: 02 Cooling building back pressure. Purge line clear.



Luckyjack
05-19-14, 06:24 PM
Greetings,

I have an 02 DeVille that I bought at about 130k miles. At 144k it started overheating. Nothing serious at first, one little spike then it would quickly cool back down. Then one day not long ago (right as the weather started to warm up) the temperature started to spike rapidly. I parked and let it idle to cool but the temp just kept rising, so I shut it down, which may have been a mistake. As soon as i shut it off, the water pump rear seal blew and coolant started spewing. It held coolant and stayed cool long enough to get it home and park it. I replaced the water pump and gaskets, refilled with dex and pellets, no problem for about an hour of driving afterward. Then rapid temp spike soon after i turn ac on. Parked it, shut it off again, this time the radiator burst. Had it towed home, I've got the old radiator out and am about to put in the new. going to replace thermostat and tank cap while i'm at it. I'm just having trouble locating the cause of the pressure it's building.
I checked the purge line and bolt, which was all clear. At this point I'm worried it may be a head gasket blowing exhaust back into coolant, but even if that were the case, would it still be blowing seals and radiators if the rest of the system were clear of blockages? where could these blockages be? It hasn't held coolant long enough for me to do a gas test on it, but none of the coolant was oily, there is no coolant in the oil, and it doesn't smoke or steam. Any ideas on the root cause of this would be helpful before i get it all put back together. There was a silvery metallic particulate in the coolant that leaked out, and i'm noticing the same build-up in some of the hoses and fittings. Maybe a previous owner used alumaseal or a stop leak in it? I'm at a loss here.

Submariner409
05-19-14, 07:43 PM
Cadillac stopped using the pellets in 2003. If you have no nuisance weeps now, don't use them. The sticker on the radiator sight shield, as well as the hard copy service manuals, were never updated to show that fact.

Study the sticky posts just above this for insight into cooling systems, gauges, and fan operation.

Northstars with failing head gasket(s) seldom put oil into the coolant or vice versa.

MoistCabbage
05-19-14, 07:46 PM
Excess pressure isn't the reason things are failing (the pressure cap would bleed off excess pressure anyway). The car is old, and things are going to need to be replaced.

Luckyjack
05-19-14, 07:54 PM
Excess pressure isn't the reason things are failing (the pressure cap would bleed off excess pressure anyway). The car is old, and things are going to need to be replaced.

That's fair enough. I will get it reassembled, read all I can here in the stickies and see where we are then.

Ranger
05-19-14, 08:48 PM
There was a silvery metallic particulate in the coolant that leaked out, and i'm noticing the same build-up in some of the hoses and fittings.
I think you've been had. The previous owned dumped some snake oil in there to band aid the bad HG long enough to unload his problem.

Luckyjack
05-19-14, 09:11 PM
Yeah, I'm quickly reaching the end of the denial phase of this project. I'm nothing if not bold. Changed HGs on a couple of small block chevs. I'm willing to wade into this one armed with a decent how-to.

Ranger
05-19-14, 09:17 PM
This ain't your small block Chevy. You need to drop the entire drivetrain. There are some tutorials in the Tech Tips section and a FSM (NOT Chiltons or Haynes) would be well advised.

Luckyjack
05-19-14, 09:23 PM
I figured it would all have to come out and go on a stand. I will read what i can here and see what other resources are available. This seems to be the best knowledge repository so far. If I have to send Isobel to the boneyard this early in our acquaintance, at least it will be my doing.