Hello all, my 1989 Pontiac Firebird Coupe with a 2.8L and my 1987 Pontiac Trans Am GTA with a 305 TPI are always losing Prestone. I have to check the level of it at least one time by week... Their is no Prestone on the ground, I checked in the engine oil and it is not there too... What the **** is going on? Where is the stuff going? I'm not a mecanician, so I wan't to know what exactly I have to replace or repair. And I speak french normally so try to be clear. Thanks a lot guys!

since your oil is OK, it might not be a blown headgasket...hopefully.

Fill it up (use distilled water), run your car and watch. Some holes don't open up until it gets hot or the coolant flows through the thermostat. You may just have some bad hoses or a leaky radiator.

I can't use water 'cause I live in Quebec province, in Canada, and it's very cold outside, it will freeze! Maybe when I go to another town (It's at 100km from here) where my family lives, that's when the Prestone level is going down? The guy at GM said maybe it was a pomp of something (can't remember wich one). When the car is in place, their is no Prestone on the white snow... (Pretty easy to see in the snow!) Anyone else had this experience?

If they said it's the pump, it would be the water pump, and there would be stuff left lying on the ground if it was that.

If it isn't coming out, then you are burning it. Most likely a blown head gasket. That's a ton of work or alot of $$$ to replace. It will show as white smoke in the exhaust, milky colorations in your oil, and some other symptoms I can't recall. If that is the case, don't drive your car, and fix it immediately.

Edit: Just fill it up, run the car HOT (until the fans turn on) and watch. Hopefully it will gush.

If its any help, most of the time a blown head gasket will cause the engine to run hot and it will get hotter as you drive. There is also a kit called a chemical block tester. They have them at parts stores and the instructions are self exlplanitoryn and it will help to determine if a head gasket is blown.

Kyle

I just found a similar water leak on my 305 TPI Trans Am. The water pump has a "weep hole" on the back edge of it (on the front side too) where water is allowed to leak out when the seal goes out for the main shaft running through it. I had to top mine off every other week and never found a drop of it (until the thermostat housing cracked this week). The water pump was leaking just enough coolant to make tracks down the timing cover on the block, but would steam off before any reached the floor.

The way I found it was to let it sit until the fans came on, shut the car off (because the temperature and pressure actually rise when you first turn the car off), then looked for steam or water. Finally saw what I was looking for... steam out of the rear weep hole on the water pump. It was very slight and very hard to see, but that was the whole problem.

Good luck!

You will also mysteriously lose coolant if you have an intake manifold leak.

It could also be a cracked head. It's a long shot but I see it all the time.

Never mind. I just drained my oil and it looks like I have a blown head gasket too
It was clean on the dipstick though.
Unfuc*ing believable

i have the same problem in my 92 Z28, 350 car. No problems with the oil, no visible leaks and no remnants of leaks anywhere. just disappears. car never white smokes or anything. it baffles me.

I chased a coolant leak on my TPI Z28 for about a year. The coolant level would mysteriously, slowly dwindle down, and the car showed none of the signs of a head gasket problem. The car ran perfectly. Finally after a year of scratching my head I opened the hood when the motor was hot and heard a hissing sound. Coolant spraying from the intake gasket. It would leak, of course, only when the motor was hot and it was such a slight amount that it would evaporate off the motor and I couldn't see it. New intake gaskets fixed it. Just keep your eyes open and you will find it.

I think i have the same ****ing problem. My coolant did go down a little bit. I just assume that it "evaporates" over time or something. I do get the puff of white smoke when i first turn my car on, but it clears after running the car about 20 seconds.

IF, there is a coolant leak or whatever u call it, and money and time permitting i couldnt fix it right now, isnt it just fine if u keeping filling the coolant to proper level? Like as long its at the right level, whats real damage thats happening either way, cause the car is being cooled anyway?

Maybe i should take it to a GM dealer and pay top dollar and get this **** over with.

Start small first, take a screw drive and make sure all the hose clamps on the coolant hoses are all tight. If there's even one clamp that's a little loose that may be the cause of your problem. I think these cars just like to leak coolant anyway, on both that I've owned I always seemed to be loosing some amount of coolant over time. Good luck.

Okay, I'll check this out at my GM dealer this week, I will post my results here! See ya!

Coolant in the oil doesn't automaticly condem the head gasket. Intake gaskets are just as likely to leak into the lifter valley as they are externally unto the engine. If the head gasket was blown causing coolant loss, you should see bubbles in the coolant with the radiator cap off (engine running), not to mention a fouled plug or at least excessive deposits on the plug in the bad cylinder.

BTW, here is a picture of a customers Suburban that had a "mysterious" coolant leak. They just kept adding and adding but it never came back out... (yes, it was the intake gasket)

Holy Cow!!! is that lifter valley completely full of coolant like it looks? geez...that would be like, 5 gallons worth of it.

that's one of the 96-99 vortecs, isn't it? they had hella nasty intake gasket leaks.

Yes, thats a 5.7L Vortec engine, VIN code "R". Thats one reason I didn't want to use a SDPC Vortec TPI base, cause I don't know of any better gaskets to use that fit the Vortec pattern...

I have a 97 Chevy Tahoe and I had to do that intake manifold gasket thing a year ago...vortecs have a reputation for having that problem. I don't think it has to do with gasket quality, as assembly quality. That intake manifold has the lightest torque specs of any intake manifold I've ever seen. With that light of a torque spec, I would think it wouldn't take much for a bolt or two to vibrate loose in, oh about 60-80 thousand miles. I used a light threadlocker when I reassembled mine. I so alllllmost decided to put a little more twist on than the stock torque specs called for, but at the last minute decided not to tamper with it (i never want to have to pull off a vortec manifold ever again...talk about a PITA)