Coolant leak tests are usually done at about 15-17 psi... no more than 20 psi. Leaks
can be temperature dependent... only when engine is cold or only when hot at normal running temp, or, the easiest to find... when not temp dependent and leak either cold or hot. No need to run the engine while testing... just get it up to temp, shut down engine, and pressurize it... being careful when removing cap of hot engine (might just already have test cap on before running up temp. FYI- getting engine up to running temp at dock
may be harder than you think to do since our engines without good load may not come up the operating temp with cooler Winter water temps.
If your gauge holds within 1-2 psi starting at say 15 psi for an hour or so at cold and then at hot engine condition... likely not a leak.
But give us more info:
- Are you losing coolant? How much in 8 hours of run time or some other time frame?
- Are you seeing white smoke at start-up?
- Are you smelling 'sweet' antifreeze
smell in engine area/ or exhaust?
- is your oil
showing any signs of contamination (bubbles, milky, thick mud)?
- Is a crew member
drinking it? (Just kidding)
- Have you tasted it? OK, serious now. If you have a breach in the heat exchanger
, raw salt water
can mix/ dilute the coolant in the engine coolant loop. It doesn't take much salt water
contamination to taste it. Don't drink it! Just dip your finger in the coolant at your 3-4 psi cap area and touch your finger to end/top of your tongue where salty taste buds are most dense/ sensitive. Move tongue around a bit like your a tasting a good wine. Whether you taste it or not, finish up by rising out mouth with fresh water/ wipe tongue on clean cloth/ paper town... maybe drink a little of that good wine, a coke, or rinse w/ mouthwash to erase any after taste. A salt
taste means you'll need a new or rebuilt heat exchanger
. Fortunately your Perkins
has been a popular engine in marine
for a long time and you'll have many options to chose.
Sometimes the level in the coolant expansion/ auto-fill reservoir constantly needs topping off. I'm talking about the small (usually plastic tank that has a small 1/4 - 3/8 hose going from that tank to very near the fill cap on engine. Often that small hose fails right at either end/ hose clamp that's been cutting into it/ over tightened and coolant (but not coolant actually in the engine loop) is slowly weeped out and evaporates as it hits the hot engine/ or in the hot engine compartment area. Replace hose/ clamps.
gasket is another ugly possibility and white smoke at start-up and hard starting or irregular/ rough engine running initially (low compression
on one cylinder) are usual signs (along with disappearing coolant w/ o other explanations). Do a cylinder by cylinder compression
test to check for compression health
on each cylinder. At this point you are getting near the professional mechanic
level of experience/ tools. A good diesel mechanic
while pricey has much experience and can get to your issue pretty fast with the right tools/ experience. Don't be surprised if he redoes/ doesn't just accept your test results. That just how they are and something you didn't notice during the tests nay be the give-away clue of the leak problem./ solution.
Good luck. Let us know what you find.
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