Perkins 4154

[Presto]

I am losing coolant and can find no external leaks. Ran pressure test on bowman heat exchanger and found 1 small leak, and tightened hose clamp. After running engine the coolant level sucks in about 1" of coolant into heat exchanger and level lowers about another 1" in heat exchanger over a 36 hour period. No water in oil. Anyone have an idea where the mystery leak is?

[Lancerbye]

Welcome aboard. Well if you don't see leaks externally and no white smoke out the exhaust the most common place for coolant to disappear is inside the heat exchanger due to a leak between the fresh water coolant and the raw water interface. A pin hole in a tube or just a corroded section in a tube can get rid of your coolant water fast. Do you have zincs in your heatexchanger and have they been maintained? Pressure testing the exchanger will reveal any possible problems.

[Presto]

Thanks, I thought of that, but the mechanic said that would be most unusual.

Thanks for the reply

[Redcoat]

Originally Posted by Presto

I am losing coolant and can find no external leaks. Ran pressure test on bowman heat exchanger and found 1 small leak, and tightened hose clamp. After running engine the coolant level sucks in about 1" of coolant into heat exchanger and level lowers about another 1" in heat exchanger over a 36 hour period. No water in oil. Anyone have an idea where the mystery leak is?

You need to pressure test the tubestack in your heat exchanger it is probably going out your exhaust. If you can't fix the tubestack look here.
Replacement Marine Heat Exchanger on Orca Marine Cooling Systems
If not check your bilge.It could be blowing out your resevoir.

[Presto]

Originally Posted by Redcoat

You need to pressure test the tubestack in your heat exchanger it is probably going out your exhaust. If you can't fix the tubestack look here.
Replacement Marine Heat Exchanger on Orca Marine Cooling Systems
If not check your bilge.It could be blowing out your resevoir.

Thanks, this makes sense. Appreciate the link.

[gettinthere]

are you sure it's a leak?

I have the 4.154. I kept topping up the water in the heat exchanger so I called TAD to discuss it. I was told that it will not hold coolant all the way to the top, let it settle down about an inch from the top.
I let the coolant find this level pretty quickly and it stays there.

Call TAD to confirm this if you need more details.

[Presto]

Who is TAD?

[Redcoat]

Trans Atlantic Diesel.

[gjordan]

By any chance is the coolant changing color(getting lighter/clearer) after a few hours of running? I had a 4-154 that had the rubber fittings on each end of the heat exchanger go bad, and it would slowly run the coolant out through the exhaust, but keep the level in the exchanger normal. End result was an engine being cooled with salt water. It caused lots of heating problems later on. 4-154 is a great engine!_____Grant.

[gauvins]

Originally Posted by gjordan

By any chance is the coolant changing color(getting lighter/clearer) after a few hours of running? I had a 4-154 that had the rubber fittings on each end of the heat exchanger go bad, and it would slowly run the coolant out through the exhaust, but keep the level in the exchanger normal. End result was an engine being cooled with salt water. It caused lots of heating problems later on. 4-154 is a great engine!_____Grant.

Same thing happened to me. I've replaced the tubestack and end plugs with brand new parts. The heat exchanger (Bowman) appears to be severely corroded, with parts becoming brittle. I plan to change it with a part taken from another engine.

My question is - if the engine has been cooled with salt water (for up to 500 hours would be my guess) what kind of damage should I expect? At the moment the engine purrs. I hope that a refitted HX will do the trick but fear having to change everything in a short while.

[gjordan]

I have no idea of how many hours my engine was run like that before I bought the boat. It took me a while to realize that there was a problem. The engine would overheat if it was run above 1800 RPM for any length of time. When I discovered that the salt water was displacing the fresh, I replaced the end rubbers on the exchanger, but it made no difference in the over heating. I continued to use the engine with a self imposed 1800 RPM limit for the eight years that I owned the boat. That was enough horse power for me. When I sold the boat, I told the new owner about the overheating and he wanted more power, and ended up pulling the cylinder head and finding all of the cooling passages clogged with salt and rust. That is the real danger of salt in the system (rust and percipitation). If you dont have any heating problems after the exchanger is fixed, then just run some of the coolant system cleaner through it and dont worry too much about it.____Good Luck.____Grant.

[gauvins]

thanks