[CGGage]

Hi, all,

I have a '97 DeVille that I just had the radiator, water pump, and thermostat changed. Here's what happened:

Over a period of many months, I occasionally would get a "check coolant level" message. I would add coolant to the engine coolant side-tank when it was cold in the a.m. This would last about 2 months. I could not find a leak anywhere except maybe around the water pump. It always looked dry but there was build-up of crud that could have been evaporated coolant residue.

Finally, one night, the radiator cracked, coolant was everywhere. I had it towed to a local shop who said they would not touch it because it looked like it had a head gasket leak due to the "gunk" in the cooling system.

[I'm thinking now that the "gunk" is that pellet stuff which I had never heard of being added to a system unless there was problem. I read on other posts about these pellet things. The gunk I have is like a black, smooth pasty stuff, sort of like a rotten black rubber hose.]

Anyway, I resigned myself to the head gasket problem and called a private mechanic friend of mine who gets me new GM parts at very low prices. He came over, replaced the water pump, thermostat, radiator, and hoses, for about $500 including labor. Not bad. His analysis was that the gunk was crap in the radiator and did not look to him like a head gasket problem. It did not much matter either way as I had to have this stuff fixed, even if I kept the car or sold it. So far, it has been two weeks. I have topped off the coolant as I figured there would be air in the system and it would take a bit to stabilize.

Today, I went out and the coolant tank seems to be about half-full. I added some more -- actually, too much as when I arrived at the office, some of it was coming out the overflow tube. Probably not good.

Which finally brings me to my questions:

1. What is the proper level of coolant in the black side-tank (with the "radiator" cap) supposed to be? I can't find this info anywhere. I would think half-tank would allow for expansion, etc.

2. What is a normal operating temperature range? According to the dash, the temperature runs around 197 to 205, sometimes going to 215 -- once up to 226, but then dropped back to 208 when the electric fan(s) kicked in.

3. My mechanic did not have the facilities (in my driveway) to flush/drain the cooling system. Should I flush or drain? Leave "as is"? Should I add these pellets? Will Jiffy-Lube do a good flush, or is this a Caddy-dealer issue? On a previous flush years ago, a place put in green stuff. My mechanic switched it back to a Prestone(?) 50/50 pre-mix Dex-Cool compatible stuff. He did not add the pellets/powder.

4. Any ideas what caused both the radiator and water pump to go "paws up" at the same time? I think the water pump was probably on the way out as it was leaking according to my mechanic.

5. On a completely unrelated problem (?) -- the car runs roughly in the a.m. during cold weather -- like it needs a choke adjustment (if the car has choke?!?!) Once it is warmed up, it idles nicely. I had the expensive Caddy dealer tune-up and throttle-body service -- no difference. Any ideas?

I apologize for the long post. Thanks in advance for any help. It's a great car except it should come with a pad of speeding tickets that you just mail-in every month. It is so fast, smooth, and quiet, I don't even realize I'm doing 70 in a 55! (which they will nail you for in Maryland).

Thanks,

Chuck

 

[mcowden]

1. What is the proper level of coolant in the black side-tank (with the "radiator" cap) supposed to be?

2. What is a normal operating temperature range? According to the dash, the temperature runs around 197 to 205, sometimes going to 215 -- once up to 226, but then dropped back to 208 when the electric fan(s) kicked in.

3. My mechanic did not have the facilities (in my driveway) to flush/drain the cooling system. Should I flush or drain? Leave "as is"? Should I add these pellets? Will Jiffy-Lube do a good flush, or is this a Caddy-dealer issue? On a previous flush years ago, a place put in green stuff. My mechanic switched it back to a Prestone(?) 50/50 pre-mix Dex-Cool compatible stuff. He did not add the pellets/powder.

4. Any ideas what caused both the radiator and water pump to go "paws up" at the same time? I think the water pump was probably on the way out as it was leaking according to my mechanic.

5. On a completely unrelated problem (?) -- the car runs roughly in the a.m. during cold weather -- like it needs a choke adjustment (if the car has choke?!?!) Once it is warmed up, it idles nicely. I had the expensive Caddy dealer tune-up and throttle-body service -- no difference. Any ideas?

1. The proper level is about 1-2" below the cap. If it's losing a little more through the overflow than you think it should, it could be time for a new 15 lb. pressure cap. They do go bad and they cost less than $5 to replace. A 16 lb. cap might be all you can find easily, but it's 1 lb. more than the system was designed to work with. It will probably be fine, but I'd look for a 15 lb. cap. You can order an AC-Delco 15 lb. OEM cap at www.rockauto.com or www.gmpartsdirect.com or several other discount GM parts sites.

2. The temperature range you described is perfectly normal. The fans don't kick on until 225, so obviously that's not a temperature you need to worry about. If it gets to 240 during normal driving, it's time to get it checked out. In the meantime, I wouldn't worry about it too much.

3. Sounds like a mess. Don't flush the cooling system. Just drain and refill. If the system has had green stuff in it before, you have to change the coolant every 2 years for the rest of its life no matter which coolant you use or how long it's supposed to last. The green stuff leaves silicates in the system which reduce the lifetime of coolant. A flush won't get rid of them. To be safe, have the cooling system drained and refilled with a 50/50 mix of coolant (any color at this point, but DexCool is what's spec'd for your car) and distilled water. Don't use tap water, and don't add any flush chemicals. It's too hard to get that stuff out of the system and it's more trouble than it's worth. Two tubes of Bar's Leaks powder or 6 Bar's Leaks large tablets should be added to the system in the radiator hose, NOT IN THE SURGE TANK. So, while the system is drained, put the Bar's stuff in the hose, close it up, and fill with the mixed coolant.

4. The water pumps seem to have a tendency to leak at the bearing seal. Don't know why, but I've had the same problem. I can't explain why both the pump and radiator went at the same time, but I hope they got that black stuff out of the system. Whatever it is, it doesn't sound good at all.

5. Have you checked for any codes? Does it run roughly at any other time?

If you're worried about a head gasket problem or start to have symptoms that indicate that, have the cylinders pressure tested and/or check for exhaust gases in the coolant. A Northstar won't dump coolant into the oil. I suggest using the Search feature above to look for more information about this stuff. Proper cooling system maintenance is critical on a Northstar and there is lots of information available here about how to do it right. Let us know what questions you have beyond that.

 

[rudykip10]

great info!

 

[CGGage]

Mike,

Thanks for the great info! I have had some additional problems that scream to me "head gasket". The temperature shot up to 260 and the overheat message came on. After it cooled down, I put in close to 1-1/2 gallons of coolant. A friend said he thought the exhaust "smelled sweet like coolant". Not sure if that makes sense or not.

Anyway, the pressure test sounds like a good idea. If it is the head gasket, a 1997 with a 142,000 sounds like a trade-in to me. I cannot imagine a head gasket replacement is cheap. Any thoughts on that?

Otherwise, the car is fine. I'm in DC with no road salt and just beltway driving so if the head gasket could be re-done and it would last awhile, I certainly would consider having it done, unless it is absurdly expensive (I have no idea).

Thanks!

Chuck

 

[ewill3rd]

Chuck,

It sounds like head gaskets to me, granted I didn't go over your posts with a fine toothed comb but I saw some real telltale indicators:

Runs rough when cold then runs fine... this is a pretty good one
Overheated for no apparent reason... combustion gasses in the cooling system can cause this.
Loss of coolant... if you lost that much coolant and you can't see where it's going, it's probably coming out the tailpipe.
That "sweet" smell is likely coolant. It's unmistakable if you have been around it much.

You can call us over here in Alexandria at Lindsay Cadillac if you want us to do it. For a ballpark estimate you can call 703-998-6600 and talk to one of the service advisors.
I think it's close to $3,000 but I could be way off. I don't actually do that type of work. We have a crew of guys over in a special "heavy duty" area that handles that stuff. If the heads have to come off it will need timeserts also.

It might be time for a trade-in. We have a used car lot right around the corner and lots of new cars in stock if you want to take a look