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Old 18-10-2019, 19:22   #16
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Re: MD7A Exhaust Manifold Mystery Hole

I found a volvo shop. He had photos of the manifold with that port open. He thinks I’m OK. Told me to run the piss out of it and check the temp. When I had it off I ran water thru it and it seemed connected to the little ports. Now that I got the hang of it I might take it off again and check it out better. Ive been posting it all on CDSOA forum. I think its titled md7a raw is water exhaust manifold
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Old 18-10-2019, 19:34   #17
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Re: MD7A Exhaust Manifold Mystery Hole

I found a volvo shop. He had photos of the manifold with that port open. He thinks I’m OK. Told me to run the piss out of it and check the temp. When I had it off I ran water thru it and it seemed connected to the little ports. Now that I got the hang of it I might take it off again and check it out better. Ive been posting it all on CDSOA forum. I think its titled raw water maintenance question
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Old 19-10-2019, 07:03   #18
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Re: MD7A Exhaust Manifold Mystery Hole

Here is the photo of my MD7A manifold. It’s orange because I’ve just out some gasket material in it.
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Old 19-10-2019, 07:24   #19
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Re: MD7A Exhaust Manifold Mystery Hole

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Originally Posted by jeffjd View Post

[Bold]I don't know if there is a trick, but lining up the pipe from the raw water pump is difficult without creating leaks... I did it before when I rebuilt the water pump.[/bold]


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I too have always had trouble with this connection. When I had the manifold off this summer I tried to put the tube in and it became immediately obvious when approaching it from above without instructions that the tube was TOO LONG. I shaved it off a bit and perfection.

Also I’ve found there are some kitchen faucet o-rings that are a perfect fit. I can’t recall the make or part number. Take an old o-ring to Home Depot and dig through their faucet washer supply.
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Old 19-10-2019, 14:58   #20
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Re: MD7A Exhaust Manifold Mystery Hole

Yours doesnt have that round port between the two rectangular exhaust ports
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Old 19-10-2019, 16:14   #21
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Re: MD7A Exhaust Manifold Mystery Hole

Then I guess it’s not needed?
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Old 19-10-2019, 16:48   #22
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Re: MD7A Exhaust Manifold Mystery Hole

???Still I wonder if I ruined mine
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Old 19-10-2019, 16:59   #23
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Re: MD7A Exhaust Manifold Mystery Hole

Ah, now THAT is the question!

I doubt it’s “ruined”. At worst you could have a machine shop cut some threads and put in a plug.

But the question is entertaining, especially when it is not my manifold I question.
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Old 19-10-2019, 17:01   #24
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Re: MD7A Exhaust Manifold Mystery Hole

Yea, Good title” Mystery Hole”
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Old 23-10-2019, 09:08   #25
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Re: MD7A Exhaust Manifold Mystery Hole

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Here is the photo of my MD7A manifold. It’s orange because I’ve just out some gasket material in it.
Did your manifold have that round hole. Is it just covered up with gasket material? Also I was told not to use gasket material on exhaust gaskets Thanks
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Old 23-10-2019, 18:14   #26
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Re: MD7A Exhaust Manifold Mystery Hole

Some engine manufacturers have a dirty little secret that helps avoid warranty payouts..... it's a low melting point metal pellet in a hole drilled into (usually)the head at manufacture that records an overheat by melting and deforming. This was mostly found on larger automotive diesel engines but I wouldn't be surprised to find that VP did it. Mostly the use of thermal plugs was discontinued when electronic monitoring was introduced.....the CPU records everything now.
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Old 23-10-2019, 19:28   #27
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Re: MD7A Exhaust Manifold Mystery Hole

This hole is about 1” -1-1/4”. Im trying to get an official statement from a Volvo rep. No luck yet. One guy thinks it might be a type of freeze plug.
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Old 24-10-2019, 09:44   #28
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Re: MD7A Exhaust Manifold Mystery Hole

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Did your manifold have that round hole. Is it just covered up with gasket material? Also I was told not to use gasket material on exhaust gaskets Thanks
I vaguely recall that hole, just a round depression. It may well be covered with gasket material. As I recall I saw it, I pondered it, I forgot it. That was about 10 years and 700 hours ago.

I know folks say not to use gasket material. But what do you do when your nearest gasket is 3 weeks away? I use the Permatemp ultra high temp “copper” material and it works fine. Good up to something like 650°F. When I took the manifold off the gasket stayed adhered to the block, the gasket material makes up any imperfections. You need to be careful around the small holes that you don’t close them with it when it squeezes out. This is about the third time I’ve had this manifold off with the same gasket. But I did buy 2 new ones, just so I never have to do it again.

I even use it on my kerosene stove, it will burn in a sustained flame. And on the exhaust elbow on our big boats Yanmar turbo. I consider it a necessary maintenance item.
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Old 24-10-2019, 09:51   #29
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Re: MD7A Exhaust Manifold Mystery Hole

Google the phrase “Volvo MD7 exhaust manifold” and select images.

Look at the pictures here.
https://www.sfbaysss.org/forum/showt...haust-Manifold

Then I saw a picture of an MD 6 manifold, there it looks like that round spot is open. So I’m betting it’s open on an MD6 and not on an MD7.
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Old 24-10-2019, 10:01   #30
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Re: MD7A Exhaust Manifold Mystery Hole

Also peruse here.

http://www.cruisersforum.com/forums/...-134515-5.html
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