: My mechanic wants to put in a new radiator, should I let him?

07-07-06, 08:56 PM
Hey Guys,

It's been a while since i last posted, I think my account was deleted due to inactivity! Anyways, my 97 Eldorado has been runnin great up until recently, until it started overheating and boiling coolant out of the over flow of the resevoir that is. So far I have replaced the cap and theromostat, and still no luck. Recent work done includes a replaced blower motor and water pump. The other day steam was coming through the dash and floor vents, so he bypassed the heater core. Sadly, the coolant is still boiling over and shooting out of the overflow. My mechanic says that the only thing left is my radiator. I have read some over heating threads in this forum and have learned that thermostats, caps, slipping water pump belt tensioners, clogged purge lines, and the dreaded head gasket can cause symptoms similiar to what i have. I asked him about the head gasket and he said he didnt see any water in my oil or any funny discharge from my exaust, so he dosnt think thats a problem. I have'nt asked him about the belt tensioner or clogged purge line yet, but if they check out ok do you guys think a radiator is a logical explanation? Please help as im going in for the radiator on Sunday, any advice guys?? :confused:



07-07-06, 09:49 PM
Our old Guru has always said that due to its design, the Northstar is not likely to leak coolant into the oil when a head gasket goes. Coolant from the exhaust is not always seen either as the cylinder can be pressurizing the cooling system with exhaust gasses, thus causing the overheat, as opposed to sucking it in on the intake stroke and burning it. It all depends on where the breach is. Steam coming from the vents is usually a sign that the heater core is leaking. Bypassing the heater core should rule that out but maybe there was still air in the system (check the purge line). I think I'd watch for bubbles (exhaust gasses) in the coolant surge tank when first started, then run a cylinder pressure test before throwing parts at it unless he is positive that the radiator flow is restricted and causing the overheat problem.

STS 310
07-08-06, 02:15 AM

You sly dog I aint talked since you got that DHS, you devil!!!!

Riding around in that bad boy, hows it treating you ? Sorry for Off Topic..

07-08-06, 09:54 AM
Thanx ranger, sounds like good advice. I also noticed something this morning on the way to work. The faster I'm going the higher the tempature gets. Does this point to pressure maybe building up in a cylinder or the water pump belt loosing grip with the higer RPMs causing it to boil over ? Maybe point to a radiator? Either way I'm gona have the cylinders tested but this problem is driving me nuts.

Thanx agaian

07-08-06, 10:48 AM
Hard to say. Could be belt tensioner, purge line, radiator or head gaskets. You really just have to eliminate them one by one.

STS 310,
Believe it or not, the DHS is parked in the garage. Other than the ride home, I haven't driven it. I am using the SLS til my daughter sells her '99 and takes possesion of mine. I do go out and sit in it every day and drool a little.;)

07-08-06, 07:41 PM
Shizzy, can you do any work on your own?

To reiterate: Check the water pump drive belt. Check for flow through the purge line. Have the coolant checked for combustion byproducts (this is best done at a radiator shop if there are any near you)

The N* does NOT put oil in the coolant until the gaskets are totally blown out, nor do you notice excess moisture in the exhaust. Your mechanics diagnostics suck.

It is fairly easy to replace the radiator yourself.

07-09-06, 12:55 AM
Shizzy, it very well could be your radiator, assuming the new thermostat is good, the cap is good and the water pump belt is tight. That little pruge line needs to be checked to make sure that it isn't clogged, I've taken mine off by the coolant tank and simply blew threw it. If I'm not mistaken, the radiator is not overly big on these cars so it wouldn't take but a few clogged tubes and you would have a slow over heat condition. Before I changed the radiator I would have it back flushed and then try it again, not a big deal to back flush.

With what you've said, check the purge line and belt tensioner first as they are the simplest things to do. If it is still overheating, flush the radiator! At that point, report back what changed if anything. That little purge line serves a huge purpose so don't overlook that purge line, air could be trapped in your system and it cannot work itself out if that purge line is clogged. Your radiator is either partially plugged or it's not, no other reason for it to be the cause of your problem!

Good luck, hoping you report back with it being something simple like a clogged purge line!

Rob Benham
07-09-06, 01:25 AM
There is a 'snap-on' tool that 'looks' at your hoses and gives a readout of the real temps. In V out is a very good indication of the rad's condition.

I put in a Chinese rad which was a detailed copy of the origional...the car has never been the same. 199-201 always, but now it swings about even putting the fans on. Air temp in the 90's though. The infrared detector did show a lower temp off the rubber hose surface, and the guy thought my temps might be reading high. After days of fussing over it, I have just learned to live with it, and the car has done several k like it.

07-09-06, 08:30 AM
Your symptoms are classic of blown head gaskets.
There are a couple of tests you can do, if it boils over badly neither may work.

There is a CO (carbon monoxide) sensitive fluid out there on the market, it's blue.
With the engine running you can carefully take off the radiator cap and draw some of the vapors out of the cooling system through the fluid using the test kit. If the fluid turns yellow then there is exhaust gas present in the cooling system. You can also use a "sniffer" or smog machine or emissions tester, whatever you want to call it.
Check for the presence of HC and CO.
The problem if it's boiling over is you can draw coolant into the tester and contaminate the fluid or screw up the sensor probe on the emissions tester.

Based on your description, I'd say you are looking at a head gasket problem.
Don't replace the radiator, it's not going to help.
There are some other good suggestions here, but do nothing until you properly check for exhast gasses in the cooling system.

By the way, the reason you are having problems with overheating, etc.... is because gasses will not let the thermostat act properly. The thermal transfer to the sensing bulb is not right and the t-stat won't open in the presence of gasses. It has to be in full contact with fluid. The combustion gas is getting past the head gaskets, remember the pressure inside the combustion chambers is nearly 200 psi. (much more during combustion) The cooling system pressure is only 15 psi. The gasses get into the cooling system and wreak havoc.

Good luck.