Truck Eats Coolant

[LorenS]

My truck has consistently eaten coolant since I've owned it, 65k miles or so. If it isn't leaking (can't see or smell it), is it possible for the coolant to find its way into the combustion chamber but not have exhaust gas get into coolant?

 

1/4 - 1/2 gallon a month, new radiator and obviously coolant last summer. Coolant looks new (not surprising considering how much I add).

 

[Mopar1973Man]

Let the truck cool down completely over night. Now take a coolant pressure tester and pump the system up to 16 PSI and let it sit come back in 30 minutes and look for the coolant either on the floor or in the cab.

[wil440]

20 hours ago, LorenS said:

My truck has consistently eaten coolant since I've owned it, 65k miles or so. If it isn't leaking (can't see or smell it), is it possible for the coolant to find its way into the combustion chamber but not have exhaust gas get into coolant?

 

1/4 - 1/2 gallon a month, new radiator and obviously coolant last summer. Coolant looks new (not surprising considering how much I add).

 

In a nutshell NO.... spread a little thinking on your question ..... coolant pressure around 14psi...... combustion pressures way way higher, although I have seen coolant leaks into cylinders when motor is cold but you know this is happening on startup as 1. if it fires then it wants to snap the crank into peices as a liquid is not compressable at all, 2. if it's just a little bit of coolant getting into a cylinder then it's steam train for a few minutes on startup

Purchase a Cat  oil lab test kit, not expensive for 1 sample kit, this checks for everything in a compartment and if coolant is getting into a combustion chamber it will find it 

[LorenS]

I sure didn't think it should be possible, but I learned long ago that just because the laws of physics seem to not allow something, there's a wrinkle in the law I hadn't considered.

 

For instance, if the 14 PSI plus water pump dynamic head could overcome turbo boost and push coolant into the intake. Especially if the failed head gasket acted like a check valve, thus preventing boosted intake air from ever pressurizing my coolant.

 

I have a pressure tester but of course it's across town at my little shop. Will drop by to pick it up this week.

[AH64ID]

If it’s going out the tailpipe then odds are good it’s a head gasket issue. 
 

Cylinder pressure is high, but not always. Cylinders go thru many different pressure levels with normal rotation/combustion. 
 

any evidence of soot in the coolant? 

Edited May 17, 2021 by AH64ID

[LorenS]

22 minutes ago, AH64ID said:

any evidence of soot in the coolant?

No. Looks like it's brand new. It's probably leaking externally, I just haven't found it yet. Everything leaks on this truck except brake fluid, t-case, and FINALLY the transmission. A/C, steering, fuel, oil from every gasket, both diffs, coolant all leak. Probably vacuum leaks, too!

[wil440]

3 hours ago, AH64ID said:

Cylinder pressure is high, but not always. Cylinders go thru many different pressure levels with normal rotation/combustion. 

That is so but a low pressure part like induction is then followed by a high pressure compression and ignition, it would pressurize the cooling system and also cause combustion gas to be in the coolant which if bad enough will make the motor overheat, a combustion gas tester for coolant will find that.

One other thing to consider, has the truck got the same plastic expansion tank as mine... side of the radiator, is this ok and the pipework to it, I've seen machine drivers put 2 gallon of coolant into a machine every day, turns out it pushes out what it doesn't need when hot but can't pull it back in when cold

[Mopar1973Man]

Usually in Fords the EGR cooler will leak soot into the coolant. The coolant gets a burnt smell. I think it would be the same on a Dodge.

[wil440]

EGR coolers are only on newer stuff with regen and coolant goes into the intake

[Mopar1973Man]

Still that about the only time I've seen coolant getting burnt carbon back into the cooling system but never lost coolant which was weird. As for Dodge never seen it yet with EGR leaks (coolant vs. exhaust).

 

Still in all pressurize the coolant system would push coolant out of its leak. Like my first head gasket did always leak on the floor being block was hot enough to dry up before the floor.

 

As in my 1996 Dodge never leaked on the floor either but was leaking from the intake manifold gasket and drying up before hitting the floor.

 

In both cases the pressure tester after pumping pressure into cooling system cold made it show the leak in both cases.

[wil440]

1 hour ago, Mopar1973Man said:

Still that about the only time I've seen coolant getting burnt carbon back into the cooling system but never lost coolant which was weird. As for Dodge never seen it yet with EGR leaks (coolant vs. exhaust).

 

Still in all pressurize the coolant system would push coolant out of its leak. Like my first head gasket did always leak on the floor being block was hot enough to dry up before the floor.

 

As in my 1996 Dodge never leaked on the floor either but was leaking from the intake manifold gasket and drying up before hitting the floor.

 

In both cases the pressure tester after pumping pressure into cooling system cold made it show the leak in both cases.

The newer small Cat engines are pants for it, but then again they are Perkins engine, Cat don't make nothing themselves anymore other than frames as far as I know, EGR coolers get changed more than injectors   down to the idiot in the cab, turning engines off while cooking and bubbling instead of letting them idle for a spell

[LorenS]

16 minutes ago, wil440 said:

Cat engines are pants for it, but then again they are Perkins

I've heard those referred to as "Perkipillar" engines.  I thought that was funny.

1 hour ago, Mopar1973Man said:

was hot enough to dry up before the floor

I considered this, just figured I've have smelled coolant at some point.  When my old radiator started to weep at the side tank crimp I would smell it.

 

6 hours ago, wil440 said:

has the truck got the same plastic expansion tank as mine... side of the radiator

I'd say it's likely the same.  I always remove the radiator cap to check the fluid level there as well as the plastic tank, and it's always full.

 

I have so much fuel leaking, however, that maybe it's masking the coolant smell AND might be mixing with the fuel so I don't really see it, assuming it is diesel.

 

I really need to get my K5 running and licensed again so I can have the Dodge down for more than a weekend.  Having children really cuts into my ability to get anything else done!  Couple years and the boy should be able to help a little.  My dad said that around age 7 I started to be "helpful" to put it nicely...

[Haggar]

Pressure test the system while cold.    That will tell you if you have a gross leak somewhere.

 

Mine loses coolant only at certain temperatures from the passenger side front headgasket.   I never see it wet.  It does not leak cold (will hold 16 psi cold for hours)  but I can see the dried coolant from that corner.    I have to add about a quart a month. 

 

HTH

Hag

[wil440]

2 hours ago, LorenS said:

I've heard those referred to as "Perkipillar" engines.  I thought that was funny.

Yes that would figure

The story of how Cat bought perkins is funny.... Perkins used to supply engines to JCB, JCB is a direct competitor to Cat in the smaller machine market so Cat bought Perkins and then stopped JCB buying engines.... backfired really cos JCB now make their own engines and they are actually quite good, did the same with Turner transmissions which are fitted to the cat backhoe, forced them to the brink of bancruptcy then bought them for next too nowt

[Mopar1973Man]

5 hours ago, wil440 said:

Yes that would figure

The story of how Cat bought perkins is funny.... Perkins used to supply engines to JCB, JCB is a direct competitor to Cat in the smaller machine market so Cat bought Perkins and then stopped JCB buying engines.... backfired really cos JCB now make their own engines and they are actually quite good, did the same with Turner transmissions which are fitted to the cat backhoe, forced them to the brink of bancruptcy then bought them for next too nowt

 

Interesting...