99 burb leaking coolant

I have a 99 burb 1500 5.7 liter 2wd, the last several weeks I have been finding drops of antifreeze on the garage floor. I have checked the level of the radiator - ok, also checked the level of the reservoir - empty. It seems to do it occasionaly, the temp guage is still normal does not change even when I'm pulling the boat with A/C on. I've checked the hoses, drain plug, and even looked at the freeze plugs on the block. Any Ideas what's going on????? Thanks

It is most likely the intake manifold gasket. It is very common on all the 96 and up 5.7 liter engines. If you look down by the alternator in the morning you will see antifreeze or crawl underneath and and look at the back of the engine.

I have a 1999 Suburban 5.7 and the drip start the same way. It was the intake/manifold gasket and I think gm charge me $750.00 or $1,200.00 to replace it. It was a lot and I tryed to forget it. It been find now for 2 years. Dave

If it is the intake gasket they are not that hard to do yourself. Just time consuming and without a scanner you have to mark the distributor and block very well before removing the distributor and make sure you don't turn the engine over. The reason for marking it good is because there is no way to time it without a scanner and by marking it you will be able to put it back where it was and it should fall within the acceptable range of 0 degrees + or - 2 degrees.

you know it may not be the gasket like other think it is if your looking at the front of your truck and you look to the left passager side you will see a hose that connects to the intake manifold..
look at that connector is a male plug. quick disconnect type... these are made of a composition of medal copper and plastic.. go figure? anyhow these crack over time and its hard to spot the leak since it runs down the block... check for loseness rotting/corrosion... its about 15.00 form the dealer for the part..

you know it may not be the gasket like other think it is if your looking at the front of your truck and you look to the left passager side you will see a hose that connects to the intake manifold..
look at that connector is a male plug. quick disconnect type... these are made of a composition of medal copper and plastic.. go figure? anyhow these crack over time and its hard to spot the leak since it runs down the block... check for loseness rotting/corrosion... its about 15.00 form the dealer for the part..


Good point Mike !!

I've had both types of leaks (also 99 suburban) search on my name for threads on this. I've added what I learned in these threads so not going to repeat here except to say....

If its dripping and running down the back off the tranny bell housing, probably its the intake manifold gasket. It took me a while to do this as pulling the manifold is time consuming first time. Make sure you clean off that manifold and use lots of sealant.

If it is dripping more to the front, could be the heater hose outlet fitting. This comes out of the pass. side to the front of the engine. Had a quick connect fitting. Made of "pot" metal and fails after your warranty expires. New ones are steel - make sure you check they give you steel - use a magnet. Pot metal not magnetic. Also will probably need to ream out the fitting's threads as the pot metal gets stuck down in the hole from detrioration.

There are several GREAT postings, in addition to mine :smile: in SUBURBAN and more over in TAHOE forum discussing this including the fitting size and thread count for the tap you'll need.

I see where you mantion about finding more specific information regarding the , ahem, tapping of the Quick Connect fitting. Man, there are certainly some bonehead moves out there but this one amazes me!

Mine rotted, put a socket on it and it was like melted butter. Tried to ream bit the lock tite is working!

Need to rethread. Size help?

Great site! I'm new and hope to be reciprocal with helpful info.

to remove that fitting that broke in your intake manifold you use a reverse threaded easy out.. you take the tool and tap it into the slot enough to get a grip and you unscrew it... they have these at your local hardware store you need a size 8.

good luck

I have a 99 and I also have a water leak about once a week. Not much fuild lost and small drips from the front pulley area. If I start the engine and run it for a mile and then I shut it off the leak will stop. I am thinking is the water pump seal and when the engine stop at one spot it leaks. I had the head gasket replace by GM last year for $800 or so. Dave

Well it has been completed! If ever you find yourself having to replace this quick connect; do yourself a favor. Stop at the plumbing supply house and grab a 1/2" pipe thread tap. It will turn a nightmare into a 20 minute job!

Hi Y'all,
This is a great site for used car owners, and is great at showing how GM cut every corner it could find with poor materials and design.

I've had that corroded fitting replaced, I've had my water pump and coolant hoses replaced, and I've still got this slow leak of coolant through the intake manifold gasket.

I just replaced my transmission after 90,000 miles and am looking to try and save some money on fixing this leak.
1. Do After market sealant products work for fixing the intake manifold gasket coolant leak problem? Has anyone tried using them???

2. Also, if it comes to replacement, is there a new and improved gasket made of an improved material that should be used?

3. Finally, since I've been driving it with this slow leak for years, can I assume the failure occured in such a way that it won't destroy my engine (the engine would have failed long ago if coolant was leaking in, wouldn't it)??

Thanks,
Suburban Bob