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Deville 2000. Cooling problems, building up way too much pressure

12K views 54 replies 10 participants last post by  blackmill86 
#1 ·
Okay, i tried to look for a thread with this same problem but couldn't find it. Kinda mew here.

My deville 2000 is overheating and building up alot of pressure un the main rad hoses, and I mean alot, it already cracked one rad, I already checked for flow throughout the whole system and cleaned the hoses that were plugged with rust. I can pretty much blow through the whole system by mouth and flow seems good. I already took the thermostat out but it still does it. Heater core hoses take a little longer to get as hot as the rest, and also the rad doesn't get as got until I rev the engine a little bit, it gets hot evenly after that. However air and water flow goes right through it.. Water pump failing maybe??
 
#2 · (Edited)
========================
My deville 2000 is overheating
how hot is it running -

and building up alot of pressure un the main rad hoses,
and I mean alot, it already cracked one rad
the pressure cap is rated for 18psi -
if you think the pressure is higher than that -
test the cap - or replace it -

I already checked for flow throughout the whole system
and cleaned the hoses that were plugged with rust.
did you check the PURGE LINE for a constant - gentle flow of coolant -

I already took the thermostat out but it still does it.
our cars will overheat without a thermostat installed -
so - put it back in - or replace it with a genuine ACDelco or STANT unit -

Water pump failing maybe
check the waterpump drive pulley/belt/tensioner/and idler pulley -
 
#5 ·
Okay, I don't know how to check the exact temperature, it just reaches all the way to the "coolant hot" message. I kinda do think the pressure goes past 15 or 18 psi, didn't think of the cap replacement. And no I haven't performed a block test.. Is that a mechanic's job or something I could go for myself?? I'm not getting oil/coolant mixture at all..
 
#6 ·
Northstars with failing head gasket(s) do not normally mix oil and coolant or vice versa. Much more info in Engines; Northstar, both in the sticky threads and in the main forum threads.

Actual system temperatures are best observed with either a ScanGauge-II (any 4 of 12 gauges at once) or use an IR thermometer from Radio Shack.

Block test - a cylinder block exhaust gas test - done by sniffing the airspace over the coolant in the surge tank. Rent the tester from any large parts store, buy one at a NAPA, or look at https://www.google.com/search?q=amazon+lisle+75500+tester&ie=utf-8&oe=utf-8
 
#9 ·
So the over pressure is most likely a head gasket failure?? From the few posts I've read before I haven't seen anything with over pressure. I think its better off I let a mechanic take over.

Maybe
. But the system is designed to hold 18 psi, so anything in excess of that should blow the pressure cap relief, not a radiator end tank. These plastic tanks DO get brittle and leaky over the years.

Did you check/clear the purge line and hollow bolt/nipple ?? See the nearby thread, here in Deville, on surge tank replacement - there's info there as well as in the sticky threads in Engines; Northstar. Might as well do some homework before you throw parts at it.

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Also i just noticed that the spring on the cap to the reservoir hardly moves at all by hand, could that maybe not let the air out and create that extra pressure..
A new Gates, DAYCO, AC Delco pressure cap is about $7 at any parts store. Might be worth a try. If your present one is screwed up you'll need one anyway.
 
#11 ·
Yeah, all the lines have been cleaned, and the purge line was a little clogged up but I put my compressor to it and blew all the nasty stuff out. The second clog was down in the line that goes into the radiator, both are clean now. Now I haven't gotten the new cap but the one present now will open up but by the time it opens up the pressure is way beyond normal. I'll grab the new cap tomorrow and go over the recommended threads. Im not ready to see her go just yet.
 
#16 · (Edited by Moderator)
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the purge line was a little clogged up
but I put my compressor to it and blew all the nasty stuff out.
did you actually observe coolant flowing through the PURGE LINE? -
did you check/clean the HOLLOW BOLT that the purge line attaches to?

The second clog was down in the line that goes into the radiator
do you have a water-cooled alternator?

I haven't gotten the new cap
but the one present now will open up
but by the time it opens up the pressure is way beyond normal
you continually refer to the system being overpressured -
HOW did you come to that conclusion?

without a pressure gauge - it's impossible -

18psi doesn't sound like much -
but trying to squeeze a hot radiator hose - under full pressure -
you won't be able to compress it at all -

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Okay, today i did the block test like the video shows, no change in color of the testing fluid, i did it 3 times so im assuming no hg problem here.. however i checked the purge line that goes back to the rad and nothing but steam came out of it, every now and then a couple drops but not a steady flow of coolant.. could the water pump be the issue?? I didn't let it go up to the max on the temp but it was going after like 30 mins running in the driveway.*
========================
i checked the purge line that goes back to the rad
and nothing but steam came out of it
the PURGE LINE goes FROM the HOLLOW BOLT at the thermostat housing -
TO the nipple on the side of the SERGE TANK -

so - not sure what you are looking at -

I didn't let it go up to the max on the temp
but it was going after like 30 mins running in the driveway.*
idling in the driveway is just wasting gas -
there is no stress/strain on the engine idling -
you need to drive it - hard -

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I just got back from retesting it, blue liquid stays blue. Now i noticed on the tensor for the water pump, that it moves I'd say a 1/4 inch every spin I'd say.. and I can move it with a screwdriver as if it was not tense enough, also the main hose towards the pass side of radiator does not carry the hot water fast at all.. it can be burning hot out the wp housing then cold 2 inches towards the radiator. As if the water is not being pushed into the rad fast enough??!!
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i noticed on the tensor for the water pump, that it moves I'd say a 1/4 inch every spin I'd say.
it's possible the tensioner has lost a little strength -
it's also possible the belt has stretched some -
these conditions could allow the waterpump to slip a little -

another issue is a worn idler pulley -

with the engine off -
relieve some of the tension -
and spin/wiggle the idler pulley -

the pulley should spin smoothly -
and there should be absolutely no wiggle/side to side play -
 
#13 ·
Put the thermostat back in, the car needs it to properly operate without overheating.

If air is coming out of the purge line, the system is airbound. Keep adding coolant to the surge tank and don't let it go dry.*

If some coolant comes out of the purge line I would assume that the water pump is working. Northstar water pumps hardly fail, anyways.*
 
#18 ·
Yes I have a line that goes into the alt, it was a little clogged up but i put the compressor to it and cleared it, and I meant to say the purge line that goes into the reservoir im sorry. That line only throws out steam. Maybe a few drops but nothing like a steady flow.
Also I keep saying overpressure because it already cracked one radiator, i don't have a gauge to really test the system but im pretty sure this is way past normal pressure, i had never seen the main hoses towards the rad look like they are swelling up. And then the cap releases letting all the built up pressure out at once along with a good amount of antifreeze. But then again I'm no mechanic.
The tensioner does feel like I can move it too easily, I moved it by pushing it with a screwdriver, I just bought a new belt and I'm thinking I'll grab a new tensioner as well just to rule it out. And a new reservoir cap.*
Also I can feel the water does not travel through the main rad hose towards the pass side fast at all.. maybe the wp is not spinning properly therefore not pushing the water like the system needs??

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I did flush the system and pumped air through it, when i filled the system it took 2 gallons.. even after running, the reservoir stays half way to the top.*
 
#19 · (Edited by Moderator)
OK - the line from the alternator to the radiator -
has nothing to do with the PURGE LINE -
it is strictly for the liquid-cooled alternator -
which was - thankfully - only used for a couple of years - then dropped -

I meant to say the purge line that goes into the reservoir im sorry.
That line only throws out steam.
that's not good enough - it must flow coolant -

with the engine off -
remove the PURGE LINE from the HOLLOW BOLT at the thermostat housing -
either remove the hollow bolt - and clean it -
or - use a metal coat hanger - straightened out - or something similar -
and poke it into the hollow bolt -
it should go in about 3 inches -

before re-installing the hollow bolt or hose -
BRIEFLY start the motor -
and watch for coolant flow -
if YES - you have SUCCESS - put the bolt/hose back together -
run the engine at 2000 rpm for a couple minutes -
check the coolant level in the SERGE TANK - fill as necessary -

take it for a few mile ride - and drive it "hard" -
meaning - hard acceleration - high engine rpm -
you need to work the trapped out of the system -

re-check the coolant level -

--------------------

if still no coolant flow -
you have bigger problems -

either the SURGE TANK is empty -
or the hose at the bottom of the SURGE TANK is clogged or kinked -

or the water pump is not turning -

do you get any heat from the vents if you turn the AC temp up to 90* -
if no - that verifies low coolant -
---------------------------

I keep saying overpressure because it already cracked one radiator
NOT UNUSUAL - and not caused by over-pressure -
the plastic radiator side tanks get brittle with use and age -

every engine cycle subjects the plastic tanks to temps of 225+ degrees -
and pressure of 18psi -
this constant heating and flexing weakens the tank -
and eventually - they crack -

so - let's get away from the "over-pressure" issue -
because it just doesn't exist -
Also I can feel the water does not travel through the main rad hose towards the pass side fast at all.
two things to consider -
first - the water pump can not push/pump air -
if there is air trapped in the system - there is no flow of coolant - second - assuming no air-lock -
the thermostat controls coolant flow through the radiator -

the thermostat STARTS to open - when coolant temp reaches 188* -
and doesn't fully open until the coolant temp is over 200* -
and at idle - there just isn't that much coolant flow anywhere -

------------------------

last thought -
I believe your problem is low coolant level or air trapped in the system -
 
#20 ·
Okay, I'll check the coolant level and take it for a spin tomorrow morning, it hasn't left the driveway since it started overheating so yeah maybe I need to push it a little bit. Thanks everyone for putting up with my very basic knowledge, you guys been alot of help.
Im still keeping an eye on the tensioner for the wp though. Didn't like how loose it felt.
 
#25 ·
Those kevlar-backed belts do not stretch. If the belt seems even remotely loose it's either the tensioner pulley disintegrating or the tensioner arm spring has packed it in.

RockAuto, your make, model, year, "belt drive". The 3-rib belt, pulley, tensioner. Whole thing, Gates, #38197. If the tensioner is good the pulley alone can be replaced at 2/5 the price.
 

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#26 ·
Okay, i just replaced the belt, and took it out for a drive.. within 15 minutes it overheated again. I checked the line going back to the reservoir and its clear, however no coolant comes out of it. The nipple that the hose comes out of is clean as well, im going to try the tensioner tomorrow, because it still moves about 1/4 inch every spin. Since the belt doesn't strech then maybe the spring on the tensioner is giving out?? Checked the fluid before and after the drive and it stayed pretty much at the same level.
 
#28 · (Edited)
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I checked the line going back to the reservoir and its clear,
however no coolant comes out of it.
The nipple that the hose comes out of is clean as well,
that just can't be -

before I forget to ask -
did you put the CORRECT thermostat back in? -

the hollow bolt is the highest point in the cooling system -
any trapped air would migrate there -
and that air would be directed to the serge tank -
along with a small amount of coolant -

the ONLY possibility for no coolant flow through the PURGE LINE is -
failed water pump -
low coolant level -
blocked/clogged hollow bolt -
PERIOD -

the immediate problem is NOT the belt - and NOT the tensioner -

even if the water pump WAS slipping - a LOT -
there would be SOME coolant flowing through the PURGE LINE -

you need to concentrate on the coolant flow - or lack there of -
from the hollow bolt to the serge tank -

when you solve that problem -
your airlock will go away -
and the overheating problem will be resolved -

-------------------
this - from the first thread -
I already checked for flow throughout the whole system
and cleaned the hoses that were plugged with rust.

this entire engine is all aluminum -
including the radiator and heater core -
where did the RUST come from -

unless the "rust" was just crud - and old stop-leak powder/pellets -

ONE TIME - and one time only - on a Northstar -
I saw a water pump impeller that the blades were almost completely corroded away -
so the water pump was spinning - but there was virtually no water flow -
-----------------
 
#29 ·
Damn!! I never put that thermostat back. I forgot all about that, and yeah yesterday when i did the block test with the blue fluid, there was a little bit of coolant coming out of the *hose rowards the serge tank, im talking about a few drops every 2 seconds. I guess the stuff clogging the lines was sealant or who knows what that was, it was mainly in the hose by the reservoir tank and inside the alternator. After that I have been able to blow through the system. Im not sure but i think my wp has white plastic propellers. And it seemed to spin normally. I could be wrong though i really didn't pay attention to what it was made of. But today when i first started the car I noticed no flow of coolant through the hose. Is it okay to put compressed air to the lines?? And also I saw a coolant cap with a pressure gauge on it. I think I'll grab it as well to have an exact idea of the pressure.*
 
#30 ·
===========================
Damn!! I never put that thermostat back.
start there -

there was a little bit of coolant coming out of the *hose
there should be a constant - gentle - flow of coolant -
with an occasional bubble of air -
from the hollow bolt - through the purge line - into the serge tank -
if not - there is a problem -

And also I saw a coolant cap with a pressure gauge on it.
I think I'll grab it as well to have an exact idea of the pressure.*
still on the pressure kick -
for THE VERY LAST TIME -
nevermind - I give up
 
#32 ·
Lol, I apologize basscat, at this point i think i just want it just to know its there.. Okay so I'm putting the thermostat back in as soon as the sun comes up, after that im checking the level, topping stuff to where its supposed to be, and taking her out again. Is the hollow bolt supoosed to have coolant coming out of it as soon as the car is started or does it have to warm up a little bit??*
 
#34 ·
Okay so I'm putting the thermostat back in as soon as the sun comes up, after that im checking the level, topping stuff to where its supposed to be, and taking her out again.
Be sure to check your coolant level again after it cools down again for the next 2 -3 drives. I have had it take 3 times to purge all the air out of the system. That could be your problem.
 
#33 ·
The hollow bolt - purge system - is at the system high point and is near the water pump outlet which feeds the water crossover - heads and block circulation. There should be a clear, steady stream of coolant from that purge line ANY time the engine is running, whether at idle or wide open throttle redline.

You really need to go to Engines, Northstar and read the several stickies concerning cooling systems, gauges, and fan operation. Put the thermostat back in correctly, fill and check the system, make sure the water pump drive is in perfect condition, and make sure the purge line is clear - as well as the small purge line nipple at the surge tank.
 

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#36 ·
Okay, just got done with her.. i bought a new tensioner and boy does it make a difference, no moving at all on it, i took all the hoses i could out and one by one i put pressured air into them lots of it, alot of rust like stuff kept coming out. Im guessing its those pellets. I see a strong, steady coolant flow to the reservoir now and the radiator warms up evenly. I poked into the hollow bolt with a metal hanger, it went about 4 inches in there, came out nasty.. topped system with water, ran it for 30 mins, as soon as i hit the hwy the temp went up, only reached 2 lines after the middle (digital dash). Let it cool off, topped the water again, it dropped a little bit and ran fine for 1 1/2 hrs. Tomorrow im putting coolant in it and test it out the whole day.. wish me luck.*
 
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