: Northstar 4.6 Overheating



gtoman1970
01-15-12, 01:24 AM
Ok I hope I am in the the right forum. As I have been reading about the Northstar 4.6 it has a history of overheating while driving down the hwy. My problem is mine overheats while at idle or low rpms. When driving down the hwy it seems to run fine. I have had it in the shop, run a car fax on it, called other dealers that have
recorded repairs on it. It looks like water pump, sending unit, thermostat, radiator cap have been all replaced. My GM shop is not set up to test for exhaust gases in
the coolant.

I have been reading about some solutions for head gasket repairs, have even called a company that sells steel-seal. When telling him about how my overheats while
at low rpms he wondered for sure if mine was actually head gasket. So now I'am at a stand still. I have found a 96 Cadillac Deville with hail damage and trany
problem and thought about pulling that engine, but would I end up with same problem. Then I thought of replacing the engine and have found a GM engine for 4800.00. Will I still have the same problem after a few years. Is it worth putting that kind of money in a 1998 Cadillac Seville with 127000 miles on it. The car is probably a
8 on a scale of 1-10, 10 being great. I just bought the car and the dealer won't stand behind it. I may have 300 miles on it since Dec 28 2011.
gtoman1970

vincentm
01-15-12, 03:18 AM
1. There's no history of the Northstar overheating while on the hwy.

2. You can test the for exhaust in your coolant by doing a block test, rent the kit from.any auto parts store, if your dealer/mechanic says they're not equippedbto do so, they suck..period, its a simple test


3. Only way to fix the HG is to remove the engine, snake oils will render your engine to the grimm reaper


Have a good day:)

maeng9981
01-15-12, 07:02 AM
It is too early to diagnose it as a HG problem. You have done no tests.

Are your fans running when the temp reaches 222-224? (between 4/8 and 5/8 tick mark)

Submariner409
01-15-12, 12:35 PM
This thread is a duplicate of one I have seen somewhere else in CF.

gtoman 1970, You are misinformed on the Northstar - You NEED to do some homework: Go up to the black bar ^^^ and study the entire Cadillac Technical Archive. Then go down to Discussions, Item Specific and wade through the pages of Cadillac Tech Tips, skimming threads of interest. Then, try to surf through Seville pages............Yes, it's a lot of reading, but without some real knowledge base you'll be flying blind.

Overheating at idle or low rpm is either fans, dirty A/C condenser fins (front of radiator assembly), or poor coolant flow..........all can be diagnosed and repaired with some basic knowledge of the engine and systems.

Ranger
01-15-12, 03:08 PM
Have you checked the purge line to be sure it is clear?

gtoman1970
01-16-12, 08:10 PM
Yes we have done testing. I have had it in a GM dealership, they tested to see if fans were kicking in as per GM specs, test showed sending unit recorded same as cluster. When idling you can feel coolant pulsating, when rps were increased up flow increased in top radiator hose and temp dropped. Tech talked with GM tech and told him to check cross over hose for blockage which he did. When temp increased left fan would blow cold air. Vehicle has been in several shops to figure out the problem, least 1 Cadillac dealer. GM is advising head gaskets.
gtoman1970

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1. There's no history of the Northstar overheating while on the hwy.

2. You can test the for exhaust in your coolant by doing a block test, rent the kit from.any auto parts store, if your dealer/mechanic says they're not equippedbto do so, they suck..period, its a simple test


3. Only way to fix the HG is to remove the engine, snake oils will render your engine to the grimm reaper


Have a good day:)

I am about to turn the vehicle over to the grimm reaper, Maybe just add enough snake oil to unload it to another dealer since a dealer sold it to me and won't stand behind it. Hate to pass on the problem.
gtoman1970

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This thread is a duplicate of one I have seen somewhere else in CF
.
Yes I posted in in the wrong spot according to you so I re-posted it here. Will do some reading up above.
gtoman1970

gtoman 1970, You are misinformed on the Northstar - You NEED to do some homework: Go up to the black bar ^^^ and study the entire Cadillac Technical Archive. Then go down to Discussions, Item Specific and wade through the pages of Cadillac Tech Tips, skimming threads of interest. Then, try to surf through Seville pages............Yes, it's a lot of reading, but without some real knowledge base you'll be flying blind.

Overheating at idle or low rpm is either fans, dirty A/C condenser fins (front of radiator assembly), or poor coolant flow..........all can be diagnosed and repaired with some basic knowledge of the engine and systems.

Yes I posted in in the wrong spot according to you so I re-posted it here. Will do some reading up above.
gtoman1970

ThumperPup
01-16-12, 08:59 PM
[QUOTE=gtoman1970;2832242]
gtoman1970

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I am about to turn the vehicle over to the grimm reaper, Maybe just add enough snake oil to unload it to another dealer since a dealer sold it to me and won't stand behind it. Hate to pass on the problem.
gtoman1970

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/QUOTE]


If you want to do the not so nice thing and pass it to the next dealer without be honest and disclosing the issue then so be it
its your Karma that will come back 10 fold lol

if you bought it as is no warranty at all then thats what happend
dealer probably new it was bad and just wanted to unload it

if they can't do a block test then they are full of BS and know what the problem is but don't want to admit they sold you a car that they already new was baad

Ranger
01-16-12, 10:19 PM
I edited your title to make it more descriptive.

tateos
01-19-12, 09:50 PM
This is not a HG - N* overheating at idle is almost unheard of. I am 100% with Sub - if water pump is good and coolant is flowing, either the fans are not coming on or you have a clogged radiator or blocked/obstructed radiator or condenser...and these are not common problems. I think you should suspect your radiator is clogged (internally)

sts 03
01-20-12, 11:58 PM
How bad is it over heating past the middle mark on the gauge.my temp gauge will move maybe a half a centimeter pass the middle mark some times only in idle but goes back to normal range by its self but my gas gauge jumps around sometimes too so I don't know if my temp gauge is acting up like my gas gauge or is it really running hot.

maeng9981
01-21-12, 09:05 AM
How bad is it over heating past the middle mark on the gauge.my temp gauge will move maybe a half a centimeter pass the middle mark some times only in idle but goes back to normal range by its self but my gas gauge jumps around sometimes too so I don't know if my temp gauge is acting up like my gas gauge or is it really running hot.

Yours is working normally.

ThumperPup
01-21-12, 10:52 AM
How bad is it over heating past the middle mark on the gauge.my temp gauge will move maybe a half a centimeter pass the middle mark some times only in idle but goes back to normal range by its self but my gas gauge jumps around sometimes too so I don't know if my temp gauge is acting up like my gas gauge or is it really running hot.

it perfectly normal for it to get up to 230 on hot days at idle
even though i still panic when mine gets to the 1:00 and 2:00 Oclock mark every now and that when its in the 90s and idling
with ac on
but ones i start moving again it goes back down
and i know its normal but i still panic about it

sts 03
01-21-12, 11:01 AM
so thats normal for it to jump a little pass the half way mark.

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i was thinking something was starting to fail.

ThumperPup
01-21-12, 11:01 AM
so thats normal for it to jump a little pass the half way mark.

yup
look in Sub's Profile Picture ALbums i think there is a graph there that shows temp rangs what is normal fine ok and then the Oh Shit factory LOL

vincentm
01-21-12, 11:08 AM
Yes we have done testing. I have had it in a GM dealership, they tested to see if fans were kicking in as per GM specs, test showed sending unit recorded same as cluster. When idling you can feel coolant pulsating, when rps were increased up flow increased in top radiator hose and temp dropped. Tech talked with GM tech and told him to check cross over hose for blockage which he did. When temp increased left fan would blow cold air. Vehicle has been in several shops to figure out the problem, least 1 Cadillac dealer. GM is advising head gaskets.
gtoman1970[COLOR="Silver"]


They didn't do a block test?

Submariner409
01-21-12, 11:54 AM
so thats normal for it to jump a little pass the half way mark..........i was thinking something was starting to fail.

This exact same question and the answers were posted up in Seville earlier this morning. Ranger posted the temp gauge picture.

We now return to gtoman1970's thread.

Mark D
01-24-12, 06:03 PM
It almost seems like low coolant, but I'm sure you've looked at that already.
But here's something nobody ever seems to look at - The water pump belt, tensioner and cam pulley.
The tensioner can become frozen from dirt and road salt. From there, it no longer provides tension to the belt. The belt begins to slip. I recently had to replace a pulley, belt and tensioner on a '94 STS (who's trunk is held shut with a tie-down strap for an indication of the type of service this car has had) because it had been slipping so much for so long that the drive pully on the left intake cam was worn to the point where there was nothing left for the belt to ride on. The car had similar symptoms to your car. It heated up at idle. It did not overheat to the point of boiling coolant out, but it would get quite hot, even in the lower tempratures we've had in December in this area, which are far warmer than normal. It was getting up to 230 or better, which is not out of line but is hot for only short stops in 30 degree weather.

If the car isn't boiling coolant out of your car, you can be pretty sure that it probably isn't head gaskets.

And if it is head gaskets, you asked the question of whether it's worth it to do that job on a car with 127K miles on it (going from memory here) Well, I just did head gaskets on a '98 STS with 200K on it and I feel it was well worth it. The car has been well maintained in all other respects, so I expect it to go at least another 100K miles, mostly trouble free. You will need to do what works for you, but unless the car has been abused and neglected all its life, it's still a fairly new car in most respects.
Mark D.

Caddys 32
01-26-12, 10:54 PM
I have a 02 Deville & the radiator temp always goes 2 the half way mark never once over it. My question is that's normal dead center?

Caddys 32
01-26-12, 11:02 PM
4 got 2 mention I have a digital dash board. If that even matters it doesn't have actual temp readings. Half way mark guess n about 220 degrees?

Ranger
01-26-12, 11:06 PM
Not sure about the digidash, but if that is where it always sets, that's the normal position. I would expect it to be about at the half position.

Caddys 32
01-26-12, 11:46 PM
Cool thank u!

gtoman1970
01-27-12, 12:39 AM
Gauge pegs out in the red
gtoman1970

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Not positive but I think center or just below center seems to be normal for mine, then it hits red and the alarms go off.
gtoman1970

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Update on the 98 Seville, drove it for the first time since I have had it in the show. Got the shop to order the testing equipment to test for exhaust in coolant. Didn't take the test long to change the bad color. If I keep the car I think it will just get a new GM motor. Then pull this one apart and check the head gaskets. I found some GM head gaskets at a very good price.
gtoman1970

tateos
01-27-12, 02:01 PM
I agree with Mark in post #17 - that's a good insight. I had the bearings on the water pump tensioner pulley seize - the belt made a slight squealing sound upon cold startup, but that was it. After about 30 seconds or so, it quieted down - the belt kept moving, and so did the water pump, but the belt was slipping on the tensioner pulley. Needless to say, I replaced the pulley (rest of the tensioner was fine), and the belt, and all was well again

Mark D
01-28-12, 11:07 PM
Gauge pegs out in the red
gtoman1970

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Not positive but I think center or just below center seems to be normal for mine, then it hits red and the alarms go off.
gtoman1970

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Update on the 98 Seville, drove it for the first time since I have had it in the show. Got the shop to order the testing equipment to test for exhaust in coolant. Didn't take the test long to change the bad color. If I keep the car I think it will just get a new GM motor. Then pull this one apart and check the head gaskets. I found some GM head gaskets at a very good price.
gtoman1970

Eh, you haven't priced a new Northstar engine lately, have you?
I think you might find it advantageous to simply do gaskets on your engine.
Be mighty sure it really is head gaskets first, though.
And head gaskets aren't all you'll need to do the job. They are about the cheapest part of the job, though.
You WILL want to get the stud kit and do it right. For the amount of work involved, there is simply no other way to do it than the right way the first time. If you don't do it the right way the first time, then this won't be the last time you have the problem.
Mark D.