A new to me 89 305 TBI, has what appears to be an aftermarket or OE replacement radiator. When I test drove the car, the radiator fluid was red...like tranny fluid, and the owner added regular gylcol "green stuff" antifreeze... Well I was told that the mixture would solidify at high temps, and there is now a nasty gunk on the block below the thermostat housing. I scraped most of that off and it has not returned.

I did a standard flush and fill, did not use any flush additive or anything... Replaced with dexcool-compatible fluid, it took 7 quarts (4 quarts rad fluid, 3 quarts water)

That amount filled the vehicle to the "full cold" level on my resevoir. When I drive the car around, the level does not rise or fall, but I added more water/fluid mix to raise the level to the full hot level...

And even though there's no sign of a leak anywhere, the fluid level has fallen back down to the "full cold" mark, where it stays constantly. I haven't replaced the cap yet... no visual signs of damage, but are vapors leaking from there?

I had a 318 V8 dodge that did the same thing with the radiator fluid level.... Anyone know why?

James

 

What temp is the thing running at? Check the trans dipstick. Coolant in the trans? In rare cases the radiator can develop internal leakage between the engine coolant and the trans fluid. If it staying clean that is good news but I would keep a close eye. You mention different radiator. Is it one of those multirow units. Maybe the coolant is not getting hot enough to generate pressure. I would do a system pressure test and see if anything shows. These cars are notorious for running hot.

 

Danno,

It was suggested I might have trans fluid in my radiator and vice versa, but since the flush and fill there's no evidence of that. Others on thirdgen suggested there is pre-mixed dexcool radiator fluid that is red... so I'm not worried about a leak between the two.

The car is actually running at 160-170, in the city, which is something remarkable considering my 87 runs about 230 on the same roads and same driving. I figure if it's running that cool, there cant be too much wrong.

I'm gonna try replacing the cap to see if that helps, but if it doesn't, and none of the hoses are leaking (no drip leaks anyway), do radiators...just...loose efficiency as they age? I know they obviously dont cool as well, but do they lose coolant in the process?

Also, there was a 15-lb cap on there, stock calls for 16lb cap. Any significant difference?

Are there other problem areas (head gasket?) to look at?

James

 

First of all, GM uses almost exclusively 15lb caps. The Stant replacement catalogue lists a 16lb unit as a replacement, either will work fine. The dealer will supply you with a 15lb unit if you get one from them. GMSPO part #10409635 for stock cap. You have the opposite problem most TG owners have. I suspect that you either have a bad stat, no stat, or one at a lower temp than stock. If you are lucky enough to be running in the city at that temp something is amiss. The reason the recovery bottle is not changing is that the coolant is not getting hot enough to expand. After you shut the engine off the temp will go up because of lack of circulation and as the coolant cools it will draw back into the radiator. The fact that it sucked it down tells me everything is probably OK. You will know pretty quick if you have a bad head gasket. Check the oil for the consistency of a milkshake and a milky color. If OK then it is not leaking to the engine internally. That is good. If it is leaking out, you will probably find it. From what you tell me, I think you ought to check the stat. I ran a 160 in my 89 5.7 TPI and my recovery bottle level did not move much. I found MPG went way down. Keep me posted

 

Danno,

Sorry it's been forever but I've got an update... The stat is fine, I replaced it with little change in the operating temp. The car will heat up if I leave it sitting, obviously because of air flow... I've never really seen it creep up above 230 because the fan will kick on and the temp steadies off..

The coolant level is still worrying me... it just can't be right to have such little fluid in the resevoir, even if the car is running cool. I realize that the gauge could be reading incorrectly, but it moves so freely through the temp range that I dont think that's a significant problem.

The update is that the coolant in the resevoir has turned color. I put orange coolant in, it's now a brown-orangish red, definately contaminated, but I cant figure out with what. The transmission fluid level is perfect, never changing, and the fluid itself looks good.

When I did the flush and fill, I just stuck a garden hose to the radiator, let it fill, drain, repeat... almost no sediment left at the drain plug, but if the coolant was old, would this new dexcool compatible prestone loosen old rust deposits or likewise?

I'm really worried about my radiator!

The only other thing I can think to mention at this point is that when I bought the car there was a strange ... like oily, almost sticky residue on the inside of the windshield where heat would most likely strike the windshield... I've since windex-ed it off, and run the heater, and it has not reappeared, so it may be completely unrelated, unless someone out there knows something I dont.

James

 

the residue on the windshield was probably from a leaking heater core. especially since you say it was right where the heat would come out. Have you run the heat at all to see if it reappears? It wouldn't reappear unless you have the temp set to hot.

If nothing happens when you do that then the heater core must have been fixed already.

Hodge

 

Pray it's not the heater core and that it just is a small vapor leak. I had to replace my heater core and I swear on the life of tiny tim that it was the dang hardest thing I have had to do on this car!! Even puting my headers and making a new y pipe was easier I had the level problem and turns out it was vapor locked or something once I purged the system I had to add more fluid (about 1/2 gallon)but everything has been fine for about 8 months now :hail:

 

The radiator is aluminum, you will not see much come out of it by way of rust. If it does not have an internal leak to the trans which I believe it does not then it sounds like rust and the typical crap with an older car. To do a good flush you need to remove the stat and I inserted one of those in-line prestone fittings. You cut a heater hose and this thing gets put in, it has a fitting for a hose. In this way you can close up the system and force the crap out. Most of the rust and sediment will be in the block. It sounds like you need a good reverse flush to clean it out. The oily stuff on the WS I agree with the other guy's is probably a leaky heater core. I went through the same thing.

 

Still could be a Blown Head Gasket. I was always topping off my radiator fluid (once every month or so) in another car I had and there were no signs of leaks or the engine running bad. the engine was like this for about a year when one day while driving, the cars water temperature climbed really high (230* normally it's 180*) in traffic and when I pulled over the radiator was almost empty. After I filled the radiator up, I drove the car to the mechanic (ran fine) and found out that the Head gasket had a little tear in it next to one of the cylinder walls. A tiny bit of coolant was being sucked into the combustion chamber and being burnt with the air fuel mixture. There was also, no sweet smell that I could notice and the car would drive fine. After the Head gasket was changed, everything was fine. Anyways, that's just my experience, hope it helps.

 

The wierd coolant color is a result of mixing green and orange coolants. Don't mix coolants, they are not compatible!!
In fact, we shouldn't even be using orange coolant in our cars. In this (last) month's Car&Driver, Patrick Bedard (the Tech Editor) had a really great column about this. (I just can't put my hands on the magazine right now)

Flush the crap out of it (literally), once it's flushed, run it for a day or so with straight water, flush again, then fill up with green stuff.
My car does the same thing with the coolant tank, no matter how hard I run it, the level never moves from 'Full Cold' but the raditator stays full, and the car runs right at 200 degrees (I have a 195stat)

You may also want to pull up the carpet on the passenger side and check for coolant residue on the floorboards. This is another indication of a heater core leak. I wouldn't wish a heater core leak on any one, it's such a pain in the ***. Well, maybe on my Ex, but that's a different story.

 

the brown **** is from the damn red coolant--normal expecially if it is like a paste i've seen it more than once at work all the cars with red(almost) dexcool have this stuff on the cap and other places..as said before you should be running green not red, red was not widely used untill '95 and if i remember correctly '96 is the first year exclusively for red

 

Well, first of all, I did NOT mix the dexcool and the glycol antifreeze... I flushed the 'green stuff' and filled with the 'orange stuff'... on another thread I was led to the impression that the dexcool coolant has a higher capacity to dissipate heat and can strongly outlast traditional glycol coolant... that's the reason for the switch.

I'm going to go the 'reverse flush' route tomorrow morning... see if I cant come up with the prestone fitting mentioned to try to do a bona fide cleaning of the cooling system...

I'm less worried with the coolant level than the consistency and color... one problem at a time

James

 

From what I've learned, the two coolants are compatible. They can be mixed without causing any adverse effects, other than that the long life properties of the Dex-Cool will be compromised so you'll have to flush every three years instead of five. As soon as you add silicates to the mix, you need to drain it more frequently.

The difference between the two is mainly that the Dex-Cool has no silicate additives, so deposits form more slowly. The Dex-Cool also has other anticorrosion and lubricating additives that make the concentrate less viscous and have a greater latent heat capacity (it absorbs, holds, and moves slightly more heat energy). I don't own a vehicle that doesn't use it, including all those made before 1996. The disadvantages are the slightly higher cost, slightly lower availability, and the tendency of the coolant to wick through the smallest openings (like diesel fuel). You have to have a tight system to use it. I use it since too many of my vehicles sit in storage for extended periods and I'm tired of changing heater cores. After changing the second core at 33K miles, I bit th ebullet and changed. I haven't had to touch the cooling system now for four years, and I'm crossing my fingers.

As for the cooling system level dropping, that is a natural tendency of the water used in the coolant mixture. All water except deuterium oxide (heavy water) has an affinity for air molecules. Until the water is heated enough to drive off the air molecules (deaerated) it will bubble out air slowly until all the entrapped air is gone. In a cooling system, this can take a week or more. Every time the coolant warms up, more air is driven off, causing the liquid level to slightly decrease as the air bubble is created. Large commercial boiler installations have separate deaerating vessels to prepare the make-up water so that an air bubble isn't developed inside the boiler (that would be a bad thing).

If you keep topping off the system, this phenomenon should stop after a week or so. If it really bugs the crap out of you, you can pre-boil the water that you use to mix the coolant before you pour it in the radiator, so that this effect will be minimized. That would be pretty ****, though.

And you really need to thoroughly flush the system before refilling. Consider a "leaner" mixture, too. About 30/70 is usually best for cooling and protection, as long as it meets the freeze protection you can realistically expect in your region.