: Coolant Drain Plugs On the N*



jamesmdx1
11-16-05, 11:54 AM
Hello everyone

where are the coolant drain plugs on the N* engine
and how are they accessed?
I want to change the coolant today
thanks

mcowden
11-16-05, 12:06 PM
Hello everyone

where are the coolant drain plugs on the N* engine
and how are they accessed?
I want to change the coolant today
thanks

Didn't you just ask the same question yesterday?

There are no block drain plugs on a Northstar 4.6L V-8. Other engines may have them. The radiator drain is on the bottom driver-side corner. It's kind of difficult to access well, but if you take the air box out of the way, you might be able to reach it by hand from above. It's not in a very accessible location, so it's hard to see, but it is there.

If you're going to change coolant, just open the radiator drain and let it empty. You can run some distilled water through it with the drain open to clear out some more of the old coolant. Close the radiator drain and install the 6 Bar's Leaks large tablets or 2 tubes of Bar's Leaks Golden Seal powder to the radiator hose. Do NOT put them in the surge tank. Close up the hose again and refill the system with a 50/50 mix of distilled water and coolant. If your car is a 96 or newer, use a DexCool coolant such as Texaco or Prestone. If it's a 95 or older, use the green stuff. Do not use tap water.

There is no need to drain the block of coolant. Just drain the radiator and refill as suggested above and you'll be fine. Do not use any flush chemicals in the system as it's difficult to get them out of the system and they could lead to problems down the road.

Is that what you needed to know?

jamesmdx1
11-16-05, 12:11 PM
Thanks Michael
Yes I did ask a similar question yesterday
I was reading in the service manual about draining the left and right engine block plugs, but they did not say where they were.. I really didn't want to bother with them anyway..
I know you said to use the green stuff for a '94, any reason?
Can I use the orange one (DEX COOL)
thanks for the response

mcowden
11-16-05, 12:31 PM
Thanks Michael
Yes I did ask a similar question yesterday
I was reading in the service manual about draining the left and right engine block plugs, but they did not say where they were.. I really didn't want to bother with them anyway..
I know you said to use the green stuff for a '94, any reason?
Can I use the orange one (DEX COOL)
thanks for the response

You can use DexCool with any other type of coolant, but you have to change it following the recommendations of the lowest common denominator. Green coolant contains silicates that plate the internals of the cooling system. The silicates will invalidate the extended protection properties of DexCool so, while it won't hurt anything to use it, you don't really get any benefits from it either. I would just use the green stuff and continue to change it every 2 years.

jamesmdx1
11-16-05, 12:41 PM
Thanks for the quick response!

Jan Olsson
05-09-06, 03:55 PM
Didn't you just ask the same question yesterday?

There are no block drain plugs on a Northstar 4.6L V-8.

Itīs not my intention to be a smart-ass but there is drain plugs. At least on my -93 STS.
The rear one is ok to reach but the front was a challenge.
The owners manual doesnīt say or show were they are located, but they are there. The reason I had to look for them was having to drain the block to fix burned exhaust valves. Youīll never see a Cadillac doing over 50 mph here in Sweden because people still thinks of them in terms of pink, fins, etc... :rant2: Everyone says "Itīs a Cadillac itīs not supposed to go fast" :mad:
Well, this caused the burned valve.

Ranger
05-09-06, 05:42 PM
How does slow driving cause a burnt valve? If that where the case, every city driven car would be burning valves.

chevelle
05-09-06, 11:42 PM
The 93/94 Northstars had block drain plugs. They were eliminated after that so most all the Northstar engines in the field do not have block drain plugs.

Excessive carbon buildup to the point that it starts to prevent the exhaust valves from seating completely can cause burnt exhaust valves. The carbon can actually build up on the valve seat itself in extended low speed operation (like extremely long idles and never any WOT operation) and insulate the exhaust valve from the seat preventing any heat transfer from the valve head to the seat and ending up with burnt exhaust valves. If the carbon is heavy and a chunk breaks loose and sticks under the valve when it is closing it can cause high temperature combustion gas leakage past the valve and also torch that spot on the valve. This might happen when a heavily carboned engine is run hard for an extended period suddenly....like taking grandma's car out for a top end run right off the bat. Very heavy carbon buildup can also dramatically increase the odds of preignition (due to glowing carbon deposits) leading to detonation.....or detonation (due to the increased compression ratio) cuasing preignition. Either can cause burned exhaust valves (or other failures) if a heavily carboned engine is suddenly subjected to extended full throttle operation.

That is why it is a good idea to do many short WOT's with a heavily carboned engine to clean out the carbon with short bursts of WOT followed by engine braking with the throttle closed to make sure the carbon doesn't instigate a problem during a long, full throttle run.

Jan Olsson
05-10-06, 06:54 AM
How does slow driving cause a burnt valve? If that where the case, every city driven car would be burning valves.

Thanks Chevelle for the great explanation. Ranger, I should have said low rpms, Iīm not THAT stupid you know... :)
The guy who resurfaced the head and valves said it would propably never have happened if it was driven on the a-bahn. One exhaust valve cracked on no 1 cyl. Lots of carbon on that.

Ranger
05-10-06, 11:08 AM
Never meant to imply that you are stupid. Hope you didn't take it that way. I think what Chevelle is saying is that anything is possible, but I still think it is very unlikely. Many many cars driven aroung by "blue hairs" that never see high RPM and you just don't hear of a rash of burnt valves. If the type of driving you discribed burnt a valve, I would expect there to be an epidemic of burnt valves at most city dealerships, no?

Jan Olsson
05-10-06, 12:31 PM
Never meant to imply that you are stupid. Hope you didn't take it that way. I think what Chevelle is saying is that anything is possible, but I still think it is very unlikely. Many many cars driven aroung by "blue hairs" that never see high RPM and you just don't hear of a rash of burnt valves. If the type of driving you discribed burnt a valve, I would expect there to be an epidemic of burnt valves at most city dealerships, no?

No offence taken! Youīre right about that being unlikely. What worries me most is the fact that the car had 100000 miles on the counter when I bought it and several previous owners too. Couldnīt resist the price though...9000$ for a car like that here in Sweden -03 it was cheap :crybaby: For all I know they could have been using any kind of oil in it, not to mention what they could have done to the cooling system.

The rest here is extremely off topic but in some way related. :rant2:
I only pulled the rear head on my STS, figure I do the other if I ever get problems with leaks/overheating. The gasket in place looked as new, all bolts were on tight and the front head had good compression values so I just considered the front head to be fine.
The most time was spent on timeserting it, otherwise it was ok considering I did it with engine in car.
Since Iīm being used to drive tractors (Volvos), Iīm not used to service the cooling system with other than 50/50 glycol/tap water. My father is a bit extreme though, he has been driving Volvos since 1960 or so and he claims that he has newer changed coolant at all in any of them (otherwise he is extremely cautious with maintenance, canīt figure him out sometimes)
I myself had to do an engine job in a Volvo 740, the head gasket was a copper one, heavily corroded but still in one piece. Iīm not surprised that Volvo motors of that vintage can get away with so much abuse with all that iron between the cooling jackets and cylinders....
Since the cooling system in the Northstar is much more efficient, it also requires attention regularly, canīt convince my father though who believes (like 99% of the Swedish people I talk to :mad: ) that american cars are unreliable crap...well well.
But he also likes to irritate me just to get me going, only way to shut him up is tell him all the stuff I had to do with my last Volvo (-93 960) just to get everything to work like it should. AC-compressor replacement, rear main seal on engine, electrical problems, wheel bearings, drive axles, rebuilding the exhaust system hangers to reduce vibrations and noise....all within 100000 miles...and rust and corrosion on the rear suspension assembly. Talk about crap. But now its ok, sold it to my father :)

thu
05-10-06, 01:25 PM
But now its ok, sold it to my father :)

LOL!!!!!! :bouncy: :excited: :woohoo: :histeric: