Water leak? Overheating? 1999 Suburban

1999 Chevy Suburban, 350 engine, auto tranny.

I recently purchased this vehicle. About a month after having it, I noticed a large puddle underneatht the vehicle after a 20 minute trip into the grocery store. The vehicle was NOT running while I was in the store, it was parked and turned off. Trying to figure out what it was, I was led to beleive it was coolant.

I then found that the engine coolant reservoir was well below the cool fill line. I noticed no liquid in the radiator after the cap was removed. I purchased a gallon of engine coolant from autozone, filled it to the cold fill line, drove it home, then filled it to the hot fill line.

About a week passed, I noticed no other puddles under my truck, but I must not have been looking hard enough. This morning my trucks temp gauge was going back and forth, very hot, to cool, to very hot, to cool, until a warning light came on to check the gauges. When I got to work I noticed that the reservoir was EMPTY. I filled it with the coolant somewhere between the cold and hot fill lines, and worked till 3. No puddles under vehicle when I left work.

On the way home the temp was fine. less than 200 degrees. A little less than halfway on the temp gauge. Checked the reservoir when I got home, completely empty. Filled it up between the hot and cold lines. Now I am posting here. What should I do?

Thanks,
Goose

 

If you were leaking antifreeze, you will know it. This stuff stinks!

The "puddle" might have been just the condensation from your air conditioner. If it produces another puddle, verify if it's antifreeze or water.

You could have a leaking hose, radiator, water pump, bad thermostat, faulty radiator fans.

Do your radiator fan turn on? During the summer months, it's almost always on.

I would first determine if the system is leaking. Look under the engine area and see if there are signs of antifreeze (green). If it looks clean, I would then replace the thermostat, which is pretty easy and cheap.

 

It has to be leaking antifreeze, where else is all of the stuff I keep putting into the coolant tank going?

Its hard to verify what color the leaking liquid is because it falls onto the dirty parking lot. I will try and check when the engine cools.

I dont think the leak was the AC because the AC is currently not hooked up (i was trying to fix it, but hvaent had time to finish).

I dont think its the thermostat, because it only goes hot when I let the tank go empty. Once I filled the tank, the temp was fine.

The lid of the coolant reservoir has a tube sticking out that sticks straight down. A buddy of mine told me this is an overflow tube so that if the level of coolant is too high, then it spits out the excess. But why would it be spitting out excess coolant if it doesnt have enough in there to keep the engine cool?

Thanks for the reply!

EDIT*** Im not sure if the radiator fan turns on. You mean the main fan, the big ole giant thing in front of the engine? Yes, that thing is always spinning.

Goose

 

Update:

I just got back from outside, decided to check my radiator level, and the thing was EMPTY, I couldnt see anything in there at all. I filled a 2 gallon jug with water, and poured it in. The thing took 1.5 gallons to fill, then I made sure the reservoir was filled to the appropriate line.

My plan is to drive around for about 20 minutes to get the engine hot, watch the temp, then check under the hood to see if any leaks make themselves visible. The big puddle I saw could have been a one time thing, although I dont see what would have caused it.

Will post back soon with results.

Goose

 

You probably have a busted radiator hose if you lost that much already.

Let it sit idling in the driveway, it will heat up pretty quick.

 

Does the engine temp only climb to a hotter temp after the coolant is low? Or can this also happen if you idled the car for 15-30 minutes, where you can keep your eye on it (and the gauge of course!), while vehicle is parked over cardboard or hard surface where you can see signs of leak if there is one?

When you drive that 20 minute trip, is that highway miles or is that through town with stops and gos?

Are your a/c cooling fins clean out in front of the radiator and are the radiator fins clean and not packed with grass, feathers, or bugs?

Do you have an electric fan?

Has anything been modified about the fan area where say a shroud was left off?

Depending on what you might discover with suggestions already made, you could refill the reservoir, leave the cover open and see if it bubbles down in there, right away, when the engine is running. If it does, you could have a bad radiator cap or worse. Radiator caps increase the pressure of the coolant in the engine to about 15-17 psi and this raises the boiling point of the coolant. Without a good operating/sealing one, the engine can boil out the coolant, especially if you sort of fudge, the way some people do in the summer and have the coolant more watered down (coolant is pretty expensive these days so it is temptingto cut back on it, especially if it leaks. Always run the proper mix as that also lubes the water pump, and keeps the entire coolant system cleaner.

Have you ever run straight water over extended periods?, as this can lead to lime and a clogged radiator. I always use distilled water in my mix.

If there is a leak when you are running the engine, be parked over cardboard or hard surface where you can see where the dripping/spotting is in say relation to that overflow or the water pump, or from ?.

We know that either that water or coolant in that parking lot was either your coolant (not your A/C as it is inoperable), or you parked over someone elses A/C condensate water or leak.

Overheating engines is nothing to procrastinate on. You can blow head gaskets, if you have not already. And that will spit out water even if low and cause temp gauges to swing up and down. And with blown head gaskets, you don't even have to have a leak; the engine burns it inside. You may be able to smell it at the exhaust pipe if it is. It smells sweet. If in doubt, smell your other car or neighbors, then yours, to compare. It can also cause spark plugs inside to clean themselves, and a telltale sign is a spark plug, compared to the others, that looks like brand new and has no graying, tanning or carbon on it - the insulator in there could be pure white.

 

Thank you for your elaborate response. I will answer your questions to the best of my abilities.

Yes, the temp gauge only messes up when low on coolant. Whenever I filled the reservoir with coolant, the temp gauge stayed below the halfway mark.

Vehicle parked over pavement where leak can be seen.

Oh, also. I know that coolant found in that parking lot was mine, because it definately wasnt there when I parked there, and the puddle was so large that it was well out from underneath the vehicle.

20 minute drive thru town, with stops and go's, then idling for a few minutes.

I have only had this suburban for a month. I doubt the previous owners ran on straight water, they were wealthy and had all their work done by certified mechanics.

I have it about half and half, coolant and water.

Other questions I am unsure of.

After my 20 minute drive, I parked, left the engine idling, and went over to see where I thought it was leaking from. Sure enough, green coolant drops had already formed a small puddle. I climbed under the vehicle to find the drops coming off of the frame, which is located more or less directly under the reservoir, and the overflow tube. The drops fell about a foot behind the passenger front tire, 6 inches to the left.

I observed under the hood. Reservoir level normal (hot fill). I could see the top part of the frame, located more or less underneath the reservoir. It appeared wet, I am assuming with coolant, but the source of its wetness remains undetermined. I could not see anything dripping onto the frame. I saw where the rubber hosing and aluminum hosing goes into the firewall on the passenger side, the other end of the tubes heading either to the radiator or the engine block. These tubes did not appear wet, and I tried to touch the underside to make sure they werent leaking. But it was a tight spot, right next to a hot engine block, so I couldnt check every inch of it.

So what could it be?


In order to do this test you recommended, did you mean fill the reservoir, or fill the radiator, and leave the radiator cap off, start the engine, and check for bubbles? The bubbles would indicate boiling water, which could be how I am losing water? Or is the fact that I found leaking antifreeze evidence enough that my radiator cap should be fine?

The vehicle only hit the red zone in temp ONCE, today, for a few seconds when I pulled into my work and filled the reservoir with coolant. Could that really have been enough to blow a head gasket?

Thanks again for all replies. Let's find the source of that darn leak!

Goose

 

Okay, so we know you defintiely have a leak and yet the overflow is not overflowing the top of it. The bottom line is you have to find the source of that leak.

If too tight to see from above and below, you may have to cave in and take it to at least some cheaper mechanic who can do oil changes or go to a place that will give you perhaps an oil change, grease and at least try to find the source of the leak.


To check for bubbles, you look in the overflow reservoir.

As far as blowing a head gasket today goes: You had your issues before today. And it does not seem to be an issue of it boiling it out. It's just leaking it out; at least under pressure and heat.

 

i think i could better address the issue with one of those telescoping mirrors, that way I could see underneath. I dont imagine it should cost much to have a mechanic help me find a leak, but will he help me if I am not willing to let him fix it?

How specifically do I spot a leak? I dont think its drippng, I thnk its running, because I saw where the frame was wet, and nothing was drippng on it. So I just need to find a part of rubber tube that is wet, right?

Thanks again. You guys have been a huge help.

Goose

 

Wash it all down with a hose, then get up underneith. I'm guessing a busted radiator hose.

 

Find someone to pressure test the cooling system, or find somewhere to rent/borrow a cooling system pressure tester. The tester goes on the radiator in place of the cap, it is then pumped to create pressure in the cooling system, and force coolant out any leak that is present. To check for a blown head gasket install the tester pump in about 5 pounds of pressure, start the engine, if the pressure rises very quickly(in seconds) to 15 pounds or more then you have a blown head gasket. As for my guess, I am thinking either the heater core or a leak at the rear corner of the intake manifold, just guessing by location of where you said the puddle had formed.

 

Good news! I found the source of the leak.

Once the engine was a little cooler, I poked around in there some more, and saw the slow but steady drip on something my buddy called a bypass valve? (something like that). When we saw a slight crack, we pulled on it to get a better look. Pulling caused the crack to form into a full break, and coolant came pouring out (yes it did stink). It was a 3 way connector (3 hoses, two about 5/8 inch, one 3/4). I think one hose went to the reservoir, one to the engine, one to the radiator.

After removing it for me, a buddy of mine drove me to autozone (open 24 hours) and they didnt have the part. So now I am heading out first thing in the morning to get it from another store, and I am going to try and fix it before work.

I figure the system has more or less drained most of its fluid. I am going to add a gallon of antifreeze into the empty system, and the rest with water. Then hopefully we can put this thing to bed.

Thanks again to all replies. I'll post back once I get it completely fixed and am ready to celebrate.

Or I will post back when I screw up and end up in tears.

Definitely one of the two.

Goosey

 

Are you thinking of the quick-connect that is screwed into the intake? Those have a bad habit of corroding through.
Otherwise, the intake gaskets or water pumps are what usually leak on those.

 

Pretty big coincidence! I just posted my own thread about what I think is a similar issue. The late 90s 5.7 liter Chevys have had a problem with coolant leaks, both at the intake manifold gasket internally into the engine (bad!), and at the cheap quick connect for a hose on the intake manifold (replace with a $10 steel version). Sounds like you have at least one, hopefully not both.

I'm worried that my brand new Tahoe may have one of the internal leaks and am unsure how long to wait to fix it -- if it's not losing significant amounts of coolant, is it still something that could hurt the engine (small amts coolant contaminating the engine oil) that I should fix? If anyone has any ideas, please lemme know! Thanks.

 

If you are leaking internally, you will notice your spark plugs will be very clean, because the leaking antifreeze will basically steam clean them. You could also do an engine compression check.

If this vehicle is brand new, it should be under warranty, eh?

 

... because it's a '00 with 109,000 mi.!

Thanks, Mark! I'll check the spark plugs, and am kicking myself for not insisting on a prepurchase compression test -- meant to include that but forgot. I'll probably go get a tester and do it myself. Again -- thanks.

 

Well when those leak internally, they leak into the crankcase, not the combustion chamber. It will show up with a substance that I like to call butterscotch pudding under the oil filler cap.

 

I didnt read all of the posts above, but it sounds to me like your water pump is going out. We have had to replace two pumps on 1999 chevys here. The strange thing is that they only leaked randomly and not continuously when running like I am used to seeing. Let us know what you find out.

 

My vehicle (totally different make) has leaked coolant for 3/4-1 year, about the same amount as has not got worse, in that time. I measure the amount I add in a quart jar, and record the mileage, so I am accurate about this.

It has not gotten worse! None on the asphalt-cement, either; not one drip. #3 and #4 spark plugs get steam cleaned. Yet no coolant burning odor from tailpipe. The fact it is 2 adjacent cylinders would lead one to think of head gasket, but I am not so sure. Never heard of a head gasket leak that leaks for this long with the engine running strong and like a top and not completely burning trhough and causing a catastrophic failure like hydro-lock.

So when you add coolant, keep track of dates and mileage. Mine drinks a 1 quart between 200-300 miles. It varies as if where it is leaking, the hole gets plugged sometimes. My driving has been identical for years, so that is not the cause for any discrepency. I have opted to just sit back and observe this without adding any stop leak to my newer radiator in my car with - 263,000 miles!

BTW, none is in my oil - which I have not changed since I bought the car 3 years ago, and I've put on over 60,000 miles.