I'm posting this in hopes someone may have an answer for me or at least a little advice... I have a 99 2wd 2dr blazer. 4.3 vortex, around 164k miles. I have a leak from hell that I cannot pinpoint. Seems it leaks more after about 5- 10 mins after I turn engine off. It's not oil I know. It has gotten all over the bottom of the vehicle due to leaking while driving. I'm going to put some pics and hopefully a video in hopes someone sees or knows something. I believe it's either antifreeze or power steering fluid. Fluid has a slight greasy feel and is light orange in color. It comes down from around the oil pan and trans pan. I've kept an eye on fluid levels but nothing seems to be getn lower. I am confused. It could possibly be water and antifreeze and resovoir replacing fluid loss in leak. Ive replaced the radiator, thermostat and water pump. Water pump about 1 1\2 months ago. I'll let pics speak for themselves... Thanks for checking this out...
need some help in Alabama.....

 

So is the coolant reservoir level dropping? What color is your coolant, Dexacool red, the std issue green stuff or a non-descript yellow? Due to all of your repairs that's the most likely source especially since your not seeing a fluid change anywhere and that's the largest amount of fluid in the truck, providing the largest source volume. You can confirm or rule it out with some UV dye and a black light. You can rinse it off under there and then run the truck in the driveway looking for the source.


George

 

As George said, wipe it off, then run engine in driveway to pin-point leak. Driving around blows the fluid all over the place.

 

How old are the coolant hoses? A while ago a forum member reported that he had a leak that was in the form of a pin hole in a radiator hose that would only leak when the engine was hot and the coolant was under pressure. Such a leak might not be noticeable while driving with fluid only accumulating when the vehicle and engine are stopped after which the coolant would still be under pressure, leak but then also accumulate.

 

Thanks George, when I replaced the water pump about 1.5 months ago I put a 50\50 mix of regular green stuff and water in the radiator... No dex. Can I spray a degreaser on everything on the undercarriage and then pressure wash it for cleaning?

 

Thanks to Lanny and Christine too....
to answer hoses are prob orig. They don't look to be in too bad a shape but pinhole could be poss. Blazer sat up for 4 years before I obtained. I've been gradually replacing things on it as needed. It has def been a project for me but I enjoy the challenge a ND the learning experience of trying to diagnose... I am just an average mech. Can do minor replacement s and stuff. I'm gonna go try and get some new hoses, upper and lower, clean it up and run in my drive. See if I can pinpoint or duplicate the leak. Oh, and the fluid in overflow seems to be going down.. I hope my water pump hasn't gone out again... How often should water be in upper hose on right side of radiator? Only when thermostat is open? Doesn't ever seen to have water in it.... Thanks guys & gals...

I've also just replaced these oil cooler lines shown above... Don't think they are leaking...

That's my project on the left....

 

In above I read that you added 50/50 water/green coolant, no DexCool.....if you did not completely flush the cooling system to remove all the DexCool....you have created a problem for yourself....green and DexCool do not mix! Creates chucks that clog-up thermostats, heater cores, radiators.

I have had a pin hole leak that only showed-up when coolant was hot and under pressure in the past.....so quite possible. Could also be the wonderful plastic tanks on each end of the aluminum radiator have a leak. Could also be the lower intake manifold gaskets, which are a known issue. Use a flashlight to look between intake and heads...if there is any green-orange fluid there....they will need to be changed. Use a paper towel to wipe under the upper radiator hose at the radiator, again looking for any fluid there.
Back to the radiator; there are four metal lines, two on each end. Left side is oil cooler lines, right side is transmission cooler lines. Look for fluid around these connectors.

Hopefully some RTV was used on the coolant pump to block connection gaskets. Surfaces were cleaned prior and bolts torqued-down correctly with a side to side, left-right pattern. Use paper towel around these two as well.

Let us know what you find.

I actually have a coolant leak right now that I have to go find on my 2002. Probably the radiator as it has been 10 yrs since I replaced it.

 

What Lanny and Christine said. Another clue of a failed set of LIM gaskets is you might start getting coolant in your oil. It’ll start looking like a milkshake. As far as under the truck I would just rinse it off, let it dry, run it in the driveway until it’s nice and hot then shut it down with the temp spike and then start looking around.

George

 

Do u think I would be able to change LIM Gaskets myself if that turns out to b the problem..I'll let y'all know what's up after I clean it up and run.... Thing is I drove it 4 awhile 2day and I could not get it to leak at all. Crazy!!

 

That you have coolant on the outside of the engine that could be because of the LIM gaskets but I've normally heard of them leaking into the lifter valley. If the LIM gaskets were leaking to the outside of the engine it would be from the front and rear of the heads.

I've heard of LIM gaskets on the verge of going out where it could be seen that there was some coolant in the oil. The thing is the LIM gaskets can fail catastrophically so that when that happens and then the mixed coolant and oil gets pumped through your engine the main-bearings can be ruined almost instantly. The only exception to this I have heard is when the person reported that they had used full-synthetic oil. Still this is something you want to avoid. As soon as I had heard of this possible failure mechanism and had decided that I wanted to keep the truck for awhile, I decided to do the LIM replacement.

As for doing the job yourself. If a garage is available in which to do it, most anyone can do it. You will need an inch-pound 3/8" drive torque wrench to do it right. I found it a pain to do because of all of the things you have to move out of the way. There was a nut on the lower end of the PS bracket that totally stymied me for a bit! LOL

If you decided to do this there are lots of threads on it. There are some other nice write-ups many of us have found on doing the job. The recommended gaskets are from FelPro and have a metal frame.

If you plan to keep your Blazer for awhile, replacing the LIM gaskets is a good investment. It is also a good time to upgrade the fuel injector system if you have a pre-2002 CSFI system with the MPFI system. https://www.motormanfuelinjection.co...onversion.html