Head gasket

[TobyU]

Funny you should mention that about putting the bolt in the middle. I finally got tired of replacing head gaskets and a flywheel that cracked off a piece at the keyway and replaced it with a JD labelled engine, just so I could sell it. A few weeks after it left for it's new home I went to visit a friend, who had just purchased the same model tractor. Within a few months he had similar issues. Being an even more stubborn person than myself, he drilled & tapped a hole in the block and a clearance hole in the head for either a .190 or .250 bolt (Inco718, of course). That actually fixed the problem for several years.

I I was going to mention just doing that in my other post but they really didn't design it for that and there's an awfully large pushrod galley that doesn't need to be so big so they would have had more metal between the cylinder and the opening but you could certainly put something there with the metal that you do have and it would help the issue.

Has myself and others have stated though this should not be a recurring problem. I have never had one fail a second time and I don't even always mill the heads down on a flat surface..
I have done many of these by just scraping off the head and getting it nice and clean and not even putting a straight edge on it to see if it's warped at all!
I simply clean the head and the block up thoroughly and put the new Briggs & Stratton gasket on there as I have never used an aftermarket gasket even though I think there's a potential they could be better than the factory one and I torque it now with the new tightening pattern and the 250 inch pounds procedure but I used to do these with the old torque sequence and the 220 or 225 or whatever it was and I still never had any failures back then either.

So while it is an epidemic problem, once I put a new gasket on there it's not been an epidemic problem in the future at all.
However, if I were having repeated failures I would certainly take extra steps and if milling the head flat and permatex spray gasket didn't solve the problem I would be drilling a hole and tapping some bolt threads!!

 

[bertsmobile1]

I used to fit the Stens gaskets which are cut from the same sheet material as exhaust gaskets and work a lot better
However they only do 1 size down here so I found a supply of after market ones in a kit that are the same material as the B & S ones and come with rocker cover gasket.
Down side was MOQ was 50 but as I do quite a few of them then that was not a big problem .
If the same mower comes back twice then they get one of Lanni's copper gaskets, they never ever come back.
I also use the copper gaskets if the block is under cut as the copper will conform to the shape if the head is flat
And some times even fill a big undercut with POR15 or Devcon and in that case it also gets a copper gasket .
Lanni is goon because he makes up packages for me that are the full weight limit
From memory that is 7 intek only gaskets but as I buy a lot of gaskets from him I often make up weight with them when ordering 1 of unique gaskets .
The intek is taken from the Vanguard and if yo put them side by side you see the Vanguard has a lot more thickness and a better bolt positioning .
as with a lot of these things , they are cast on a machine that has dozens of moulds on a carousel so if one mould is not as good as the the others then 1 in 10,20, 30 etc will be weaker.
Then there is start up & shut down faults plus Silicon burn off so at the end of the day the actual mo;ten alloy in the furnace changes slightly.

All of these things can introduce random faults in a small percentage of the castings that are very hard to pick up in QC so you get a small percentages of Inteks that just keep on blowing the gaskets , just the same as a small percentage of Courage engines developed that cylinder crack .

It all comes down to the reluctance of the purchaser to pay a reasonable price as we have all been indoctrinated ( brain washed if you like ) that everything will get cheaper because of advances in manufacturing technology so we will be able to afford what ever we want .
There is a sound reason why there are no more mowers with Honda or Generac engine in them and it was not because the engines were trash & constantly gave problems.

 

[closecut]

I have a Husquvarna tractor. 18.5hp. Can anyone tell me why I have gone thru 4 head gaskets? This one being the 4th. Blows out right across from the plug. There is no way I screwed up 3 headgaskets. Getting a little tired of this crap. Are these engines junk? I can change a hot cylinder in a 2500hp EMD but can't keep this running. Should sell everything and buy a diesel....

Do you use starting fluid?This will blow a head gasket if used to much.It can also STRETCH the head bolts,and the bolts will bottom out without actually crimping down on the head properly.
A washer under the head bots is a cheap fix,but the best way is new head bolts,or grade 8 bolts from the local hardware store.May have to go to an automotive store to find grade 8 bolts. They cost more,but will not stretch.
Also,use a Felpro gasket.The OEM has a very thin section between the plug and block.Felpro is much wider.
Run for a few minutes,and then let it cool and tighten the head bolts again to spec.
This is after doing the recommended checks above.Let us know how it comes out,don't leave us hanging.
Good luck!

 

[closecut]

No firing order found?Here is an old school method to get the tightening sequence right:
Start in the center and tighten in a expanding circle from the center outward.
Imagine flattening a sheet of paper from the center.Same thing.You want the wrinkles to go toward the ends.The metal is flexible,but not visible,but it does act like stiff paper.Even cast iron heads on big engines flex as they are tightened.

 

[hlw49]

Might what to check and see if the head is flat. I take a large piece of artifical granite and emery cloth and lap the head. Use 400 grit emery cloth. You can use a piece of glass it works as well.

 

[grpascott]

Hi Oar,
Here's what I did, it's lasted 4 years so far.
Engine started to smoke once in a while, I knew Inteks had a bolt pattern (spacing) problem. The head bolts are also a lousy alloy. I went and got grade 8 bolts the same length. They weren't threaded far enough so I got a die and threaded them deep enough to torque down. I didn't even take the head off, just took the old bolts out and replaced and retorqued one by one to 22 ft lbs (264 in lbs). No more smoking or problems since then. I also use a little zinc additive in the oil to protect the flat tappets. This may sound a little involved but I'm a born tinkerer and I love to make lousy engineering work. Hope you give it a try, never give up...never surrender!!

 

[barny57]

Do you use starting fluid?This will blow a head gasket if used to much.It can also STRETCH the head bolts,and the bolts will bottom out without actually crimping down on the head properly.
A washer under the head bots is a cheap fix,but the best way is new head bolts,or grade 8 bolts from the local hardware store.May have to go to an automotive store to find grade 8 bolts. They cost more,but will not stretch.
Also,use a Felpro gasket.The OEM has a very thin section between the plug and block.Felpro is much wider.
Run for a few minutes,and then let it cool and tighten the head bolts again to spec.
This is after doing the recommended checks above.Let us know how it comes out,don't leave us hanging.
Good luck!

I have a Husquvarna tractor. 18.5hp. Can anyone tell me why I have gone thru 4 head gaskets? This one being the 4th. Blows out right across from the plug. There is no way I screwed up 3 headgaskets. Getting a little tired of this crap. Are these engines junk? I can change a hot cylinder in a 2500hp EMD but can't keep this running. Should sell everything and buy a diesel....

Like the guys said, bolts, flat head, gasket, solve your problem

 

[TobyU]

Do you use starting fluid?This will blow a head gasket if used to much.It can also STRETCH the head bolts,and the bolts will bottom out without actually crimping down on the head properly.
A washer under the head bots is a cheap fix,but the best way is new head bolts,or grade 8 bolts from the local hardware store.May have to go to an automotive store to find grade 8 bolts. They cost more,but will not stretch.
Also,use a Felpro gasket.The OEM has a very thin section between the plug and block.Felpro is much wider.
Run for a few minutes,and then let it cool and tighten the head bolts again to spec.
This is after doing the recommended checks above.Let us know how it comes out,don't leave us hanging.
Good luck!

How are you possibly going to find a felpro gasket for a lawn mower engine?
The most common one for these is going to be the Briggs which has not been approved at all and is the same old one they've been using for 20 years that certainly will blow out because of the bad design of the head and the too much spacing between the right to head bolts.
I have seen other like aftermarket ones online often where you get two or at least the gasket and some other additional gaskets for a cheaper price than the Briggs and some of these are actually better built and you might even find one with a fire ring around the combustion cylinder but don't quote me on that BUT unless I'm really out of the loop, I've never seen a felpro for one of these 31XXXX or 33xXXXX Briggs.

 

[TobyU]

Like the guys said, bolts, flat head, gasket, solve your problem

Yep, and also using a torque wrench and maybe even the Briggs recommended tightening sequence for the bolts.
Those bolts are fairly wimpy so it certainly wouldn't hurt to replace it with new ones and especially much better ones like grade 8.
However, a lot of people just use their 3/8 Drive fraction and tighten these things up by hand in any haphazard order.
I don't think the order matters nearly as much as getting them properly torqued or at least torqued enough and not too much so as to stretch the bolt or snap It off - which I'm not really convinced is the same as that thing as properly torqued. Lol
You just must have an inch pound torque wrench for this and it must be accurate because many are not.

Also, as you mentioned, these heads are normally not flat. Some aren't even close.
If I'm doing one I really care about, I will lay it on a piece of 60 or 80 grit sandpaper on a piece of plate glass or something quite extremely flat and do a little backyard Mill job of the head .
It's not perfect but it doesn't have to be and it certainly makes it a lot better.

In just a few strokes you start to see where the high spots are being rubbed off but it takes a long time to get down to where you've touched the head everywhere because the high spots are no longer that high.
When you do this you want to change the direction of the head in your hand like rotate it a quarter and a half turn many times as you're pushing it back and forth applying pressure on your sandpaper.
I normally tape the sandpaper down with duct tape.
The last time I did one I counted and it was almost 600 strokes until I got it to where it was evenly sanded..
This can take 20 to 30 minutes and then you want to remove all of the nasty sanding grit and metal shavings.
But then you have a much flatter head and then of course you want to clean up the block service with a scraper and maybe some fine sandpaper etc but don't sand it any one spot too long because you're not doing the flatness any favors by standing around with sandpaper on your fingertip!
I have never had one of these fail once replacing them.
I hear people that have had repeated failures and I only can assume they're just yanking it off and wiping off the head and the surface with a shop cloth and barely, if even, scraping off all the old gasket and then throwing it back together and just tightening It up by hand without using a torque wrench.
This is what I assume contributes to most of these failures.

 

[melvin1942]

I have a Husquvarna tractor. 18.5hp. Can anyone tell me why I have gone thru 4 head gaskets? This one being the 4th. Blows out right across from the plug. There is no way I screwed up 3 headgaskets. Getting a little tired of this crap. Are these engines junk? I can change a hot cylinder in a 2500hp EMD but can't keep this running. Should sell everything and buy a diesel....

Have you checked the flatness of the head and block?