View Full Version : Northstart - Blown Head / Headgasket?

06-09-06, 11:05 AM

I'm having what I think could be a major problem with my 1996 Eldorado ETC. It has 110k on it. For the past few months, I've been getting the "Check Coolant Level" mesage along with the smell of antifreeze. On close inspection, I was unable to determine where the loss of coolant was comming from. When I would top-off the coolant, it would leak down after a week or so( back to the level where the check coolant level message would appear again) My first guess, since I couldn't tell where the leak was, was to replace the waterpump. I though mabey the seal could be the cause. I was also getting an O2 sensor OBD-II code so I replaced both front O2 sensors and put in a new thermostat while I was at it.

Ok. After doing the above mentioned repairs, the first time I started the car I noticed some thin blackish smoke for a few minutes; probably from the new O2 sensors and the paste stuff that I put on the threads. I know that it's suppose to burn off and leave glass pellets in the threads; could be wrong though( wouldn't be the first time :bouncy: ). I also disconnect the battery for while to reset the error codes.

Now, when I start the car I always get white smoke out the exaust. And, I'm getting a current ODB-II code of 0300( Random MIsfire Detected :gun2: ). It runs kinda rough intermittantly, especially before it's warmed up. I did some research and it looks like these symptoms point to either a cracked head :thepan: or a blown head gasket :bighead: .

I'm hoping that it could be something else. I doubt that it is, but I though that I would ask you guys for your take on the situation.

I'm probably going to take it to the dealer on Monday for a diag to make sure that it is what I think it is. I know for sure that I'm not going to pay them 3500 to replace the head gaskets or 1500 for a new head + labor. I might consider doing the work myself, though I'm not took crazy about the idea of taking my engine out to do the work.

What do you think?


06-09-06, 04:30 PM
If the gaskets are gone replace the engine. IMO $3500 for headgaskets on an engine with that many miles its still going to wear out down the road.

06-09-06, 04:42 PM
Thanks for the reply. That's a good point. Who know's what else could go wrong in the future. I know for a new enigine they want around 8500 for it. I only paid 12k for the car with 58k on it. I might be better off parting it out and getting something else. I have a daughter now and a two door is a pain.

Thanks again.

06-09-06, 04:45 PM
I meant Northstar in the title, it's a typo. :eek:

06-09-06, 05:23 PM
Have you changed the plugs and wires?

That doesn't cover the coolant leak but the head gaskets would have to be REALLY gone to cause a miss. You're only filling the surge tank once a week.

06-09-06, 07:28 PM
The fact that you can smell coolant lead me to believe that is is an external leak. Surge tanks have been known to get hairline cracks (been there, done that). Pressurize the cooling system and see if it holds pressure. If not, look for the leak. If it does, then do a cylinder pressure test to confirm or rule out head gaskets.

06-10-06, 12:01 PM
I changed the spark plugs less than a year ago. Your the second person that has mentioned plug wires. I give that a try and see if it runs better. Thanks for your help.

06-10-06, 11:34 PM
You can get a rebuild for $4500 (a quality one) but may have to have the car shipped by truck if its too far from you. Search around. Someone here just got theirs rebuilt (i think 94greencaddy or someone) for $3500 or $4k (the cost of gasket replacement) and it has so much more balls.

That said, good luck with everything hopefully its not the heads.

Oh yeah i forgot. Make sure to check for used engines maybe around $2k if the heads are gone.

06-11-06, 12:20 AM
That's not a bad idea. Where could I look to find a used Northstar? Junkyard? Are all years of the engine compatible with the wiring and computer system?

06-11-06, 11:34 AM
Yep junkyards and ask your mechanic. Well since yours is OBDII i would suggest using the same year and VIN (vin 9 i think yours should be). Someone else fill me in here. Wouldn't he be able to use a 1997 or 1998 engine or did they change little things like the TPS etc. Even then you could probably just put the old one back on.

06-11-06, 09:09 PM
He can use a '96 - '99 or a '95 if he changes intake manifolds.

06-11-06, 10:52 PM
Yep. the Vin's a 9. I dropped the car off at the dealer and I'll hear from them tomorrow. I'm searching around the net for rebuilt northstars right now. I'm probably just going to get one and put it in myself. I've swapped engines and transmissions before, but never FWD. My first car was an 85 Monte SS and I put a 383 in it, also when through the original th700 and a few th350's. Do you think it's worth it to do the work myself. I really don't want to pay someone to do something that I can do myself. While I have it out, there are a few things that I can get to on the backside on the transmission that I would like to replace. Every one and a while a get a service transmission message. I forgot the error code, but it's related to the pressure control solanoid and I would like to replace the wiring harness too.

I really don't want to get another car. My previous car was a 93 eldorado etc and I just love them. I figure if I put a rebuilt engine and do a bit of work on the transmission it will be worth the effort and should( hopefully ) last for a while.

06-12-06, 10:52 AM
If you are thinking of doing it yourself look at the Head Gasket thread in Tech Tips.

06-12-06, 04:11 PM
Talked to the service guy at the dealer today and he confirmed what I was thinking: Head gaskets are blown. He said that it looks like the problem is centered around the #4 cylinder and that the #4 is on the front side of the engine. They quoted me 3800 to fix it and said that oil is leaking from the main engine seals( 1200 to fix that).

I think for now I'm going to garage it and buy something to get me around for a while. I'll probably just get a rebuilt engine and put it in there eventually.

Do you think that the front headgasket can be replaced without taking the engine out?

06-12-06, 04:37 PM
The front can be changed in the car, but if you are thinking of keeping the car I wouldn't recommend it. The rear gasket is probably close to going. You may have a leak there already and they didn't catch it.

06-13-06, 11:13 AM
I've decided to drop the powertrain and fix it myself. While I'm in there I think I'll send the block to a machine shop and have them rebuild the lower half of the engine( mabey). What would you recommend? I plan on keeping the car for a very long time so I'm gointo pull the transmission and have it rebuilt too. I have a digital camera and a camcorder so I think I'll do a detailed photo documentary for the forum fo the entire process. I'm going to start a new thread for this. I checked out the FAQ on replacing the head gaskets last night. Thanks for pointing me in the right direction.


06-13-06, 01:36 PM
Yes please take tons of pics! That would be very appreciated by everone i'm sure. good luck with everything

06-13-06, 01:56 PM
The engine will last 250K-300K miles with reasonable care. I don't think it's cost effective to have the bottom end rebuilt. Caddy parts are pretty expensive. Having the trans done is a possibility bet how is it acting.

As I've run into problems after rebuilding things I tend to leave good engines/transmissions alone.

If you are doing the work it is very hard to take pics. You might try to get someone to take pics for you.

06-13-06, 09:16 PM
Our old Guru always said that the lower ends are very robust. I think that is true as we almost never hear of anyone having any lower end problems. I'd leave it alone and just Timesert the block and replace the gaskets. It should last a long long time after that as Zonie said.

06-14-06, 10:13 PM
Used engines.

If you have time to wait and will rebuild it your self check papers like the thrifty nickle and the like. Also check on line classified listings.

In time, one with a blown head gasket can be found for < 300.00

Purchase of a rebuild longblock can be tricky.
My 99 DeVille has one purchased on eBay, with 10K on the clock it needs replacement. It came with a 3 month replacement warranty. PO told me that the longblock always ran hot, my son finally overheated the engine after having it one month.

No matter what you do, it depends on the cars value and how long you intend to keep it.

We have tried selling the 99 for 4K as is with the builder 96 4.6L included, without a single call.

Since a 99 DeVille Ele, is not a hot seller and sales average < 6K its not worth the expense of another $2000 rebuilt and $1600 + installation charge at a shop.

Its a hard decision no matter what. I have started work on the builder engine so that the car with the bad engine can be used around town.