Slowly Losing Coolant

[drumrpunk]

So I have noticed that I am slowly losing coolant on my 2000 limited edition (5.7 Vortec). I have to refill my reservoir about once a month. I have looked everywhere and I have yet to find it. Not a drip on the garage floor and my oil color has not changed at all. Now I searched and found related topics about common intake gasket issues causing loss of coolant. If that is the case, where would it be leaking into? The oil? The combustion chamber? It's so weird because I have no loss of power and no leaks yet my coolant is disappearing. Can anyone relate?:confused2::confused2::confused2:

 

[boostaholic]

Check the fitting that goes into the intake, it's a metal fitting that is very prone to leak (connects to the heater core outlet on the passenger side firewall. Check the lines too, my buddy that I sold my old limited to was having a similar issue. Oh yeah where are the pics at? I love those limiteds and still miss mine

 

[drumrpunk]

I will check that in the morning. I never thought to check the heater core lines...thanks! OK, for your viewing pleasure....

 

[treepete]

right on. that thing looks awesome.

You may be losing coolant, just so slowly that its evaporating off the intake. When my IMG was leaking, I found no drips, and took about a month to empty the overflow tank...

what a pain. I hope your is just the connector giving way. you can always smell it after driving around, but can never see it... the worst kind of leak ever.

 

[drumrpunk]

Thanks for the compliment! Well I looked and no such luck on the heater core hoses on either end. However, I did see a bit of water stains on the main hose connected on the top of the motor. But I am not sure if it's that becuase after I drove it I looked everywhere and did not see any water. You may be right on the money on this Treepete...It way just be evaporating so quickly I can't see. And since it's only about a quart or 2 a month, a whole lot is not lost during just driving around the neighborhood. Argg...looks like I am going to have to really get in there deep to see what the F is going on.

 

[DaveEye]

In doing research before I bought my wife's 99 Yukon I saw that a common problem is the intake manifold gasket leaking. There was a TSB on it as well. Apparently the gasket leaks which causes coolant to enter the combustion chamber and be evaporated. So, coolant loss without any noticable leaks anywhere.

Seems like fuel pumps, transmissions, and driver's side inside door handles are all problems to deal with when owning one of these

 

[drumrpunk]

In doing research before I bought my wife's 99 Yukon I saw that a common problem is the intake manifold gasket leaking. There was a TSB on it as well. Apparently the gasket leaks which causes coolant to enter the combustion chamber and be evaporated. So, coolant loss without any noticable leaks anywhere.

Seems like fuel pumps, transmissions, and driver's side inside door handles are all problems to deal with when owning one of these

OK, I knew I read about this somewhere. I bet this is the issue. I would think there would be a bit of vapor out the tail pipe on startup but who knows! Still no leak found yet.

 

[peterey2]

If you can find someone with a kit to pressurize the system thru the cap it should help you solve where its coming from.
That's how we do in the dealerships, and the only way I know of besides using the old flash lite.

 

[qlc1964]

i was loosing coolant too. after driving it i was looking under the the truck because

i just changed the transfer case oil and i seen a drip by the pass tire . raised up the hood

it was leaking out the heater control valve .And i never seen a puddle before finding

the leak.

 

[treepete]

man... take a look between the alternator and the AC compressor. see if you have signs of a leak there. not wet, just discolored... like it leaked and evaporated right away.

if you cant see the leak, and are not getting smokey exhaust, maybe you still have time.
the rate of coolant loss seems to be low.

mine was like this also. take some pics of what you saw at the thermostat area if you can.

 

[treepete]

heres that link with a pic of the leaky area..

http://www.tahoeforum.com/showthread.php?t=6663

 

[drumrpunk]

Treepete....looks like I have the same issue as you. Although mine does not look like it's leaking as bad. It may even be the hose, but I assume that since it's leaking in the same spot that it is inevitably going to need a new gasket there. I am surprised that your thread did not come up during my search. It could have saved me some time posting this but ohh well! I saw the hassle of taking the whole thing apart on your thread and it looks like I have quite a journey ahead of me. Now was there any upgrades to the top intake section that you could have done (aftermarket and such)? Since I am going to tear it apart I might as well replace some of the factory crap with some aftermarket bling.

 

[treepete]

yeah I wanted to do that as well. I guess you can put in a "marine" intake or possibly replace the plastic upper intake with a metal one.... but thats adding steps.. its the lower intake manifold gasket thats leaks on these things. I didnt research adding bling at the time, but I should have. I think JP422 has a marine intake on his 5.7 but Ill have to check. Maybe he will pop in to this thread

Mechanic Jiminey said only use the felpro gaskets, dont skimp on that part.

dont forget that dorman hose disconnect. cause yours will break off when you try to take it out. Maybe have a 1/2"tap laying around too.
If you want to get over the top, have all the stuff re-surfaced while your in there.

Youll have the engine half apart when you do this.. might be a good time to think of a camshaft or some drop in heads if $ is not an issue. If it IS, then maybe $100 in parts, and a weekend. Its not as bad as it looks. LMK if you want to talk about it some more or if you have other/additional questions.

 

[boostaholic]

Do the marine swap if you plan to keep the truck, makes a HUGE difference on these trucks. http://www.pacificp.com/forum/viewtopic.php?t=317

 

[treepete]

wow thats awesome.

 

[drumrpunk]

Thanks for your help Treepete. And that manifold conversion looks awesome. But since I live in communist California, I don't even want to mess with the smog issues that may arise. I want to do mild upgrades and have the money too but I need to make sure that they won't affect smog. I was looking for some 50 state legal bolt on's. I even failed smog on one of my cars becuase I put aftermarket plug wires on it that did not have a C.A.R.B. sticker for them....Can you F'ing believe that? So as you can tell I must tred lightly. Or I can pay a guy 300 bucks to look the other way when I smog it.

 

[treepete]

Sure thing. I wish you the best of luck, and let us know if you think of other questions about anything.