Alright well I've been having some coolant loss issues for the past couple of months now and could not find a leak anywhere. I know my heater core is on it's way out but I could smell the coolant outside the truck as well which led me to believe that there was a coolant leak somewhere else too. I changed my oil last night and as I was under the truck I could see coolant on the oil pan, transmission bellhousing area and near the starter so I have no idea where to start lookin for this leak. The freeze plugs that were visible looked ok. Could it be those infamous freeze plugs hidden by the transmission?? Also, as I let the oil drain I could see a little bit of white in the oil which my friend said was coolant...great. Is this a sign of a bad head gasket and if so, since there wasn't a lot of coolant in the oil, can I just replace the head gasket without doing an extensive amount of work?

 

Bad head gasket will turn your oil into a chocolate milkshake. If there was only a little discoloration... you might just be seeing condensation in there.

Behind the drivers side engine mount there is another freeze plug. Due to the way things are set up, dirt and crud gets trapped there, and the plug rusts out nicely. While driving, the coolant will be blown to the rear of the engine. Mine leaked for quite a while before I actually started seeing a puddle under the truck. Changing that one isn't really all that bad.

Another favorite spot is the timing cover...... someone in engineering thought it would be a good idea to have coolant pass thru it as well, and the aluminum likes to corrode, and it will develop leaks in the upper corners at the block mating surface.

Pick up a cooling system pressure tester. They aren't that expensive. Put some pressure on your cooling system, and watch the gauge, if pressure drops off, you have a leak, how bad the leak is, will be shown by how fast pressure drops.

So, pump it up to about 16 pounds, and start lookin'. See where it gets wet.

 

don't jump to the conclusion of a head gasket leak. it's generally associated with milkshake oil, overheating, coolant blowing out into the overflow, loss of compression, and maybe white smoke in the exhaust.

coolant on the outside of the block and not an overflowing overflow tank is more than likely a leaking water pump seal at the shaft, timing cover leak,hose, or freeze plug.

check for tell-tale drip under the water pump pulley.

 

I agree with the two previous posts. My 98 5.2 litre developed an "anti freeze" odour under the hood yet I had trouble finding the source. Months later the leak finally progressed to where I could trace it. The leak originated at the upper right corner of the timing cover and tracked down the block and along the oil pan rail. It was an elusive leak to say the least. I had to lay underneath the fan and use a really bright light to pin point it. Not a bad repair to have to make ....be advised, if you do end up changing the timing cover gskt there are a multitude of preventative repairs you will want to do at the same time. Trust me! Someone else will chime in to add to the list. Let us know what you find.

Thermostat, bypass tube/o-ring, distributer cap/leads, timing chain/gears, plenum plate, water pump...just a few you might want to consider.

 

I looked at the water pump and couldn't see any visible leaks. I'll take the pump off when the weather warms up just a little bit to check for sure. My pump and thermostat are fairly new but they aren't expensive so I'll replace those too. Timing chain only has 45k miles on it. Should I replace that while i'm down there? Also, my plenum also only has 45k miles on it as it was replaced at the same time as the water pump. The guy didn't think it would leak again but that was before I was on DF. Is the plenum easier to get too with all the stuff off the front of the motor?

 

Either job is easier with the stuff on the front gone, the bracket for the alt, and a/c compressor needs to be out of the way anyway, to do either job. But, as opposed to ripping it apart, just to replace parts that might... be the problem, find the leak. It might be as simple as the hidden freeze plug. a buck and a half for the part, and an hour or two to change it.

 

Thanks heyyou. I wasn't gonna tear anything apart till I found the leak. I'll search for that freeze plug and do a pressure test. Can you see the freeze plugs at the back of the engine block without removing the transmission because I could not see them at all.

 

i very highly doubt it

 

No. you cant. They are cleverly concealed behind the drive plate...... If you pull the inspection cover, you would get a better view of any coolant dripping out of there though. On mine, the timing cover was leaking at the top, on the drivers side, but, the coolant would run down the mating surface of oil pan to block, and it LOOKED like it was dripping off of the bottom of the bellhousing.....

If the freeze plugs at the rear ARE leaking, only way to change them out is to drop the trans, or, pull the motor...