Best way to test exhaust manifold?

[YOBE]

Hi,

Mercruiser 165, 70's 6cyl in-line
I want to double check if my exhaust manifold has any crack's inside.
On the forum I have seen different approaches.
1. Use the acetone method to see if the level drops (both for intake an exhaust I suppose)
2. Use compressed air (not sure to what PSI it should hold)
3. I have a vacuum pump at home for AC-units => could do a vacuum test.

Any suggestions on what test is the most reliable to verify the condition of the exhaust manifold? As I also wonder if it could behave differently between room-temp versus warm?

PS: is it wortwhile to also check the Riser for cracks?

Thanks Yorick

 

[Scott06]

Hi,

Mercruiser 165, 70's 6cyl in-line
I want to double check if my exhaust manifold has any crack's inside.
On the forum I have seen different approaches.
1. Use the acetone method to see if the level drops (both for intake an exhaust I suppose)
2. Use compressed air (not sure to what PSI it should hold)
3. I have a vacuum pump at home for AC-units => could do a vacuum test.

Any suggestions on what test is the most reliable to verify the condition of the exhaust manifold? As I also wonder if it could behave differently between room-temp versus warm?

PS: is it wortwhile to also check the Riser for cracks?

Thanks Yorick

acetone is pretty universally used and accepted here, it wicks in cracks much more so than water soul you would see it.

Unless the manifold is hot I could see it hiding cracks using compressed air. Also with air you need to block off the riser connection.

One other items to look at are the water passages for clogging and the flatness of the surface between manifold and riser/elbow. On wet style manifolds like this - if the water passages from manifold to riser/elbow are corroded or not flat or degraded such that it wont seal , that is grounds for replacement

yes also check riser/elbow for cracks and corrosion/clogging, the water can only be let into the exhaust stream on outlet of elbow not before.

givewn the age unless its fresh water only replace them.

 

[YOBE]

acetone is pretty universally used and accepted here, it wicks in cracks much more so than water soul you would see it.

Unless the manifold is hot I could see it hiding cracks using compressed air. Also with air you need to block off the riser connection.

One other items to look at are the water passages for clogging and the flatness of the surface between manifold and riser/elbow. On wet style manifolds like this - if the water passages from manifold to riser/elbow are corroded or not flat or degraded such that it wont seal , that is grounds for replacement

yes also check riser/elbow for cracks and corrosion/clogging, the water can only be let into the exhaust stream on outlet of elbow not before.

givewn the age unless its fresh water only replace them.

Thanks for the feedback. I will use the acetone setup.
I will double check the corrosion. No disrespect, but I live in Belgium and spare parts for this engine here are almost “zero”. So have to test and try to use maximum what I have.

 

[Scott06]

Thanks for the feedback. I will use the acetone setup.
I will double check the corrosion. No disrespect, but I live in Belgium and spare parts for this engine here are almost “zero”. So have to test and try to use maximum what I have.

No disrespect taken, understood about Merc parts availability. Only issue is you can leak test it now and not leak doesn't mean it wont later and possibly take out your engine. really just depends on how long you want to keep it. Typical salt water change out is 5-7 years.

If you do need one I think Barr still makes them or if you can find a fresh water used one. Some guys on ebay sell used ones from fresh water. Fresh water they last the life of the boat.