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  #1  
Old 07-17-2013, 12:01 AM
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OM617 sounds like it is leaking compression while cranking, but not when running.

Hey All,

Since I have replaced the head on my OM617, I have noticed a loud whooshing noise when it's cranking over before it starts, but after it starts I can't hear it or locate it.

While the hood is down it doesn't seem that bad, but with the hood open it is very noticeable.

I had just finished replacing the starter this evening, and was cranking it over with the hood still open when my Dad pulled in, parked, and walked over. He heard the noise from quite a distance.

I stopped cranking, and we discussed it for a moment, then he turned the key so I could hear it from the outside of the vehicle. When the engine started to run, we could not hear it anymore. Let it run for several minutes and nothing. Shut it off and restarted it several times. Every time it would make that loud noise like a valve leaking, or an exhaust leak makes, but it immediately disappears as soon as it starts running.

Any body else have this issue, or have any ideas what might be causing it?

This is a sound head, cleaned at the machine shop, where they also pressed out the old valve guides, and installed new ones. Ground the valve faces, and valves to match them, and installed new valve seals.

I installed the head with a new gasket set, and head bolts purchased from Peach Parts. And I adjusted the valves to the book, then went back to double check my work and measured every one a second time.

We are stumped. Any thoughts will be appreciated very much.

Thanks in advance.

Rick

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  #2  
Old 07-17-2013, 12:47 AM
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Intriguing - it wouldn't by any chance be the cooling fan would it?

Video or sound recording time?
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  #3  
Old 07-17-2013, 12:48 AM
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Get one of those hand pump sprayers like laundry stain remover uses and mix 1/4 cup of Dawn Dish Soap with one quart of Water. This makes a Bubble mix like Kids would use.

Spray that on the Cold Engine and start it up. Any where you have an exterior leak blowing will bubble.

The woosh sound could be an Exhaust leak as a compression leak would pulsate to what ever Cylinder is leaking.
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Old 07-17-2013, 12:53 AM
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Quote:
Originally Posted by Rolson View Post
Hey All,

Since I have replaced the head on my OM617, I have noticed a loud whooshing noise when it's cranking over before it starts, but after it starts I can't hear it or locate it.

While the hood is down it doesn't seem that bad, but with the hood open it is very noticeable.

I had just finished replacing the starter this evening, and was cranking it over with the hood still open when my Dad pulled in, parked, and walked over. He heard the noise from quite a distance.

I stopped cranking, and we discussed it for a moment, then he turned the key so I could hear it from the outside of the vehicle. When the engine started to run, we could not hear it anymore. Let it run for several minutes and nothing. Shut it off and restarted it several times. Every time it would make that loud noise like a valve leaking, or an exhaust leak makes, but it immediately disappears as soon as it starts running.

Any body else have this issue, or have any ideas what might be causing it?

This is a sound head, cleaned at the machine shop, where they also pressed out the old valve guides, and installed new ones. Ground the valve faces, and valves to match them, and installed new valve seals.

I installed the head with a new gasket set, and head bolts purchased from Peach Parts. And I adjusted the valves to the book, then went back to double check my work and measured every one a second time.

We are stumped. Any thoughts will be appreciated very much.

Thanks in advance.

Rick
Was anything done to the Prechambers?
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  #5  
Old 07-17-2013, 01:01 AM
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It happened to my 300SDL. After I torqued down the head, I only put on the injectors 'finger tight' and forgot all about it. Started the engine and it ran OK. However, when I cranked the engine I would hear a whooshing sound. Found it out a few days later.

Spray soapy water around the base of injectors and around valve cover would give you a clue, hopefully.
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  #6  
Old 07-17-2013, 09:03 PM
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Thanks for the input.

Thanks Everybody,

Will give the soapy water a try tomorrow between shifts.

I'm still trying to understand why it is so noticeable when it's just cranking but goes away immediately once it starts.

Is there a compression release built into these engines that I've never heard about?

My Husqvarna chain saw has a blue button on the side of the engine to reduce the compression when starting it while cold. As soon as it starts, it closes.

As a side note: I checked my mileage last week on a trip of just over 400 miles with about half on the freeway, and half at 55-60 mph. I achieved just over 32 mpg. I'm very happy with the way it's running. I just want to get this strange noise located and resolved.

Will let you know what I find with the soapy water.

Regarding the prechambers: To my knowledge they were never touched. I know I never attempted to remove them. The machine shop that hot tanked it did not say anything about them one way or the other, but I believe they did not have any reason to remove them for the work I asked them to do.

Rick
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  #7  
Old 07-17-2013, 11:36 PM
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Quote:
Originally Posted by Rolson View Post
Thanks Everybody,

Will give the soapy water a try tomorrow between shifts.

I'm still trying to understand why it is so noticeable when it's just cranking but goes away immediately once it starts.

Is there a compression release built into these engines that I've never heard about?

My Husqvarna chain saw has a blue button on the side of the engine to reduce the compression when starting it while cold. As soon as it starts, it closes.

As a side note: I checked my mileage last week on a trip of just over 400 miles with about half on the freeway, and half at 55-60 mph. I achieved just over 32 mpg. I'm very happy with the way it's running. I just want to get this strange noise located and resolved.

Will let you know what I find with the soapy water.

Regarding the prechambers: To my knowledge they were never touched. I know I never attempted to remove them. The machine shop that hot tanked it did not say anything about them one way or the other, but I believe they did not have any reason to remove them for the work I asked them to do.

Rick
No compression release.
So the Cylinder Head was deemed flat enough that it did not need to be resurface? And, because it was not resurfaced the Prechambers were not removed?

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