I have the standard B&S head gasket blow by between the piston and the rod chamber. I ordered a new copper gasket from Lani at CGI hoping that it would hold up better than the graphite POS, and was wondering how flat the head needs to be?
The engine block is dead flat, but the head has some minor out of flatness. I cleaned it down to the mill marks. It is totally flat where the gasket blew out, but on the opposite side of the cylinder it seems a little cupped. If I put a straight edge across the full width of the head, I can fit a 0.0025" feeler gauge under. If I just measure across the area where the gasket goes (it only extends 1/2" or so on the outside of the cylinder bore), I can fit a 0.0015" feeler gauge under.
Do I have to flatten that head? Since the copper gasket is reusable I can give it a try and see how it works, then if I have a leak, I could pull it apart again and flatten head…?
Flat yes
Remove all of the mill marks no
They actually hold the gasket in place just so long as there is no continous "tunnel" to allow the gasses to escape .
#3
sgkent
put a magic marker all over the mating surface and lay it on a thick piece of glass with like 2000 grit on it. Wiggle it a little and see what you are actually looking at as to the pattern. You can try sliding thin blades from a feeler gauge set on the areas where the sharpie still exists to see how badly it is warped.
I decided to sand the head on sandpaper on glass, but probably should have left it! I managed to make the edges lower, one side is 0.004" lower. I'll slap it together and hope for the best! I remember having the problem before when I tried to sand the head of a Subaru. It seems like I am not quite steady enough with my hand when I move the head back and forth and it grabs the edges more than the middle. Any suggestions for the future?
B & S Say 0.002"
There are two different things that get conflaited
Flatness & smoothness
B & S Heads are flat
But they are not smooth because they are fly cut to make them flat
The grooves left by the cutter hold the paper gasket tight
The copper gasket will need to be annealed before you fit it
IF it is full soft you can leave a crescent shaped indent by rolling your thumb nail hard on it .
#7
sgkent
Next time sand in an X. then flip it 90 degrees and sand in a circle, the flip it 90 more degrees and sand in an X or a +, vary the pattern as you flip it 90 degrees each couple sanding movements. If you have to take that much off it so one side is low now, the head was pretty warped. You would not have been able to get a good seal with out surfacing it.
The gasket is annealed and the manufacturer recommends copper spray a gasket on each side of the gasket. I'll stick it on today and give it a try. The valve cover gasket is still in the mail, arriving tomorrow, so I should get it started up tomorrow afternoon, if all goes well.
Double check the gasket
I get a lot of gaskets from Lanni and most of them are not fully soft
I think he lazer cuts them which means he can use commercial soft sheet but that is still not full soft
You can do it with a propane torch or a BBQ burner
hmm, when I talked to him he said I didn't need to anneal it and all I needed to do was clean it and spray it with copper spray a gasket. He specifically wrote annealed copper by hand on the packaging, so I hope it is fine
In any case, it is in there. The low point I made is on the head the thin bit on the far side of the valve rod bay and it may be leaking a tiny bit of oil, but I'll have to run it longer to see if that is the case. It did fix the blowing out oil of the oil pump along with all the white smoke.
When I changed the oil after running it for a few minutes, there were a lot of copper colored particles in the oil. What could that be? Is something deteriorating from having a bad head gasket or fuel in the oil? What is made of copper or brass in the engine?
Nothing
IT is the copper coat washing off the gasket
Run it for at least 10 minutes,
a full mow would be fine, let it cool down then retorque the head bolts
Great, I was considering that it was the copper coat, but it looked like so much it made me worried! Ran a full mow and no leaks, the torque stayed the same. I have high hopes that this gasket will hold for a long time!
There are a lot of inteks running around here with one of Lanni's gaskets on them .
Very important now is to fit a fuel tap between the filter ( or pump ) and the tank.
Should the float needle fail with a copper gasket fitted you can bend a conrod or break a ring should you try to start a hydrolocked engine .
The soft gaskets B & S fir are a fail safe because they just blow out but the copper ones won't .
Is hydrolocked the same as flooded? That is what seemed to have happened this spring when my house mate (who's lawn mower it is and is not mechanically inclined) went to start it. White smoke, oil coming out fuel pump, fuel in the oil, a few loud bangs when cranking the starter. They did not use fuel stabilizer over the winter. I cleaned the carb and float needle and couldn't see anything that looked like it had failed, but may be it just leaked slowly all winter? The solenoid still worked as well, which I thought that was supposed to shut off fuel when engine is off? Could it gravity leak through the fuel pump and fill up the cylinder with fuel?
Good to know about that risk…I may just put the B & S gasket on, since I don't trust them to turn off the fuel valve every time and a head gasket blow out will be cheaper than a bent rod or broken ring. I did install a fuel valve, but mostly for winterizing and for ease of working on the carb/fuel system.
The fuel solenoid just plugs off the main jet so when your turn the engine off by killing the spark fuel is not sucked into the engine & blown out the exhaust .
It accumulates in the muffler till the air : fuel ratio is within the combustion at atmospheric range then it ignites & goes bang .
It does not stop fuel entering the carburettor .
Unfortunately some You tube / face book "experts" said it did 20 years ago and that has stuck .
Pop the tap in & tell them to use it
You can not protect every person every day
People have to learn to look after themselves
Hydro locking is what happens when the carb floods big time or for a long time
So it looks like after two hours of running there is a tiny bit of oil on the lower right side (from front) below the low side of the head I made on the far side of the valve rod chamber. No oil dripping down on the shroud. Should I take the head back off and try to flatten it better? What grit do you recommend? I probably caused the problem by getting impatient and using 100 grit, which hit that edge really hard
Next to no chance of repairing this by hand without a surface plate & scrapers
If you know some one with a mill buy them a bottle of their favourite intoxicant
Or take it to a machine shop
Or a real mower repair shop
But the difference between the above & replacement is not particularly big .
I'd start with 220, progress to 400 then 800 wet/dry paper. Let the PAPER DO ALL THE WORK. Use a spray bottle with soap and water. Keep rotating the paper as you clean up the area.
This is aluminum, no need for aggressive grits here. Get a small piece of plate glass from a glass shop. They have scrap laying all over their shops.
No wonder you have a leak aggressively using 100 grit LOL. S l o w i t d o w n a little.
#23
sgkent
rotate the piece and pattern you do. Another option is find a machine shop with a good belt sander that does NOT have a new belt on it cause that is soft aluminum. They can flatten it in seconds. I used to lay small heads, manifolds etc on a belt sander, move them to a couple different positions so it sanded evenly and in a minute I had a level surface. One thing you will run into is that if you keep milling that head you are raising compression which will cause other issues on a worn engine.
You used a copper head gasket. Copper has no give if it is hard. It gets annealed to soften it so it can compress. The Type 4 VW engine I have on a bus uses copper rings on the exhaust to seal it against the head. If they are put on as is the copper is so hard the copper rings will bounce and ring like a small bell if you drop one on concrete. But if they are annealed to cherry in color they get softer so if one drops it then it will go thud and deform. That has to be done on them before using them or they are too hard to deform to seal. I use factory gaskets myself on engines, even when in my racing days and have never had one not seal. I've had blown head gaskets on engines but it always happened over time.
Have done three head gasket jobs on the KT735 shees what lousy machine work. You can see the bad machining on the heads. When you do head gaskets on an engine that only has one blown do you do them both or just the blown one. I do them both.
#29
sgkent
don't hold the outside edges when you mill it, and make sure the piece of glass is thick enough to remain flat. I use an old piece of 3/8" glass. Let the sandpaper do the work. Cover the area in a sharpee or prussian blue dye if you have any, so you can see when you are flat.
