Broken valve new engine

GregM
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Broken valve new engine

Postby GregM » Thu Aug 30, 2018 8:59 pm

So I have this newly rebuilt 318 engine/longblock form Rapido Marine and I am at about 10ish hours and I heard a noise that turns out to be a broken valve. Fortunately it didn't drop in the cylinder and destroy the engine. Now I may be faced with sending the head back to them. Alternatively I am wondering if I can replace the valve myself and get the motor running or does this require a machine shop to intervene?
Looking for advice as I am trying to take my family to our local annual fireworks display this weekend. Any guidance would be much appreciated! Does a valve replacement require the head to be re-machined?

EWRice
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Re: Broken valve new engine

Postby EWRice » Thu Aug 30, 2018 9:47 pm

Did the valve break, or did the retainer loosen up. I have never heard of a valve breaking and not dropping. Either way, there is likely work that will need to be done on the head. The seat will more than likely have damage.
Muskegon Lake
1972 32' Express flybridge
"AL13"
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson

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Busia
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Re: Broken valve new engine

Postby Busia » Fri Aug 31, 2018 12:36 am

Any warrantee ? What broke? A spring, retainer or the actual valve? If it is a spring or a retainer a real mechanic will blow air into the cylinder and change the spring or install the retainer. If the valve is bad, pull the head and you will have to at least lap the valve. Or maybe change the seat, grind the seat, install a new valve and lap it for fit. I would see about having them send you a new head and just swap them.
BUSIA
located in Ketchikan, Alaska. Gods country
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Fastjeff
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Re: Broken valve new engine

Postby Fastjeff » Fri Aug 31, 2018 7:17 am

For heavens sake, send the head back to get it replaced.

You are damn lucky the motor didn't grenade! That almost always happens in this situation.

Jeff

PS: If I were you, I'd run out and buy a lottery ticket!
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington

GregM
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Re: Broken valve new engine

Postby GregM » Tue Sep 04, 2018 5:29 pm

Well after taking the head off it wasn't the valve. It turns out the valve dropped into the cylinder and destroyed the piston. I have to pull the engine and ship it back. At least Rapido Marine is going to send me a new long block to replace what I have but I will need to do the labor. When I pulled the head the #1 piston was gone aka pieces are in the oil pan. This sucks! Nothing like getting to do the job twice

GregM
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Re: Broken valve new engine

Postby GregM » Tue Sep 04, 2018 5:39 pm

image
Attachments
broke engine.jpg

EWRice
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Re: Broken valve new engine

Postby EWRice » Tue Sep 04, 2018 8:29 pm

Looking at your picture, I think you need to measure the diameter of your push rods. If they are bigger than 5/16" diameter (.290" is factory), then that is most likely the cause. Some rebuilders like to put 3/8" diameter push rods in rebuilds, and what happened to yours is usually the end result. Look for wear marks about an inch below the top of the push rod. If they are oversized and have the wear marks, check the other engine too.

Because the lifter and pushrod are at different angles, the pushrod rocks back and forth in the clearance hole in the head. There is not enough room for oversized pushrods to do this. They bind, hold the valve open, and bang. Bad day.

Also, is that your reverse rotation engine?
Muskegon Lake
1972 32' Express flybridge
"AL13"
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson

GregM
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Posts: 16
Joined: Sat Jul 22, 2017 5:01 pm

Re: Broken valve new engine

Postby GregM » Wed Sep 05, 2018 6:03 pm

Thanks for the info, I will check that on the next engine. And yes that is the reverse rotation engine. This really stinks as I am not getting re-embersed for the labor, good times! This sucks as this was not a small job as you know!

EWRice
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Re: Broken valve new engine

Postby EWRice » Wed Sep 05, 2018 8:01 pm

I can't see clearly in your picture, but it looks like the notches on the tops of your pistons (not the valve reliefs, but the small notch to show installation direction) are facing the front of the engine. If they are, the rebuilder installed the pistons backwards.
Muskegon Lake
1972 32' Express flybridge
"AL13"
Twin 318s
On board air & prime 920
1963 Thompson Super Sea Lancer
Graymarine 327
1961 Alumacraft 12'
'55 10hp Johnson

Joe
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Re: Broken valve new engine

Postby Joe » Wed Sep 05, 2018 8:51 pm

Looking at the pic. The head gasket between the two center cylinders looks very black . The firing ring looks burnt to me . Was it running hot.
1988 sedan flybridge. Black / White. 318 240 hp Aluminum aft deck hard top. Louisville Ky . Tartans landing. " KNOCKEFELLERS"