Need some advice on my STS if you would...

OK, so here's the skinny of the story... I've got this '92 Cadillac STS Arabian Edition that I bought back in January, and she's in a little rough shape inside, but cosmetically straight. The engine is strong and the trans is too. My issue has been the cooling system. The water pump was shot when I got it, had that replaced. It was overheating according to the dash, so I replaced the thermostat and the cap. No difference. I noticed a pinhole leak in the upper hose, so I replaced that. No difference. I cleaned out the reservior and the hose to it, still no difference. She wasn't putting out any heat during the winter months, couldnt' tell you if she is now cause I don't use the heat (A/C works great). Out of the dozen or so time the gauge stated it was above 250 and overheating, it probably actually only got that hot twice that I could feel. It seems the system is either over pressurizing or not getting any at all. When it did overheat it backflowed to the reservoir and spilled out through the topper. The second time it did it (last week) it actually hissed when I shut it off in the driveway and I could see a definite leak on the driver side plastic housing... which sucks. I figured I'd have to replace the heater core - assuming that was clogged up - but wasn't expecting the radiator to go out on me.

Ok, that said... here is a post that I did on the Seville Forum... they aren't getting back to me quick enough and I need good advice, so I'm turning to trusted friends on VFRWorld...

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I'm getting ready to replace the radiator in my '92 STS as I'm pretty sure I've narrowed it down to that being the faulty component in the system. Still having overheating issues after replacing the thermostat, water pump, cap and upper hose. I know the lower hose needs replacement as well, but I figured I'd do that when I pull the radiator. Not sure of the condition of the heater core - but I don't have heat in the cabin, so either there is a blockage from the radiator to the core or the core is clogged as well.

Anyways, the system was mysteriously evaporating coolant and overheating after about 2-3 hrs of operation. Fill the radiator to the top with water and she'd run fine for another few hrs. Never a puddle under her, and no steady water marks. Occasionally the cap would leak, and the reservior would overflow like it was backed up. Really puzzled the crap out of me. Was it getting too much air pressure (HG issue) or not building enough (pinhole leak)???

Finally last week she overheated on the way home and when I pulled into the driveway and shut her off I heard a hissing (that's a first). I popped the hood and she was steaming out the drivers side plastic on the radiator and puddling underneath the car - another first.

My question for this thread is do I replace it with the 'OEM' 1 row radiator that everyone and their mother is selling for this model, or do I go with the more heavy duty 2 row radiator that I've found for sale on EBay that seems to be a good match for what I already have. I'm pretty sure my baby also has the built in oil cooler and trans cooler options, too. I was just thinking that with living in Phoenix and the excess heat that we have here, a larger radiator couldn't hurt.

Anyone know how large of a core I can put in her without making major mods?

Where's the best place you know of to get one? I'd rather not inherit someone elses crap by getting from the junkyard as has been recommended to me already.

Also, to be noted... the temperatures have been flucuating from 195 to 205 during normal operation, and then in stop n go it'll creep up to like 243-250 and claim 'overheat' and then 3 seconds later be back down to 222 and hover there till I start moving again and then it'll be in the 210-225 range up and down. But, if I start out with a full radiator and drive down the freeway at full speed (65-80 mph) then it'll go all day without going above 207. The minute I stop it climbs. Isn't that backwards of a head gasket issue???

I'm so confused :frown:

Help me VFRWorld.... you're my only hope!

oh... and btw...

my girlfriend is reggers: and due 12/29/11!

 

Lazy - well congrats on the baby-on-the way.

Been 20+ years since I've worked in a garage, but it definitely sounds like the heater core, specifically because you have no heat. Although, I seem to recall that when a heater core "went bad" it often led to the coolant leaking inside the car, on the front passengers floor.

Wish I had actual mechanical advise to give you, but I guess I concur with the heater core assessment. Something is amiss with it.

Larger radiator (i.e. more core or rows) definitely can't hurt. We all know that heat will kill any engine. If its the same fit, I'd definitely go with it.

Good luck, sir.

 

the problem turned out to be the radiator itself. When removed it weighed nearly 20 lbs on the bottom end cause it was full of gunky and grime. She was clogged up and that was holding back the flow.

Replaced that, both hoses, and with the new thermostat, new cap, and new water pump, she stopped overheating.

NOW I have a new issue. Since replacing the radiator, the charging system took a crap on me. Seems whenever I ran the a/c (which blows cold as it should) the voltage indication on the digital dash will drop from 13.5 to about 12.5 and sometimes she'll stall out or even overheat cause the electric fans just don't have enough juice to push the amount of air needed to keep the 4.9L V8 from burning up. Turn off the a/c and she's fine. This wouldn't be a problem if it wasn't going to be 115 for the next few days!

So, I replaced the alternator with a re-man from Copperstate in Phoenix (Best place to go for alternators and starters in the Valley, btw) and had the battery replaced at Auto Zone (sold them the standard one that was in it for an upgraded Gold version just for extra comfort). Still isn't doing what it's supposed to and I'm getting frustrated. The a/c pump, if it were failing, could cause enough of a drain to draw the power from the alternator and prevent the battery from charging. BUT, if that were the case - wouldn't the air coming out NOT be cold???

I've been putting the battery on the trickle charger every night and it green lights steady by the next morning. Turn the key and it's at 12.2 VDC. Fire it up and it goes up to 13.7 and holds there until the air comes on.... then it's a steady drop from there. Understand that the alternator on a Cadillac doesn't put out anything at idle, but comes to life at 1600 rpms with full juice at 6k rpms. At the higher rpms it'll maintain the air and it won't go below 13.3 VDC so I know the alternator is working and the battery is good.

*sigh*

If my friggin wrist wasn't broken and I could ride my bike this wouldn't even be an issue right now!