I've got a slow coolant leak somewhere. I can smell it from time to time but it doesn't leak on my driveway when parked. When I bought the truck the overflow tank only had about 1.5 inches of coolant in it. The radiator was full. Even though I smelled anti-freeze from time to time, neither of those ever changed. Before I went to AZ last month I topped off the overflow tank with new DexCool. Same thing on the trip. Just anti-freeze smell sometimes. When I got home and popped the hood, the overflow tank was back down to the same level as before and the radiator is still fill. But I could see coolant all over the engine. It was all over the timing cover there by the oil fill. It appeared to have blown back from the radiator. I cleaned it up and have been driving it still but watching it. There is no difference in engine temp. As a matter of fact, I seem to run cooler than what I have read here. I stay well below the halfway mark, nearer the 3/8 mark. Still no marks on the driveway.

I did crawl under it yesterday and saw that it looked a little damp around the lower radiator hose. I figure that it ran down to there though and everything else is covered with a shroud. The reason I figure it ran down to there is that a leaky lower radiator hose shouldn't blow water on top of my engine.

Any trouble spots I should look for. I'd love to have an idea before I start blindly taking it apart or replacing stuff.

Thanks.

 

buy or borrow one of those pumps to pressurize the cooloing system.

 

look right on top of the radiator to the right of the cap...the plastic probably has a hairline crack that spews coolant under pressure..its a defect and it seems like its happening to everyone. Try to get gm to replace it if it is the mfg. defect. There are plenty of posts about this issue as well.

 

In Nov my check engine light came on with a code P0128. That code had 3 possible causes and it ended up being the last - thermosat. Got that replaced and in less than a week found a coolant leak - upper radiator tank crack. The replacement radiator cost me $200 and GM paid the rest (about $800). The service folks at Sewell pursued GM on my behalf - Sewell has be great for my service needs.

 

Also check the lower radiator hose where it is routed very close to the front crankshaft pulley and can be slowly sliced into if one of the plastic hose keepers becomes loose.

 

Songman, I have the same exact issue. My truck was not running hot either. The resevoir was low but the radiator was full. I topped it off but slowly but surely I was able to smell the fluid and noticed my resevoir going down just a bit over the last 30 days. I just bought mine about a month ago and the lady told me she's been driving it like that for a few months. My H3 has 100k so I decided to do an Amsoil engine flush and replace the oil with an additional added quart of Lucas engine treatment. I noticed then on the drivers side of the radiator from the bottom that it was leaking very slightly were the plastic tank meets the aluminum part of the radiator. I don't know if it's a hairline crack or just a bad meet between the plastic tank and radiator seem.

I ordered a new radiator and it was supposed to be in earlier this week but with the ice/snow storm we had come through here it's been delayed for a few days now. I bought mine for $140 bucks with shipping from Shepperd Auto Parts. Here's the link:

http://www.shepherdautoparts.com/aut...Obw5rCog==.htm

I figured since I'm going to tear into this issue and my H3 having a little bit of higher miles. I've ordered and going to replace the following. Radiator, water pump, Serpentine Belt, upper and lower hose. All made by Gates except for the radiator. I know the radiator sounds it may be to good to be true for the price, but it can't be any worse than the GM radiator that seems everyone is having issues with. So between $140 Shepperd's vs $500 GM's crappy radiator, I will take my chances.

I will update you once I have all my stuff installed.

I hope this helps...Cheers

 

think of it like you are fixing to get your hummer man card... you are joining a fraternity of men who have had to replace your h3 radiator. it makes me feel a little better to think of it like that...lol

mine did the exact same thing. it was a slow leak on the seal where the plastic meets the aluminum. its better to go ahead and change the whole radiator bc in a few thousand more miles the platic would crack and you would be out $800 more... just bite the bullet and get a new radiator...

 

My 07 adventure 5speed had a coolant smell for a short time and no coolant on the garage floor. It did have a leak, tho.
It was a small leak at the radiator cap and the leak was so small it would dry up before hitting the garage floor.
I got a new cap and it solved my problem.
Hopefully yours will be a simple to find and fix
good luck.
Pressure test your system

 

I think I have a buddy with a pressure tester. Might try to get that hooked up this week. Hopefully it is a radiator or easier. I think anything more would have already given me more trouble. I'll let ya'll know what happens. Thanks for the input.