- 04-29-14 10:45 AM #1
My 99 Seville sls has been at the shop for 2 weeks now. They cannot figure out what's causing it to overheat. Previously before all that, I have replaced the radiator and thermostat . A lower hose would leak coolant badly till it finally got to the shop. There they replaced the water pump, thermostat, tensioner, pulley, belt, flush tests. There is no white smoke, there is no milky oil, the overflow only gushes out when you remove the cap and no radiator fix additives have been put in. I really doubt it's a HG but it's all pointing to it now. They are HG testing it today. It all just makes no sense. What am I missing?
- 04-29-14 11:00 AM #2
You are missing the obvious. It's a '99 and they have the worst HG failure rate. Too bad you took it to a shop that throws parts at it at your expense until one sticks. Do the block test and if you get a positive result make sure this is not their first rodeo. Based on what you said, I'd be looking for another shop that has done this repair before.
Northstars almost never mix coolant with oil and you won't see steam until it gets really bad, so don't hang your hat on those symptoms.
Has the purge line been check for coolant flow?
- 04-29-14 11:12 AM #3
I don't think it has yet.
- 04-29-14 11:35 AM #4Cadillac Owners Fanatic
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- 04-29-14 04:51 PM #5
The mechanic said he has checked the purge line already. He also thinks that the overflow tank needs to be replaced and is his last best bet. That it has warped from so many overheats. How would that help? He says it keeps spewing at the cap in idle.
- 04-29-14 05:03 PM #6
get your car out of that shop .... like yesterday
- 04-29-14 05:08 PM #7
I've been suspecting how stupid they were ever since I had my steering rack replaced there. Other than what I have said has transpired. Any ideas of what it could be or am I doomed with a blown HG ultimatum?
- 04-29-14 05:27 PM #8
The mechanic said he has checked the purge line already
this "mechanic" might not fully understand the PURGE LINE -
the PURGE LINE is the only way of expelling - PURGING - air from the Northstar cooling system -
it is a 3/8 diameter hose that goes from a hollow bolt in the thermostat/waterpump housing area of the engine - and plugs onto a nipple on the side of the SERGE TANK -
with the engine running - there should be a gentle - constant flow of coolant - from the engine - to the serge tank -
if there is no flow - the most likely cause is a blockage in the hollow bolt -
follow the hose towards the engine - with the engine OFF - remove the hose - use a straightened metal coat hanger - or something similar - and poke it into the hollow bolt -
the coat hanger should go in about 2 1/2 inches -
once the hollow bolt is cleared - you can briefly start the engine to verify coolant flow - be sure to use some sort of container to catch the coolant so you don't make a mess -
check the hose and serge tank for blockage -
He also thinks that the overflow tank needs to be replaced
and is his last best bet.
the "overflow" tank - properly called the SERGE TANK -
would only need to be replaced if it was leaking -
He says it keeps spewing at the cap in idle.
he might be over filling it -
FULL - when cold - is only about 1/2 filled in the tank -
the pressure cap might not be holding the correct 18 PSI -
thus allowing the coolant to boil at a much lower temperature -
do a BLOCK TEST -
the DEFINITIVE test for failed head gaskets in a Northstar motor -
most large auto parts stores have a tool lending program -
and will let you "borrow" the test kit -
you just pay for the blue juice - around $10 -
ANY color change of the BLUE fluid is a POSITIVE result -
which is BAD NEWS -
here is a video -
MOST test kits you borrow will have a hand pump -
and will not require an engine vacuum source -
- 04-29-14 05:30 PM #9
thanks, i'll be sure to pass the info along and will post any updates.
- 05-02-14 06:13 PM #10
He's still waiting on the serge tank part to come in lol. I left an email and note on the work order two days ago to check purge line and lower radiator hose. I haven't got any updates going 3 business days now. I will keep posted.
- 05-02-14 06:24 PM #11
- 05-02-14 06:25 PM #12
That's what I said. He said he wants to try it but won't charge if it doesn't work.
- 05-02-14 06:27 PM #13
Need parts for your Northstar Engine? www.northstarperformance.com
Evrett, Sales Executive of the SureGrip™ Cylinder Head Stud Kit
- 05-02-14 06:29 PM #14
It was all being "handled " by a family friend while I was out of town. Until I got back early and walked into this mess.
- 05-02-14 09:07 PM #15
Anyone changing a non-leaking surge tank in hopes of solving an overheating problem has no idea what he is doing.