I Got Issues! Part I - Coolant Leak

[pwgood1]

I know it is difficult to help someone diagnose over the internet something that could have multiple origins, but, hey, isn't trying what internet forums like this are for?

I was crawling around under my truck just now with a flashlight trying to get the model number off some Rancho shocks that I just had put on on Friday. In the interest of organization, I think I'll reserve the shock issue for a separate thread.

While I was under there, I noticed what was clearly engine coolant dripping from the front edge of the bell housing, almost as if it were coming from the rear main seal. I say "dripping" but it was more like "evidence of dripping" as you could see where droplets had been forming on the edge of the bellhousing but there wasn't enough flow at the time to have it actively "dripping."

Immediately, I think "Ah, crap. I have a head gasket leak," only the coolant is straight coolant (not an oil-coolant mix) and when I checked the crankcase I could detect no signs of coolant (oil seemed like straight oil..not milky, no greenish hue, and no smells that smelled like anything other than oil that is probably about due for a change..although it wasn't overly dirty).

I don't think a head gasket leak *always* means coolant and oil mixing, but wouldn't mixing be fairly probable with a head gasket?

A few additional pieces of info that may or may not have any relation to the issue at hand...

- I had new fittings put on the A/C along with a new compressor not long after I got the truck. Since they had to go after the compressor, I went ahead and had the shop put a stock crank pulley, water pump pulley, and belt on it. At some point not long after this service, the truck developed a gurgling/trickling sound behind the dash on the passenger side. I've read up on a few things this could be. It is my understanding that a stopped up drain would eventually dump water in the passenger side floor board. My A/C still eliminates water outside of the firewall like normal and the floor is dry. Air in the coolant is another I've heard but the truck doesn't run hot (at least not according to the needle in the dash, but who knows if I can trust it). I turned the heater on defrost a few days ago to test out the heater core. It doesn't get not enough to make you want to move your hand off when holding it over the vents, but it is gets noticeably warmer than ambient air temp.

- Probably not coincidentally, I just towed extensively for the first time since owning the truck. I've towed a few light loads around town, but this weekend leading up to the leak discovery involved towing a utility trailer just big enough to fit a 500cc quad 160 interstate miles on Friday and 60 southern-WV state highway miles on Saturday. A few good, long climbs coming up I-77 from NC to WV and since it pulled the load like it wasn't even there I didn't exactly baby it up the road, but I wasn't winding it out and doing anything stupid, either. Even though the temp gauge read normal the whole time, it just seems unlikely that the leak springing so soon after all this towing is purely coincidental.

- It appears the leak probably sprung nearer to the end of my driving yesterday evening - or after I parked it - based on the relatively small amount of liquid underneath the truck, the fact there is seemingly no 'blowback' onto the rest of the bellhousing or trans pan, and the little amount of coolant lost. The coolant reservoir is a little low but fluid can still be seen in the bottom and there is plenty of fluid visible in the radiator.

- The side of the bellhousing on the driver's side of the bellhousing plug is dry. The side on the passenger side of the plug is wet with coolant. Seems to indicate that the leak is on the passenger side above that point (obvious, I know, but just "talking it out"). I couldn't locate the origin or even see anything wet at all on the top side of the engine bay when I popped the hood, but I was also hunting with a flashlight because it is dark.

- The radiator cap was a little tough to get off and the check valve is a little crusty. Could a sticky valve cap plus towing equal high enough pressure to blow some coolant out through a gasket or hose somewhere but not overheat the engine or entirely blow out a hose?

- The dealership replaced 2 (maybe 3..can't remember) freeze plugs when they took the truck in prior to my ownership. The truck as been leak-free for four months and 6,000 miles until now, but it has me worrying that maybe all the freeze plugs could have been corroded or had issues and they replaced only the ones that were easy access. Reaching here but wanting to provide all possibly-relevant information.

Sorry for the long post, but I'm 200 miles from home and a little stressed about this wonderful discovery.

I certainly don't expect an actual diagnosis over the internet, but....what should be my next steps here?

I'll obviously be out there in the morning searching for the source of the leak, but where, exactly, should I be looking?

Any suggestions for methods or "tricks" to help me identify the leak source?

 

[StruckBy]

I have seen stock oem head gaskets leak. It is also normal for the radiator to pump fluid into the over flow tank and draw from it as needed. You are right about your heat. It should be pretty hot when you put your fingers in front of the vent when the engine is warmed up.
Stock lower intake gaskets could also be an issue and so could the line that feeds coolant from the radiator to the EGR system.

There is no real way to check the lower intake gaskets without just replacing them.

If you are concerned about springing a bigger leak on your way back home then I do have a recommendation for you to get it back home with a little piece of mind.
Stop by a local GM/Cadillac/Chevy dealer on your way out and get a pack of GM cooling system tabs.
They come in a 6 pack. Crush up 1 and put it in your radiator, top off the radiator, and fill the over flow tank just the appropriate line....hot or cold.
Only 1 coolant tab at a time until the leak stops to your satisfaction. You may not need them all.

I do not recommend any other cooling system sealer out there. I am only basing this on personal real world experience. I know there are similar products but this is the only one I have first hand experience with.
When you get back home look a little further into the leak and replace gaskets as needed.

Oh and have the heat on and the engine running when you fill the cooling system. That should stop the bubbling sound under the dash.

**Note...still use appropriate caution when filling the cooling system with the engine running. Protect your face and have a thick rag to remove/install the radiator cap. The coolant should not come flying out with the engine running. Open it slowly it may bubble over a little.
Buy a good radiator cap without the pressure relief valve.

 

[tomlightning]

Could be a few things. I myself just did my lower intake gasket and found that it was getting ready to leak antifreeze from the back and front ports. Could be that. Could also be the egr spacer leaking, or the hoses itself behind the egr spacer. Ill bet its one of those.

 

[pwgood1]

I have seen stock oem head gaskets leak. It is also normal for the radiator to pump fluid into the over flow tank and draw from it as needed. You are right about your heat. It should be pretty hot when you put your fingers in front of the vent when the engine is warmed up.
Stock lower intake gaskets could also be an issue and so could the line that feeds coolant from the radiator to the EGR system.

There is no real way to check the lower intake gaskets without just replacing them.

If you are concerned about springing a bigger leak on your way back home then I do have a recommendation for you to get it back home with a little piece of mind.
Stop by a local GM/Cadillac/Chevy dealer on your way out and get a pack of GM cooling system tabs.
They come in a 6 pack. Crush up 1 and put it in your radiator, top off the radiator, and fill the over flow tank just the appropriate line....hot or cold.
Only 1 coolant tab at a time until the leak stops to your satisfaction. You may not need them all.

I do not recommend any other cooling system sealer out there. I am only basing this on personal real world experience. I know there are similar products but this is the only one I have first hand experience with.
When you get back home look a little further into the leak and replace gaskets as needed.

Oh and have the heat on and the engine running when you fill the cooling system. That should stop the bubbling sound under the dash.

**Note...still use appropriate caution when filling the cooling system with the engine running. Protect your face and have a thick rag to remove/install the radiator cap. The coolant should not come flying out with the engine running. Open it slowly it may bubble over a little.
Buy a good radiator cap without the pressure relief valve.

Lower intake and EGR sounds like it needs a closer look tomorrow when I have light other than what it coming from a flashlight. I'm thinking I might as well look for a new radiator cap, too. Mine had "13 pounds" stamped on it. I assume it is the stock cap and that the metal "button" in the middle is a valve.

As far as filling the coolant....thing is, I haven't really lost much. It is clearly leaking under there, but the radiator doesn't have much room for additional coolant. The reservoir could use some, though. This is with the engine cold (it hasn't been run since about 10pm Sunday night..I discovered the leaks about 9pm Monday night).

Of course, this changes if when I start the truck up tomorrow to drive it home I start spewing coolant everywhere.

 

[Adam@CGM]

I've had this coolant leak issue before. IIRC, the leak originated from the front cover, runs down the top edge of the pan and then appears to be leaking out of the bellhousing. Also, in my experience check the front of the lower intake gasket where the intake meets the head. x2 on the GM sealant tabs/well cubes. Pioneer also makes some that are great.

 

[bumperquip]

Check the small angular coolant hose from the lower EGR spacer coolant nipple to the rear driver's corner of the lower intake.

... super common failure resulting in a coolant leak/seep.

 

[droppedf100]

I would rent a cooling system pressure tester. Make sure the motor is cold, wipe everything down and put pressure to it and you should see it seep from wherever it is coming from.

 

[LSMOLIGHTNING]

I've had this coolant leak issue before. IIRC, the leak originated from the front cover, runs down the top edge of the pan and then appears to be leaking out of the bellhousing. Also, in my experience check the front of the lower intake gasket where the intake meets the head. x2 on the GM sealant tabs/well cubes. Pioneer also makes some that are great.

I have a small leak just like that right now. I am pretty sure it is coming from the TC as well. Its very small and hard to see where it is coming from with all the old oil and crud caked on the front of the engine. The leak is just big enough to be slightly annoying.

 

[motorhead1024]

Based on what you're describing, you should be fine getting home. Lots of good recommendations here ^^^. I would get the coolant tabs and pop one in before you hit the road tomorrow, then when you get home check the timing cover, EGR spacer, and use an inspection mirror to check the lower EGR coolant hose for leaks.

If there's no sign of leaking from the timing cover or EGR gaskets, then you should consider pulling the upper intake plenum. Replace the TB, EGR and plenum gaskets, the EGR cooling hoses, and replace the PVC valve and hoses -- all good preventative maintenance items on a 20-yr-old truck.

Good luck!

 

[Ranchero 1968]

EGR hose or my favorite, the pesky small leak on the timing cover, that drips down on the pan and runs back onto the midpipe and trans housing. It will imitate a leaking freeze plug. I finally repaired mine last Spring after three years of re-tightening the lower cover bolts.

I have a lengthy thread on it, which also has detailed pics and part numbers to include under hood detailing & restoration.

 

[Old white ford]

Dude.. I hear ya.. most likely the noise you hear with the ac on is the Freon pumping through the lines, which is normal. no worries.
2nd just ease that baby on home and clean it up, check it out, you will find the leak..
The hose on the back of the intake could be the leak. don't stick your hands back there and wiggle it around till you get home...

 

[IVSVS]

Dude.. I hear ya.. most likely the noise you hear with the ac on is the Freon pumping through the lines, which is normal. no worries.
2nd just ease that baby on home and clean it up, check it out, you will find the leak..
The hose on the back of the intake could be the leak. don't stick your hands back there and wiggle it around till you get home...

Gurgling in the cab and no heat from the defrosters = air locked heater core. It needs burped.

 

[Old white ford]

Gurgling in the cab and no heat from the defrosters = air locked heater core. It needs burped.

Could be but he went 6000 miles on it since freeze plugs. He didn't notice the noise till after compressor was fixed. He thought it was condensate/ clogged drain making the noise. turn AC of next time it makes noise and see if it stops.

 

[Old white ford]

Plus it gets noticeably warmer. It's not gonna get so hot you gotta move your hand

 

[chesebro]

Check the small angular coolant hose from the lower EGR spacer coolant nipple to the rear driver's corner of the lower intake.

... super common failure resulting in a coolant leak/seep.

This!! Its mostlikey this hose bump is reffering too... Mine was leaking from there too

 

[pwgood1]

Wow..lots of responses and good information. You guys are great.

Let me update you...

Went out Tuesday morning and looked everywhere trying to track the leak. Everything topside looks dry as a bone. Underneath I just can't see up in there far enough or well enough to figure it out. All I can see is pretty much what I described earlier - fluid is ending up on the underside of the oil plan flange as well as the area just above the input shaft (or whatever the part is called that enters into the bellhousing). Most of the wetness is on passenger side and the truck being parked facing slightly up a hill is a consideration. When it drips, it is coming from two points: 1) the oil pan bolt furthest to the rear and to the passenger side and 2) the edge of the bellhousing.

Wiped excess fluid away with a towel and took it for a short drive into town to get some coolant tabs from the local Buick/GMC dealer, some pre-mixed coolant from Advance, and a new radiator cap just in case.

Did another visual check when I got back to see if the drips are back already. Didn't see anything.

Crushed two tabs, put in radiator, filled radiator, filled overflow tank to cool line (very short trip, so truck wasn't very warm). Left cap off and started the truck per Eddie's suggestion (at least I think I was following his suggestion). A few bubbles and gurgles from the radiator, then I turned off the truck and put the cap back on. Not sure if maybe that simple action was enough to purge any air in the system, especially since I forgot to turn the A/C temp knob to heat to open up the heater core, but I haven't heard the gurgling behind the dash in the day since I did this. (BTW, Shaun, the gurgling would happen whether the A/C was not or not and occurred most often during startups and accelerating from stop).

Now for the interesting part... and as you read the rest of this, know that the temp gauge on the cluster has never, whether prior to the discovery of the leak or since, gotten past halfway (needle pointing directly up) and for the most part hovered around closer to the "O" in "NORMAL"....

I decided to say "screw it" and just hook the trailer up to the truck and drive it home. I drove the unloaded truck about 20 miles across town to where I was keeping the trailer and quad. When I got out to hook the trailer up, it looked like the bottom (side facing the road) of my driver's side wheel well filler (whatever you call the plastic piece that goes above the tires to fill in the gap between the fender and frame) was soaked with coolant. I open up the hood expecting to find a blowout of disastrous proportions, but the only signs of fluid was a little around the radiator cap, which could have just been some spillage from the fill, and a few drops on top of the overflow tank.

I would have thought maybe I overfilled (my stepdad poured some more coolant in the radiator after it receded when the truck was running, which I wasn't sure was a good idea, but it happened) and expansion pushed fluid out of the tank and down onto the wheel well area, but the top-side of the wheel well filler was dry except for the very leading edge of it towards the front of the truck and the sides of the overflow tank were relatively dry. It just seemed like it would have been wetter basically everywhere if the tank was purging ounces and ounces of fluid out of the top of it.

I hook up the trailer and take off, keeping an eye on the temp gauge and stopping at pretty much every rest stop along the way (about once per hour) to check the straps on the quad and to see if I can find any new developments on the truck. I wasn't crawling all the way under the truck, but I was taking a peek underneath to see if the drip off the bellhousing was back and popping the hood to look for fluid. I found nothing. Truck drove back home the same way it came up. No signs of struggle and nothing of concern from the cluster temp gauge.

Fast forward to this morning, I drive it to work and look under it again. All I see is 1) lots of water coming from the A/C off to the far passenger side, which is typical and 2) a drip coming off the very front edge of the bellhousing (not trailed back at all like the green coolant pic from the discovery moment that I also attached, but that trailing was probably due to the uphill parking angle). I catch a few drops on a paper towel and notice the fluid is not as green as what I found the first time. Maybe the coolant tabs take some of that fluorescent effect off the color, because I'm pretty sure it is still coolant and not a new fluid (pic of paper towel attached). To me it looks almost like fresh, new engine oil....if engine oil had a watery consistency.

I'm not sure my untrained eye is going to be able to see what the hell is going on in there, at least not without the convenience of a lift versus my fat butt wiggling underneath and getting a limited view of things. I think at this point I'm probably taking it to the shop that has been pretty easy to work with on some of my other services, paying for an oil change (it is due anyway) and asking the head shop guy there if he can take a look at the leak for me while he has it.

A few pics...

Water under the bridge at this point since I already got all kinds of great advice, but here are a couple pics of the initial discovery of the leak. It was dark with a flashlight, so not sure this really shows much, but...



Paper towel from this morning...

 

[LSMOLIGHTNING]

I feel your pain man. It has taken me quite a while to locate the very small coolant leak I have. I had to get it hot and drive i up on ramps and crawl under it with the engine running and wait till a drop finally oozed out of the T/C gasket.

 

[StruckBy]

your doing all the right things and way to stay after it.
Hopefully it will just turn out to be one of the small hoses behind the lower intake as Ron suggested.

 

[Ranchero 1968]

Maybe a pin hole or hairline crack that hasn't been located yet. You stated the overflow coolant tank boiled over? If so, something is definitely going on.

 

[Ranchero 1968]

With the engine cool to the bare hand, place an old blanket over the upper plenum, take some clean paper towels and climb up on the front bumper and lay on the upper plenum. Reach behind and down the back of the heads and lower intake, run the paper towel back and forth a few times, and then have a look. Do you see any coolant? If so, there is a good place to start.