[wulf]

my vehicles all fine now thanks to you guys but could do with advice regarding the northstar lump fitted to a mates deville 2001ish it`s been overheating for some time so i said i`d try and help ! we`ve replaced water pump , thermostat , radiator and fan temp switch all to no avail i`ve also just heard about an sts with the same prob ! is this a common prob and does anyone have a clue as to how to sort it ?
thanks in advance !

 

[sunsetdart]

Biggest problem I have seen , especially with GM vehicles is the Dexcrap(cool) antifreeze in the radiator. It allows electrolysis to eat the inside of the radiators. The core starts to collapse on itself and prevents flow without it showing any signs of leaking.

 

[curtis73]

Hate to suggest it, but head gaskets are a bit of an issue with that era of Northstar.

 

[6426yy]

A kid I work with had the same problem with his Caddy did everything that you've done and just decided to trade it off.

Sorry I couldn't help, could be the head gaskets, let us know if you figure it out though.

 

[joe_padavano]

Is it actually boiling over or are you just going by the gauge reading? A leakdown test will tell you if it's the head gaskets or not. If the car has or continues to boil over, the head gaskets are likely gone. Otherwise, check the condition of the radiator. Verify that both electric fans are working. Check for any stored codes in the computer. Verify that the temp sender is working properly. Note that there are two independent sensors, one for the temp gauge and one for the computer. With a good scan tool you can watch the computer data while driving and compare that temp to what the gauge says.

 

[cobalt327]

Hate to suggest it, but head gaskets are a bit of an issue with that era of Northstar.

They sure are.

I'd run a cooling system pressure test on the (warmed up) engine.

 

[wulf]

the engine is reaching high temp and then spitting it`s water out and then boiling ! i`ve had a vehicle rescue service out to it and they say there is no trace of combustion gasses getting to coolant system so in their opinion head gaskets are ok ! they are tho used to working on euroboxes so may not be correct

 

[wulf]

the radiator is brand new as is stat and waterpump also hoses ! flushed full system ! sensors all ok fans cutting in and out and no fault codes setting

 

[T-bucket23]

Is the belt for the water pump tight and not glazed. Those engines had huge head gasket issues amongst other things. You also have to make sure ALL the plastics around the radiator are in place.

Does it overheat at idle or just going down the road. It takes a lot of air to cool that big V8. Make sure the condenser isn't plugged up and restricting air flow.

 

[wulf]

thanks for the advice all ! will have another look at weekend and keep you posted !