Omega Owners Forum

Chat Area => General Discussion Area => Topic started by: tunnie on 14 April 2014, 08:53:11

Title: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 14 April 2014, 08:53:11
I've got an old lawn mower thanks to FatherT  :y

It's engine is a Briggs & Stratton Quantum XM 35, was a pig to start this year. So took off the float, cleaned it all up, fairly clean anyway, blast of carb cleaner in all its bits, new air filter and put it back together. Problem was the gasket on the air-intake was in a right state, so took it off for now. Re-assembled, without gasket.

Pull cord 3 times to prime, pull again and bang, straight into life.

Runs well, apart from after a while, the revs get very lumpy, it gets so bad it stops every so often. I'm thinking as it heats up, it's letting air in at the intake, more than it should, lack of gasket giving it lumpy hot revs?

Thinking of this:

http://www.ebay.co.uk/itm/Briggs-Stratton-Carburettor-Gasket-Set-fits-Max-and-Quantum-Engines-/221242600987 (http://www.ebay.co.uk/itm/Briggs-Stratton-Carburettor-Gasket-Set-fits-Max-and-Quantum-Engines-/221242600987)

But can I use a liquid sealer? Or is better off going for one of these kits?  :-\
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Andy B on 14 April 2014, 08:59:10
at £6 I'd go for the gasket kit. Other than that, if it's just the carb to manifold/head gasket you could use the time honoured cornflake packet  ::) ::)
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 14 April 2014, 09:00:22
at £6 I'd go for the gasket kit. Other than that, if it's just the carb to manifold/head gasket you could use the time honoured cornflake packet  ::) ::)

I'm liking that idea, tunnie bodge  :D  ;D  :y
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 14 April 2014, 09:01:21
Seriously though, think will get kit. Cheers  :y

As can stash the head gasket for another day  :)
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Kevin Wood on 14 April 2014, 10:55:08
A little smear of hylomar or the aforementioned cornflake packet will be as good as anything. We're not talking about highly strung technology here!

Oh, and the running issue sounds like the float chamber might not be refilling, or is flooding. Check the float valve, float level and make sure the breathers to the fuel tank and float chamber aren't blocked. Could also be a blocked idle jet if it's difficult to start and then hunts while running. :y
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 14 April 2014, 12:59:49
A little smear of hylomar or the aforementioned cornflake packet will be as good as anything. We're not talking about highly strung technology here!

Oh, and the running issue sounds like the float chamber might not be refilling, or is flooding. Check the float valve, float level and make sure the breathers to the fuel tank and float chamber aren't blocked. Could also be a blocked idle jet if it's difficult to start and then hunts while running. :y

Thanks Kevin  :y

If primed, it starts on the first pull and runs well. Problem is when hot, the revs hunt, as if you were in a car at idle reving the engine on the throttle.

I have taken the float cap off, clean it all up, the bolt with the little hole (that is the float valve?), blast of plus gas up into the 'float chamber' it appeared clean and moved ok.

Where is the idle jet? That said as above, it does start fine, hot running is problem  :)

Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Kevin Wood on 14 April 2014, 13:54:34
Sounds to me like it could be the idle jet, then. Mine was the same - would start only after using the priming bulb generously, and would hunt once warmed up. If you hold the throttle closed against the stop it should run at a slow idle, but with a blocked idle circuit it will just stall.

This might help.

http://outdoorpowerinfo.com/repairs/tecumseh_carb_640017.asp (http://outdoorpowerinfo.com/repairs/tecumseh_carb_640017.asp)

The idle jet comes through a small hole in the bowl retaining nut and up a passage drilled in the carb body to the progression holes just under the throttle plate and a jet somewhere in the bore. I think there's also an air bleed into it somewhere. A good blast of carb cleaner followed by some compressed air should clean it. Might need to soak the carb in carb cleaner first, though.

Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 14 April 2014, 14:03:04
Awesome link, perfect. Thanks  :y  :y  :y

I cleaned small hole in the retaining nut, must be a blockage further up.  :)
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: aaronjb on 14 April 2014, 14:35:37
Not carb cleaner being used for it's actual intended purpose?

Shock, horror! ;D
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: omega3000 on 14 April 2014, 15:30:24
Bloke next door was swearing at his petrol mower , yanking the pull cord for half an hour and all it did was pop and bang  ;D ;D Ah its good to have gravel garden  :)
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Taxi_Driver on 14 April 2014, 18:59:01
My mower doesnt have an idle jet .....

You press the bulb several time to flood the carb.....then keep the lever pulled back on the push bar.....and pull the cord....it usually goes first time with loads of white smoke to start with on full throttle and stays on full throttle until you release the the lever which not only kills the engine but puts a brake on the blade  :y
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Rods2 on 14 April 2014, 20:30:53
I've got an old lawn mower thanks to FatherT  :y

It's engine is a Briggs & Stratton Quantum XM 35, was a pig to start this year. So took off the float, cleaned it all up, fairly clean anyway, blast of carb cleaner in all its bits, new air filter and put it back together. Problem was the gasket on the air-intake was in a right state, so took it off for now. Re-assembled, without gasket.

Pull cord 3 times to prime, pull again and bang, straight into life.

Runs well, apart from after a while, the revs get very lumpy, it gets so bad it stops every so often. I'm thinking as it heats up, it's letting air in at the intake, more than it should, lack of gasket giving it lumpy hot revs?

Thinking of this:

http://www.ebay.co.uk/itm/Briggs-Stratton-Carburettor-Gasket-Set-fits-Max-and-Quantum-Engines-/221242600987 (http://www.ebay.co.uk/itm/Briggs-Stratton-Carburettor-Gasket-Set-fits-Max-and-Quantum-Engines-/221242600987)

But can I use a liquid sealer? Or is better off going for one of these kits?  :-\

Check how clean the petrol tank is and any filter in there, as they have a tendency to collect grass cutting over time which as you use the mower migrate to the fuel filter and block it, when the engine stops they are released from the filter and when you start it the cycle starts again.
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Sir Tigger KC on 14 April 2014, 22:54:13
Electric mowers are a bit poofy, but by the time you guys have got yours going I've plugged in, whipped around and have my feet up admiring my handiwork!  :y
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Kevin Wood on 14 April 2014, 22:56:55
Electric mowers are a bit poofy, but by the time you guys have got yours going I've plugged in, whipped around and have my feet up admiring my handiwork!  :y

.. unless you maintain your mower, in which case it starts quicker than it takes to get the extension lead out. ;)
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Sir Tigger KC on 14 April 2014, 22:59:18
Electric mowers are a bit poofy, but by the time you guys have got yours going I've plugged in, whipped around and have my feet up admiring my handiwork!  :y

.. unless you maintain your mower, in which case it starts quicker than it takes to get the extension lead out. ;)

I've got an Omega, I don't want a mower that needs constant fettling as well!  :P  ;D
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Vamps on 14 April 2014, 23:40:39
Electric mowers are a bit poofy, but by the time you guys have got yours going I've plugged in, whipped around and have my feet up admiring my handiwork!  :y

.. unless you maintain your mower, in which case it starts quicker than it takes to get the extension lead out. ;)

I've got an Omega, I don't want a mower that needs constant fettling as well!  :P  ;D

Nice post..............  :D :D :y
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Marks DTM Calib on 15 April 2014, 03:16:57
My mower doesnt have an idle jet .....

You press the bulb several time to flood the carb.....then keep the lever pulled back on the push bar.....and pull the cord....it usually goes first time with loads of white smoke to start with on full throttle and stays on full throttle until you release the the lever which not only kills the engine but puts a brake on the blade  :y

It will still have an idle jet setup
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 15 April 2014, 08:52:53
I've got an old lawn mower thanks to FatherT  :y

It's engine is a Briggs & Stratton Quantum XM 35, was a pig to start this year. So took off the float, cleaned it all up, fairly clean anyway, blast of carb cleaner in all its bits, new air filter and put it back together. Problem was the gasket on the air-intake was in a right state, so took it off for now. Re-assembled, without gasket.

Pull cord 3 times to prime, pull again and bang, straight into life.

Runs well, apart from after a while, the revs get very lumpy, it gets so bad it stops every so often. I'm thinking as it heats up, it's letting air in at the intake, more than it should, lack of gasket giving it lumpy hot revs?

Thinking of this:

http://www.ebay.co.uk/itm/Briggs-Stratton-Carburettor-Gasket-Set-fits-Max-and-Quantum-Engines-/221242600987 (http://www.ebay.co.uk/itm/Briggs-Stratton-Carburettor-Gasket-Set-fits-Max-and-Quantum-Engines-/221242600987)

But can I use a liquid sealer? Or is better off going for one of these kits?  :-\

Check how clean the petrol tank is and any filter in there, as they have a tendency to collect grass cutting over time which as you use the mower migrate to the fuel filter and block it, when the engine stops they are released from the filter and when you start it the cycle starts again.

Thanks, not seen a filter, when I removed the fuel line to the float, it was pouring out nicely, had to stand the feed pipe vertically with some paper towels in it.

As I'm not used to Carbs, I released the bolt holding the float and pondered for a few minutes why it was still draining fuel out of the tiny cap  ::)

Tempted to drain the tank actually, as for many years it was left over winter with fuel in it.

Is the filter at the bottom of the tank? I've not seen one  :-\
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 15 April 2014, 08:53:44
It's never had an oil change either, GM 10/40 Semi ok  ::)  ;D
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: pscocoa on 15 April 2014, 08:54:53
Tunnie - when I was your age I messed with petrol mowers. The older ones are a pain in the ass and if you value your time go out and get something that does the job - electric or petrol.

Parents give you stuff believing they are helping you out and you feel obliged to deal with the problem which is why they gave it away to you in the first place.

Time is money ...
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 15 April 2014, 10:52:45
Tunnie - when I was your age I messed with petrol mowers. The older ones are a pain in the ass and if you value your time go out and get something that does the job - electric or petrol.

Parents give you stuff believing they are helping you out and you feel obliged to deal with the problem which is why they gave it away to you in the first place.

Time is money ...

There is truth in that, but the lawn area I have is not vast.

FatherT did buy himself a new Mower as this one was becoming problematic, but like the Omega, a little TLC and it could run for a good time yet.
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Kevin Wood on 15 April 2014, 11:30:57
Tunnie - when I was your age I messed with petrol mowers. The older ones are a pain in the ass and if you value your time go out and get something that does the job - electric or petrol.

Parents give you stuff believing they are helping you out and you feel obliged to deal with the problem which is why they gave it away to you in the first place.

Time is money ...

There is truth in that, but the lawn area I have is not vast.

FatherT did buy himself a new Mower as this one was becoming problematic, but like the Omega, a little TLC and it could run for a good time yet.

If you enjoy tinkering with it, then it's not wasted time. If it saves you a couple of hundred quid on a new mower, so much the better.. IMHO, at any rate. :y
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: tunnie on 15 April 2014, 11:40:16
Tunnie - when I was your age I messed with petrol mowers. The older ones are a pain in the ass and if you value your time go out and get something that does the job - electric or petrol.

Parents give you stuff believing they are helping you out and you feel obliged to deal with the problem which is why they gave it away to you in the first place.

Time is money ...

There is truth in that, but the lawn area I have is not vast.

FatherT did buy himself a new Mower as this one was becoming problematic, but like the Omega, a little TLC and it could run for a good time yet.

If you enjoy tinkering with it, then it's not wasted time. If it saves you a couple of hundred quid on a new mower, so much the better.. IMHO, at any rate. :y

It's done exactly that, even with it's current 'issues'. I did enjoy a little tinker with it, never done anything with Carbs or floats, so all new to me. Being basic as well, nice and easy. It's a welcome change in pace from work IT stuff  :)

Back to one of my questions above, is there a fuel filter on these things?
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Kevin Wood on 15 April 2014, 13:01:05
Back to one of my questions above, is there a fuel filter on these things?

Probably a screen built into the bottom of the tank. Best thing to do is to remove the tank and give it a rinse out with some soapy water, rinse it well and leave it in the sun to dry before refilling.
Title: Re: Lawn Mower Engine - Air intake gasket.
Post by: Rods2 on 15 April 2014, 19:46:29
Tunnie - when I was your age I messed with petrol mowers. The older ones are a pain in the ass and if you value your time go out and get something that does the job - electric or petrol.

Parents give you stuff believing they are helping you out and you feel obliged to deal with the problem which is why they gave it away to you in the first place.

Time is money ...

There is truth in that, but the lawn area I have is not vast.

FatherT did buy himself a new Mower as this one was becoming problematic, but like the Omega, a little TLC and it could run for a good time yet.

If you enjoy tinkering with it, then it's not wasted time. If it saves you a couple of hundred quid on a new mower, so much the better.. IMHO, at any rate. :y

I agree, mine when it started to give trouble was easily solved with a service and £7 for parts. It now needs a bit of welding where tin worm is taking its toll on the blade cover, but an offcut from the blacksmiths down the road, and a bit of welding practice, should hopefully have it ready for the next 18 years. :y :y :y