bowman heat exchanger venting

[stevec1968]

Hello
I have just rebuilt my perkins 4108 and have been test running it .It was fine until last night when i ran it for 30 mins and water started coming out of the filler cap on the bowman heat exchanger .The engine was running fine and didn't seem to be overheating but for safety i shut it off .I had filled the heat exchanger to the brim before running and i was expecting to see some expansion but not the flow of water i saw ! Any help on this would be appreciated Thank you

[GordMay]

Greetings and welcome aboard the CF, Steve.

Do you have an expansion tank?

FWIW
Troubleshooting Fresh Water Marine Cooling System
➥ https://www.perfprotech.com/blog/art...ouble-shooting

[stevec1968]

Hello Gord .Thanks for the reply .the engine is not fitted with a expansion tank .
Regards
Stephen

[stevec1968]

this is a photo of the engine as it is now .there was no other tank or hoses attached to it on the boat.the only thing i added was a thermostat as there was none fitted .https://www.instagram.com/p/BhTwIailiON/

[dneve]

I just had a coolant internal leak in my Perkins 4-108 which we think was caused by a crack in the manifold allowing coolant to be pushed into the exhaust but not enough to create steam in the exhaust. I put a new tube stack in so that was not the problem.
I tried a radiator/block leak stopper called H & K which is available on Amazon.
I added it to the fresh water coolant and after running the engine for several hours the coolant level is not dropping. It appears that you have exhaust forcing fresh water coolant out the over flow given the high pressure you have pushing coolant out. A new exhaust manifold from Bowman is expensive so worth trying a liquid fix before spending big bucks.
Overall, my Perkins has been very reliable. Likes to run at 2000rpm.
Good Luck!

[stormalong]

You will find that the coolant expands quite a bit when the engine warms up. An expansion tank is necessary. You can buy them at many auto parts stores. When the engine has cooled down you will see that the coolant level is just above the tube stack. This is completely normal.

My 4-108 did the same thing and I initially worried about it too. After the initial overflow if you don't top up the coolant you will be OK. The expansion tank holds the overflowed coolant and as the engine cools the vacuum formed will suck it back into the heat exchanger.

[FionaJC]

I have a 4107 and it was always filled up with coolant. After running for a while the coolant would leak out the cap. I then talked to a mechanic who knew these engines. It needs an expansion tank. The coolant comes out when hot and is sucked back in when it cools. I fitted one and have had no problems since in two years. The tank doesnt have to be above the engine. look at the radiator cap and sout will see a scrung circle and a reversed inner cap.

https://www.youtube.com/watch?v=QhLUwsCdM08

[DougR]

I would suggest two possibilities, assuming that there is no major problem such as a cracked head, leaking head gasket, etc......

- Your engine has an expansion tank built into the heat exchanger/manifold housing, but you shouldnt fill it full to the brim. When the engine gets fully up to temperature it will push out a good bit of water if it started out filled to the brim when cold. Leave about an inch or more space below the filler neck when cold and see how that does.

- Make sure that both hose clamps on the rubber boots on the front and rear of the HE tube bundle are tight. If the front most or rear most clamp is loose, pressure from the sea water pump can force sea water into the cooling system, causing overflow such as you are experiencing.

DougR

[waterman46]

Originally Posted by DougR

I would suggest two possibilities, assuming that there is no major problem such as a cracked head, leaking head gasket, etc......

- Your engine has an expansion tank built into the heat exchanger/manifold housing, but you shouldnt fill it full to the brim. When the engine gets fully up to temperature it will push out a good bit of water if it started out filled to the brim when cold. Leave about an inch or more space below the filler neck when cold and see how that does.

- Make sure that both hose clamps on the rubber boots on the front and rear of the HE tube bundle are tight. If the front most or rear most clamp is loose, pressure from the sea water pump can force sea water into the cooling system, causing overflow such as you are experiencing.

DougR

Great answer there.

I have the Perkins 4-154, same arrangement of Bowman exchanger. I always had the same problem, coolant forced out of radiator cap, so I also learned to fill my heat exchanger only to the point where the water just covers the highest tubes in the core as viewed from the cap opening. Engine never overheats. Filled to that level, most of the tubes are well under the coolant due to the tilt of the heat exchanger.

Tank cap on my boat has a tube on the side to capture the overflow. If you want to add an expansion tank you will need that type of cap. Sounds like the cap you have may not be that type otherwise I assume you would have mentioned it. These caps are available but they surely cost a lot of money for such a simple item!

[Capt Gill]

There's an answer for you in the prior posts, however they address different causes of the problem, so doing a little diagnostic work to determine the cause would be in order,i.e., is the water that's being expelled fresh or raw ?
(if the boat's in sea water there'll be a salty taste). Does the problem occur at high, low RPM or both ? Exhaust gas in the heat exchanger tank ? Is there a relation between engine temp and when the problem occurs ?
Answering the above give you a much better shot at a proper fix or just r & r parts until you get it right, if you got the time and money.

[waterman46]

Originally Posted by Capt Gill

There's an answer for you in the prior posts, however they address different causes of the problem, so doing a little diagnostic work to determine the cause would be in order,i.e., is the water that's being expelled fresh or raw ?
(if the boat's in sea water there'll be a salty taste). Does the problem occur at high, low RPM or both ? Exhaust gas in the heat exchanger tank ? Is there a relation between engine temp and when the problem occurs ?
Answering the above give you a much better shot at a proper fix or just r & r parts until you get it right, if you got the time and money.

Hi Capt,

Good suggestion on smelling the opened tank after running to see if exhaust is present. But, if he's using antifreeze in the fresh water I would not recommend tasting it!

If any leakage is suspected from the fresh water system, you can rig up a pressure test using a bike pump and water pressure gauge - once I needed to do this so I drilled a hole in the side of a 1/2" pipe and soldered a metal tire valve to it (remove the internal valve stem and replace it after soldering).

His problem is most likely just having filled the fresh water to very top of exchanger, and certainly as you suggest there would be a relationship of temperature to change in coolant water level. Not sure why the coolant level increases with temperature in these installations, but it does, at least in my engine. Water does not expand but does antifreeze expand?

Doug

[Wulf]

Originally Posted by waterman46

Water does not expand but does antifreeze expand?

Water DOES expand with temperature increase. It is at its densest at approx 4C. Heat it and you will need room for it to expand. That is why you always need to leave room for expansion or have an overflow tank (aka expansion tank).
Without an overflow tank...If you fill the system right to the neck (with water, antifreeze, does not matter) it will expel some fluid past the radiator cap as it heats up. Cool it down and one may think the level is down...it is not, it has just found its correct level. Heat it up past the previous temp, it will expel a bit more. Heat it up to a lower temp, no “loss” as it has already created room for expansion expand within the system.
You can do the same with an unsealed container on a stove if yo want a visual.

[waterman46]

Originally Posted by Wulf

Water DOES expand with temperature increase. It is at its densest at approx 4C. Heat it and you will need room for it to expand. That is why you always need to leave room for expansion or have an overflow tank (aka expansion tank).
Without an overflow tank...If you fill the system right to the neck (with water, antifreeze, does not matter) it will expel some fluid past the radiator cap as it heats up. Cool it down and one may think the level is down...it is not, it has just found its correct level. Heat it up past the previous temp, it will expel a bit more. Heat it up to a lower temp, no “loss” as it has already created room for expansion expand within the system.
You can do the same with an unsealed container on a stove if yo want a visual.

oops you are right. I stand corrected.

[Capt Gill]

Originally Posted by waterman46

Hi Capt,

Good suggestion on smelling the opened tank after running to see if exhaust is present. But, if he's using antifreeze in the fresh water I would not recommend tasting it!

If any leakage is suspected from the fresh water system, you can rig up a pressure test using a bike pump and water pressure gauge - once I needed to do this so I drilled a hole in the side of a 1/2" pipe and soldered a metal tire valve to it (remove the internal valve stem and replace it after soldering).

His problem is most likely just having filled the fresh water to very top of exchanger, and certainly as you suggest there would be a relationship of temperature to change in coolant water level. Not sure why the coolant level increases with temperature in these installations, but it does, at least in my engine. Water does not expand but does antifreeze expand?

Doug

Another simple way to check for saltwater intrusion is to take a sample, boil off the the liquid then see if any salt crystals remain;though It takes a little longer than the "taste" test.
The OP needs to provide more info, just too many unknowns, too many possible causes for me to provide all the possible fixes.

[osprey877]

The plastic expansion tank on my boat and all cars I have ever owned is located so that it is the highest point in the cooling system. I assume this is to allow any air in the system to eventually make its way to the expansion tank and eventually to be expelled through the pressure cap as required and also to allow the Coolant level to be topped up via the expansion tank. Not sure if system will work as well if the expansion tank is lower than the heat exchanger.