35 hp vanguard broken pushrod

[earnies2]

I have a 20kw generator with a 35 hp vanguard engine with a broken pushrod. Somewhere on the internet and I can't find it now someone mentioned check valve guide hight. It appears the intake guide with the broken pushrod is higher than the exhaust guide.
Is there a fix for this or should I just replace the head?

 

[ILENGINE]

Normally the exhaust guide is the one that moves due to the extra head. the intake guide most likely has a seal installed which make it appear higher. The question is determining the cause of the broken pushrod. Did it break because the valve didn't fully open and jamming the pushrod, or did the pushrod wear thin and then break. Most of the pushrod issues I have seen on the Vanguards bent the rod not breaking it. The broken ones had the head broken off.

 

[earnies2]

Normally the exhaust guide is the one that moves due to the extra head. the intake guide most likely has a seal installed which make it appear higher. The question is determining the cause of the broken pushrod. Did it break because the valve didn't fully open and jamming the pushrod, or did the pushrod wear thin and then break. Most of the pushrod issues I have seen on the Vanguards bent the rod not breaking it. The broken ones had the head broken off.

The pushrod is broken. It does appear that the guide I raised up I plan on taking the spring off to verify. If it is raised is there a fix becides replacing the head?

 

[Ertik]

If the guide moved at all..New head. Had to replace one on a stump grinder a few months ago.Seems they had a problem with them and change the head.Was just out of warranty, so no love from B&S.

 

[earnies2]

If the guide moved at all..New head. Had to replace one on a stump grinder a few months ago.Seems they had a problem with them and change the head.Was just out of warranty, so no love from B&S.

Everything I read states that it's the exhaust guide that moves because of heat. This is the aluminum pushrod from the intake valve.

 

[StarTech]

I have had valve guides to move on both intake and exhaust before so that not usual for me. It can be cause by build up on the valve stems or lack of lubrication that causes binding when hot and the guides are slowly hammered out of position. I repaired an Kawasaki FX850V back in the Summer where all four valve guides had moved. Now of course the engine had over 3000 hrs and low oil pressure at operating speeds. That was about 300 hrs ago now.

But overheating is the main culprit.

 

[earnies2]

Well today I plan on removing the valve springs and have a look.

 

[bertsmobile1]

IT is easy to check because they are identical, except for the inlet valve stem seal where fitted .
FWIW:_
The aluminium alloy the head is made from is very soft in the as cast condition.
It is heated to dissolve & distribute the Silicon evenly throughout the metal .
Then it is aged (held in an oven at 220 to 300 C ) to get the Silicon to just start to precipitate which makes the metal stiff.
If overheated the Silicon moves from the middle of the grains to the grain boundries which initially makes the alloy very soft
In that state it can not hold the guides tightly enough to stop them moving and the threads holding the push rod studs pull out
If made even hotter then the inlet valve seat will fall out and the alloy can even collapse into the holes for the head bolts which reduces the clamping force and allows the head gasket to leak.
it can also make the head very hard to pull off .

Getting back to YOUR engine.
BEcause the exhaust is hotter and does not get the cooling of the incoming charge it has more ( slightly excessive ) provision for cooling .
Thus the inlet is the one that suffers more from overheating that the hotter exhaust which unless you have a big think seems to be the wrong way round.

 

[earnies2]

Ok pulled the spring off and the guide is ok...
What I did find is a really loose adjustment on the pushrod... I wonder if that would break the pushrod. And I also found the broken small peice in the lifter galley.

 

[earnies2]

Is there anyway I can start this generator without it being hooked up to the house gass yet.
Only to test the motor before the electrician and plumber come to install it?