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1996 Deville
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31 Posts
Discussion Starter #1
...SO things have improved after changing coolant and flushing and changing thermostat. Installing a new cap seemed to really help but here is my newest question. Now as I am driving my test runs at night ... (hot 4th of July night) I can go 17 minutes pretty OK ... staying around ... 212 ... drop to 206 ... back to 210 ... 217 ... back to 212 ... but twice today after about 20 minutes or so .... real fast .... 222 ... 228 .... 233 .... 242 .... 248 .... 255 .... 260 .... then just as fast (as I try to get closer to home with heart racing) 255 .... 248 .... 244 ... 240 .... 233 .... 228 ..... 222 ..... 217 ..... I pull in drive ... sits there and idles 217 .... WTH ... ....also the check engine light came on during the high temps ... newest codes IP2419 and TC 0027 current I believe ... then PC0300 seems to keep changing from current to history ...and the PC1380 misfire I already know about .... my next two guesses are ... needs tune up bad ... or ... air in system ... which leads me to my question ... does that PURGE line automatically take air out of the coolant system? I have no clueif that's it's purpose or something other?
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,863 Posts
...SO things have improved after changing coolant and flushing and changing thermostat. Installing a new cap seemed to really help but here is my newest question. Now as I am driving my test runs at night ... (hot 4th of July night) I can go 17 minutes pretty OK ... staying around ... 212 ... drop to 206 ... back to 210 ... 217 ... back to 212 ... but twice today after about 20 minutes or so .... real fast .... 222 ... 228 .... 233 .... 242 .... 248 .... 255 .... 260 .... then just as fast (as I try to get closer to home with heart racing) 255 .... 248 .... 244 ... 240 .... 233 .... 228 ..... 222 ..... 217 ..... I pull in drive ... sits there and idles 217 .... WTH ... ....also the check engine light came on during the high temps ... newest codes IP2419 and TC 0027 current I believe ... then PC0300 seems to keep changing from current to history ...and the PC1380 misfire I already know about .... my next two guesses are ... needs tune up bad ... or ... air in system ... which leads me to my question ... does that PURGE line automatically take air out of the coolant system? I have no clueif that's it's purpose or something other?
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does that PURGE line automatically take air out of the coolant system?
that is exactly what it is supposed to do - and it's only function - hence the name -

just be sure there is a constant - gentle flow of coolant when ever the engine is running -

NOTE - it may take a few heating cycles to purge ALL of the air from the system -
 

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1996 Deville
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31 Posts
Discussion Starter #3 (Edited)
Im reading now that a dirty air filter, bad spark plugs, can cause misfires , which I'm getting codes for ... and misfires can overheat the engine ... So ... This will be the next two things I check ... Thank you sir! ... Last recent check purge line is moving coolant through just fine ...
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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87,194 Posts
If the purge line is clear and flows coolant, you might want to do a block test.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,886 Posts
cure, the bottom line is: Between these occasional "overheats" are you slowly losing coolant or is it always at the correct half-full, cold level. There is a FULL COLD legend and flat arrow molded into the top and side of the surge tank.

Other than exhaust gas blowing into the cooling system, overpressuring it and blowing off coolant leading to an overheat, a slow coolant loss points to either a small leak or the beginnings of head gasket failure due to loss of bolt clamping pressure.

Those steel fire rings, once compressed at initial installation, will not recover to compensate for bolt hole thread failure and, regardless of magic potions and snake oil applications, the heads will continue to lift as the bolts pull further.

NOT a Northstar gasket but typical ...........

anatomy_of_a_headgasket.jpg


 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,886 Posts
Let's not hijack cure's thread.
 

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Registered
1998 DeVille
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111 Posts
Just bringing up what I noticed with very similar symptoms. Cure, the block test is the tell all. I was able to get one for free at a pepboys, but that could have just been this location
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,886 Posts
cure, if you decide to do a quick tuneup here's the diagram for your waste spark system. Use the expensive AC Delco plug wire set from Rock Auto (it fits correctly), AC Delco Platinum 41-950 plugs and disassemble and clean the coils and ICM base. Make sure the ICM ground cable is connected. Remove and clean the coils - bases and contacts. Connect the plugs, coils, and wires correctly - it makes a difference. Plugs come pre-gapped to .050". Plugs torqued to 13 lb/ft and you will find some oil on one or more plug shells. Normal cam cover plug well O-ring weep.

The CMP - CaMshaft Position sensor - is in the front of the right (rear) cam cover. The CKPs (CranKshaft Position sensor) are in the lower left (front) side of the block and bloody murder to get to. Knock sensor under the intake manifold.

Northstar Waste Spark Ignition System.gif
Northstar firing order & coils.gif
 

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1996 Deville
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31 Posts
Discussion Starter #13 (Edited)
... as an electrician ... This seems far beyond me , don't want to sound like a p**** and I appreciate all the info. What's getting me ,as I learn here, is there are no other signs, no anti freeze in oil, no oil in anti freeze ... Hardly no loss if power if at all ... No white smoke ... I've had 2 guys tell me there is no ... Beginning on a head failure ... It's either blown or it isn't ... But I'm believing you guys ... It more feels like the early stages of a failure ... So my real main question at this point for an experienced person ..i. Can it be a head gasket failing without showing all the tell tale signs? Oh , and to answer your questions ... Today it was 96 degrees in Cincinnati, I thought , screw it , off I went with AC on high ... Made it about 10 minutes 196, 201, 210 back 206 210 , 213, 217 ... 15 minutes in ... 222 ... Pulled over , parked in front of house .... Back 217 idling awhile ... Turned off, ate samich ... Went back ... Started ... Drove with AC ... Quickly to 222 228 233 238 244 250 255 sitting in front of house now ... Turn AC off warning ... I shut her down and was pissed once again ....so you guys think * can tackle this job? I'm mechanical electrically ... But never tore no engine apart ... OH yeah ... the coolant, since new radiator cap ... seems to stay steady in surge tank ... except as in today, when it boiled over onto the street a bit after it hit 255 for a breif moment. OH, and this is a 1996 , it's prior to the head bolt problem correct? ...and I haven't seen any leaks ....

. .
 

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Registered
1998 DeVille
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111 Posts
The northstar is designed in such a way that our would take a critical failure in order for coolant to mix with oil. The overheating is coming from exhaust gasses seeping into the coolant, by way of gaps as the head bolts begin to fail. That's why there's no smoke, but maybe the faintest smell on occasion of coolant.

Can you do the job? Yes. It isn't easy, and expect for the car to be down for a bit. You will have to rent some tools, and it helps to have ratcheting wrenches that wobble, anrd sockets that wobble. And a whole bunch of extensions. But you can do it. You will need to follow torque specifications for certain bolts.

There are multiple guides on this site to the process. It is recommended that you drop the cradle, and install studs on the heads. They are practically bullet proof and will last the life of the car. You can do it with the engine still in the car, but you can only do serts if you go this route. Either way you will be manipulating the cradle to get angles on the engine. It's not as scary as it sounds.

This community is always ready to help you with specifications and techniques, if you are willing to put in the work and understand the risks of half assing the job
 

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Registered
1998 DeVille
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111 Posts
You should do a pressure test to verify that there aren't additional leaks, and before you think of doing the heads, make sure that you get the block test done. If there's no exhaust gasses in your coolant, then your problem will be elsewhere
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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I've had 2 guys tell me there is no ... Beginning on a head failure ... It's either blown or it isn't .
Not true. It starts off slowly and gets progressively worse.



Can it be a head gasket failing without showing all the tell tale signs?
In the early stages, YES.



OH, and this is a 1996 , it's prior to the head bolt problem correct?
Not exactly, but the '96's where not as bad as the '97 - 99's. See the poll, in the Northstar engine forum.
 

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1996 Deville
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31 Posts
Discussion Starter #17
... talked to 2 mechanics today, one with all the tools and has done these before ... sounded very knowledgable ... gave me the time of day ... explained things very well ... says he's done over 100 of these ... current price $3200 ... 2nd mechanic gave me little time of day and his quote "put a fork in it, she's done" in your opinions is BARS head gasket repair worth a try on a car with 165k miles already ... if it doesn't work does it make the head gasket replacement job any more difficult at a later date?
 

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Registered
1998 DeVille
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111 Posts
It's pointless, because the problem is the loosening head bolts causing the gaps. it's only going to get worse over time, and no liquid gasket will help it for more than a couple weeks. I was able to drive a couple months by babying it, keeping the rpms under 2k, to reduce the load. AC was an instant overheat too, as it got worse
 

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1996 Deville
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31 Posts
Discussion Starter #19
...watched one video on a CTS I believe ... he tried it and posted months later and over 4,000 miles A- OK ...checking more out now. I understand your point well enough but I am always wondering about every possibility ... I assume it could still be possible to have the head gasket breech without it being the head bolts ... in some cases ... ???
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,886 Posts
Stephen Foster wrote a song about this - "Beautiful Dreamer".

Once the head bolt threads begin to go it's all downhill from there.
Our Northstars bear NO resemblance to a 3.6.

Discount the cooling system and purge line first, then dig into the actual cooling system.

Yes, pouring in magic potions and sealant goop makes subsequent repair quite difficult if not impossible.
 
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