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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,423 Posts
Is the thermostat installed correctly? - and if so, what temp range is it rated at and who made it ? The block and heater coolant circuits act on the 'stat wax pill, NOT the radiator coolant. A Northstar needs the 'stat in place to cool correctly. Do you know if any small coolant lines have been replaced recently?

There's quite a bit on cooling systems in the Engines; Northstar stickies (marked with a push pin - timeless info).

Thermostat and cover diagram.gif
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
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280 Posts
Discussion Starter #82 (Edited by Moderator)
It's a new stat, we boiled it and it opened, it's the right temp one, 190, I think. Even with the stat out, it still goes to 230s, just idleing, bfre I would raise idle to cool it down and shut it off. It will blow the water out of the tank, if I let it go too long. No coolant in it yet. I wanted to get it fixed, bfre I put the new antifreeze back in.

After I finish the comp test tday, if it passes, I'm gonna put antifreeze and stat back in and see what happens

Fixing to do that, as soon as the kid shows up.

It's got new hoses at crossover, when we replaced those gaskets. Everything was clear. Only other "small hose", I know of, is the purge line. It's clear also.

I even removed the expansion tank, and cleaned it out. I just cant find anything wrong with the entire cooling system.

Hes on his way out, now. I'm going out and pull the plugs. Gotta look up the firing order 1st. That way I can go from one cylinder to the next, after I find tdc on #1, with that one way socket I got for the crank bolt.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Remember - with no pressure cap in place the coolant will boil before it reaches the 224 degree fans SLOW point. With water only the boil point is even lower at 212 degrees. Install a 16 or 18 psi pressure cap.

Note that the 50/50 line is out of sequence -

Coolant Boiling point.jpg


Here's your firing order - make very sure the correct plug is connected to the correct coil tower - it's important.

Northstar firing order & coils.gif
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
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280 Posts
Discussion Starter #84
Yes Sir. Thank you, Sub! Will report back soon.
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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280 Posts
Discussion Starter #85
Ok, test done. I hooked the air comp to each cylinder. Could hear blow-by in the crankcase thru oil filler hole. Got "glug" sounds in the expansion tank, after pressure was on for over a minute, on cylinders 3, 5, and 8. A "glug", after several minutes, and air compressor cycling several times, from the blow- by. Gonna do #1 n 2 over again, and listen longer, to be sure.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,423 Posts
Bubbles or air entering the surge tank with pressure on a cylinder is not good - but now I'm lost for advice.

Given the crankcase blowby sounds you may be in the engine overhaul business, and not just cylinder head bolt hole inserts and head gaskets, either. The whole engine. At 250K miles (I overlooked that fact) the engine is on its last legs. Cams, flat-tappet cam followers, timing chain guides and tensioner shoes ........
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
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280 Posts
Discussion Starter #87
Your right. Started over, and listened longer, and could hear a glug on 1 and 3 also. This early design has no followers, but still, exhaust cams and lifters are worse out. I'm gonna put the air to my Deville, it only has 105k, and compare the blowby sounds, air comp cycling time, to see maybe it's still worth some used, better heads. It's got so many new chassis parts, it's a hard call.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,254 Posts
It's a new stat, we boiled it and it opened, it's the right temp one, 190, I think. Even with the stat out, it still goes to 230s, just idleing, bfre I would raise idle to cool it down and shut it off. It will blow the water out of the tank, if I let it go too long. No coolant in it yet. I wanted to get it fixed, bfre I put the new antifreeze back in.

After I finish the comp test tday, if it passes, I'm gonna put antifreeze and stat back in and see what happens

Fixing to do that, as soon as the kid shows up.

It's got new hoses at crossover, when we replaced those gaskets. Everything was clear. Only other "small hose", I know of, is the purge line. It's clear also.

I even removed the expansion tank, and cleaned it out. I just cant find anything wrong with the entire cooling system.

Hes on his way out, now. I'm going out and pull the plugs. Gotta look up the firing order 1st. That way I can go from one cylinder to the next, after I find tdc on #1, with that one way socket I got for the crank bolt.
==========================
I'm gonna put antifreeze and stat back in
if you are running the engine with the tstat removed - it WILL overheat -

That way I can go from one cylinder to the next, after I find tdc on #1,
with that one way socket I got for the crank bolt.

you do NOT need to find TDC - or any other specific position - to do a COMPRESSION test -

to do a compression test -
remove ALL spark plugs -
block the TB wide open -
attach the compression tester to the first cylinder - it doesn't matter where you start -
crank the engine and count SIX compression strokes - you'll hear them -

do all the cylinders EXACTLY the same for the most accurate results -

rule of thumb is that there should be no more than 10% difference
between the highest and lowest PSI -

if there is a big difference between cylinders -
you should do the test over using the "WET" test -

the WET test includes adding 1/2 oz of oil to the cylinder -
spin the engine to distribute the oil -
then do the compression test and NOTE the difference - if any -

--------------------------
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
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280 Posts
Discussion Starter #90
I wasn't trying to do a compression test, was trying to find leaking headgasket, hooking up my air compressor to the compression tester. And listening for bubbles in the expansion tank.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,254 Posts
I wasn't trying to do a compression test, was trying to find leaking headgasket, hooking up my air compressor to the compression tester. And listening for bubbles in the expansion tank.
========================
OK - but - consider this -
your engine PASSED the BLOCK TEST - assuming you did it correctly - and the purge line is clear and flowing -
meaning there are NO hydrocarbons - exhaust gasses - getting into the cooling system -

your air compressor puts out between 100 and 150 psi -
and is constant during your testing method -

when the spark plug ignites the air/fuel mixture within the cylinder -
pressure can hit between 25,000 and 50,000 psi - briefly -
and pulses down to a vacuum - briefly -
THOUSANDS of times per minute (half the indicated RPMs) -
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,254 Posts
It wouldn't hold pressure on any cylinder.
=====================
cold engine - dry cylinder walls - high mileage -
I wouldn't expect it to hold pressure -

if you listened carefully -
I bet you could hear air flow through the exhaust AND the intake -
along with the crankcase -
it doesn't really prove anything -
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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280 Posts
Discussion Starter #93
Yea, you're right, got it back together n running now. Purrs like a kitten. Still idles like a sewing machine, after 255k miles.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,423 Posts
Pre-2000 Northstar flat tappet cam followers - worn from high mileage. The associated cam lobes are also toast.

cam follower wear.jpg
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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280 Posts
Discussion Starter #95 (Edited by Moderator)
The fans kicked on highway bout 235, it still went on up to 244, even with idle raised to 1500. Shut it down. Did not boil over, just gurgling. But no heat.

Misspell stupid auto-correct. Not supps to say hiway, supps to say high.

Idk. Done with it for tday. Thanks a million, guys!
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
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68,423 Posts
No heat = clogged or airlocked heater core = no correct coolant flow.

See the little row of 3 dots in your posts - upper right? Click the icon and use the EDIT feature in the menu to add to or change your posts within 10 or 15 minutes of posting. No sense posting several times a minute apart. Thanks.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
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86,781 Posts
It wouldn't hold pressure on any cylinder.
You are rotating the engine each time you move from cylinder to cylinder so THAT piston is at TDC on the compression stroke I hope. If not, as Bass said, you are simply blowing air into the exhaust or the intake and it will never hold pressure.

You seem to have checked about everything we can think of except the WP. I'm not going back through 5 pages to see if you have, but as a last resort, you might want to pull the pump and have a look see. You could be one of those very rare cases where the impeller came loose and is not pumping coolant. Other than that, I'm out of ideas.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
Joined
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19,254 Posts
The fans kicked on highway bout 235, it still went on up to 244, even with idle raised to 1500. Shut it down. Did not boil over, just gurgling. But no heat.

Misspell stupid auto-correct. Not supps to say hiway, supps to say high.

Idk. Done with it for tday. Thanks a million, guys!
=====================
Did not boil over, just gurgling. But no heat.
NO HEAT indicates an AIR LOCK in the cooling system -
and AIR in the system indicated a clogged PURGE LINE -
and a clogged purge line will NOT dump the hydrocarbons into the SURGE tank -
and that WILL give a FALSE negative result in the BLOCK test -
 

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1999 Deville base
95 Eldorado, 99 Deville, 05 CTS
Joined
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280 Posts
Discussion Starter #99
The water pump and purge line were some of the 1st things I ckd. It WAS putting out some heat, now none, at 241 degrees. I filled xpansion tank all the way up this time. Shut it off at 240+ Ddnt boil over, just gurgled. Gonna ck it in the mrng, n see how full it is. If I could figure out a way, I would hook up my water hose to the cooling system and back flush thru the heads and heater core. Yea, I was rotating crankshaft each time in order to the next tdc. I will ck the purge line again, Basscat. Thanjs.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
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86,781 Posts
If you have gurgling and bubbles in the surge tank, no heat from the heater core and a 240° temperature, I think it is a pretty safe bet that a HG has failed.
 
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