i have a coolant loss problem. sometimes i lose coolant other times not. it has been as low as a gallon on a 400 mile trip. no leaks what so ever and it never smokes anything but black " truck is fully deleted and tuned"

the cooling system will hold presser for hour's with out leaking a drop.

WHERE THE HELL IS IT GOING!!

 

It's not puking out of the degas bottle?? If not maybe radiator leaking at top.

 

It's not coming out of the bottle and no coolant trails anywhere. I'm at a loss

 

Had a few that was leaking into the pan from the front cover behind the water pump. Neither showed a milky color, all would "gain" oil level. No external leaks.

 

Oil is always right up to full mark. Never over. I have added around 3 gallons in the last 4000 miles. To me that is a huge loss but I just can't believe it's not showing up anywhere. And the fact it's holds pressure for over an hr is really blowing my mind

 

Can you smell any antifreeze??

 

what about the tail pipes..moist? Does it smell sweet?

 

No coolant smell in or out of the cab. Tail pipe is dry and I've never seen any smoke, I have the pass side fish eye mirror pointed right at the exhaust. I've had the truck up in the air looking over everything with a work light and mirror to see behind corners. I'm almost to the point of leaving it alone till it gets worse and I can find it

I had this same problem with my d-max for about a year. Until it got bad enough that I finally noticed the valley of the motor was full of coolant and found a small rubber hose that runs coolant to the turbo had a pin hole in it

 

If it's not an external leak then it's going out the exhaust one way or the other. Mine was puking and I still don't know if I have it corrected. It seems to be since I installed the new improved degas tank. I still think I could have taken a grease pencil and drawn new "cold fill" lines below the bottom return hose on the old one and accomplished the same thing. That's all the difference I could see in the tanks.

If there is a Head Gasket or EGR problem there is a test that you can run for exhaust gasses in the coolant. I bought the kit on line for 50 bucks or so. just google exhaust gas in coolant or something like that.

When you tested the system for pressure did you do the cap. My truck was puking but there was not a lot of visual evidence of that until I started looking for it hard. The stock caps are pretty prone to fail.

Another thing I did was run the truck really hard and get the boost up to 30 psi or higher than check the hood right away. I would find the puke still wet on the degas tank. On my last trip with the trailer it puked and instead of adding I just cleaned the degas tank real good and kept driving. It did not puke after the coolant got lower in the tank. That's what made me decide to change the tank. haven't towed the trailer yet but I have made a lot of power starts from stop to 80 mph or so and no puking.

Hope some of this helps. Believe me I feel your pain. Since you have a tuner you can watch the temp. During all my problems (and there are three long threads on here) my truck never over heated. Good luck and please let us know how you resolve it.

 

Thanks stanley z I will do the head gasket test as we have one at the shop and I will also ck the bottle after a hard pull

 

The gas test doesn't always show up on diesels. I would put a pressure gauge on the degas bottle and see if it gets above 16lbs. They are easy to make and will tell you very quickly if it is head gaskets

 

Yes, I meant to add that you need to be sure and get a kit for diesel.

What kind of pressure gage and how would I hook it in? Cut into the return hose I guess.

 

Really any gauge for water. Yea you can plumb it into the return line. I wouldn't cut any hose just put a t in at the end and put a little piece of hose onto the degas bottle. You can get enough hose to run into the cab and have gauge in there so you can see it when giving boost. Just run the hose on the backside of hood into your window.

 

I have a tester/gauge that goes right on top of the degas bottle. that how I know it will hold 18 psi for well over 1hr. in fact I got tires of waiting and took it off bc it had not lost even 1 lb

 

Well, I guess you're talking about a pressure tester that you pump up to 16 PSI and do a leak down test. I'm just a shade tree guy but I don't think an hour is long enough to be sure. If the engine is cold when you do it the pressure should hold over night, or for a week, I guess. I use a kit I get from O'reilleys loan a tool. They have the only one I could find with the proper adapter for our trucks. When you get it to 16 PSI you should be able to find any external leaks. if you find none and it goes down over time that indicates an internal leak. or it may indicate the tester is failing.