Coolant Leak

I have a 1997 K1500 4WD and it is leaking coolant. Earlier this year I replaced the radiator and I've checked all the lines going into the radiator and they seem alright. The coolant seems to accumulate on the inside of the front bumper on the passenger's side.

I originally thought it was from a return stub on the new radiator that my truck doesn't use as the cheap cap they provide seems to leak a drop every now and then. But this other leak is more.

It's probably leaking somewhere towards the center and then rides down the rail and drops to the bumper. I'm looking for suggestions as to where to look as I can't seem to locate the leak.

Thanks in advance for your thoughts....

The system should be pressure tested to pin point the leak. It could be the intake manifold gaskets leaking. I have seen it leak from the block onto the frame rail.

//2000CAYukon

I have a 1997 K1500 4WD and it is leaking coolant. Earlier this year I replaced the radiator and I've checked all the lines going into the radiator and they seem alright. The coolant seems to accumulate on the inside of the front bumper on the passenger's side.

I originally thought it was from a return stub on the new radiator that my truck doesn't use as the cheap cap they provide seems to leak a drop every now and then. But this other leak is more.

It's probably leaking somewhere towards the center and then rides down the rail and drops to the bumper. I'm looking for suggestions as to where to look as I can't seem to locate the leak.

Thanks in advance for your thoughts....

If it is leaking on the front bumper it must be coming from the radiator... remove the covers and look for the leak , if necssary remove radiator to get a better inspection... and if necessary I would put 5-10psi of air in the radiator when removed and look for bubbles ...intake manifold is usually down the back of engine unless you park facing down a steep hill.


your hoses are easy to inspect so that should already have been ruled out.

Thanks to you both for the replies, this gives me something to go on. I'll be so ticked if it's the radiator. I just replaced it no more than 6 months ago. Although I did get it from NAPA....

I've also noticed that if I fill the system, including the reservoir tank, over time the reservoir will empty out, but the radiator always stays full. This made me think it had something to do with the reservoir tank or the hose(s) running to that tank, but they are so far back it shouldn't hit the front bumper.

Sometimes when I shut the engine off and I'm sitting in the truck, I here a sound from under the hood like a "glub, glub, glub....glub, glub, glub....glub, glub, glub....etc." Is that coolant moving to and from the reservoir?

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Sometimes when I shut the engine off and I'm sitting in the truck, I here a sound from under the hood like a "glub, glub, glub....glub, glub, glub....glub, glub, glub....etc." Is that coolant moving to and from the reservoir?[/quote]



ya thats what you will hear when the air is being transferred within the coolant system as when engine is shut down the coolant temp rises for a time...


lets say the radiator has a defect...NAPA should take it back with your receipt...before installing the replacement do I as I said pressure check first then install....

Just for kicks take a look at the wheap holes in your water pump, if you have any white tracking marks you need a new pump. Remember there is one on the top and bottom so check both.

This thing has me soooo puzzled, I checked the weep holes on the water pump, nothing there.

This is the latest that I've noticed, I refilled the reservoir and the leak down the passenger side of the frunt bumper got worse until the reservoir was empty again. The radiator never gets low even though it's obviously not leaking straight out of the reservoir tank and the leak is evident towards the front. It gets so bad after refilling the reservoir that it actually pools in the fan shroud. I put a pressure tester on it and could not locate the leak.

So my questions are:

1) Since it leaks more when I refill the reservoir, does that mean it's only leaking when it has a certain amount of pressure (I'm assuming if the system is truly full the way it should be then there's more pressure??)

2) Since it's bad enough to pool in the shroud but I can't see anything when I put a pressure tester on it does that lead to anything?

I suppose the radiator could be defective and leaking somehow and I just haven't been able to see it, but then why does the coolant level in the radiator itself never get low?

If it isn't leaking when doing the pressure test, then I'd guess that it is leaking somewhere between the reservoir and the radiator. Check the hose for loose fitting at the radiator or cracks. Also check the nipple itself for excessive flash from the molding process where the parting line would be...take a knife & smooth this out.

This thing has me soooo puzzled, I checked the weep holes on the water pump, nothing there.

This is the latest that I've noticed, I refilled the reservoir and the leak down the passenger side of the frunt bumper got worse until the reservoir was empty again. The radiator never gets low even though it's obviously not leaking straight out of the reservoir tank and the leak is evident towards the front. It gets so bad after refilling the reservoir that it actually pools in the fan shroud. I put a pressure tester on it and could not locate the leak.

So my questions are:

1) Since it leaks more when I refill the reservoir, does that mean it's only leaking when it has a certain amount of pressure (I'm assuming if the system is truly full the way it should be then there's more pressure??)

2) Since it's bad enough to pool in the shroud but I can't see anything when I put a pressure tester on it does that lead to anything?

I suppose the radiator could be defective and leaking somehow and I just haven't been able to see it, but then why does the coolant level in the radiator itself never get low?


the coolant system pressure is determined by the coolant cap....your cap if old should be replaced...the coolant res. should be removed and cleaned the tested with air pressure and look for leaks...then check and replace any hoses that are cracked or excessively soft...

when you reinstall wash all coolant spills and fill res to the full cold level.....idle it and block radiator air flow so it will get hot ...look for leak...

Ok, I think I've got it figured out. Are you guys ready......

loose cap

there I said it, I'm embarrased but I admitted it.

When I replaced the radiator I knew enough to also replace the cap, but it doesn't seem to fit quite right. If I push down on it hard enough, I can keep it spinning as I turn it, it never "locks in". Yesterday, I was messing with it and putting slight pressure on it as I turned it and.....click.

I didn't think you should be able to spin those things like that. I'm wondering if I should get a different cap. This one seems to be fine now that I've got it positioned right, but it doesn't seem like you should need to finnagle a cap to get it in the right spot.

Ok, I think I've got it figured out. Are you guys ready......

loose cap

there I said it, I'm embarrased but I admitted it.

When I replaced the radiator I knew enough to also replace the cap, but it doesn't seem to fit quite right. If I push down on it hard enough, I can keep it spinning as I turn it, it never "locks in". Yesterday, I was messing with it and putting slight pressure on it as I turned it and.....click.

I didn't think you should be able to spin those things like that. I'm wondering if I should get a different cap. This one seems to be fine now that I've got it positioned right, but it doesn't seem like you should need to finnagle a cap to get it in the right spot.


thanks for that info...the cap on a radiator is a bit difficult with the pushing down pressure....before rotation...the other inportant item is to get a cap with the same or slightly less pressure...never put a 16cap on a 15 psi system...

that why I stated to replace the cap when you stated the res level droping only... good luck..

I have officially learned my lesson:

NAPA sucks!!!

So I've been chasing this coolant leak for awhile. In the meantime, my wife's Pontiac Montana needed a fuel pump. Got one from NAPA, installed it, worked for a day, went back to NAPA, got another one, installed it, working ok so far, but I'm less than confident.

My coolant leak was getting worse. I removed the skid plate to see if that would help me track it down. I can replace stuff, but diagnosis is a challenge for me. So I can see coolant all over, but can't tell where it's coming from. Not getting good heat and it's cold, so I finally give up and take it into the dealer.

They call me back, said it's got two leaks. One is the intake gasket, leaking pretty good. I actually knew about this one, but was hoping to last the winter and tinker with it when it got warm. But, now that I am thoroughly defeated, I accept their offer to fix the intake for $570.00.

Second leak is ------THE RADIATOR------, so bad $300.00 fuel pump, bad $300.00 radiator. I will never, ever, in a million years buy another thing from NAPA. Call NAPA, state, I just did this radiator in May of this year. Response - that's too bad. Dealer says they can do it for parts and labor for $369.00.

Now my total bill is up to $960.00 or so with the dealer. But I'm extremely frustrated with NAPA. I believe the exact price I paid for the radiator from them was $270.00. And the dealer can put in a GM radiator with labor for $370.00????? Why the hell did I bother trying to do this one myself? I mean $100.00 is $100.00 but not when you get crap parts.

At any rate, I learned alot through this process. I was so proud of myself for doing the radiator without the help of my step father who is a mechanic. Just to find out it's leaking again.

Alas, I'll have the intake done, radiator that will be warranted and hopefully good heat in the truck.

:banghead: NAPA is the :devil: and to them I say :flipa:!!!

this is something that can happen when you put off your maintenance....working in the cold with no garage is very nasty...

you have a vehicle that is old...when you own vehicles such as this you must have/develop repair skills...the cost of having others repair/routine maintenace of this vehicle would be very costly...If you find that performing these tasks is overwhelming , you should buy a newer vehicle that will in most cases require less severe repair demands...

hopefully the dealer will give you a guarantee on this work performed ...because if you have problems,,,, napa and this dealership will be lessons learned as a vehicle owner..

NAPA has some parts with warrantee...before buying/call and find out the policy on returns....lifetime warrantee or at least 1 year is needed...if the warr is 3mo. you know its junk...

last posting I thought you had this under control...

I appreciate the thoughts J-Cat. I used to lease myself a Cadillac and my wife an Equinox and realized the money I was throwing away. I actually enjoy working on vehicles but obviously my skill set is still limited. I knew when I dumped the leases and got the vehicles we have, the responsibility of maintenance would be on me.

I still have feelings of nervousness and self-doubt before I start what I feel are big projects like my wife's fuel pump and my radiator. When you're developing those skills, it is important to have confidence. I'm also trying to limit the amount of imposition on my step-father for help.

So when I gather the courage to get one of these jobs done and I end up doing the repairs correctly but end up with junk parts. It gets frustrating and you begin to question. I just need to remember it wasn't my fault.

I was looking forward to tackling the intake gasket, but gave up. So it's done and the truck runs great but I am disappointed.

*spam removed*

My guess would be the lower radiator connection or clamp.

I hear you about changing this stuff out in the cold...just replaced my radiator in ~30-degree weather. But this truck is one of the easier ones I've worked on. If your '97 is anything like my old Jimmy, there's alot more crap crammed under the hood (danged emissions). Anyhoo, back to issue....

When I pulled the radiator, there's a nice tray-like frame underneath that goes all the way across the front that catches all the drips and directs them to drain holes drilled into it at intervals. The two foam rubber mounts for the radiator separate this tray into three sections. So anything dripping from the passenger side will drain there...rad itself into the middle...and driver's side, etc.

If you are using the stock spring clamps I would remove them and use the screw-type band clamps. As mentioned before, the end tanks are molded plastic and there may be a parting line that runs down the hose connector. If it isn't smooth, the hose won't seal. Scrape away any flash, use some hose connector lube and secure with a band clamp.

Finally, if you're unsure of how to tackle a repair or upgrade...do research, read up, size it up, and ask questions here and elsewhere. There's a ton of info on how to do almost anything online, and information is power. A good repair manual is a good start. And your collection of tools will grow with each passing day, project, and curse. Good luck!

BTW, the previous post by Jessica2008 is spam...it should be moved and the user banned.

My guess would be the lower radiator connection or clamp.



BTW, the previous post by Jessica2008 is spam...it should be moved and the user banned.

just thought I'd let you know that this guy found his leak,,, the NAPA radiator he put in was was bad.....thats why he found the antifreeze on the bumper...also he had the known intake leaked fixed all by the dealer for alot of money....

"NAPA SUCKS" in his words...

Oops...that's what I get for not reading far enough back into the thread.