MPG Drop and Smell of Anti-Freeze

[Papa Rick]

This has been going on for 2 weeks now, my mpg went from 5.2 to 4.2, and I keep smelling anti-freeze like it is leaking somewhere, but can find no leaks anywhere, and have not had to add any anti-freeze before, or during this time.

Another thing that is puzzling is when parked overnight now my air pressure will drop down to 30lbs, and if left over the weekend, it goes down to 0. It use to drop to 90 to 100 prior to this.

I did have a problem getting water in the system, but have changed filters 4 times in the last 3 weeks and no show of water now.

[boneebone]

You could have a head gasket leak that is leaking down the side of your block, but since the block is hot when it is leaking, there are no signs of leaking because it is evaporated already.

[sidman82]

Your probably like me and notice any little smell or hear any noise even if it's not there. It's been getting cooler and mabye using the heat is making it smell a little more like antifreeze.

That also is why the air is losing pressure. Temp drops will make that happen. Contraction of air hose fittings and the like make small amounts of air leak out. Not a problem in warmer weather, because the fittings are not contracting.

My first inclination anyway.

[Blind Driver]

My truck would hold air pressure over a weekend. Now it's at 20lbs overnight.

[heavyhaulerss]

Well since no one can identify the original post problem including me.. I'll just add to the list of problems & say mine leaks down to 20 lbs overnight too & i cannot find the leak. soaped everything with special leak detector that when it bubles the bubbles stay there for 12 hours & still nothing. so i'm lost on that one too.

[bob h]

This has been going on for 2 weeks now, my mpg went from 5.2 to 4.2, and I keep smelling anti-freeze like it is leaking somewhere, but can find no leaks anywhere, and have not had to add any anti-freeze before, or during this time.

Another thing that is puzzling is when parked overnight now my air pressure will drop down to 30lbs, and if left over the weekend, it goes down to 0. It use to drop to 90 to 100 prior to this.

I did have a problem getting water in the system, but have changed filters 4 times in the last 3 weeks and no show of water now.

Winter fuel mpg?

Are you smelling a/f inside or out? Is the antifreeze going down at all in the expansion tank? Have you checked the oil for contamination? Look at your hose connections, bottom corners of rad, etc. Try tying a plastic bottle to your radiator cap overflow hose to see if it collects antifreeze. When a/f leaks externally, on hot components it will usually leave a white, chalky residue behind.

If you leave it out overnight, your RES air might be getting cold… ; )

[Papa Rick]

Still have not found the reason for the mpg drop, but went to check my Truck out today after it sat for 3 days and when I pulled up I noticed it was leaking AF underneath? That was not a good feeling but opened the hood and found the O rings around my oil cooler were wore out and it was leaking from there.

I guess this is the reason that I could not find the smell of AF as it was such a small leak until it finally gave way. Have to wait until Monday and get the parts for this. I hope this fixes my smell of AF, but still stumped by the drop in mpg, as I have not a clue to what is going on here.


11-30-2008 02:21 PM
bob h


Winter fuel mpg?

Thought this might be the problem to start with, but it did this last year when fuel was switched over to winter blend, but after a couple of weeks it came back up and stayed there until now. Hard to figure on this one!

[boneebone]

Still have not found the reason for the mpg drop, but went to check my Truck out today after it sat for 3 days and when I pulled up I noticed it was leaking AF underneath? That was not a good feeling but opened the hood and found the O rings around my oil cooler were wore out and it was leaking from there.

I guess this is the reason that I could not find the smell of AF as it was such a small leak until it finally gave way. Have to wait until Monday and get the parts for this. I hope this fixes my smell of AF, but still stumped by the drop in mpg, as I have not a clue to what is going on here.


11-30-2008 02:21 PM
bob h


Winter fuel mpg?

Thought this might be the problem to start with, but it did this last year when fuel was switched over to winter blend, but after a couple of weeks it came back up and stayed there until now. Hard to figure on this one!

When is the last time you had a overhead done?

[Orangetxguy]

When is the last time you had a overhead done?

And the charged-air preassure checked?

[Windwalker]

That "charged air" could be a clue. I was not getting very good fuel economy on the truck I'm driving. Then, about two months ago, it blew the turbo. Since it's been replaced, it's been doing quite well on the economy. More than a mile a gallon more. You might also check that system for leaks.

[Papa Rick]

Got the O Rings replaced on the Oil Cooler Tuesday, and have not driven it but 150 miles since then, so not sure but keeping my fingers crossed about the smell of Antifreeze.

This shop found the air leak, and it was 2 different places, one was the pop off valve on the air compressor was not closing up all the way, not much of a leak, but enough over night to let it come down. And the 2nd place was on a valve hook up for an air line to air my tires up with. Both of these I checked, but never saw anything, but the shop tech told me he had some soapy solution that was made to stick on whatever it was sprayed on and show much better. That did the trick on the air loss.

Went to MHC KW Dealership in Chattanooga and had them check for Air to Air leak, nothing, turbo was checked out and it was fine.

Had the overhead done, as I have had the Truck for 110,000 miles now and did not know when it was last done. It showed up 2 injectors were out of adjustment very little, but tech said it was not enough to warrant the 1 mpg drop that it has.

Put the computer to it and ran for codes, none shown up, checked the mpg out by the computer in truck and it shows 5.49 mpg over the last 106,000 miles??

I asked the tech how this could show this when it is not getting this, he asked me if someone could be stealing my fuel at night? I told him no I had locking Fuel Caps and park in a well lit area beside my son’s house.

He told me the only other thing he knew of could be if the fuel lines were starting to collapse, but this usually had a loss of power under a load complaint, which mine doesn’t have.

This happened once before on the Truck after I got it out of the Body Shop last of July 08, and took it back after getting poor fuel mileage and nothing could be found, did not do overhead, but did put it on the dyno and it straightened itself out the next week.

Really do not know what to do to try and recover the fuel mileage loss after this?