Heat Exchanger on Volvo 5.0

[MarkSr]

Quick question on heat exchanger.I'm having this disagreement with my son on this.I'm thinking as old school radiators.Heat exchangers are for fresh water only,Correct? No raw water runs thru it Correct? If you open the cap on your exchanger and the thermostat opens then you should see fresh water flow thru like a car radiator,Correct?My son says when the thermostat opens the water sucks down into the heat exchanger therefore if I'm right then that means not enough water in block.Please correct me if I'm wrong.Thanks
Mark

 

[Scott06]

Quick question on heat exchanger.I'm having this disagreement with my son on this.I'm thinking as old school radiators.Heat exchangers are for fresh water only,Correct? No raw water runs thru it Correct? If you open the cap on your exchanger and the thermostat opens then you should see fresh water flow thru like a car radiator,Correct?My son says when the thermostat opens the water sucks down into the heat exchanger therefore if I'm right then that means not enough water in block.Please correct me if I'm wrong.Thanks
Mark

The heat exchanger has two sides to it. One side is the freshwater side with antifreeze that circulates to and from the block, heads and manifolds (if it is a full system.

the other side of it is the raw water side, raw water is pumped through the heat exchanger, taking the heat away from the antifreeze, then being discharged over board via the exhaust system.
the radiator analogy is correct but the raw water flow replaces airflow as the heat sink. Its a liquid to liquid rather than air to liquid heat exchanger…

not sure what question you are asking about sucking water down into heat exchanger or block. the antifreeze side is a closed system and should be full of af that is circulated by block pump.

 

[MarkSr]

The heat exchanger has two sides to it. One side is the freshwater side with antifreeze that circulates to and from the block, heads and manifolds (if it is a full system.

the other side of it is the raw water side, raw water is pumped through the heat exchanger, taking the heat away from the antifreeze, then being discharged over board via the exhaust system.
the radiator analogy is correct but the raw water flow replaces airflow as the heat sink. Its a liquid to liquid rather than air to liquid heat exchanger…

not sure what question you are asking about sucking water down into heat exchanger or block. the antifreeze side is a closed system and should be full of af that is circulated by block pump.

Scott,what I'm trying to figure out is should you see liquid flowing thru heat exchanger after thermostat opens up. My 5.0 was overheating. I replaced exhaust manifolds,impellar and thermostat (160deg).It seems when thermostat opens the water drains out of heat exchanger like its going into the block.I think when it opens you should see water flowing thru top of exchanger but nothing.I think it doesn't have enough water in system.What do you think

 

[saaristo]

Something wrong with the pipework. There should be coolant running through the block, closed loop between exchanger and block. Depending on t-stat it regulates the amount that stays in the block or flows through exchanger. The raw water side runs like following - impeller sucks it in and pumps it into heat exchanger and fuel cooler, from there it is pumped through exhaust overboard, nothing is regulating or limiting or opening or closing in that flow. The two liquids - raw water and coolant never touch eachother.

 

[MarkSr]

Okay thanks

 

[MarkSr]

Okay thanks

If you needed to add coolant,would you do it before or after thermostat opens.Do you put coolant in heat exchanger or in overflow container

 

[Scott06]

Scott,what I'm trying to figure out is should you see liquid flowing thru heat exchanger after thermostat opens up. My 5.0 was overheating. I replaced exhaust manifolds,impellar and thermostat (160deg).It seems when thermostat opens the water drains out of heat exchanger like its going into the block.I think when it opens you should see water flowing thru top of exchanger but nothing.I think it doesn't have enough water in system.What do you think

Yes top the level off in the heat exchanger. I would think you would see flow unless there is sediment built up or circulation pump on block is bad. Based on what you say i would top off and observe. If you still get no flow check circ pump and disassemble heat exchanger. Also possible raw water side is clogged with debris and needs rodding out take endcaps off if you have clogged passages you wont transfer heat. Actually clogged heat exchanger tubes is most likely situation …

here is a short video kind of explains hot to check heat xch

 

[MarkSr]

Yes top the level off in the heat exchanger. I would think you would see flow unless there is sediment built up or circulation pump on block is bad. Based on what you say i would top off and observe. If you still get no flow check circ pump and disassemble heat exchanger. Also possible raw water side is clogged with debris and needs rodding out take endcaps off if you have clogged passages you wont transfer heat. Actually clogged heat exchanger tubes is most likely situation …

here is a short video kind of explains hot to check heat xch

Heat exchanger was taken apart and cleaned,do you wait for thermostat to open when topping off

 

[Scott06]

Heat exchanger was taken apart and cleaned,do you wait for thermostat to open when topping off

dont think you can have it open when hot, so top off run it a. It then top off more. Is the circ puMp in good shape ?

 

[MarkSr]

dont think you can have it open when hot, so top off run it a. It then top off more. Is the circ puMp in good shape ?

I'll try it Sat,thanks

 

[Scott Danforth]

A heat exchanger is a device that transfers thermal energy between two thermally conductive fluids

is this a factory HX installation or an aftermarket?

when was the last time the raw water side (tube side) of the HX was cleaned out?

what is the status of your raw water impeller?

you will NOT see coolant flowing on 95% of the HX's as the cap is on the expansion tank side of the heat exchanger.

if you are overheating, you either have an impeller issue, or a HX fouling issue

 

[MarkSr]

A heat exchanger is a device that transfers thermal energy between two thermally conductive fluids

is this a factory HX installation or an aftermarket?

when was the last time the raw water side (tube side) of the HX was cleaned out?

what is the status of your raw water impeller?

you will NOT see coolant flowing on 95% of the HX's as the cap is on the expansion tank side of the heat exchanger.

if you are overheating, you either have an impeller issue, or a HX fouling issue

New exhaust manifolds, New impellar,New thermostat, New cap for exchanger,and heat exchanger was totally taken apart and cleaned.The thermostat is 160deg and now it's running around 170,175.I thought 160 is the number I'm looking for

 

[Scott06]

New exhaust manifolds, New impellar,New thermostat, New cap for exchanger,and heat exchanger was totally taken apart and cleaned.The thermostat is 160deg and now it's running around 170,175.I thought 160 is the number I'm looking for

My merc with a 160 thermostat runs 170-175 if thats what you are running you are fine

 

[dubs283]

The thermostat is 160deg and now it's running around 170,175.I thought 160 is the number I'm looking for

Ideally, yes. Should verify temp at the sender with an IR temp gun and compare number to gauge reading. Could be the guage or sender is reading incorrectly

 

[Horigan]

My heat exchanger has the cap right on top of it. In theory you should be able to see coolant flow once the thermostat opens. HOWEVER, the one time I tried that coolant blew out of the heat exchanger as the thermostat opened, making quite a mess. Now I fill it, cap it, run it until the temperature stabilizes (about 170deg indicated for me), let it cool, then top it off.

I've confirmed my thermostat opens at 160deg via an IR gun. I've tried different temp sensors with similar deltas, in the opposite direction. I just live with the error in the gauge now.