2018 2500 Cummins. Slow coolant leak from overflow.

[MeatCurtains]

I've been slowly trying to iron out issues with this truck and my last remaining issue is a coolant leak. Its coming from the overflow for sure.

EGR is dry, no signs of moisture in it at all. I did a combustion gas test with the liquid indicator it came back negative, but I'm going to get some new fluid and try it again tomorrow or maybe this weekend when I have time.

I recently put in a new thermostat, coolant bottle, and heater core. Radiator has been pressure washed and there isn't a bunch of crap packed in and air flow is clear through.

Outside of a head gasket what are some other possible causes? I'm not saying it couldn't be the HG but I doubt it. My bottle didn't come with a new cap, could that be the issue. The one on it is marked 21psi and was what I took off the old bottle.

 

[mtnrider]

If you are not seeing fluid anywhere it's most likely your head gasket. Are you tuned? If so I'm betting that's the issue.

How long has it been since the flush? If it was just done you might just have some air pockets but if it's been a while I'm back to the head gasket

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[MeatCurtains]

Not tuned. Completely stock.

I see fluid from that bottle overflow, that's it. I'll check for combustion gasses again. I didn't have any before or after replacing the bottle but my indicator fluid might be bad from being old. I don't have any other signs of a head gasket leak so I'm not completely sold on that, but it could be. I just want to check all my other angles before having the gasket replaced and the head decked.

 

[oe542bob]

I had this issue with my ‘18 2500 Cummins. All stock like it came from the factory. It started using coolant at around 119,000 miles. Did the normal checking for leaks even removing the right front fender liner to see if any leaking around the turbo. Not a drop anywhere. Changed out the overflow tank which I didn’t see any problem, wasted time and cost. Never saw anything from the tailpipe.
Took it to my local Ram dealer. After checking it out, they changed the cap to a new one and said it’s all fixed. (I knew at that point it probably wasn’t fixed) Next day driving to work, low level light came back on.
I ended up taking it to a diesel shop. They pulled the head but said the head gasket wasn’t really that bad. They finally determined the EGR had a crack in it that would occur when it was hot. Put a new EGR on it, Fixed!

 

[MeatCurtains]

I had this issue with my ‘18 2500 Cummins. All stock like it came from the factory. It started using coolant at around 119,000 miles. Did the normal checking for leaks even removing the right front fender liner to see if any leaking around the turbo. Not a drop anywhere. Changed out the overflow tank which I didn’t see any problem, wasted time and cost. Never saw anything from the tailpipe.
Took it to my local Ram dealer. After checking it out, they changed the cap to a new one and said it’s all fixed. (I knew at that point it probably wasn’t fixed) Next day driving to work, low level light came back on.
I ended up taking it to a diesel shop. They pulled the head but said the head gasket wasn’t really that bad. They finally determined the EGR had a crack in it that would occur when it was hot. Put a new EGR on it, Fixed!

EGR was my thought after the bottle replacement but my EGR looks dry. It could be the HG but as I said before I have a shop pull the head i want to explore other options.

 

[mtnrider]

Not tuned. Completely stock.

I see fluid from that bottle overflow, that's it. I'll check for combustion gasses again. I didn't have any before or after replacing the bottle but my indicator fluid might be bad from being old. I don't have any other signs of a head gasket leak so I'm not completely sold on that, but it could be. I just want to check all my other angles before having the gasket replaced and the head decked.

If the truck is still stock I wouldn't suspect the head gasket then, it can happen but is much more common on a tuned truck.

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[MeatCurtains]

If the truck is still stock I wouldn't suspect the head gasket then, it can happen but is much more common on a tuned truck.

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This entire thing is just baffling me.

The truck was parked a while ago before my uncle passed. I don't know why specifically. it has never been deleted. He used it to do local hauling for a few of his customers where using his semi was too much.

Since I've gotten it I've taken care of the cooling system stuff I mentioned, fuel filters, changed every fluid, replaced the steering gear, tie rod ends, the belt, tires and brakes.

I don't know if the coolant leak was why he parked it or if it cropped up from sitting. I might see if I can get someone to do a leak down on the cooling system and on the cylinders

 

[MeatCurtains]

Just an update.

Its 100% the head gasket. I tested it multiple times today. Strangely its fine all the way until its around 190. I was starting to think I was crazy.

I drained the oil and checked for any water or anything and the oil and filter looked good. So that's grand.

Anyone know ballpark what a HG runs to have done on one? I'm guessing somewhere in the 5k mark?

 

[06 Dodge]

Just an update.

Its 100% the head gasket. I tested it multiple times today. Strangely its fine all the way until its around 190. I was starting to think I was crazy.

I drained the oil and checked for any water or anything and the oil and filter looked good. So that's grand.

Anyone know ballpark what a HG runs to have done on one? I'm guessing somewhere in the 5k mark?

Cost will depend on the state & area you reside in along with quality of the shop doing the work...

 

[MeatCurtains]

TOok a bit but I finally got a few quotes. Seems like most places just straight wouldn't quote.

Going to run between 4500-5000 if the head isn't cracked and 7000 and up if it is with arp2000 studs. Not as bad as I feared but not cheap.

 

[MeatCurtains]

Just an update, it's in the shop and should be started at some point in the next week or so. They quoted a lengthy lead time because the machine shop they use is swamped so it'll probably be 6 or 7 weeks. Thankfully I'm driving the Forester right now and not burning $6+ a gallon diesel.

He is going to do some deeper inspection because we have no idea how long it was driven with the gasket blown.