The Stovebolt Site Forums The Shop Area Engine Shop 98 Chev antifreeze leak

I am having a problem with my 1998 Chev Suburban 2WD, with a 350 Vortec. It is leaving a small puddle (maybe a tablespoon each time it is parked) of antifreeze on the garage floor. The antifreeze is coming from the passenger side of the engine and is dripping from the skid plate on the cross member and the right side of the pan, right back to the bell housing shows signs of antifreeze dripping.

I have crawled underneath and I believe confirmed the following things;

-antifreeze is not coming for a loose hose, as all hoses do not have any sign of antifreeze residue. In my climate of cold temperatures, -30 to -45, hoses will sometimes shrink and a small amount of antifreeze will leak out.
-block heater is not leaking
-frost plug behind the starter is not leaking. Yes, I took the starter off and looked.
-driver side drain plug is not leaking

The antifreeze is showing up on the passenger side of the block. That is why I took the starter off to check the frost plug.

My two suspect areas are;

- on the passenger side of the engine, where the drain plug would be located is a sensor. A friend who is an automotive mechanic told me this is an anti-knock sensor. Has anyone ever had this sensor out? If so is it a pipe thread like a drain plug or is there an o-ring in there somewhere?

I would ask my friend but he left town last Wednesday for his two week tour at a diamond mine.

I have tried to clean off around this sensor this afternoon, and then I backed it out of the garage and warmed up the truck. It is now back up on blocks and after 15 minutes I had no signs of antifreeze leaking anywhere.

- the water pump, as the truck has 110,000 miles. But I can't really see up in to the water pump with all the other stuff on the engine. Either that or I have no idea what a water pump looks like! If the water pump were the problem wouldn't there be antifreeze dripping from the front of the engine?


Any experience or ideas are appreciated.

Oh did I mention that my nearest Chev or GMC dealership is 375 miles away! There is a local garage that will fix it, but I would really like to fix this one myself.

Blaine Dumkee
Fort Smith NT
Canada

Well ,there are many areas that could leak coolant, including the headgaskets. The laek doesnt' sound too serious,is there is no evidence of coolant in the crankcase, that could be serious. If a parts store is wth in range of your dog sled ,try some mild cooling system sealer, like the silver seal in the small tube.

NorthernGMC: This may sound a litle silly but MAWS Vortec had small leak same as yours. Chased that thing for a month. Finnally decided to change radiator cap. It would only leak after several miles, after engine got good and warm, the cap wouldn't hold pressure right and leak from overflow tube,same syptoms as yours. popcorn :p :p

The knock sensor is in a blind hole. There is no water behind it. I can't help on the gas motor, but our 6.5 diesels have a lot of leaks when they get really cold. Hoses and fittings like you said. They leak alot around the upper water crossover, and it runs down the middle of the engine and leaks out the back by the starter. Try looking higher up on the engine. Didn't that engine use the quick connect fittings on the heater hoses? Joe

After I have cleaned it up the best I can. Someone else suggested it might be the right front corner of the intake leaking. When I checked there was a small puddle of antifreeze on in a casting groove on top of what I think should be the water pump. So I cleaned everthing up as best as I could and put the truck outside to warm up. After 15 minutes no signs of any leaks.

I took it for a short drive, and still no signs of anything. So it is now parked back in the garage, and after 3 hours no sign of a leak.

Two things I am wondering about.

1) Maybe it is the upper rad hose leaking when it is left outside in temps below -30 and it takes a while to work its way down.

2) Right now I have the truck up on ramps in the garage and maybe this has something to do with it.

Thanks to all and I'm still looking for the answer!

I believe your antifreeze leak is the rear of the intake manifold. The Vortec 350 96-98 is known for this problem, It is about a 5 hour job to replace the intake manifold gasket. It leaks in the back of the manifold , in the valley. Good luck.

the intake manifold gasket is leaking... good luck. mine was not fun. and while the manifold is off you can replace the heater hose quick connect, as this should be starting to leak shortly. when you remove this fitting, it should brake off, leaving you to chisel or grind the rest of the fitting out of the manifold.

Four late model small block trucks in my family. Four intake leaks within three months of each other.
Good times, good times.

I don't think this is your problem, but my 97 1500 has the half plastic radiator. When it is cool it will leak, but after it get warm it doesn't. The leak is where the transmission fluid line goes into the radiator to be cooled. It leaks around the hose. Take a look at the trans and oil cooling lines when cool.
Also this can't be repared the radiator has to be replaced.