Question about 1999 Cadillac DeVille

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1999 Cadillac Deville Engine trouble

Hi all, I've been trying to narrow down whats wrong with my engine for awhile now and I can't seem to figure it out so here I am to tell you whats wrong with it and maybe some of you have a solution or two for me to try. A couple months ago my husband was driving home from work on the I275 here in Florida and the car over heated. He pulled over as soon as it began to do so and called me. I asked him to describe to me what he saw and what the car actually did and what is it doing now. This way his reply. "Well, while I was driving I noticed that the car didn't really want to pull (knowing my husband he probably tried to make it go by pressing more on the gas pedal) then after I initially noticed that I saw steam coming from the hood. I pulled over on the side of the road opened the hood and called you." I asked if he saw any smoke (indication of a blown engine or cracked head) he said no just steam and water. I asked if he was close enough to somewhere to get some water to put in the car. That was a negative also. So I asked if he could get it towed to a shop nearby and ask a mechanic since he was so far away from me on the highway and I was at work. He did. When he got to the mechanic he initially said the man told him (without putting it on a machine, or any type of actual testing) that he had cracked heads and blown engine and that he could do the work for $5000 or maybe more. I told him to have the car towed home and lets get a second opinion. We had a known mechanic come by and he told us to start with the radiator hoses because the car starts with no problem, it also doesn't cut off without us turning it off, neither does it smoke. There is steam and for some reason (I haven't checked the oil pan yet) it will not hold oil. Over a couple days to a week its gone again. ButI don't not see any indications of a cracked head(s) or a blown engine. I have experienced both before and it doesn't look like either. I have my hoses off and I let my husband check them for holes. He said there are none in either the top nor the bottom hose. Anyone have any suggestions? (serious replies only please)

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The most common overheating problem with the Northstar engine is a blocked purge line. It's job is to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.The hose goes in to the engine to a crossover and comes out the other side to near the thermostat housing,the blockage may be there.

Posted on Mar 09, 2010

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On the 4.6 northstar,for some reason they blow head gasket quick and cadillac hasn,t address that there is a problem.just about half of 1998 and up 4.6 northstar have had some overheating problem,but most people love there cars and just have engine fix.the ride is so good and comfortable.I hate to give you bad new,but you need to have it check by a mech.that now how to pressure test you engine.a small break in the head gasket will have it over want see any water or smoke.the only thing it does is run hot until it does damage.

Posted on Jul 20, 2008

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I am sorry to tell you this but I had the same problem. It starting about three months ago. I would be driving and when I parked my car I would see white steam coming for the passager side of the car. Sometimes i would see this and for weeks nothing. Well to make a long story short this week my car overheaded to 257 degree. My mechanic told me that my gasgets and the engines head was blown. It would cost to much to fix just get another car :(
I loved my car and I cryed all day. Good luck to you!

Posted on Mar 07, 2010

  • idssuccess Jan 10, 2011

    You should feel very fortunate. The same thing happened to my 1998 Deville except my mechanic nickel and dimed me by fixing a leak in a metal coolant line behind the engine, water pump and housing that had cracked, numerous fried sensors, new plugs and wires, oil change, transmission fluid change, and a few other things over a month period and three additional overheating breakdowns requiring towing. All said and done I was out $3,300 and my car still doesn't run. My remaining option is to sell it to a salvage yard for $200. Ouch!!!!


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On the Northstar engines, the problem is that the head bolts pull the threads out of the aluminum block. The head bolts are 11mm fine tthread which is Approx. 7/16" & over time the threads rot or pull out of the casting. & NO it is not a simple fix. There's a stud kit sold in Ont. Canada or they will do it for you. BUT IT"s NOT CHEAP

Posted on Mar 06, 2010

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