Coolant Leaking (but from where?)

Ok all, first off a little background. I am an 18 year old college student, ASE certified mechanic (in training). The other day I had the ol' girl (2001 Chevrolet Lumina 3100sfi V6) in the shop to put in some new brake pads and to turn the rotars and drums. While they were turning I decided to lift the car up and do an inspection on my steering and suspension. It all checked out good, but there was something leaking onto the dust boot of my drivers side inner tie rod. I'm not sure its coolant 100%, but the car is never down any oil, and every 3 months or so I have to add just a little bit of distilled water to my overflow tank. Thats why I think its coolant. I have not been able to actually see the leak, nor have I found where it comes from exactly. My guess is it would have to be an intake or head gasket, but any info on this would be much appreciated. Thankyou.

Take a look near the old distributor plug. Mine was leaking from the LIM at that point, and it was leaking almost half a resivoir per day before I had enough cash saved to do it myself (not having a job made saving money difficult, you see). I'd check that location as well as the upper hose, possible (unlikely) pinhole leak is spraying down to the boot.

But I'd check under the TB at the plug location. Mine pooled up there and you could really smell the coolant at drive-thrus and such places.

There is a heater hose that goes into the intake just below the t-stat housing. There is a quick connect fitting there that rots out and starts to leak. There is enough tension to keep it from leaking, but if you grab it and wiggle it up and down, I bet you'll see coolant seep out. Don't wiggle too hard, or you'll snap it off. They are famous for breaking off in the manifold when you try to remove them, and getting the broken half out will make you learn new words your mom will wash your mouth out for using.

I learned the hard way i just broke that fitting off and the end was stuck in the intake. Tried using a easy out to get the end out but it was stuck in there good. I had to drill out the hole and retap it with 1/2-14 pipe threads. A new fitting cost me $15 at the dealer. Anyway i was fixing a oil leak at the oil pump drive and had to take off the intake anyway to fix the leak. That made it easies to retap the hole

Mine started out losing a little coolant at a time, and after a while it started losing more and more. There was never any sign of coolant leaking on the ground or sitting on any parts of the engine. Next thing you know, my oil looked like a chocolate shake. I am now in the process of tearing it apart to replace the head gaskets.

IF it's leaking on the ground on the drivers side, it's probably the fitting I mentioned. If you don't see any external leak, it's more likely the intake gaskets that plague the 96-up 3.1 and 3.4 GM V-6's. If you don't catch it soon enough, then you get to do head gaskets like CNA91 is doing. Don't automatically assume because there is coolant in the oil that it's a head gasket. Do a compression test first to determine whether it's a head gasket or just an intake gasket, as a failed intake gasket will allow coolant into the oil too. The gasket fails at the coolant transfer passage, so when it lets go, oil can be sucked from the coolant passage into the lifter valley via engine vacuum, causing the oil contamination.

Intake Gaskets!.You might want look into this,Fel-Pro has come out with updated intake gaskets for the 3.1 and there is an o ring that seals around the oil pump drive,that is the oil leak.The updated intake gaskets are made out of metal instead of plastic with rubber sealing areas.I have seen one so far but for the Vortec 350s after a jasper rep that comes into my father's shop that brought one in for a sample

The new fel-pro gasket sets for both the 60 degree v-6's and the 4.3/5.7 v-8's now have metal compression stops to reduce the chance of mis-torquing which leads to leaks. It is a common problem on the factory gaskets, because the torque value is so low.

I know Jasper uses the new Fel Pro gasket sets.Jasper threw away every plastic intake gasket set they had for the 350,4.3,3100 and 3400 what they had left.Do not drive one with a leaking intake gasket.I have replaced 3 or 4 3100s and one 3400 because some one drove the vehicle with the intake gaskets leaking and the oil took a long time to drain(the oil mixes with the antifreeze)

sorry, i had to bump up this thread again, it seems to be leaking more and more. not going into oil, or onto round in any noticable places, i will look for that throttle body line though. Any ideas on how to repair it to make it last longer without breaking it? How common is a waterpump being needed on the later modle 3100's? i have not noticed any seepage, but my best guess would be that when under pressure the coolant boils out somewhere really small. also there is some black crap in the top of my resivior where the old coolant used to be when warm? I replaced the cap already, i am hoping thats getting there because air is getting let into the system from the leaking coolant. someone confirm? arguments, ideas? thanks

my 97 leaked coolant - in unnoticeable amounts. - every month or so, i would have to top off the over flow.

mine was the lower intake manifold gasket. it was an external leak - very small. but the mechanic showed it to me. I got it fixed, and never had a problem since.

with mine - if you were looking at the engine, it was leaking in the front passenger corner of the engine. you could actually see "run-off" marks on the side of the head, where the coolant cleaned the head, and evaporated before it could puddle anywhere.

i guess look for leaks where the intake meets the heads.

There is a heater hose that goes into the intake just below the t-stat housing. There is a quick connect fitting there that rots out and starts to leak. There is enough tension to keep it from leaking, but if you grab it and wiggle it up and down, I bet you'll see coolant seep out. Don't wiggle too hard, or you'll snap it off. They are famous for breaking off in the manifold when you try to remove them, and getting the broken half out will make you learn new words your mom will wash your mouth out for using.

Yes I know that fitting. It was the only leak after doing head gaskets, etc. I replaced an o-ring during assembly but it needed replacing. Ordered 2 from my dealer. Had to saw off a new wrench to get it on due to the APV dash over engine design.

Mine started out losing a little coolant at a time, and after a while it started losing more and more. There was never any sign of coolant leaking on the ground or sitting on any parts of the engine. Next thing you know, my oil looked like a chocolate shake. I am now in the process of tearing it apart to replace the head gaskets.

You might want to get the afformentioned fitting in advance.

An alternative to buying that cheap pot-metal fitting: If you can remove the broken fitting without having to retap or enlarge the threads in the lower intake, a 1/2 x 2 inch pipe nipple fits in there perfectly. Put pipe thread sealer on both ends of the pipe and use a brass reducing hose bibb so it will fit into a 5/8ths heater hose, and clamp it. No more worries about that cheap fitting.:grinno:

you only have to top it off every 3 months or so? i have to refill the entire coolant tank every 3 weeks or so! yeah..still haven't gotten that fixed, i know i asked you guys about it awhile ago..it was the reason i joined :( and my dad still hasn't gotten around to fixing it. :rolleyes:

don't even try and give me that "get off ur lazy ass and do it yourself" i don't do the whole mechanic, fixing stuff thing. i dont touch tools either. so im sorta helpless when my car breaks. oh well..:dunno:

Actually... I noticed the same problem with my 97 3.1 lumi and it was coming from the 'lil rubber hose that attaches the 2 sections of heater pipe right above the waterpump... that damn thing was leaking so little that i didnt notice it til I did the pump, but the hose was wet and a slight wetness at the top of the pump housing by the 2 bolts... just my:2cents:... ofcourse if it isn't that... all the other suggestions are worth a good checking... considering the advice Ive gotten here has saved alot of $$$, heartburn and swearing... not to mention time too...


MYX