Losing coolant

Hi Guys-
Got an Isuzu C-240 (four cylinder diesel). When run at idle (600rpm) for 20 minutes or so,
the temperature holds steady at 140, the cooling system does NOT
pressurize, and it loses about a half gallon of coolant.
The bilge is dry and the engine starts and runs easy. Exhaust appears
to be clean water with no color or odor.
What to do?

Thanks-
Eeber

I'm clueless, but John Deere says my 4045D shouldn't run at idle for longer than five minutes.

Eeber said:

Hi Guys-
Got an Isuzu C-240 (four cylinder diesel). When run at idle (600rpm) for 20 minutes or so,
the temperature holds steady at 140, the cooling system does NOT
pressurize, and it loses about a half gallon of coolant.
The bilge is dry and the engine starts and runs easy. Exhaust appears
to be clean water with no color or odor.
What to do?

Thanks-
Eeber

Click to expand...

If the coolant is not leaking, it's going out through the exhaust. The cheapest possibility is a blown head gasket. It gets more expensive from there.

If you just filled it and it only did this once, there could have been an air pocket. If you haven't messed with it and it just started loosing coolant, and keeps on loosing coolant, you're going to need a mechanic or a service manual, a good set of tools, and some serious mechanical ability.

Mark,
That's a good point but not an OMG issue.

I'd be concerned about the very low coolant temp. My Mitsu warms up quickly to almost 190. Every time. I suspect that your coolant is very likely going from the coolant side of the heat exchanger to the sea water side. I'd check the heat exchanger. And 140 degrees warmed up temp is too cool. Is it a Klassen Engine?

manyboats said:

Mark,
And 140 degrees warmed up temp is too cool. Is it a Klassen Engine?

Click to expand...

Haven't seen "Klassen" anywhere on it.

Maybe a different thermostat will fix the low temp?

There is a new exhaust elbow. Would that be a clue that maybe the
exchanger is bad? Either way, with that much coolant loss, I'll pull
the heat exchanger to begin with. Good guess?

Thanks Gentleman-
Eeber

manyboats said:

Mark,
............. I suspect that your coolant is very likely going from the coolant side of the heat exchanger to the sea water side.

Click to expand...

That's another possibility.

Eeber,
No ...the exhaust is sea water.

Yes ...a thermostat should fix the temp. Check your coolant cap (like a radiator cap). I run a 13 lb cap and about 185 degrees. If you only have a 5 pound cap you should probably run a 170 thermostat.

I still think it's the heat exchanger.

What happens after 20 minutes? Does it over heat? I know it's a stupid question but just covering the bases. I was loosing about that much and than it would over heat. I replaced the cap to 15lb cap with a good spring and problem solved.

swampu said:

What happens after 20 minutes? Does it over heat?

Click to expand...

No it does not overheat.

Thanks for the tip on pressure caps.
Eeber

If you are loosing coolant...and it's not in the bilge or the oil...my guess it's going out through the heat exchanger into the exhaust...not too many places it can go.

psneeld said:

If you are loosing coolant...and it's not in the bilge or the oil...my guess it's going out through the heat exchanger into the exhaust...not too many places it can go.

Click to expand...

I'll remove it and send it to a radiator shop for testing/repair.
It looks like it bolts all the way through from the outside?

Thank-you-
Eeber

One other question if I may;
What effect, if any, would the fact that the coolant system is not
currently pressurized, have on the operating temperature?

Thank-you-
Eeber

Nothing if the temp never gets up above 140. PV=nRT
If volume is constant, which it's not your loosing volume. Coolant is not pressurized. And your temperature is constant at 140. n is a constant and r is a value given for particular liquids. I would say if your temperature is constant and your unit doesn't overheat than the higher your temperature is the more volume you loose. If you let the unit run long enough you will develop more pressure.

I would suspect an air lock somewhere in the system.

At 140 there is no use for a pressure cap, so leave it off and keep filling if the coolant level drops.

Long ideling sucks for your ( or any) engine , as does 140F, which will not get rid of combustion products in the oil.

Go for a ride , in gear, and see what the temps become underway.

FF

Sorry to say Swampu but the Ideal Gas Law does not apply in eeber's case, his is not a closed gaseous/liquid system due to a liquid leak somewhere that occurs below temperatures where a vapor phase can be established. Think steam engines for a better application.


Eeber (if not an air lock) if you have a TX heat exchanger this would be a good time to check and clean it too. Potential leak areas are:

• Head gasket or cracked head
• Exhaust manifold
• HX
• Turbo if JWAC
• Bad plumbing

Also, double check/test your oil for coolant. As suggested get a pro on these engines. Start with boatdiesel.

sunchaser said:

Sorry to say Swampu but the Ideal Gas Law does not apply in eeber's case

Click to expand...

That is probably why it took 7 years to get a 4 year degree

sunchaser said:

if you have a TX heat exchanger this would be a good time to check and clean it too.

Click to expand...

What's a TX heat exchanger?

Thank-you
Eeber

I do'nt see how it can be an airlock as pressure would rise to some degree.

Eeber said:

When run at idle (600rpm) for 20 minutes or so,
the temperature holds steady at 140, the cooling system does NOT
pressurize, and it loses about a half gallon of coolant.

Click to expand...

How do you know it does not pressurize, is there a pressure gauge on the system?

Does the rate of loss continue if you run it longer than 20 minutes? For example, if you ran it for 40 minutes would you lose a gallon?

If it runs longer, does the temperature increase?

Before spending a lot of money on mechanics to remove heat exchangers and send them out for testing, I would get a car parts store radiator pressure tester and check it while not running. I would put a flourescent dye tracer in the coolant and view the exhaust overboard with a UV light as well as check all the plumbing associated with the cooling system.*

If you have a coolant loop in your potable water heater, check the hot water as well.

* You probably won't get anything out the exhaust with the engine shut down so after doing the pressure check with dye, start the engine and watch the overboard with the light. Do this in the dark for best results.

If you see dye glowing, disconnect the transmission cooler inlet and see if the source is upstream (the engine itself or the heat exchanger) or not. If not, then reconnect the inlet and disconnect the outlet from the transmission cooler and check it after pressurizing, dye in that location with none at the inlet shows the cooler is leaking.

rick has the right way to do it, it could be the tranny cooler,oil cooler,or the hot water heater if it is heated by the engine. take his advice it good.

RickB said:

How do you know it does not pressurize, is there a pressure gauge on the system?

Does the rate of loss continue if you run it longer than 20 minutes? For example, if you ran it for 40 minutes would you lose a gallon?

If it runs longer, does the temperature increase?

Click to expand...

I know it doesn't pressurize as I release the pressure cap.
Rate of loss is a stumper. It seems to be okay and after
running a couple of times (10-20 minutes), it's down almost a gallon.
The temperature never passed 140. I replaced the thermostat today
and it holds now at 185.
I appreciate the info on checking pressure and using dye but I can't figure out the inlets from the outlets. I'd gladly pay for a "schematic" of the cooling system.
I'm going to try and enclose a picture of the major coolant components on this vessel and maybe I can get some ideas what travels where.

Thank-you all for your time-
Eeber

Here you go ...

It looks like your engine heat exchanger has seen better days. There appears to be evidence of SW leaks around the connections everywhere.

Loosen the hose clamp where the hose out of the transmission cooler enters the exhaust elbow. Twist the hose to break it loose from the fitting on the elbow and see if you can pull it back enough to create a leak when the engine is running. You just want to see if the water that leaks out glows under the UV light. That water cools the exhaust before it enters the rubber exhaust hose so don't run without it or you will burn up the hose. The alternative is to watch the water coming out with the exhaust overboard - it is the same water.

If it doesn't glow then your leak is someplace besides into the SW loop. Or, you don't have enough dye to see, use lots, it's cheap and harmless.

If that water glows, loosen the hose clamp on the hose labeled IN, do it at the upper end as it appears to be more accessible. If that comes out clean then it confirms the leak is probably in the transmission cooler.

If you get glowing water out of that hose then the leak is probably in the nasty looking heat exchanger. If that comes out clean then look at the water heater - run the hot water into a sink for a bit and see if it glows. It could leak out someplace else on the engine or plumbing, shine the UV everywhere. What does your oil look like? Is it milky?

Losing Coolant from Heat Exchanger - Cruisers & Sailing Forums
besides a few pictures of a different coolant path other than yours I think your problem is in the transmission cooler. I don't know but it looks like the water goes from the transmission cooler into the exhaust elbow. I would think that should be fresh.

Could be leaking through the heat exchanger and going overboard with the exhaust. That's the most likely cause unless you did something stupid like seriously overheating it.

That's relatively cheap to test and remedy. Take the heat exchanger off and have it pressure tested.

From there the possibilities get more expensive (and much less likely) so test the exchanger first. If it really was a head gasket the system would likely not only be pressurized, it would be overpressurized so my money is on the heat exchanger.

Just FYI, there is no heater loop.

If the small cylinder is the transmission cooler
and the large cylinder is the heat exchanger,
what's the thing the exhaust elbow comes out of?

How about a zinc (zincs)? I see no place for one.

Thanks for the education-
Eeber

That looks like your exhaust manfold. The pencil zincs should be a 9/16" or so size bolt head on the bottom of the large cylinder.

UPDATE-

I skipped the pressure tester because it was obviously leaking bad.
Turns out I didn't need dye either. I pulled the hose feeding the transmission cooler as Rick suggested and there was coolant present. I found and removed the zinc. It was gone. I removed the exchanger and filled the closed coolant side of it with water. It pretty much ran right out the ends.
LENCO is currently building me another one and the biggest surprise
is, the cost is half what I expected.

It was a good learning experience.

Thank-you all very much for your ideas.

Sincerely-
Eeber

Hi Men-
I got the new heat exchanger and it's primed but not painted.
I'd like to spray it with some Valspar.
Do I need something more heat resistant?
Thanks-
Eeber

Eeber, you can buy some high heat primer from the auto parts place and prime it. You they make every kind of color of heat paint as well.

Its not going to get over 200 degrees so I wouldn't worry about high heat paint.