Okay, here goes. I just pulled my GTA out of the garage so I could get the body patched up (another story, another thread). So I checked the fluids and there's oil in my rad, and the coolant overflow reservoir was empty. The weird thing (to me anyway) is that there's no milky stuff in the case or in the rad, it's just dirty looking oil floating in the coolant. I took it to a quick lube place to get the oil changed (forgive me, I just don't want to deal with properly disposing of the oil) and they said it was a little dirty but free of coolant, although the engine oil was a little low. It may be unrelated but the CES light did come on a couple of minutes before I made it to the oil change place. I shut it down and fired it back up and the light went off as normal. I intend to get a pressure test on the cooling system but I thought I'd check with the experts first. Any advise? It's a '90 GTA, 305, 700R4, all stock. Thanks guys.

 

Maybe the factory oil cooler is leaking?

 

There's a good possibility you have a bad intake gasket. Is it possible for oil to only be in the coolant, and not vice versa? I suppose anything's possible. Maybe someone else can shed some more light on this.

 

There's no oil running through Chev's heads or intake. If the intake leaked, the coolant would be at a higher pressure than the crankcase, therefore there would be coolant in the oil...

It has to be an area where the oil pressure is higher than coolant pressure.

 

Flush the cooling system and then refill with the proper mixture of coolant. After that, check it for oil every day for the next couple weeks. If you see more oil...blown head gasket more than likely, although it could be a warped or cracked head or block, especially if it was overheated recently.

 

My bets not on the head gasket either. Coolant still at a higher pressure than the oil.

Another thing that came to mind is if it's a AT car, if its not motor oil, but trans fluid. Check your AT fluid. It shouldn't be pink!!!

 

Personally I was thinking head gasket but that wouldn't make much sense since the oil was free of coolant. My father brought up the oil cooler idea. Does a GTA have an in-rad oil cooler stock?

It is an auto but the tranny fluid looked alright. Kinda dirty and kind of orangish but at the right level. Besides, it's dark and smells like oil. After what I went through with my ol' Jimmy I definitely know what ATF smells like.

I'll get a shop to do a pressure test (unless someone here tells me not to) and they can flush the system for me. No sense in doing it twice. It is possible that someone had a brain cramp and put oil in the rad. Stranger things have happened, right? ...right? <grasping at straws>

 

I still am thinking head gasket, but anythings possible, start with the easy fixes first.

 

I dunno, I haven't heard of a bad head gasket with these symptoms, although I admittedly am just a rookie.

From what I've read, there's a sort of oil cooler between the filtr and the block that gets coolant rounted to it between the rad and the heater core, and this can potentially cause oil in the rad but no coolant in the block if it goes bad. Does that sound about right?

Thanks for the advise guys, please keep it coming.

 

Well I think we've found the problem. Today I had a shop flush out my cooling system and refill it, as well as add some dye to the tranny fluid since they suspected it may be a bad rad (I doubted it but what the hell, the tranny needs done anyway). On the way home it had a really strong smell of antifreeze in the cabin. I figured it was just because of the day's work done on it until I looked over at the growing pool of coolant on the passenger's floormat. Oh great, that black crap was actually a lot of very old stopleak (He estimated four or five cans when I went back) and I have a leaking heater core. Needless to say, I'm in a very crappy mood.

 

Another blow to the GTA, the tranny cooler started leaking as well. Probably due to the leak sealer being flushed out. So now I have no heater, a new rad, and an appointment to get my tranny flushed. That paint job is getting further and further away...

 

My '91 bird blew a heater core this winter (pool-o-coolant and all).

Cost to fix was $35 (US) (for... a new heater core from Checker) and 2 days of removing the dash, pulling the core, and re-assembling.

Of course, if you pay someone to do it, the going rate (where I live, don't know about Canada) is $600-800 (due to labor).

It's a pain to do, but it's not that expensive...

 

I had my heater core replaced by a GM tech as a side job. It took him less than an hour to complete the job and he only charged me $30 in labor plus $35 for the part.

 

Hmm... I forgot I had another thread I should've updated...

I replaced the heater core myself close to a month ago. It took a $60 Canadian heater core and the better part of a Saturday leisurely working on it, but it works fine now. The shop wanted over $500 to install it. Including taxes the total would have been just under $800. Screw that.

Naturally, the water pump blew up as well (between the heater core and the rad jobs). I don't mean the bearings either, it actually blew out it's backplate gasket just as I pulled into work one day. I had to take it to the nearest shop to have it replaced (too far from home, and no time to do it at work).

Now, as I'm seriously thinking about the paint job again, the A/C is getting weak. Dammit....

 

A/C...

I don't know about canada, but the easiest way to fix A/C problems in the US seems to be converting to R134A with the Interdynamics kit ($45 US from www.jcwhitney.com, some places you can buy it in stores, but that's illegal where I live (in WI, a store can't sell you R134A without a license. You can legally buy it, but no one in Wisconsin can sell it to you. So you buy it online, from a company in Illinois...).

It's a 30min job: you get someone to extract your old freon (which they'll gladly do, since freon is worth it's weight in gold), go home, put the fittings on, and shoot in the cans from the kit. BOOM! working A/C (and it's got leak-sealer in it too, so if there's a minor leak, it will fix this).

Just did this myself, fixed my AC perfectly...

 

Thanks Dave, I'll have to look into that.

Right now I'm wondering how much can be wrong with the A/C. It's not terribly cold, but it does work. My brother and I had it on full blast for over two hours today with the roofs off and the windows down (mid 30s C) and it kept chugging along at a slightly cool pace. I would've figured that if it was low on refridgerant then it must have a leak somewhere, yet it didn't die on me today.

Ah well, paint job first.