: 1999 Northstar with blown head gasket

12-26-05, 05:03 PM
Hello everyone,
After three trips to the dealer during the last four months for overheating in my 1999 Cadillac Deville with 55,000 miles on it, they now tell me I have a blown head gasket and are recommending I buy a new engine.

Should they have noticed a pending problem and provided some kind of "heads up" to me? On the previous two trips to the dealer, they simply said everything was fine after doing pressure tests, in retrospect it now seems they should have warned me the overheating would lead to a blown head gasket. Is my thinking correct? Are they more responsible than I am.

Any comments appreciated. Val

12-26-05, 07:03 PM
:welcome: Overheating was the symptom, rather than the cause of the bad headgasket. The head gasket was likely already breached when you first overheated, unless there was another explanation, like a bad thermostat, or water pump that caused the overheat and you continued to drive it beyond the point where you were advised to shut down.

That said, you don't need a new engine. You do need new head gaskets and the bolt holes need to be Timeserted. That is not cheap by any means, but it is about 1/2 the cost of a new engine.

12-26-05, 07:25 PM
Thanks for your response. That's a good point. When it first overheated, the car shut down and coasted to a stop. Then we checked the operator manual which said as we recall, the car would shut down before any engine damage. After waiting an hour we added new "dex" fluid with 50% water and the next day drove car to dealer and they made it seem like everything was fine, but they did replace all hoses, waterpump and thermostat. Could this be what caused the breach?

Two months later, same thing again and towed to the dealer. Dealer said we had lower hose was leaking. That was fixed.

Next time month later we had another episode of overheating and were towed to dealer. Now they say blown head gasket. Requires repair or new engine. I feel the dealer is responsible because they never fixed the underlying problem. What do you think?

12-26-05, 07:27 PM
What is it that makes the head gaskets so fragile on the N*?

Is the 4.0L Aurora and the ShortStar so fragile?

12-26-05, 08:24 PM
It is hard to say (and harder to prove), which came first. From my expirience here, it is usually the head gasket, but even if it wasn't, you'd have a very hard time trying to prove it and make the dealer eat the cost. Northstars seem to run for quite a while with a bad head gasket. Sometimes only overheating climbing a hill or at WOT, til it gets worse.

Poor or lack of, cooling system maintanence is one of the biggest causes of head gasket failures. Pulled head bolt threads is another casue but from what I have read, that is relatively rare. The threads usually pull on removal or retorquing, which is why it is recommended to Timesert all threads when the heads are removed. Overheating is another cause but, theoretically, the Northstar is supposed to be able to run 50 miles without coolant (camel mode) with no damage, though I would never attempt it.

12-26-05, 11:49 PM
o.k. Thanks for the info, we were in the mountains when first experienced the overheating.

What does WOT mean?

12-26-05, 11:57 PM
WOT= Wide open throttle (foot to the floor which can clean the carbon off the engine. Its recomended to limit oil consumption in the N*)

The N* is aluminum so at high temps, it is more likely to warp/crack than a non-aluminum engine

12-28-05, 11:03 AM
I was having overheating issues on my 99sts and the shop said they detected hydrocarbons and co2 in the recovery tank indicating a head gasket problem. I replaced the thermostat as suggested on this forum, now the car seems to be fine. A head gasket replacement quote from a private shop owned by a former Cadillac mechanic was $2500. Reasonable so far as I can tell. I'm just glad to not have to spend it now.

12-28-05, 04:18 PM
One issue is semantics. A "blown" head gasket does not necessarily have a hole in it. It may be the equivalent of a seep. That's why they can be so hard to diagnose. Even a cyl pressure test may not show that small of a leak initially.

Once the leak has started it will get worse but gradually.

I don't think a shop can warn you of all the possibilities of damage. Especially since you may never talk to the mechanic but to a service advisor and cashier.