Intake valve seal removal-B&S 6.25 OHV engine

[Pabilo]

I have a push mower that has recently lost all compression. It was built in 2014 and has a Briggs & Stratton 625EX OHV engine (model: 093J02-0001-F1). I found that the intake valve rocker had no clearance at all so I removed the head and found a completely fried intake valve. It has never been worked on so I assume that it came from the factory incorrectly adjusted and the small amount of blow back destroyed the valve over time. I ordered a new head gasket and an intake valve kit which contains a new valve seal. The original valve seal looks discolored by the heat but fits tightly around the valve stem. It is inside the intake port and appears to be pressed on to that end of the valve guide. I have several questions that I need help with:
1. Should I just leave the old seal in place?
2. If not, what is the best/easiest way to remove it?
3. Does anyone know the correct head bolt torque (there are four bolts) for this model?
I found one place that said that it was 140 in/lbs but I am not sure I read it right and that seems pretty low to me.
Thanks for any help!

 

[bertsmobile1]

Valve stem oil seals go on the rocker side of the valve guide not the combustion chamber side .
Otherwise the valve stem gets no oil and seizes.

 

[Pabilo]

Thanks for your reply. However, my attached photo shows the original valve seal inside the intake port. Also, I found this Briggs diagram showing this models' seal inside the port and not under the rocker arm. It says at the top of this diagram that this seal replaces previous ones that went under the spring. This seal has a base too small to be held in place by the valve spring so if it is placed on the rocker side, it will move up and down with the valve stem. I still have the issue of whether to leave it or not....and if it need to be replaced, what is the best way to remove it. Thanks.

 

[bertsmobile1]

Learn some thing new every day.
Valve stem oil seals usually fit over then end of the valve stem.
Never seen one on the other side
Sorry this one is above my pay grade.

 

[Mkala]

Hello,

I saw your post yesterday but I was surprised by this design too, so I thought someone more knowledgeable has the answer.
It seems a bit odd for many of us so I did some research...

On the part list (I am sure you already have it) it looks like this goes under the valve... thats right.

I find a 450E head with a similar design to yours I think :

Poulan Pro 450E Briggs & Stratton 08P502-0054-F1 Cylinder Head 595351

I attach the image below in case of sale ends.



About the question to change it or not, do you have oil in the combustion chamber ? If not the seal (and the rings) are ok.

If you want to change it, my idea is to make a puller with a large wood screw and a plate with a hole for the screw, against the head. Your screw it and it pull out the seal, like the way to change seat on carburetor where needle stop fuel flow. But you have to find a large screw I think, and be careful not to have the end in the valve guide before it pull the seal. Warning, this is an idea - never change a seal like this (but works great on carbs).

Do you plan to lap the valves too ?

 

[bertsmobile1]

Before you rip that seal out, put it back together and run the engine without the rocker cover on if you can.
With no rocker cover there is no oil mist to be forced down the valve stem
So if it does not blow smoke or oil the plug then the valve guide seal is the culprit.
If it does the same things then the seal is OK.

 

[Pabilo]

Hello,

I saw your post yesterday but I was surprised by this design too, so I thought someone more knowledgeable has the answer.
It seems a bit odd for many of us so I did some research...

On the part list (I am sure you already have it) it looks like this goes under the valve... thats right.

I find a 450E head with a similar design to yours I think :

Poulan Pro 450E Briggs & Stratton 08P502-0054-F1 Cylinder Head 595351

I attach the image below in case of sale ends.

View attachment 51997

About the question to change it or not, do you have oil in the combustion chamber ? If not the seal (and the rings) are ok.

If you want to change it, my idea is to make a puller with a large wood screw and a plate with a hole for the screw, against the head. Your screw it and it pull out the seal, like the way to change seat on carburetor where needle stop fuel flow. But you have to find a large screw I think, and be careful not to have the end in the valve guide before it pull the seal. Warning, this is an idea - never change a seal like this (but works great on carbs).

Do you plan to lap the valves too ?

Thanks for your reply Mikala. I am going to lap the valves. I like your idea of a seal puller but in looking at the new seal (especially the underside), I do not see how I could do this without using something large enough that I would risk damaging the inside of the valve guide. Maybe I should just grab the seal with pliers or a vice grip and try to pull it out. I have a friend who is a dentist so maybe I can consult him for help.

The plug was not fouled and the amount of carbon in the head does not look excessive. There was quite a bit on the head of the piston in one spot, if that means anything. My problem is that I have not done enough of this sort of repair to know if this is normal buildup or excessive. The cylinder moves freely and quietly and the cylinder walls look clean and smooth. I am inclined to replace the seal but this is new territory for me and I don't want to damage the valve guide and end up with a repair that exceeds my limited skill set or the value of this old mower. This mower would blow some white smoke at startup for a few seconds and I had to add oil a little more often than I would have with a new engine. The stem of the burned intake valve was darkened and scorched....even the part that was on the rocker side of the valve seal. I had assumed that this was due to the combustion gasses leaking into the intake port from the bad intake valve but that could suggest that the seal was leaking. I would like to replace the seal since I have a new seal on hand and the old one is discolored. I worry that the rubber component may be damaged by the excess heat. I am waiting for the new head gasket to get here so I do not have to decide yet.
Thanks!

 

[Pabilo]

Before you rip that seal out, put it back together and run the engine without the rocker cover on if you can.
With no rocker cover there is no oil mist to be forced down the valve stem
So if it does not blow smoke or oil the plug then the valve guide seal is the culprit.
If it does the same things then the seal is OK.

Thanks Bertsmobile1,
I think I understand what you are saying. It would be a lot of labor if I have to open the engine back up again and wouldn't I risk damaging my new head gasket?

 

[bertsmobile1]

Well you are only pulling the head off and it can all be done with the engine in the mower so not a big job.
And yes you will need a new gasket but they should only be around $ 5.00 over there .
Unless the breather is blocked and causing excessive crank case pressure I do not see a blown seal causing that much trouble.
For near 100 years motorcycles ran without any seals on the valve guides at all without laying a smoke screen behind them.

seals only became manditory when he EPA started shoving meters up the exhaust and demanding a 0% reading on the unburned hydrocarbons.

Usually excessive oil is due to fuel dillution of the oil, a broken oil scraper or stuck breather valve.

I rather fear that all you will susceede in doing is wrecking a head .

 

[Mkala]

You are welcome. Perfect if you lap the valves.

Some bolts/screws have pretty coarse thread, if they cut good this can work.

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If you measure et cut it to good length (no need of a sharp tip) you can't go in the guide, the puller plate retain the screw (puller only have a hole, screw can turn indefinitely in).
The "only" problem is the seal is damaged if the screw can't grab it and its worse than now