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lpasekof · 12-23-2018, 08:30 AM

Merry Christmas!
I have a 2003 Cat 3126E that appears to be leaking coolant from the breather tube.

I obtained a cooling system test kit from Autozone and pressurized the system to about 12 lbs. The radiator cap is rated to 13lbs. I found 3 small leaks on hoses....all tightened and resolved. However, I'm still loosing a good amount of coolant and noticed a big puddle under the breather tube. Further investigation indicated coolant.

I'm going to take it into my mechanic to have resolved but would appreciate any insight.

CountryB · 12-23-2018, 08:56 AM

It's unlikely to be coming "out of" the breather tube. That tube comes off the top of the valve cover. No coolant is going to be there. Could be condensation (water) dripping from tube, which would dry out as the engine reaches operating temp.

But if you're sure there is coolant on the floor under this tube, I would suspect there is a coolant leak on the engine and its just running down the outside of the breather tube. There is a coolant temp sensor on that side of the block just under the fuel filter.

Also be sure to check your oil for coolant contamination. If it looks milky you're screwed.

twinboat · 12-23-2018, 09:10 AM

If not run in a few days, loosen the oil drain plug a few turns. If coolant drips out, don't run it.

Coolant in the oil will destroy the engine.

Gaspumpcity · 12-23-2018, 09:19 AM

Pull one of your valve covers off easy to do! Is there is build up of what looks like a milkshake or white mucus? Could also be a stuck open t/stat not allowing engine to heat up or short engine startups Check engine oil level is it overfull? After you pressure check radiator for water leaks and cured all outside leaks leave tester on overnight see if pressure drops this would indicate an internal leak that ends up dripping down draft tube.

Cat · 12-23-2018, 07:04 PM

Are you sure its antifreeze on the ground under the breather or just water? Depending on the climate you can get a lot of condensation around the breather tube. Freightliner is famous for leaking coolant surge tanks. But the guys are right make sure you check your oil level to make sure its not over full from coolant getting in and or loosen the drain valve to see if there is coolant in the oil. You do not want to run it if you do have coolant in it.

lpasekof · 12-24-2018, 06:59 AM

Quite sure it's antifreeze, nice clean pink! I'll pull an oil sample later today and see what's in that.

thanks

Bigd9 · 12-24-2018, 07:10 AM

If you are losing alot of coolant and you see "bright pink" water on the ground, I would closely check the white plastic coolant reservoir or surge tank. These have been known to crack and leak. On my coach it is located passenger side of the actual radiator.

Water leaks can travel a great distance before they make their presence known.

steve52 · 12-24-2018, 07:31 AM

When you say breather tube, do you mean the one coming from the valve cover, or the overflow tube from the coolant reservoir?

Gaspumpcity · 12-24-2018, 08:47 AM

Let’s wait till OP checks with his mechanic all of here imho nailed it. Would be a big help to us if he could answer some of our simple questions

lpasekof · 12-24-2018, 09:39 AM

OK, so I've been able to check the oil. The oil is a nice black. No milky discoloration. The oil level is not higher than expected. With loosing about 2 gal of coolant if it were going into the oil I would expect to see both, milky oil and a higher than expected level.

I'm seeing the coolant drip of the end of the breather tube down at the bottom near the road. Yes, it is the one coming off the top of the valve cover. Do I know, for sure, that is dripping OUT of the tube and not OFF the tube, no. I guess I could go wrap a paper town around the breather tube a few inches above the end and see what occurs.

Could it be the plastic coolant reservoir? I suspect I could only be so lucky, but no, I don't know. It's not easy to get to.

MO Fred · 12-24-2018, 11:17 AM

I had a similar problem with my 8.3 Cummins in a previous coach. As it turns out, coolant was leaking to the outside from the head gasket but had not yet penetrated to the inside of the motor. The mechanic was able to show it to me as it was running and oozing out. I was able to get the gasket replaced and no harm came to the motor.

Gaspumpcity · 12-24-2018, 11:48 AM

Sample of the oil is in the right direction. Did you recheck for outside leaks (concrete or large cardboard under motor) when you pressured up the radiator tank and then let it set for a while to check for any pressure drop? I can lead you to your problem but just how far can you go to do repairs? Doing a visual for outside leaks number one you could run the engine to build up some heat!Number two pull valve cover list goes on.Did you lose two gallons of antifreeze overnight? Is there any different smoke coming from the exhaust?

Cat · 12-24-2018, 11:52 AM

How far are you going to have to drive it for a tech to inspect it? Just a suggestion, I would drain the engine oil in to a container that you can take with you when you go to tech. And refill the engine with oil. Then you should be able to drive it with some confidence that aren't going to be doing damage or further damage to the engine.
The tech will want to look at the oil you drained out. If you do have coolant in the oil, then have to tech remove cut open the oil filter and inspect the pleats for metal. There should very very little metal in the filter pleats. FYI Maybe a half a pin head size piece every 5-7 pleats or maybe none. If there is metal in every pleat or ever other one its an indication of a problem. The more the more the more the damage.
Also might want an oil sample taken. Good Luck

Gaspumpcity · 12-24-2018, 12:10 PM

OP It requires a can cutter to inspect inside the oil filter but he will verify whats under the valve cover first! All we have here is a water leak lets do the simple tests first before we start talking about an overhaul or a trade in. tech will check for current events or logged faults also