitude of the air loss indicates the severity of any problems.

 

All engines, even new ones will have some loss, so as long as the loss is in the green section of the meter, the engine is good.

 

If the needle is in the yellow or red sections then one, or more of the compression components is worn.

 

By listening to the air leak it is possible to locate a specific component.

 

Air heard hissing through the carb indicates inlet valve leakage. Through the exhaust indicates the exhaust valve.

Air heard escaping around the head gasket indicates a head gasket failure, whilst air heard escaping through the dipstick hole indicates worn rings.

 

The test is carried out on an engine that has been run for a few minutes to get it to operating clearances.. The spark plug is removed and the engine turned to TDC on the comp stroke, A screwdriver inserted through the plug hole and resting on the piston is used as an indicator for TDC.

 

The engine must be 'locked' at TDC with a clamp plate, or, on a mower the blade can be locked. This is essential or the air pressure on the piston will rotate the engine with substantial force.

 

Then install the gauge in the plughole and test.

 

This tests the combustion chamber, not the crankcase, so a crank seal fault will not show up.

 

 

 

[bobh]

Firstly Mike, no vid. Have you any idea of the production costs of one of my vids?

Script writers, editors, producers, voice over celebrities, camera crew, sound crew etc. An astronomical amount. So, NO VID!!

 

I'd sack the lot of 'em, you're not getting value for money! 😁

 

 

Sent from my Nexus 7 using Arbtalk mobile app

[GardenKit]

I'd sack the lot of 'em, you're not getting value for money! 😁

 

 

Sent from my Nexus 7 using Arbtalk mobile app

OK Bob, I will sack the lot and do them myself. Shame about losing the posh spoken narrator though:biggrin:

[mikerecike]

Firstly Mike, no vid. Have you any idea of the production costs of one of my vids?

Script writers, editors, producers, voice over celebrities, camera crew, sound crew etc. An astronomical amount. So, NO VID!!

 

Secondly, The Leak Down Test. This is to test the sealing capability of the compression components, including Rings,Bore, Piston, Valves, Head, Head gasket, Valve seats.

 

A regulated amount of pressurised air is used to pressure up the combustion chamber, and a gauge is used to show air loss in comparison with air input.

 

The magnitude of the air loss indicates the severity of any problems.

 

All engines, even new ones will have some loss, so as long as the loss is in the green section of the meter, the engine is good.

 

If the needle is in the yellow or red sections then one, or more of the compression components is worn.

 

By listening to the air leak it is possible to locate a specific component.

 

Air heard hissing through the carb indicates inlet valve leakage. Through the exhaust indicates the exhaust valve.

Air heard escaping around the head gasket indicates a head gasket failure, whilst air heard escaping through the dipstick hole indicates worn rings.

 

The test is carried out on an engine that has been run for a few minutes to get it to operating clearances.. The spark plug is removed and the engine turned to TDC on the comp stroke, A screwdriver inserted through the plug hole and resting on the piston is used as an indicator for TDC.

 

The engine must be 'locked' at TDC with a clamp plate, or, on a mower the blade can be locked. This is essential or the air pressure on the piston will rotate the engine with substantial force.

 

Then install the gauge in the plughole and test.

 

This tests the combustion chamber, not the crankcase, so a crank seal fault will not show up.

 

[ATTACH]150631[/ATTACH]

 

[ATTACH]150632[/ATTACH]

 

[ATTACH]150633[/ATTACH]

 

Barrie if you want to be in contention for next years oscars you've gotta keep your production team together and working. Think big

 

Anyway thanks again.didnt realise about locking the blade - how do you do it with blade attached?

 

Ps had an engine on the kitchen table last night for a bit of valve removal practise. Have gone from 2 hrs on sunday to 3 minutes out and in this morning.much appreciated.

 

Sent from my GT-N7000 using Arbtalk mobile app

[GardenKit]

 

Anyway thanks again.didnt realise about locking the blade - how do you do it with blade attached?

 

 

 

Sent from my GT-N7000 using Arbtalk mobile app

 

 

Anyway you can.

 

Vise-grips, G-clamps, wooden blocks, proper blade clamp, combination of all the forementioned.

 

Just remember that the air pressure could push the piston down either way, i.e to rotate the crank clockwise or anticlockwise, so you need to clamp both sides. If you are skilled and get the piston exactly TDC the force will be straight down the con rod and no rotation will take place, but still clamp it just in case. By taking it past TDC and bringing it back to just 'over the top', you should ony get clockwise rotation, but still lock both sides in case.

 

If the fan cowling is off you may be able to lock the flywheel instead. but be careful not to snap off any fins with heavy handed application of vise-grips.

[mikerecike]

Thanks for that barrie.think i,m gonna invest in a ld tester now.cheers.

 

Sent from my GT-N7000 using Arbtalk mobile app

[GardenKit]

I love servicing all John Deere machines, but the X540 is just incredible. The engineering is superb and they are an absolute joy to work on.

They clean up nice too!

Just finished this one.

 

 

[Rich2484]

Nothing runs like a Deere.....

[GardenKit]

Indeed...

[GardenKit]

Just another Manic Monday....

 

The sun has been shining and suddenly everyone who has there mower in with us for service wants them back.. Done... NOW.

 

And everyone who forgot to get them serviced wants to bring them in and have them done..NOW.

 

I wish it was Sunday.

Edited March 10, 2014 by GardenKit
spelt Monday wrong. I need rest.