Appetite for antifreeze????

[Dvldog 8793]

Howdy
I'm getting ready to pull the top off of my 99 6.5. In the last 200m it drank about 3/4 gallon of antifreeze. No leaks, nothing in the oil, no residue anywhere. The exhuast smells and looks like Diesel exhaust. Has anyone had a similar problem? Does anyone have any ideas as to what it could be? What I'm hoping for is the "Oh Gee, that happened to me 4 yrs ago and it just the whatchahozit. 4.99 at autozone and 15 minutes of labor!" I don't think I'll be that lucky but ALL ideas and info are helpful! Also any ideas or tips for pulling the top-end off.
Thanks for the help!
L8r
Conley

[dstoops]

Hi Conley,
First thing that comes to my mind would be a slight head gasket leak. Slow enough that you aren't noticing it in the exhaust. Next would be a leak in a hose or fitting that only happens while on the road. I'd run it some more and watch it cause it'll probably get worse and reveal itself. Maybe do a compression check before you pull the top off. Check heater core and freeze plugs as well.

[markrinker]

How about replacing the pressure cap on the overflow tank. If you truly have no other signs of the engine 'ingesting' water, I'd start there and look for external leaks.

BTW - Both of my '94 use coolant to the tune of 1 gallon per 10,000 miles. Enough that I carry it on the truck and refill 1 quart at a time. I don't have any idea where it goes.

[JTodd]

I was slowly loosing coolant mysteriously as well. It turned out that a plastic joint connector to the heater line had a slight crack. The leak was small enough and in the right spot to never show up on the ground under the truck. I think it only leaked when running, and the engine heat caused it to evaporate immediately. The connector is between the engine and the firewall on the passanger side.

[rjschoolcraft]

My Suburban is doing this as well... has for almost a year. I was beginning to suspect a freeze plug, but havn't seen any evidence yet. I think I'll try replacing the pressure cap as suggested above and see if that helps at all. I too have been carrying antifreeze with me now for a while because of this problem.

[JohnC]

If coolant is getting into the cylinders then cylinder gasses must be getting into the coolant. Pull the crossover tube off, run the engine and look for bubbles before you pull the heads.

[curmudge1]

My '94 Blazer 6.5TD uses coolant, too.

Isn't there some kind of dye that we could buy at AZ or somewhere, & find leaks, even if the liquid evaporates? Maybe using UV light?

Just a thought.

[Marty Lau]

When I did a bunch of maintaince at the first of the year I had two leaks.
1. The quick connect on the heater pipe. It started slow and became evedant after awhile.
2. Lower corner of radiatior, this leak was not apparent until the radiator was pulled. That corner only leaked under pressure and very slight and the coolant got mixed with the cooling air and was not detectable.

[Phil Holmen]

I used to work at a shop that had an air pump that you would put in place of the rad cap and pressureize the system to whatever the rating of the cap was, usually 15 psi. Leave it for a couple hours and usually you could find the leak. Unless of course it was internal, but it eliminated alot of extra work and expense, I suppose you could use an old rad cap and fit it with a valve stem and do the same thing just be sure not to put too much air pressure...

[Dvldog 8793]

FANTASTIC!!
These are the kinds of posts that I like! Many new good ideas for me to try before I do the major stuff. Too many times it seems like whne it is my vehicle I go straight to the worst possible problem when I could be checking many little problems first.
Thanks again.....
L8r
Conley Janssen

[Barry Nave]

Had the same on my 95. No leak yet was going some where. Found hose clamps at lower rad and tighten most all the clamps. Had not done this after installing gear drive and cooling mod's.
That's been four years now.
Thought the worse also :eek:
Now all is, well still have to keep my eye on it for now and then I may have to add a pint once every two-three week's.
Had to do this two-three times a week :eek:
My Rad. may need to be check now, though I have always flush good and kept good care of the cooling system. :D

[tom.mcinerney]

Mine had a small crack in coolant reservoir, near fluid level sensor; not apparent until i removed the expansion tank to get behind it, only found when i cleaned up the tank before reinstallation {went with new reservoir}.
There was a second coolant leak on mine, which i originally thought to be an oil leak. This was at the small (bypass) hose from the water pump to the [base of the] coolant crossover. The antifreeze seemed to have cooked into a sludge which i assumed was oil, smearing down the front of water pump/timing cover. New hose/clamps rectified.

[Kennedy]

I'd suggest an oil analysis and look for glycol presence. Pressure test with a quality tester at 16psi. You can also try running up to temp w/o cap on (no psi) then intstalling psi tester and see if psi builds after expansion has stabilized.


Typically, a head gasket or cracked head will overpressurize the cooling system.

Typically, a cracked block will make gelatin in the CDR, and eventually crankcase.

Being a 99, I'd hazard a guess that the block may cracked up the cylinder wall from the oil spray hole. Some cracked on the deck, but that seems to be more Hummer related.

You may get lucky, but IMHO, it is more practical at this point to pull the engine and dismantle on an engine stand where you can inspect/evaluate most thoroughly and accurately, as you'll likely end up there anyhow.