Merc 470 Heat exchanger PSI ??

[billywhizz]

So my new (used) heat exchanger has arrived, looks fine but should I pressure test it before I fit it?
what pressure do I test it at?
and i can see the raw water inlet and outlet but how does the raw water get from one chanber to the other? they seem to have solid partitions? and yes i apreciate that i have left myself wide open to a deluge of sarcasm and astonishment at my stupidity,
but would still like to know the answer have a great crimbo guys!

 

[Bt Doctur]

Re: Merc 470 Heat exchanger PSI ??

There are 2 sections to a heat exchanger,the raw water side and the fresh water side(A/F).
The A/F flows thru the tubing that is surounded by the raw water . The water removes the heat from the A/F and exits out the riser .The 2 small ports are the raw water inlet/outlet and the 2 larger ones are engine coolant.

 

[billywhizz]

Re: Merc 470 Heat exchanger PSI ??

Yes got that, but if you take off the end plates and have a look the small tubes are divided into 3 chambers? with the inlet on the left chamber (looking down) and the outlet on the right chamber, how does the water gwt from one side to the other? as the wall looks to be solid without any gaps or holes?

 

[billywhizz]

Re: Merc 470 Heat exchanger PSI ??

There are 2 sections to a heat exchanger,the raw water side and the fresh water side(A/F).
The A/F flows thru the tubing that is surounded by the raw water . The water removes the heat from the A/F and exits out the riser .The 2 small ports are the raw water inlet/outlet and the 2 larger ones are engine coolant.

looks the other way around, the raw water is flowing into the small tubing?

 

[EddiePetty]

Re: Merc 470 Heat exchanger PSI ??

.......So my new (used) heat exchanger has arrived, looks fine but should I pressure test it before I fit it?
what pressure do I test it at? .......
..............

The normal operating pressure of the coolant(shell) side of the exchanger is the same as the pressure rating on your 'radiator' cap. Test pressure should be NO more than 110% of that rating.

Assuming we're talking Mercruiser here, attached is a link to a diagram of the exchanger system that should answer some of your questions.

http://www.crowleymarine.com/mercury_parts/908/120.cfm​

The difficult part is understanding that the seawater flows THROUGH the tubes, the engine's coolant flows AROUND the tubes.
FWIW....Ed in 'ol Virginny

 

[EddiePetty]

Re: Merc 470 Heat exchanger PSI ??

So my new (used) heat exchanger has arrived, looks fine but should I pressure test it before I fit it?
what pressure do I test it at?
and i can see the raw water inlet and outlet but how does the raw water get from one chanber to the other? they seem to have solid partitions? and yes i apreciate that i have left myself wide open to a deluge of sarcasm and astonishment at my stupidity,
but would still like to know the answer have a great crimbo guys!

Please reply to your 'Private Messages' as I have a sketch and notes I can share with you.

Ed in 'ol Virginny