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Valve guide moved

#1

Phillybo

Phillybo

Working on a v twin briggs(44t977 -0015g1) with a bent intake push rod. The valve guide is pushed (has a spring,rubber seal on top)out slightly higher than the exhaust guide. Can anyone tell me how much the guides should stick out of the head?
Thinking about readjusting and peening valve guide.


#2

A

Auto Doc's

Helo Phillybo,

Have you compared it to the other head to verify what is going on? Often times a pushrod get bent on these when the valve lash is too far out of spec. The pushrod come to the edge of the rocker cup and it binds up on these.


#3

Tiger Small Engine

Tiger Small Engine

Phillybo said:
Working on a v twin briggs(44t977 -0015g1) with a bent intake push rod. The valve guide is pushed (has a spring,rubber seal on top)out slightly higher than the exhaust guide. Can anyone tell me how much the guides should stick out of the head?
Thinking about readjusting and peening valve guide.
Click to expand...
You posted the same question on Lawnsite (another forum). How could anyone possibly know the exact spec on valve guide on that specific Briggs model cylinder head, without having a good one out on the bench?
If the valve guide actually moved, the only real way to make it right long term is a new cylinder head. Yes there are ways to “bush fix” it, but not recommended.


#4

Phillybo

Phillybo

Auto Doc's said:
Helo Phillybo,

Have you compared it to the other head to verify what is going on? Often times a pushrod get bent on these when the valve lash is too far out of spec. The pushrod come to the edge of the rocker cup and it binds up on these.
Click to expand...
Think that may be the case here. Springs push down same amount on both exhaust and intake. Valve lash was VERY loose so I may have gotten lucky and just bent a push rod. Thanks for the response!


#5

Phillybo

Phillybo

Tiger Small Engine said:
You posted the same question on Lawnsite (another forum). How could anyone possibly know the exact spec on valve guide on that specific Briggs model cylinder head, without having a good one out on the bench?
If the valve guide actually moved, the only real way to make it right long term is a new cylinder head. Yes there are ways to “bush fix” it, but not recommended.
Click to expand...
Thought maybe someone had a manual that would tell.


#6

R

Rivets

This manual may help you out. Valve guides are above the head body. https://www.hunterlomison.com/pdfs/0C8221.pdf


#7

A

Auto Doc's

Phillybo said:
Think that may be the case here. Springs push down same amount on both exhaust and intake. Valve lash was VERY loose so I may have gotten lucky and just bent a push rod. Thanks for the response!
Click to expand...
Hi Phillybo,

The manuals do not give the exact design specification for the installed height of the valve guides.

If this head has a pushrod guide plate mounted below the rocker arm retainer bolts, be sure to check them for excessive wear in the area that pushrod comes through. These are often overlooked.


#8

sgkent

sgkent

manual say replace head if it overheats and damages guides. Ne factory kit per head is $200 - $220. What is your time worth? Or lets say you fix it, it lasts 10 hours, guide moves, a valve sticks open, takes out the piston, valve, connecting rod, scores the cylinder wall ... what then?


#9

R

Rivets

Verify that the guide has moved before replacing the head. As I stated the guide does protrude above the head base. A good repair shop should be able to help you.


#10

Phillybo

Phillybo

Rivets said:
This manual may help you out. Valve guides are above the head body. https://www.hunterlomison.com/pdfs/0C8221.pdf
Click to expand...
Thanks!


#11

Phillybo

Phillybo

sgkent said:
manual say replace head if it overheats and damages guides. Ne factory kit per head is $200 - $220. What is your time worth? Or lets say you fix it, it lasts 10 hours, guide moves, a valve sticks open, takes out the piston, valve, connecting rod, scores the cylinder wall ... what then?
Click to expand...
Guess guides were good. Should have did leakdown first. Bad rings. Massive air from oil dipstick


#12

Phillybo

Phillybo

Auto Doc's said:
Hi Phillybo,

The manuals do not give the exact design specification for the installed height of the valve guides.

If this head has a pushrod guide plate mounted below the rocker arm retainer bolts, be sure to check them for excessive wear in the area that pushrod comes through. These are often overlooked.
Click to expand...
Thanks


#13

A

Auto Doc's

How did you determine bad rings? Are the cylinder scored?


#14

Phillybo

Phillybo

Auto Doc's said:
How did you determine bad rings? Are the cylinder scored?
Click to expand...
Did a leakdown test and massive air from distick


#15

Phillybo

Phillybo

Phillybo said:
Did a leakdown test and massive air from distick
Click to expand...


#16

A

Auto Doc's

What was your leak down test gauge showing? I ask because you cannot always trust what the dip stick fill tube is indicating.

Was this engine a "smoker" before the pushrod incident?

Was the head releveled by sand with fine sandpaper on a true flat surface, and a new head gasket used during reassembly?


#17

Phillybo

Phillybo

Auto Doc's said:
What was your leak down test gauge showing? I ask because you cannot always trust what the dip stick fill tube is indicating.

Was this engine a "smoker" before the pushrod incident?

Was the head releveled by sand with fine sandpaper on a true flat surface, and a new head gasket used during reassembly?
Click to expand...
Test guage was building virtually no pressure with almost 100 psi going in.Not sure about the mowers past. Guy just brought it by and asked me to check it. Put new plugs in and they were getting oily immediately.
Runs perfectly for couple minutes and then starts pouring white smoke.


#18

sgkent

sgkent

if the head has not been off, do a visual inspection with a bore scope on the piston. You may find that the pushrod was bent when the piston and the valve met. That can be because the piston cracked and broke into a top and bottom, or a valve hung open. The leak can be either the hole in the piston, cracked piston or a broken guide and bent valve where air is leaking past the guide. Usually that will also show up in the intake or the exhaust.


#19

A

Auto Doc's

I would suspect head warpage and compression pressure blowing past the head gaskets into the valve pushrod area. (That goes straight into the crankcase) Rings are a seldom failure unless they are smoking badly and have scored cylinders due to excessive dusting and poor oil changes.


#20

sgkent

sgkent

Auto Doc's said:
I would suspect head warpage and compression pressure blowing past the head gaskets into the valve pushrod area. (That goes straight into the crankcase) Rings are a seldom failure unless they are smoking badly and have scored cylinders due to excessive dusting and poor oil changes.
Click to expand...
example of warped head



#21

Phillybo

Phillybo

sgkent said:
if the head has not been off, do a visual inspection with a bore scope on the piston. You may find that the pushrod was bent when the piston and the valve met. That can be because the piston cracked and broke into a top and bottom, or a valve hung open. The leak can be either the hole in the piston, cracked piston or a broken guide and bent valve where air is leaking past the guide. Usually that will also show up in the intake or the exhaust.
Click to expand...
I don’t have a scope.It did sound like some air movement around the valves also But mostly out of the dipstick. The plugs got slightly oil running it just for a couple minutes so I’m guess rings or piston.


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