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Head gasket
- Thread starter Oarhead
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Export threadYou would literally never get done doing it this way..Almost certainly a warped head, but some of the methods being suggested here to flatten it are a good way to ruin a perfectly good head. Do not use sand paper or concrete both are far to coarse and inaccurate. The best way is to use fine valve grinding paste on a piece of glass, preferably 1/4" or thicker as that's flatter. Do not use a scrap double glazed panel as they're often slightly concave. oil the glass, then smear on some fine valve grinding paste. Place the head on it and move in a figure of eight motion, every dozen or so figures of eight stop, turn the head through 90 degrees and continue. Every so often lift up the head and check the lapped surface, low spots will be obvious. Continue, adding more grinding paste as necessary, until the whole surface is an even mat colour. Wash off, then refit using a new head gasket and torque down gradually, ie bring the bolts up together, do not torque down one fully then the next and so on. If the order is not known tightening diagonally is a good rule of thumb.
One other thing to check is to make sure the bolts (or one possibly) aren't bottoming out too early. Without the head try fitting them, and make sure when fully inserted the gaps between the block and the head of the bolt are all less than the thickness of the head. If they are bottoming out, even when torqued down they won't be squeezing the gasket correctly.
Well, you would stop but in the end, it wouldn't be much different from just leaving alone and wiping it off with a rag after you scraped it in the first place.
These heads are so warped and have such large dips and valleys in them that you're never going to accomplish anything that way.
There is absolutely no problem with laying them on a fairly flat surface, with sandpaper on that surface and working them in all directions as you turn the head around a quarter turn multiple times so this way you're making up for any possible surface of regularities.
I prefer to start with 80 grit but I'm guessing you're going to say that's too course but it works great for me. Sometimes I'll go over it afterwards with something a little bit finer but nothing finer than 120 because this doesn't need to be polished to a smooth surface and you'd be amazed how pretty and smooth they look after doing 500 to 600 strokes with the 80 to 120 grit that I do.
Yes, it takes about 500 strokes doing it this way and I put a good deal of pressure down on the head to get it to where you have actually sanded the whole surface so there's no more high spots holding the rest of the head up off of the sandpaper.
They are that bad. And this is probably why so many people have repeat problems with head gasket failures despite the fact they claim their twerking them in the correct pattern and to the proper specs.
This is not rocket science and it's not very precise either. They are still very forgiving and it does not need any certain type of machine slash engine builders and finish on it to work perfectly.
These engines are actually junky little low performance turds that just luckily are pretty forgiving of most of the abuse, neglect, and design flaws, and low quality parts they're made with.
Sometimes though you have to take matters into your own hand to make a head relatively flat and smooth versus the abomination it was when you removed it.
So sandpaper away I say. It's worked well for me and I've done this more than most human beings alive.
The average person or the majority of people in this group probably haven't done over five in their life and maybe not even over three.
I really don't see that as a large enough sample to prove anything.
Ruin a perfectly good head by sanding it with sandpaper on a somewhat flat surface??
My biggest argument will be with calling it a perfectly good head to begin with. Lol
These heads are junk as most lawnmower heads are. At least overhead valve ones with inferior Preston valve guides and they're lousy pressed in seats.
Nothing pinned, nothing staked, nothing!
Lousy little junk engines as I have always called them. Low performance little turds. It's really amazing they perform as well and as long as they do but it's a shame the manufacturers won't do just a couple of little things to solve constant problems and failures.
You couldn't do much to a head to make it much worse on these Briggs engines and their answer for everything is just replace it with a new one! LOL
I've never replaced a Briggs & Stratton OHV head in my life. I had to do a Kawasaki once because the commercial guy kept running it for 2 days or whatever on one cylinder and he burnt so much aluminum out of the head it would have cost more to fix it than it was to buy another one.
But on the briggs, I would never buy a new head because it's not a bit better than the old one that failed.
I fixed them. I put the guides back into place and I staked them and even drilled and pinned a couple. I put seats back in and state them and I'd be willing to bet money they are in better and will stay in better than they were when they were new or a brand new one will.
Briggs & stratton.. perfectly good head.. that's funny right there.
My biggest argument will be with calling it a perfectly good head to begin with. Lol
These heads are junk as most lawnmower heads are. At least overhead valve ones with inferior Preston valve guides and they're lousy pressed in seats.
Nothing pinned, nothing staked, nothing!
Lousy little junk engines as I have always called them. Low performance little turds. It's really amazing they perform as well and as long as they do but it's a shame the manufacturers won't do just a couple of little things to solve constant problems and failures.
You couldn't do much to a head to make it much worse on these Briggs engines and their answer for everything is just replace it with a new one! LOL
I've never replaced a Briggs & Stratton OHV head in my life. I had to do a Kawasaki once because the commercial guy kept running it for 2 days or whatever on one cylinder and he burnt so much aluminum out of the head it would have cost more to fix it than it was to buy another one.
But on the briggs, I would never buy a new head because it's not a bit better than the old one that failed.
I fixed them. I put the guides back into place and I staked them and even drilled and pinned a couple. I put seats back in and state them and I'd be willing to bet money they are in better and will stay in better than they were when they were new or a brand new one will.
Briggs & stratton.. perfectly good head.. that's funny right there.
SureI 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....
Sure sounds like something is not true and straight. I have run over 20 B&S engines during the past 50 years, and have not blown one head gasket. I did on my Ford and Chevy engines, but never on a Kolar or Briggs. Something is unusual alright. Something didn't come out right on that engine. I had a drag engine specialist tell me that he had seen the line bore on a V/8 1/4" out of line. He found that those engines don't make it very long. Good luck.
I believe you need the right torque sequence. also you might try making your own gasket with permatexI 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....
The single v twin ohv Briggs are notorious for this.Sure sounds like something is not true and straight. I have run over 20 B&S engines during the past 50 years, and have not blown one head gasket. I did on my Ford and Chevy engines, but never on a Kolar or Briggs. Something is unusual alright. Something didn't come out right on that engine. I had a drag engine specialist tell me that he had seen the line bore on a V/8 1/4" out of line. He found that those engines don't make it very long. Good luck.
It's really not "if" but "when".
I think it's all about heat cycles and not hours at all though.
Most people fire up their rider once every 7-10 days and run it for 45 mins to 1hr and 15 mins.
I feel if a person keeps several of these 10+years and 185-225 hrs, they will see blown head gaskets.
Someone who cuts 4 times as much after each start could wear the machine or and replace it with newer before the gasket ever gives way.
I don't think there is anything you can do to make them more likely to last unless your mowing fits the longer pattern.
Joe In Des Moines
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How are you lapping your surfaces?
I got hold of a good sized chunk of marble counter top. I spread out some valve lapping compound on the marble (med grit), along with a bit on the head or block (whatever I'm wanting to make flat) then start in using random orbital motion. Using no consistent pattern, go in an oval clockwise, then counter clockwise, then throw in a circular motion, a figure 8, whatever motion comes to mind EXCEPT FOR straight line back and forth. That's a big NO NO !
Every 5 - 7 minutes or so, stop and clean off your surface with Brakleen or whatever. If you have a low spot, it WILL show up. If so, go back at it.
It's time consuming, and it'll give you a work out, but it WILL be flat when you're done !
Once all is flat, give everything a thorough cleaning. Remember to get all of the lapping compound cleaned out as it IS a cutting agent. Follow all the other steps and that engine should run better than ever !!
I got hold of a good sized chunk of marble counter top. I spread out some valve lapping compound on the marble (med grit), along with a bit on the head or block (whatever I'm wanting to make flat) then start in using random orbital motion. Using no consistent pattern, go in an oval clockwise, then counter clockwise, then throw in a circular motion, a figure 8, whatever motion comes to mind EXCEPT FOR straight line back and forth. That's a big NO NO !
Every 5 - 7 minutes or so, stop and clean off your surface with Brakleen or whatever. If you have a low spot, it WILL show up. If so, go back at it.
It's time consuming, and it'll give you a work out, but it WILL be flat when you're done !
Once all is flat, give everything a thorough cleaning. Remember to get all of the lapping compound cleaned out as it IS a cutting agent. Follow all the other steps and that engine should run better than ever !!
You would literally never get done doing it this way..
Well, you would stop but in the end, it wouldn't be much different from just leaving alone and wiping it off with a rag after you scraped it in the first place.
These heads are so warped and have such large dips and valleys in them that you're never going to accomplish anything that way.
There is absolutely no problem with laying them on a fairly flat surface, with sandpaper on that surface and working them in all directions as you turn the head around a quarter turn multiple times so this way you're making up for any possible surface of regularities.
I prefer to start with 80 grit but I'm guessing you're going to say that's too course but it works great for me. Sometimes I'll go over it afterwards with something a little bit finer but nothing finer than 120 because this doesn't need to be polished to a smooth surface and you'd be amazed how pretty and smooth they look after doing 500 to 600 strokes with the 80 to 120 grit that I do.
Yes, it takes about 500 strokes doing it this way and I put a good deal of pressure down on the head to get it to where you have actually sanded the whole surface so there's no more high spots holding the rest of the head up off of the sandpaper.
They are that bad. And this is probably why so many people have repeat problems with head gasket failures despite the fact they claim their twerking them in the correct pattern and to the proper specs.
This is not rocket science and it's not very precise either. They are still very forgiving and it does not need any certain type of machine slash engine builders and finish on it to work perfectly.
These engines are actually junky little low performance turds that just luckily are pretty forgiving of most of the abuse, neglect, and design flaws, and low quality parts they're made with.
Sometimes though you have to take matters into your own hand to make a head relatively flat and smooth versus the abomination it was when you removed it.
So sandpaper away I say. It's worked well for me and I've done this more than most human beings alive.
The average person or the majority of people in this group probably haven't done over five in their life and maybe not even over three.
I really don't see that as a large enough sample to prove anything.
Wow generations of engineers have been wrong - what I suggested in the recommended procedure that's been taught since engines were invented. Heads only ever warp by a few thou and half an hour using glass and grinding paste will leave the surface perfectly flat. If half an hour is too long for you, pay a professional to do it properly rather than b' it up with a five minute bodge.