# 24 HP ELS Briggs & Stratton engine problems



## watsotd

I've got a 2005 Cub Cadet LT1024 with the Briggs 24 HP ELS725 engine with 168 hours and it has a problem I need some help with. I'll start by saying I have keep it well maintained by changing the oil 2 to 3 times every summer and the air filter replaced twice every summer including cleaning it with compressed air before each use. The problem is this, its starts with no problem but once it warms up at high idle it starts backfiring and running rough, at idle it doesn't backfire but it surges a little, but when I engage the PTO at high idle and start cutting grass it smooths out but is down on power a little and smokes like crazy, oil consumption is about a quart every time I cut grass which usually takes 2 to 3 hours. This engine ran fine until recently and this started all of a sudden. I would appreciate some help on this as it is driving me crazy.


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## MrChooks

:wave: & welcome to TSF

Hate to say this - but, in the absence of you having overfilled with oil - these symptoms (especially the high oil burn and smoke) sound a bit ominous:sigh:

Let's start with the easy symptoms - is the smoke black or blue?? - if its burning lots of oil it will be blue and have an acrid small about it - if it's too rich - the smoke tends to be black.

Take the plugs out - have a look at the electrodes - are they covered in an oily film and black - or just black (they should be grayish). Have you changed them ever and set the correct gap?? - as when they get tired - they can badly affect engine performance.

The engine performance issues might also be a fuel / air mix issue as back firing can be caused by the carb float level being too low or high - lots of dry black soot on the plugs can indicate the mixture is too rich.

Can you come back to us with what you find and let us know if you have good and correctly set plugs pls.


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## k2skier

Check the breather hose that goes to the air box, does it have oil in it? Any sort of crankcase leak will cause a drop in crankcase pressure and that will cause the oil to be pulled into the air box through the breather hose. A bad breather check valve (think PCV) will do the same. You mention blowing out the air filter after every use??! Is it being used in very dusty conditions? You would have to be careful to not damage it (dirt getting past) when cleaning it. I personally don't like the cleanable filters, they are supposed to be washed with water, I use standard air filters and keep the pre filter clean and oiled. One more thing, use should always use a straight 30W oil in temps over 40F, they will use oil with multi-weights.


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## watsotd

I've replaced the plugs they were covered in an oily film and black, and also noticed that they were not platinum plugs like they were supposed to be, anyway still have the same problem. Also have checked the breather system and it is not stopped up, this was my first thought,and cannot find any oil leaks anywhere. I am using the standard air filter and pre filter, I clean and oil the pre filter and blow out the pleated filter. Also I have been using 30W oil like was recommended.


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## k2skier

I would recommend performing a leak down test. Sometimes this can be a little deceiving, a piston can have a worn oil control ring, but have a good enough seal in the compression rings to show OK on the leakdown. If it's using that much oil without it coming in from the breather then it's coming from the valves/cylinder head, (which would be a lot for that area), or most likely the oil control ring.


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## watsotd

But why did this start all of a sudden, I mean this did not gradually happen it went from using no oil to using this amount in the matter of one cut of my yard.


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## k2skier

A leakdown test is what needs to be performed next. It may have blown a head gasket on one cylinder, which would suck in a lot of oil and still run OK. How long does it take to mow your yard? Cleaning the filter before each use is a little excessive, unless you're mowing in extremely dusty conditions for 4-6+ hours. Knowing the model number could help. Does it have a loop on the side of the air filter, kinda like a suitcase handle?


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## MrChooks

:wave: K2skier has a good suggestion - a blown head gasket would account for the rough running and the slight power loss you mentioned as well as allowing oil into the combustion chamber - and if he is right - it's an easy fix:grin:

When you pulled the plugs - were they both oily / dirty or was one noticeably worse than the other - as the really dirty one would indicate that that is the suspect head gasket and it is pretty unlikely that you would blow both head gaskets at the same time.

Let us all know how you get on


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## MrChooks

I just noticed the following post on MyTractorforum regarding the B&S ELS Engine air filter - and this sounds all a bit ominous :sigh:- *suggesting that the B&S air filter on this engine is defective in design and allows "dirty air" to bypass the filter *- the link to the article is:

http://www.mytractorforum.com/showthread.php?p=406856

watsotd - if this is also your problem - I fear that dust my have by-passed the air filter (despite all your efforts) and certainly adds weight to k2skier's comments regarding oil rings (and maybe compression rings) being worn - sorry - but if it's not a head gasket - then I fear you my be looking at an engine rebuild

See extract from the thread below - also have a look at the thread as there are some photos included 

_*Briggs & Stratton 26hp ELS air filter problem *

I have a 2004 Craftsman GT 5000 with a Briggs & Stratton 26 hp ELS engine. I have been having a problem with dust bypassing the air filter and getting into the engine. I have been chasing this problem for some time now and I think I finally found where it was coming from. The air filter and intake passage of this engine were inspected and cleaned 1 hour prior to when these photos were taken. The pre-filter was also cleaned and re-oiled at that time. I had been mulching leaves and was creating a lot of dust, but in a worst case scenario it should plug the filter, not bypass it. Luckilly the engine still runs like new. I recall someone else either here or at GW reporting a problem with dust bypassing the filter on their machine (same engine) also but I have never seen a solution.

The air filter is accessed by unlatching a clasp (yellow part at top of 2nd photo) and removing a plastic cover. The air is supposed to travel up from underneath, through the prefilter and filter, into the plenum created between the cover and filter, and down through the "D" shaped opening in the gasket. Somehow, with everything in place, dust gets past the "extended life filtration system" (extended from what?).

This time I think I found the culprit. The surface that the air filter seals on the underside is composed of two pieces, the large plastic engine cover and the "D" shaped intake passage. Running my finger along the two parallel surfaces that butt against each other, I noticed that the cover surface was not very even with the intake. At one end of the intake (right side in first photo of next post) they were fairly even but on the other end of the straight leg of the "D" the cover surface was higher. I believe the air filter gasket material was compressed too lightly against the intake on that side since the cover surface was compressing it more. The photo inside the intake shows a greater dust concentration on this side.

The large plastic engine cover is secured using shoulder type screws. This method provides little to no ability to shift the cover to align it with the intake. However, these shoulder screws thread into sheet metal pieces that are attached to the engine with standard hex head screws in clearance holes. I attached the cover and loosened the screws holding the sheet metal pieces. I shifted the cover until it was aligned as evenly as possible with the intake surface and secured the screws holding the sheet metal pieces.

Since winter came after that, I have not since used this in dusty conditions. This spring I will find out if it is cured or not. If dust still finds its way in, I may put some RTV silicone in the seam between the cowl (a.k.a. cover) and the intake.

Thanks for reading,
Roger
Attached Thumbnails
_[/I][/I]


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## k2skier

If it is a blown head gasket, it will easily show up with a standard compression test.


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## MrChooks

:wave: Yes k2skier is right - you need to identify a likely cause before running off buying parts / doing repairs that you may or may not need. The compression test would identify a blown head gasket pretty quickly and that would be a relatively easy fix :wink: and it may also show if you have had "dirt ingestion" problems leading to oil and / or compression ring damage - which is a much bigger problem

watsotd - after your recent post, I did a quick "Google Search" on the B&S EMS 725, which is where I located the material in my post regarding B&S EMS air filter issues / massive oil burn issues - some on engines with with barely 100+ hours on them :upset:. 

There were numerous articles regarding this topic and all sorts of gripes on the effectiveness of the B&S OEM filter assembly. The fix, most of these people seemed to have opted for, was a "re-ring" of the engine with a parts cost of about $150+/- But imho - if that turns out to be your problem - it is a waste of money if the air-filter assembly is not updated with a new modified B&S assembly - as without correcting the "leaky airfilter box" issue 1st, the whole problem will simply repeat itself.

So, at this point, I agree with k2skier - get yourself a compression test 1st - then you can decide which way you need to go, as whilst replacing head gasket/s is a relatively easy task - re-ringing is a total strip down and re-build task - read - "lots of tools & know how":sigh: and depending on your skills level and tools / equipment availability - it might be easier to "bite the bullet" and go for a replacement or shop rebuilt engine - but you can't make that decision with any confidence until you have compression test results.


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## vulcan93

MrChooks said:


> :wave: Yes k2skier is right - you need to identify a likely cause before running off buying parts / doing repairs that you may or may not need. The compression test would identify a blown head gasket pretty quickly and that would be a relatively easy fix :wink: and it may also show if you have had "dirt ingestion" problems leading to oil and / or compression ring damage - which is a much bigger problem
> 
> watsotd - after your recent post, I did a quick "Google Search" on the B&S EMS 725, which is where I located the material in my post regarding B&S EMS air filter issues / massive oil burn issues - some on engines with with barely 100+ hours on them :upset:.
> 
> There were numerous articles regarding this topic and all sorts of gripes on the effectiveness of the B&S OEM filter assembly. The fix, most of these people seemed to have opted for, was a "re-ring" of the engine with a parts cost of about $150+/- But imho - if that turns out to be your problem - it is a waste of money if the air-filter assembly is not updated with a new modified B&S assembly - as without correcting the "leaky airfilter box" issue 1st, the whole problem will simply repeat itself.
> 
> So, at this point, I agree with k2skier - get yourself a compression test 1st - then you can decide which way you need to go, as whilst replacing head gasket/s is a relatively easy task - re-ringing is a total strip down and re-build task - read - "lots of tools & know how":sigh: and depending on your skills level and tools / equipment availability - it might be easier to "bite the bullet" and go for a replacement or shop rebuilt engine - but you can't make that decision with any confidence until you have compression test results.


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## vulcan93

I have the same motor in a 2005 Husqvarna 24/46 mower. At about 80 hours it started burning oil like crazy. At 128 hours it is FUBAR.After reading numerous sites it seem like the problem on all the motors with the plastic lift off cover to the air filter. The cover does not seal allowing dirt to enter the intake. After cleaning my filters I have noticed the intake tube is filthy. If you have this type of filter and the mower is under warranty take it to a authorized dealer and have them check it out. They will probably give you the run around but print off alot of the discussions and take them with you. Demand a new motor with the new design for the air filter. The motor will not last espically in dusty conditions. I use mine to get up leaves and it is real dusty. If your mower is not under warranty whay I have read is tuff luck. There are replacement motors available for 700 dollarss on the internet.I hope this helps. If you are thinking about buying a mower check out the air filter assembly. If it has a plastic top with a yellow pull tab, STAY AWAY from it.


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## MrChooks

:wave: vulcan93

Yes - looks like this air cleaner problem with the bigger B&S twins is real nightmare and sorry to hear that you have also been caught up in it. 

I haven't heard of anyone getting B&S to give any tangible assistance - so if it were me confronted with a burnt out engine due to a dodgy B&S filter - I think I would look very seriously at just biting the bullet and replacing the engine with another make - even if the transplant is a bit of PiA:sigh::upset:

Maybe Kohler or Honda have an engine with identical face plate / shaft length diameter configurations that would fit your mower. They both have web sites that should have the face plate / shaft length / diameter spec + the overall engine dimensions that might help you decide if you can give B&S the flick


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## vulcan93

vulcan93 said:


> I have the same motor in a 2005 Husqvarna 24/46 mower. At about 80 hours it started burning oil like crazy. At 128 hours it is FUBAR.After reading numerous sites it seem like the problem on all the motors with the plastic lift off cover to the air filter. The cover does not seal allowing dirt to enter the intake. After cleaning my filters I have noticed the intake tube is filthy. If you have this type of filter and the mower is under warranty take it to a authorized dealer and have them check it out. They will probably give you the run around but print off alot of the discussions and take them with you. Demand a new motor with the new design for the air filter. The motor will not last espically in dusty conditions. I use mine to get up leaves and it is real dusty. If your mower is not under warranty whay I have read is tuff luck. There are replacement motors available for 700 dollarss on the internet.I hope this helps. If you are thinking about buying a mower check out the air filter assembly. If it has a plastic top with a yellow pull tab, STAY AWAY from it.


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## vulcan93

After talking with a briggs repair man today at a local retaier he said he has repaired this motor too many times with new motors and short blocks. He said the problem is two fold. The air filter letting in dirty air for later oil consumption and the oil sump has baffles inside the motor that if the mower is on a incline it starves the number one rod of oil and thay break. He sid there is no recall on this motor and no after warranty repairs are being made by Briggs. The 24 hp mptpr has gone through 4 model changes to fix these problems. He siad the new model is doing fine. I guess I will put a new motor in.


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## MrChooks

:wave: Hi Vulcan93
Sorry that you have had problems with your B&S and as I said in earlier posts - I don't think B&S have _showered themselves in glory _in the manner they have handled the problems with this engine line:upset:

I wasn't aware of the oil supply issues and am a little surprised as I thought this engine had a positive pressure oil pump, which "should" deliver oil to all parts of the engine whilst ever its pick up has access to oil - anyway, your local dealer will have more experience with these engine than I - so I would defer to his advise. All that suggests is that the original B&S design was a real lemon

Your approach in talking to your dealer on a recommended transplant is a good one. If you trust his advise, then I agree, the revamped model B&S will be easiest to transplant - albeit with attendant "wallet shock"


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