Missing anti freeze?

I have a 95 with the 2.5 (I think) I know it's a four. Anyway a couple weeks ago my heater wasn't warming up and my temp gauge was very erratic so I checked my anti freeze overflow and noticed it was bone dry so I refilled and kept out an eye for puddels or wet spots under the truck to try to determine where it's going to but never could find where it'd going and two weeks later it's low again? Oil level is fine and no discoloration, no seepage around radiator or cap, I did notice it being a little wet in the backtop of the engine (upper left as looking at it) that looks like it could be it and it's not by the heater core input/output in the fire wall just by the top left of the manifold? any ideas?

Yeah I got a couple of ideas for ya. Assuming you have checked all the radiator hoses lets move on. Look around your intake manifold, I think this is what you were talking about by "the backtop of the engine". If you don't know where the intake manifold is here ya go...look for your air filter and where ever it is connected to the engine will be it. It is aluminum and is bolted right to the engine heads, also it will be right after the throttle body. Look where the intake manifold bolts to the head and make sure it isn't coming out of there. If not then you may have a leak into your intake and I would have it checked out if you don't have the tools to do so yourself.

h-m-mmmm, I haven't wrenched on anything other than my v-max in a while but I'll give it a try as you recommended. Bout time to get my hands dirty. THANKS!

even if you do have the tools, have the intake looked at by professionals unless your machanic skills are exceptional

yeh man i got an s-10 94 that had the same problem the radiator has these rubber plgs inbetween the engine and the transmision and sometimes the plugs over long periods of time(100k miles) get rotted and cracked and only cost about a couple of bucks and there are 4-6 pluges the problem is u have to drop your trans to get to the plugs which will cost you in the 400's to get fixed because of the labor of getting the trans out but there are ways of getting around paying that much money... you can get something called radiator plug sealent which you get every 6 months and costs you like 7$ and you just pour it in your radiator and let the engine run for like 15 mins the only thing is you have to hope that the pugs arent too damaged or you will pay the mechanics price

Yes, if you are not an exceptional mechanic don't try to work on the intake manifold. I would consider myself a decent home auto mechanic and it took me a good 15 hours to do my 4.3L's intake manifold gasket from start to driving again. Just look around it for leaks and go from there. Also, check around the head gasket. With both of these you may not see any liquid but a white trail where the antifreeze burned off. Thats what mine looked like with an intake manifold gasket leak.

on th 1995, do you use the green coolant or the orange dexcool? i have heard many problems with dexcool "disappearing"!

My son's '98 S10 w/4.3L engine had the same problem of disappearing coolant. Turned out to be the intake manifold gasket.

REplace the rad cap. It is causing your problem.

Man BlazerLT, stop doing that. How can you say for sure the Radiator Cap is the problem? If it is the radiator cap there will be either a stream or residue of coolant coming from it. If the cap is original I would replace it anyway, they do get old, but with no sign of leak and the use of green stuff I would say intake manifold gasket. If dexcool is used then have it flushed out and put in the green stuff, go from there.

i had the same prob on my 93 4.3 w....
replaced the old rad cap.....didnt show any visable signs of leaking...........
problem solved......for me anyway.

good luck

Man BlazerLT, stop doing that. How can you say for sure the Radiator Cap is the problem? If it is the radiator cap there will be either a stream or residue of coolant coming from it. If the cap is original I would replace it anyway, they do get old, but with no sign of leak and the use of green stuff I would say intake manifold gasket. If dexcool is used then have it flushed out and put in the green stuff, go from there.

Who gave you the right to tell me to stop anything.

Buy the sounds of your post, you consider a bad rad cap to blow steam and spill fluid? What, did you learn you automotive knowledge from a movie or something?

Yea, maybe he should replace the engine seeing by your account, because there isn't any steam and puddles of coolant anywhere, it HAS to be something major right?

Maybe when we have a clunk in the drivetrain we should replace the transmission.

Air is introduced into a cooling system via a defective cap when running AND when cooling. When the truck is running, the cap will not be able to hold the 15-16psi required in our cooling systems and hence you will get the constant temperature fluctuations.

Also when cooling and the radiator and its respective fluid is cooling, it is supposed to draw coolant in through the coolant overflow resevoir to keep the system topped up. When the rad cap seal is defective, the rad will draw in air through the cap instead of the coolant that it is intending to draw.

So before you question my advice again, think logic, not drastic.

I know all you have just told me and even told him to replace the cap regarless because they do get old. Here is a question for you OH WISE ONE...If you read all of his post he states that the overflow was loosing water so where is this water going? I don't get it, if the water level is going down in the overflow tank then it has to go somewhere. With no drips, no steam, and no residue I would think a small amount is leaking into the intake. Last, if the leak is coming out he would smell the anti-freeze.

I know all you have just told me and even told him to replace the cap regarless because they do get old. Here is a question for you OH WISE ONE...If you read all of his post he states that the overflow was loosing water so where is this water going? I don't get it, if the water level is going down in the overflow tank then it has to go somewhere. With no drips, no steam, and no residue I would think a small amount is leaking into the intake. Last, if the leak is coming out he would smell the anti-freeze.

There is air in the system, from time to time the rad cap will seal properly and displace the air in the system.

That is also why he could be seeing temperature flucuations.

If it was a manifold gasket, he would be burning the coolant and from what i have heard from him, he hasn't report billowing white smoke out of his tailpipe yet.

Ok, so where is the antifreez going? I still don't know where you think the antifreez is going if the cap is letting air into the system. Here is a basic rule of engineering...In a system of specific temperature, pressure, and volume only a specific amount of gas or liquid can be present. If you increase the amount of liquid or gas one of the three constant values will change. By introducing air into the system he will not use more antifreeze but less because some of the volume is now being occupied by air.

BTW...I am only guessing the leak is into the intake because he has already said there are no leaks from any hoses, the radiator, or any where around the intake manifold. That doesn't leave too many options, unless it is dexcool.

Don't forget to check the passenger floorboard for wetness. It's possible that you heater core may be leaking as well.

The liquid is going to displace the air in the system.

This is not a hard thing to wrap the brain around.

I too had this same problem and the cap solved it and I had to add coolant to the system.

That makes no sense at all if he is getting air into the cooling system. The system is designed to not have air in it, liquid only. If air is sucked in then the air is displacing the coolant, air comes in causing coolant to stay in the overflow tank. I can understand adding fluid if you go from a bad cap to a good one because your engine will be able to suck up coolant from the overflow instead of air from the atmosphere, requiring more coolant. As said before, if air is in the system it will take up space normally filled with coolant.

Yes, and after a while, it won't require refilling anymore when all the air is out.

So it seems we are in violent agreement.

Yip.....

Now shut up.....




















...I kid..I kid....