M16 commander intake and exhaust manifold questions

M16 commander intake and exhaust manifold questions

Joined: February 15th, 2010, 7:39 pm

March 31st, 2018, 12:56 am #1

Hi,

On to the next repair in my quest to make the M16 more road-worthy. The exhaust has been getting louder and louder and I could feel exhaust gases leaking out from between the manifold and the block so I bought a new gasket and this morning I pulled of the manifolds. (I previously tried tightening the manifold nuts but it only helped a tiny bit)

(you can see the soot from where it was leaking badly)

 Unfortunately the manifold surfaces that go against the block don't seem all that flat and the exhaust surfaces are somewhat pitted.so I am thinking about taking it to a shop to see if they can grind it flat again.



There is also a crack in the manifild although no evidence that it goes right through and was leaking.



Last problem is that the shaft for the heat riser valve in the exhaust manifold (I am assuming that is what it is) is super loose in it's bores and causing even more exhaust leakage and noise. I looks like I'd have to split the intake and exhaust manifolds apart to remove the heat riser valve blade and shaft and I am tempted to do that and just drill, tap and plug the heat riser shaft holes.

vidoe of loose heat riser shaft at: 
video - loose heat riser   video - other side of loose heat riser

Questions: 

1/ is the gasket available for between the intake and exhaust manifold?
2/ any other options for the heat riser besides removing the valve & shaft and drilling, tapping and plugging the shaft holes? (I assume there was once a bimetallic spring to close the valve when cold - is that available anywhere? If it was I'd still have to do somethig about those loose bores...)
3/ I assume normal practise would be to have the manifolds machined flat while the 2 are bolted together, true? (I have never worked on this style of engine before)
4/ With that crack there, is it even worth machining these intake/exhaust manifolds flat or are good used manifolds available
5/ were those 2 bolt holes in the very front and very back of the manifold ever used? (I haven't cleaned off the block yet but I don't recall seeing holes in the block that line up with those outer manifold holes)

Thanks in advance for any info/thoughts you may have to share!

Ed
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Joined: October 29th, 2014, 2:42 am

March 31st, 2018, 2:47 am #2

edbee wrote: Hi,

On to the next repair in my quest to make the M16 more road-worthy. The exhaust has been getting louder and louder and I could feel exhaust gases leaking out from between the manifold and the block so I bought a new gasket and this morning I pulled of the manifolds. (I previously tried tightening the manifold nuts but it only helped a tiny bit)

(you can see the soot from where it was leaking badly)

 Unfortunately the manifold surfaces that go against the block don't seem all that flat and the exhaust surfaces are somewhat pitted.so I am thinking about taking it to a shop to see if they can grind it flat again.



There is also a crack in the manifild although no evidence that it goes right through and was leaking.



Last problem is that the shaft for the heat riser valve in the exhaust manifold (I am assuming that is what it is) is super loose in it's bores and causing even more exhaust leakage and noise. I looks like I'd have to split the intake and exhaust manifolds apart to remove the heat riser valve blade and shaft and I am tempted to do that and just drill, tap and plug the heat riser shaft holes.

vidoe of loose heat riser shaft at: 
video - loose heat riser   video - other side of loose heat riser

Questions: 

1/ is the gasket available for between the intake and exhaust manifold?
2/ any other options for the heat riser besides removing the valve & shaft and drilling, tapping and plugging the shaft holes? (I assume there was once a bimetallic spring to close the valve when cold - is that available anywhere? If it was I'd still have to do somethig about those loose bores...)
3/ I assume normal practise would be to have the manifolds machined flat while the 2 are bolted together, true? (I have never worked on this style of engine before)
4/ With that crack there, is it even worth machining these intake/exhaust manifolds flat or are good used manifolds available
5/ were those 2 bolt holes in the very front and very back of the manifold ever used? (I haven't cleaned off the block yet but I don't recall seeing holes in the block that line up with those outer manifold holes)

Thanks in advance for any info/thoughts you may have to share!

Ed
Ed: You have encountered one of the inconveniences of owning a commander engine. I will try to answer your questions.
1. Gaskets are available. I have several and can sell you one.  With the manifold being uneven like you say you need the original sandwich gasket and not the ones that are sold in gasket kits today. If the manifold is uneven enough even the sandwich gasket will not stop the leak.
2. The flapper valve will likely need to be replaced along with the weight, shaft, thermostat and bushings. They are all available. The bushings wear out and the shaft gets floppy. you probably did not hear it leak because of your other leaks.
3. You are correct they need to be machined with both halves bolted together, the gasket is available for the partition of the manifolds.. Good used manifolds are not many in number. I do have some manifolds. I pick them up anywhere they are available then machine them and install new flappers.
From the looks of yours you would be wasting your time to machine it unless you can find someone who will first weld shut those cracks before they spread.  They might spread any way unless you know some one who is good with Cast Iron.
4. The holes in the front and rear of the exhaust side of the manifold are just holes. they do nothing.
Ted
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Joined: February 15th, 2010, 7:39 pm

March 31st, 2018, 5:16 pm #3

Hi Ted,
First, thanks for this helpful info. STT is such a great resource/wealth of knowledge (well, it's members really).
 
That brings up 2 more questions:

a/ based on those videos of the current state of the flapper valve, do you think rebushing the manifold will work or is it likely too far gone for that? (I mean bushings worn away and the bores they sit in worn too much to support new bushings)?

if the manifold flapper valve is rebushable/rebuildable and if I can find a competent person locally for cast iron welding repairs, then I can deal with it
or

b/ failing either of those 2 things, how much would you want for an already reconditioned exhaust manifold?
 
If the exhaust manifold can be dealt with locally, then I would need to buy from you the gasket for between the intake and exhaust manifolds, plus everything needed for the flapper valve reconditioning, How much would those bits cost? I already have the manifold to block gasket which I bought from one of the Studebaker vendors (can’t recall who) and I think it is the type you recommended (I’ll put a photo of it below).

Thanks again for your help with this.  It will be nice to be able to drive my truck without people hearing me coming from half a mile away.

Ed
(you can see how burned away the old gasket was, nothing left but the thin metal part, no wonder it was so noisy)

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Joined: October 29th, 2014, 2:42 am

April 1st, 2018, 2:25 am #4

edbee wrote: Hi Ted,
First, thanks for this helpful info. STT is such a great resource/wealth of knowledge (well, it's members really).
 
That brings up 2 more questions:

a/ based on those videos of the current state of the flapper valve, do you think rebushing the manifold will work or is it likely too far gone for that? (I mean bushings worn away and the bores they sit in worn too much to support new bushings)?

if the manifold flapper valve is rebushable/rebuildable and if I can find a competent person locally for cast iron welding repairs, then I can deal with it
or

b/ failing either of those 2 things, how much would you want for an already reconditioned exhaust manifold?
 
If the exhaust manifold can be dealt with locally, then I would need to buy from you the gasket for between the intake and exhaust manifolds, plus everything needed for the flapper valve reconditioning, How much would those bits cost? I already have the manifold to block gasket which I bought from one of the Studebaker vendors (can’t recall who) and I think it is the type you recommended (I’ll put a photo of it below).

Thanks again for your help with this.  It will be nice to be able to drive my truck without people hearing me coming from half a mile away.

Ed
(you can see how burned away the old gasket was, nothing left but the thin metal part, no wonder it was so noisy)


Ed: the gasket you show is the one you need.
I did not see any video so will comment only on what you have said. If the bushings are gone and the bores are egg shaped  they will need to be filled when you have the crack welded. then bored and new bushings installed.  The complete kit is available from Studebaker International. I have sold three manifold units in the last month and do not have any finished and available for quick delivery. contact me at studepickups  at optonline dot net and we can discuss your needs should you not find a local shop to help.  Ted
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Joined: February 15th, 2010, 7:39 pm

April 3rd, 2018, 6:03 am #5

Hi Ted,

Today I separated the intake and exhaust manifolds and unfortunately I can now see that crack in the exhaust manifold extends much further than I could see before.

I did get the name of a local shop that does cast iron welding so I'll try to contact them tomorrow but I don't know if this will be fixable. 

Anyone have a spare commander exhaust manifold? 

Also Ted, when you remove the old flapper valves, can you usually get those 2 screws that hold them to the shaft to come out or do you have to take more drastic measures (like grinding the heads off or ...)?

thanks,

Ed





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Joined: October 29th, 2014, 2:42 am

April 3rd, 2018, 11:03 am #6

edbee wrote: Hi Ted,

Today I separated the intake and exhaust manifolds and unfortunately I can now see that crack in the exhaust manifold extends much further than I could see before.



I did get the name of a local shop that does cast iron welding so I'll try to contact them tomorrow but I don't know if this will be fixable. 

Anyone have a spare commander exhaust manifold? 

Also Ted, when you remove the old flapper valves, can you usually get those 2 screws that hold them to the shaft to come out or do you have to take more drastic measures (like grinding the heads off or ...)?

thanks,

Ed





The only way is drastic. You will not be able to use any left over flapper parts. I do have manifolds. Ted
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