: 96 Deville 4.6 North* overheating problem



richbanta
10-03-06, 01:47 PM
I am looking for a little direction here. All of a sudden, the engine started overheating on occasion. I dont seem to be losing coolant anywhere. It would overheat, then run fine for a couple days, then overheat again. The temp would flucuate wildly from 202 to 248, go down rise, etc. I changed the thermostat and coolant, ran good for a couple days, started running hot on occasion again. Changed water pump, old one seemed good, still seems to run hot. (BTW, forget about the head gasket, if that is it then I am getting rid of car but it only has 94,000 miles, and runs fine otherwise)

I read somewhere about some tube that goes from one side of engine to the coolant tank should be checked. What exactly is that? and how do I check? Shoulod I check it with engine running and warm? Should fluid squirt out when I disconnect it from coolant tank?

Also, how do I check to see if the radiator is any good? Do I have to remove it from the car? Is it difficult to change? (trying to save a little money!)

Also, assuming no head gasket problem, is there any preventive maintenance that can be done to forestall any head problems?

Thanks
Rich

Ranger
10-03-06, 03:40 PM
The "tube" you are talking about is the purge line. It enters the surge tank on the side near the top. Start the engine (cold so as not to burn yourself) and pull that line loose. If there is coolant flow (there should be) quickly plug it back on. If there is none, remove it, locate the obstruction and clear it.

If the purge line is clear, do a cylinder pressure test to confirm or rule out head gaskets. Also when you first start the car and it is cold, you could remove the surge tank cap and look for bubbles. You will have a few min. before the stat opens and you have to close it up. If you see bubbles, the head gaskets are going.

Regular cooling system maintanence is the best preventative maintanence for head gaskets.

richbanta
10-05-06, 07:59 PM
Follow up. I had radiator flushed and new coolant with tabs added. It seemed to take forever to get all of the coolant in! Now what happens is when I drive it, it seems to get kinda hot, up to 240, and then when I am idling at a light, it cools off rather quickly. If I just let it idle, it seems to cool off to about 212 or so and stays there. I wonder whats going on?

Ranger
10-05-06, 08:19 PM
Did you check the purge line like I told you to? How about the water pump drive belt tensioner? Have you checked it to be sure that it is providing enough tension and not allowing the belt to slip?

richbanta
10-07-06, 09:21 AM
Hey, thanks for the input. As far as the purge line, I blew air through the line and coolant squirted up through the overflow tank. However, when I started the car up in the morning, disconnected the purge line at the coolant tank and revved the engine up a little to see if coolant was coming out of the line, it wasn't. It doesn't make sense. If I blow into the line air goes through the one way, but coolant doesn't flow out when I start it. Its like there is a valve or something that allows it air to go one way but not the other. BTW, do I need to have the rad cap on when I pull the line from the overflow tank? The reason I ask, is that I had the rad cap off when I revved the engine to make sure there was no exhaust gases leaking into coolant system. I read a thread that said one way to check if the HG may be bad is to take off the radiator cap and start and rev engine to see of it bubbles or blows any coolant out. (It didn't)

As far as the water pump pulley, when I changes the pump, the pulley seemed fine and I did change the belt too.

Thanks alot for your help in this Ranger.

Rich

Ranger
10-07-06, 10:54 AM
Ok, seems like you have found the problem. You have confirmed that the line it clear. Sounds like the blockage is where the line connects to the pump housing. Makes no difference whether the cap is on or off. When you pull the line at the tank, you should get a coolant flow and it should be much stronger as the RPM is raised. Either pull the line at the engine side and clear the obstruction where it mounts or try blowing air in from the tank side of the line. Whatever is blocking the line (cooling system suppliment probably) will go back into the water pump and get chopped up. Then check the line again for flow.

MUGSANDLUKE
10-07-06, 01:10 PM
Don't waste any more time. Just check all the entries on this formum regarding the same problem and you will see that the only, repeat, only solution is to replace the head gaskets. I just went through months of grief and had everything changed except the air in the tires and it all came down to head gaskets. They were just changed and guess what? Problem gone! Save yourself a lot of time and BS. Get them done now and don't play around with a lkot of other "maybe" solutions.

Ranger
10-07-06, 01:56 PM
Doing a head gasket job without proper diagnosis is like having open heart surgery because you have heart burn.

zonie77
10-07-06, 02:20 PM
Doing a head gasket job without proper diagnosis is like having open heart surgery because you have heart burn.

Good One!:highfive:

I'll remember that next time I have heartburn!

I~LUV~Caddys8792
10-07-06, 04:04 PM
Doing a head gasket job without proper diagnosis is like having open heart surgery because you have heart burn.


LOL good one!

AlBundy
10-07-06, 06:32 PM
Doing a head gasket job without proper diagnosis is like having open heart surgery because you have heart burn.

Dam Ranger I can't resist to post because that is one hell of a statement. I hope you don't mind if I use it:thumbsup: .

Ranger
10-07-06, 11:00 PM
Dam Ranger I can't resist to post because that is one hell of a statement. I hope you don't mind if I use it:thumbsup: .
Be my guest. It just seemed so appropriate.

boricuacaddy
10-10-06, 07:14 AM
Doing a head gasket job without proper diagnosis is like having open heart surgery because you have heart burn.

Wow! That is deep man!

David

richbanta
10-11-06, 03:46 PM
Follow up. I removed the purge line where it goes into the water pump housing and blew everything out forwards and backwards. Seemed clear. The nipple that the hose connects to on the housing shoots out coolant when the engine is running but it doesnt seem to go all the way through the hose to the overflow tank. I took it into a shop recommended by a friend to chek the head gasket. They swear its the head gasket based upon what it does now. That is when idling, the temp is fine but when driving, it heats up to 250, and when idling again cools down. The upper radiator hose also gets hot and rock hard. They said they didnt do the heads on this engine so I thought I'd call a couple dealerships. They said it would take 40 or so hours and cost over $4,000.00! I called a couple other shops and most wouldnt even consider doing it. My understanding that it is the same as any other head job, with the exception of putting in the timeserts. Anyone know of a dependable shop in the Detroit area who will do the job for a reasonable price. I hate to get rid of car, its in grat physical shape with 95,000 miles. BTW, the dealerships all called it a very high mileage car not worth fixing! I dont know, I had Cadillacs before that ran great with over 200,000 miles. Thanks

Ranger
10-11-06, 04:52 PM
Have you seen this link?
cadillac46northstar (http://www.ae-engines.com/cadillac46northstar.html)

richbanta
10-11-06, 10:41 PM
Follow up. I pulled the purge line where it goes into the water pump housing. Blew it out both ways and was getting some flow, not much. I does squirt out the nipple that the hose attaches to on the water pump housing. It is continuing to over heat as before, except it is getting worse. Car runs fine though. It will idle all day without getting hot but when I drive it it overheats, gets up to 240 250. The upper radiator hose does get rock hard when it warms up indicating to me that there is some blow by or exhaust gases getting into coolant system and pressurizing it. Took it into a reputable shop, they diagnosed head gasket but they do not repair Northstars! Called a couple dealerships. Number one, they expressed amazement that someone would want to repair a 96 Deville with such high mileage. ( I dont thing 95K is that high!) Both places indicated it would cost over $4,000 to fix! (over 40 hrs they said!) I called a couple indpendent shops and most wouldnt touch it. Is it that big of a job? I might try to do it myself. I am getting a FSM first. Where do I get the time-serts? Any advice as to making the repairs? Any threads I should look at? and should I do anything else to engine while I have it out? I wouldnt object to paying about 2k to have the job done but I cant seem to find anyone with experience to do it for that price. I appreciate all of the advice thus far. Thanks alot

richbanta
10-11-06, 10:46 PM
Sorry. I thought my last post did not post for some reason so I repeated myself. I saw that remanufactured engine site before. It looks fine, but as most of us, I am somewhat short of money! So short, I was tempted to try that stuff called steel something guaranteed to fix a leaking head gasket for about 90 bucks! I still might try and do it myself though

Ranger
10-12-06, 09:27 AM
Sorry. I thought my last post did not post for some reason so I repeated myself. I saw that remanufactured engine site before. It looks fine, but as most of us, I am somewhat short of money! So short, I was tempted to try that stuff called steel something guaranteed to fix a leaking head gasket for about 90 bucks! I still might try and do it myself though
Put the money toward the Timeserts. Repairs (hope) in a bottle don't work. Rfishing had a very lengthy post about this stuff a while back. Didn't work for him either.

rugby2
11-03-06, 11:46 AM
from reading this it seems 210 to 220 ok to run at, yet at 240 time to pull over and let idle? seems like not much margin of error. what kind of eng is this anyway? takes secounds to go from 220 to 240.

dkozloski
11-03-06, 03:17 PM
from reading this it seems 210 to 220 ok to run at, yet at 240 time to pull over and let idle? seems like not much margin of error. what kind of eng is this anyway? takes secounds to go from 220 to 240.
It's the kind of engine that will operate with no coolant at all by going to a self protecting "limp home" mode that limits fuel flow and cuts out cylinders to keep temperatures below dangerous levels. I understand that you bought a problematic car. Ask nicely and there are a lot of good people here who will help you find your way to a reliable fix. Good Luck!

aero11
11-28-06, 01:41 AM
This has been happening to my car.. same exact car with pretty much the same symptoms. It will overheat on occasion, due to a slow ongoing loss of coolant. It took a while for me to notice, but I finally found that the coolant crossover pipe is leaking. This leak is VERY hard to see, I can really only see it via looking through a tiny hole laying underneath the car. That and there's coolant dripping off everything since it's been going on for about a month.

Looks like I'm going to replace thermostat, crossover, gaskets, and water pump. The project looks to be a pain, as the throttle body and a whole bunch of other shit has to be removed. Hopefully I'll get it done this week and HOPEFULLY I don't have a bad headgasket.

Ugh, I know what you mean about the lack of margin between 220 and 240, it takes probably 20 seconds at freeway speed to escalate between them. It's a good thing they designed the "limp-home" mode into the engine but I personally have no desire to operate my engine under those conditions.

Thankfully this problem happened in the winter, because otherwise I'm sure the car wouldn't be driveable.

96Deville
11-29-06, 04:27 PM
Rich,
I have a 96 Deville with 120,000 miles on it. The head gasket went right at 100K with symptoms very similar to yours. I don't know if you have done it yet but, as Ranger suggested earlier in the thread, do the compression test so you know exactly what you are dealing with. He has helped me diagnose things in the past and he knows this shit backwards... Do this before anything else.

I paid $3500 to have mine repaired correctly (timeserts, etc). I learned that this job is not for the faint of heart or even a decent do it yourself mechanic as the preferred method is to drop entire cradle prior to pulling the heads.

I considered dumping the car but decided to have it fixed and haven't regretted it once. I love this car!! I originally bought it as a winter driver (the winters get pretty extreme here in Minnesota) but ended up driving it more often than my LT1 Formula even in the summer time.

Good luck man.