Head gasket

[barny57]

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....

Head can’t be flat , even 1 not torqued bolt wouldn’t cause that

 

[joea99]

Point is that there is zero chance of stretching a steel bolt in an aluminium casting, it just can not happen
Bolt stretch when tightening into a cast iron block can happen but not into an alloy block tensioned to 20 ft lbs
That sort of torque is not even in the elastic deformation range.

Nothing wrong with the nut test for thread deformation except it is not applicable to mower engines .
And yes threads should be clean and dry but that should be a given .

I have personally stretched a brand new steel head bolt in an aluminum block. Granted, it was an automotive engine (a Subaru) and the ultimate torque was far over 20 ft lbs, but it IS an aluminum block.

It happened when doing a head gasket replacement, doing the first bolt with a bad clicker torque wrench that had "worked last time". Since it was my first Subaru overhaul and I was following a script, it did not dawn on me, till too late, that I was WAY beyond where is should have clicked. Short story is that after redoing the torque sequence with a new wrench, I was not confident of a good job and pulled the head.

Yep, that bolt was clearly stretched very badly. I was concerned about having deformed or pulled the threads, but after checking the block and the bolt holes, got a new gasket and new bolts and finished the job. My own car, so not sorry at all, except for the expense.

 

[TobyU]

Well, if you did all that then something wasn't done right or something is atypical and even though you're doing what you're supposed to be doing you're not getting the results and it's letting the procedure fail.
I have red posts over the past 10 years or so about people who have had more than one head gasket failure and it always astounds me because I have done a lot of these Briggs & Stratton 31xxxx and 33xxxx and I have literally never had a repeat failure!!

Maybe I'm just lucky but I don't think that's the case.

At bare minimum the head needs to be scraped clean with a razor blades scraper or putty knife or whatever and white clean with brake cleaner or carb cleaner or whatever and a rag and the same for the block surface. That's the bare minimum.
Then it is a must that you use the proper head bolt torquing sequence which has been revised and an accurate inch pound torque wrench.
Maybe you're rich is off one way or the other??
I want snapped a rod bolt on a 12-point headed Buick 455 engine because I borrowed a torque wrench when I was a teenager and didn't own one myself and it was calibrated way off! It must have been 25 to 30 lb minimum off because it snapped that off and I had to go to the junkyard to get another one..
So that's all I ever do and I never have failures but if I'm trying to prevent a failure I will go two extra steps..
I will place it on a flat piece of glass or very flat metal with some 60 or 80 grit sandpaper taped down..
Then I will send the heck out of it until the entire surface is even.
This of course isn't as good as actually milling one but you will quickly see the high spots and then as you keep going you're saying will start to hit the other spots so you know you have it much more flat than when you started.
It takes a long time and gets annoying. The last time I counted I had to do at least 500 strokes before I even got close to being smooth and acceptable.
Also, I do it in all different directions as I rotate it a quarter turn throughout the process multiple times.

Then the second thing I will do is spray the permatex copper spray gasket on both sides of the gasket.

Like I said I rarely do either of these and they still last for years after I put them together so I'm very surprised you're having repeated problems.

Are you using the Briggs & Stratton gaskets or the ones you get on eBay and amazon?
In this case the ones that are aftermarket could very well be better than the briggs one because it is junk from beginning and they sell you a same junk when to replace it.
I believe I saw a couple online that seemed to look like they had a fire ring around the combustion chamber which would be an improvement.

When Kohler had this problem back in the early 2000s they recalled all of their original head gaskets and replaced it with a head gasket kit, while expensive, it was a much improved head gasket much beefier and with a fire ring around it so the problem would not reoccur.
Briggs does nothing!

 

[charleneje]

If that is true about headbolts not stretching why do all automobile manufacturers in the workshop manual say to replace all headbolts on aluminum heads and even on some other uses where aluminum parts are used. I remember back in the 1960's that when taking the head of an all aluminum engine Hillman Imp you stood a good chance of breaking headbolts when taking the head of the engine to do a decoke something very few engines nowadays. I know that is about automotive but it proves the point about bolts stretching I believe.

 

[Tommy Mckeown]

Well, the same spot would indicate that either the block, the head, or both are not true. I think you need to get a precision straight edge and check that area on both surfaces. A Starrett brand will be about $100 while an Amazon one will be $30. One is accurate to .0003". while the other is .001 You are just checking not machining so the $30 one should be just fine.

 

[reynoldston]

I use a flat pace countertop and cover it with sandpaper. I start with 100 grit and work up to 600. I sand the head surface and engine. Then retorque head bolts to specs starting with a low setting and working up to the full setting. I have never had a gasket problem doing it this way. Also when removing the head you need to do that in the proper sequence also.

 

[charleneje]

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....

I had the same problems on a 22hp Briggs engine I would replace the head gasket and it kept on blowing after just a short amount of use, I came on here and was suggested to make sure the head was flat by testing with a straight edge and using a piece of glass and sanding it I got some 240 grit sandpaper and spray glue and stuck the paper to a sheet of thick glass I have it took a long time but i used a figure eight sanding pattern and it finally got flat in every direction I checked also when sanding a head you can see all the highs and lows because of the sandpaper marks. I ordered a head gasket from CopperGasketsUS. having discussed my problem with Lanni and he sent me an already annealed head gasket, so I made sure everything was cleaned properly and sprayed Permatex copper spray gasket on both sides of the gasket and on the head and cylinder assembled and torqued the head according to manual I then left it for two days everything covered with a big rag and then retorqued the head bolts, put everything together and haven't had any problem's since I do have a fuel shut off on the mower because fuel will leak past the carb and fill the crankcase. I check my oil before each use and not long after I first got the mower the oil was right up the dipstick and it smelled of gas hence the fuel shutoff.
I did the repair thanks to advice from others on this forum Like you I was ready to just replace my few years old mower now my only problem is the rear automatic axle/gearbox makes noise and slips but I cant get it off with my equipment to check it out so I will wait for it to quit then replace the mower.

 

[TobyU]

Well, if you did all that then something wasn't done right or something is atypical and even though you're doing what you're supposed to be doing you're not getting the results and it's letting the procedure fail.
I have red posts over the past 10 years or so about people who have had more than one head gasket failure and it always astounds me because I have done a lot of these Briggs & Stratton 31xxxx and 33xxxx and I have literally never had a repeat failure!!

Maybe I'm just lucky but I don't think that's the case.

At bare minimum the head needs to be scraped clean with a razor blades scraper or putty knife or whatever and white clean with brake cleaner or carb cleaner or whatever and a rag and the same for the block surface. That's the bare minimum.
Then it is a must that you use the proper head bolt torquing sequence which has been revised and an accurate inch pound torque wrench.
Maybe you're rich is off one way or the other??
I want snapped a rod bolt on a 12-point headed Buick 455 engine because I borrowed a torque wrench when I was a teenager and didn't own one myself and it was calibrated way off! It must have been 25 to 30 lb minimum off because it snapped that off and I had to go to the junkyard to get another one..
So that's all I ever do and I never have failures but if I'm trying to prevent a failure I will go two extra steps..
I will place it on a flat piece of glass or very flat metal with some 60 or 80 grit sandpaper taped down..
Then I will send the heck out of it until the entire surface is even.
This of course isn't as good as actually milling one but you will quickly see the high spots and then as you keep going you're saying will start to hit the other spots so you know you have it much more flat than when you started.
It takes a long time and gets annoying. The last time I counted I had to do at least 500 strokes before I even got close to being smooth and acceptable.
Also, I do it in all different directions as I rotate it a quarter turn throughout the process multiple times.

Then the second thing I will do is spray the permatex copper spray gasket on both sides of the gasket.

Like I said I rarely do either of these and they still last for years after I put them together so I'm very surprised you're having repeated problems.

Are you using the Briggs & Stratton gaskets or the ones you get on eBay and amazon?
In this case the ones that are aftermarket could very well be better than the brakes one because it is junk from beginning and they sell you a same junk when to replace it.
I believe I saw a couple online that seemed to look like they had a fire ring around the combustion chamber which would be an improvement.

When Kohler had this problem back in the early 2000s they recalled all of their original head gaskets and replaced it with a head gasket kit, while

If that is true about headbolts not stretching why do all automobile manufacturers in the workshop manual say to replace all headbolts on aluminum heads and even on some other uses where aluminum parts are used. I remember back in the 1960's that when taking the head of an all aluminum engine Hillman Imp you stood a good chance of breaking headbolts when taking the head of the engine to do a decoke something very few engines nowadays. I know that is about automotive but it proves the point about bolts stretching I believe.

There is no point to prove about head bolts unless you know the design parameters and the materials used of the particular head bolts and we don't.

Head bolts in the old days up until the late '80s were never TTY torque to yield.. then along came the ttys for a couple of reasons but I think mainly just they can sell more bolts.
There is a little more to it than that as they wanted to downsize everything including the holes in which these bolts resided because there wasn't as much meat in the heads and block and stuff like that around the holes so they didn't want to make the bolts as big and the bolts simply weren't as big with tons of Overkill where they can be used multiple, multiple times like many of the old head bolts on most of the engines I've built over the years were which did just fine.
They decide to use a smaller fastener and then tighten it to the point of starting to stretch so it was giving its most fascinating ability but we all know what happens then it's like a one-time use.

I don't believe these Briggs & Stratton head bolts are designed that way and I also don't believe they're very high quality either. There are some times where I can't quite get them to the new revised torque rating of 250 inch pounds without being afraid one will snap off or strip out the threads so often I don't know quite that high. It used to be 220 or 225 and now it's 250..
I think tightening in three steps which I forgot to mention in my other post, which I always do, and tightening them down evenly is more important than your final torque amount.

I have reused many of these old head bolts multiple times and I just keep them laying in a bowl somewhere they work just as well whether they've been used once or five times in my opinion.
You're not stretching them much if any and you're certainly not stretching them to yield in my opinion when you reinstall the head..
When you get good at the feel for it you can tell if one is out of whack by just using the torque wrench on it or even a 3/8 drive ratchet so maybe if one was messed up or I've been over Titan there could be an issue but other than that I think any old bolts work just as fine as buying brand new ones. Or if we could go buy some ARP head bowls I don't think it would make a bit of difference on these particular engines because it's a lousy design and a lousy gasket.

 

[Honest Abe]

Then I ask why it specifically says to replace head bolts in manuals for aluminum block and heads.
I had a 4-wheeler with aluminum block, 650 cc that keep blowing head gaskets after a few hours of running. I made sure there was no cracks or warpage. Come to find out after I finally found a manual on it and after 5 head gasket replacements it stated, "Head bolts must be replaced when head is removed for any reason". It did not give a reason. I purchase all new head bolts and it has been running for about a year now with no problems.

if I had to "guess" I'd say that it's because these dang bolts are similar to trying to get nuts of aluminum rims. It seems to take infinitely more torque to break them free than to tighten them down. Just a wild guess though . . . . .

 

[Honest Abe]

Well, if you did all that then something wasn't done right or something is atypical and even though you're doing what you're supposed to be doing you're not getting the results and it's letting the procedure fail.
I have red posts over the past 10 years or so about people who have had more than one head gasket failure and it always astounds me because I have done a lot of these Briggs & Stratton 31xxxx and 33xxxx and I have literally never had a repeat failure!!

Maybe I'm just lucky but I don't think that's the case.

At bare minimum the head needs to be scraped clean with a razor blades scraper or putty knife or whatever and white clean with brake cleaner or carb cleaner or whatever and a rag and the same for the block surface. That's the bare minimum.
Then it is a must that you use the proper head bolt torquing sequence which has been revised and an accurate inch pound torque wrench.
Maybe you're rich is off one way or the other??
I want snapped a rod bolt on a 12-point headed Buick 455 engine because I borrowed a torque wrench when I was a teenager and didn't own one myself and it was calibrated way off! It must have been 25 to 30 lb minimum off because it snapped that off and I had to go to the junkyard to get another one..
So that's all I ever do and I never have failures but if I'm trying to prevent a failure I will go two extra steps..
I will place it on a flat piece of glass or very flat metal with some 60 or 80 grit sandpaper taped down..
Then I will send the heck out of it until the entire surface is even.
This of course isn't as good as actually milling one but you will quickly see the high spots and then as you keep going you're saying will start to hit the other spots so you know you have it much more flat than when you started.
It takes a long time and gets annoying. The last time I counted I had to do at least 500 strokes before I even got close to being smooth and acceptable.
Also, I do it in all different directions as I rotate it a quarter turn throughout the process multiple times.

Then the second thing I will do is spray the permatex copper spray gasket on both sides of the gasket.

Like I said I rarely do either of these and they still last for years after I put them together so I'm very surprised you're having repeated problems.

Are you using the Briggs & Stratton gaskets or the ones you get on eBay and amazon?
In this case the ones that are aftermarket could very well be better than the briggs one because it is junk from beginning and they sell you a same junk when to replace it.
I believe I saw a couple online that seemed to look like they had a fire ring around the combustion chamber which would be an improvement.

When Kohler had this problem back in the early 2000s they recalled all of their original head gaskets and replaced it with a head gasket kit, while expensive, it was a much improved head gasket much beefier and with a fire ring around it so the problem would not reoccur.
Briggs does nothing!

you touched on something I meant to bring up earlier, i.e. "Torque wrench calibration". When was the last time folks had their calibrated? My son builds all kinds of engines for a living, and his are sent out every 6 months and recalibrated. When you're building $75k+ engines little things count, maybe not so much for some and a B&S . . . . . .