Block Head Gasket Testing a Cadillac Northstar V8

Before you buy ANY Cadillac with the VIN Y or 9 Northstar V8, this is a NECESSARY, and cheap test that doesn't require any modifications to the car to perform. Northstars up to 04 or so are vulnerable to the head bolts pulling out of the block, causing thousands of dollars in repairs. In most situations, the car isn't worth the repair cost. Do yourself a favor, spend $9 on the test fluid, and RENT the tester for $25 from AutoZone, spend 15 minutes doing this test before you shell out a few grand on a Caddy. The only reason I didn't do this test, is because I bought it from the original family owners, and it had been very well maintained. Thank goodness it didn't turn yellow lol. Now, on to the tune up!

[@bolivardigriz8847]

If you overspent on your vehicle the best way to recoup your money is to keep it forever and drive it into the ground. If you like it, just take as good care of it as is necessary for it to last you as long as you want to drive it. Vehicles are only an investment to the dealerships. To us consumers they're just tools to use for getting around. Anything extra is just to get something we like a bit more, not to save money.

[@starxlr7863]

Proper maintenance is everything. If you properly maintain your Northstar Cadillac or any Cadillac for that matter, they will run forever and I mean it!

[@starxlr7863]

A friend of mine still drives his moms 1997 Deville with over 460k! His mother bought the car brand new and always kept it well maintained. The engine is all original and never rebuilt or anything. He still drives it and never had any problems. His mother bought an Eldorado and she loves that car very much. So maintenance does play a key role in the longevity of these engines. I do know that if the wrong coolant is used, mixed or has gone acidic, it will eat away at the head gaskets and then corrode the lower head bolts making them weak. That seems to be the same problem with other GM cars and trucks around the same time. I keep my cars well maintained and they have been excellent cars.

[@AutoAuctionRebuilds]

+AMCNorthstar 93 Very true!

[@starxlr7863]

Uber Man Did you sell your Deville or are you still driving it?

[@dakeda2024]

460 k wow.. Any engine oil leaks??.. I have 96 deville 92 k..slight oil drip .very very slite .Lucas oil stop leak is good though .and I maintain it also ..

[@starxlr7863]

God First I'm sure there is some oil leaking but nothing bad at all. And if it did get bad I'm sure it was fixed. A slight oil drip is nothing to worry about. Many people forget that many of the old classic cars always use to both consume and leak oil. I drive a 05 Deville and 99 STS. Yes just keep your Deville maintained and you should be fine. The biggest thing as with any GM is the cooling system. Follow exactly what your manuel says to use. In my Caddy's I like using Mobile 1 or Valvoline High mileage blend and seems to work very well. My parents have a 95 Seville SLS with over 300k and still running excellent to this day with hardly any engine work except general maintenance.

[@dakeda2024]

AMCNorthstar 93 yes .I just replaced antifreeze ..adding 3 of those coolant tabs they said and put them in the lower rad hose..the porosity of the aluminum was the reason the tabs we're used .to seal up any porosity problems ..

[@tjoyce81]

All that being said - this is a great video and a good place to start on a northstar exhaust in coolant issue, and "phantom coolant loss" issue.

[@AutoAuctionRebuilds]

Tom Joyce Thanks

[@Pistol54Pete]

That fluid was clear looking to me. Not blue after the test.

[@Tom-wq2mz]

Your safe. Check your purge line from your coolant tank follow it over to the driver side. Remove the hose and remove the bolt with the nut on it and clean the tube out with a rat tail file. I bet it solves your problems. Once done remove the whole line and soak it in carburetor cleaner use a metal coat hanger to free any debris then blow the purge line out. connecting the driver side line back unhook the purge line at the coolant tank put the line in the tank and see if you have flow if it's slow give it gas. I bet that Is your problem

[@kaleelbennett6345]

Aye tom same problem

[@gregoryduffin524]

Thought you should know that the 41-950 plug, or any platinum plug for that matter is a waste of money, the standard copper core plug 104 gives a greater spark and yields a better burn within the cylinder.

[@chrislemaster2695]

If you want to it go down even more change the Dex Cool crap out and out regular green antifreeze in it . I had my 1999 Deville rebuilt and the GM guy told me to use regular green antifreeze when I did that mine ran at 170-180F.

[@AutoAuctionRebuilds]

Good info! Thank you.

[@scotta9114]

@@AutoAuctionRebuilds We changed ours to Prestone G-05 Coolant. The G-05 is listed as a low conductivity coolent. We've used it in several Aluminum and Aluminum/Iron Engines with no issues.

[@nicotoscani8270]

Would this tool work for the crankcase too? Like in the oil fill cap? Sometimes a head gasket will leak exhaust into the crankcase too

[@clintonrand9580]

Also I remember your blue devil treatment on the 250 dollars mercury cougar it was one of your hardest blue devil treatment we almost thought it was not gonna work

[@clintonrand9580]

I got a question you seem to be pretty good with repairing automobiles I watch a lot of your stuff I got the infamous Northstar engine with a blown head gasket I've tried the blue devil treatment about 4 times which I don't think any of them was done right so I was working on it on yesterday and found out if I leave the purge line apart from reservoir it doesn't run hot after running a whole 1 hour and one of my biggest problems with all my blue devil treatments were I could never get it to run 1 hour because it would run hot before that time so my question to you is can it be driven or used with purge line loose from reservoir

[@JEE7600]

So I did this same test. It started out Blue but then turned Green. I read on other places. Green or Yellow means a bad head gasket is that true?

[@CH67guy1]

After testing the engine I went to the back of the car and put the tester at one of the exhaust tips. Four squeezes on the bulb and the fluid instantly turned from blue to yellow, as I had expected it would. I was very impressed with this tester!

[@pablopicaro7649]

April 2021 - still rolling in that ol Caddy?

[@AaronKey1986]

Very helpful thanks.

[@deapozol]

I have a 2011 DTS with the northstar, only 47k miles on it and so far so good. I maintain my engine well by using only premium fuel and full synthetic Mobil1 oil. I just had my coolant flushed by the dealer as well. I guess that's all I can do to help the life of the engine. What do you think?

[@AutoAuctionRebuilds]

deapozol I think if you take great care of it, it will be just fine. VERY nice ride BTW!

[@bigluxurycar6952]

You got a great car man. Maintain it and enjoy it!!

[@gabrielparent9088]

Up to 2004 no problem whit headgasket, its under 2004 have problem

[@stevek8829]

@@gabrielparent9088 they went in my '01 before I bought it.

[@jameswhite1319]

You still have this car or is gone ? Thanks for sharing

[@starxlr7863]

This problem of head gaskets seem to be for years 1997-1999. I rarely ever see any pre-1997 northstars with these issues. My parents have a 1995 Seville and had it for many years. We never had a problem with it beside general maintenance. I now have a 2001 Deville myself as my daily driver. And I have Dexcool in my car. I believe 1997 - 1999 had the most problems due to the coolant change during these years. Not so much before or after these years. And most of this problem stems from poorly maintained cooling systems and not changing out the old coolant when needed!

[@AutoAuctionRebuilds]

AMCNorthstar 93 Very true.

[@dtspilot]

Lol. Yea right. I had a 99 Deville that went to 180xxx miles before I traded it in. Never had a HG problem. I traded it for an 04 DTS back in 2006. 2012, at 155k miles, the 04 DTS blew its gaskets. I also have an 05 DTS. It just hit 105k. Guess what? Just got that out of the shop. Why? Had to get the headgaskets replaced. I'm personally done buying any Northstar Cadillacs. They suck. Two out of my three Cadillacs blew headgaskets. And yup, I did coolant changes with only Dex Cool and I did them every three years.

[@starxlr7863]

Jason Roberts Coolant is still the cause for this issue. And they do not blow but rather start leaking. Only if the coolant is flushed out and refilled when needed and done correctly, the problems never happen. I have seen this problem happen on many other GM vehicles and not just Cadillac.

[@bigluxurycar6952]

Well your cars were NOT that well maintained cause otherwise you wouldn't have had any of those problems! that shop saw you coming and scammed you into an unnecessary job!

[@Samuelfish2k]

AMCNorthstar 93 The reason that the 97’ Northstars are said to be the most susceptible for the failed head gasket is due to the metal of the cylinder walls being thinner than in other years. I own a 97’ SLS with 185,000 miles and still running smooth *knock on wood*

[@UberTrooper1]

you should start a channel dedicated to automotive repair.

[@tjoyce81]

This test can be done as soon as you start the engine (or shortly there after). The coolant flow is ALWAYS flowing through the cylinder coolant ports on a northstar and always flowing through the coolant fill tank. The thermostat has nothing to do with coolant flow through the engine. This test can be a false indicator of a blown head gasket. On a northstar, coolant can be exposed to exhaust gases by a failing coolant cross over manifold gasket (which is also a very common leak associated with the northstar). When the EGR valve opens, exhaust gas flows through exhaust ports in the coolant manifold crossover to cool exhaust gases before the gas goes into the intake. A failing gasket here will introduce exhaust gases into the coolant - thus causing this test to be positive for exhaust gas -- but not necessarily a blown head gasket positive test. The ONLY way to prove that a northstar has a blown headgasket is to do a proper cylinder leak down test on a warm engine - which should take 2 or 3 days...

[@F8LXEPSHN]

How does a T-stat not have anything to do with the coolant flow? The bottom rad hose goes to the motor and the T-stat is right there. Makes no sense??? 1997 Eldo ETC here.

[@tjoyce81]

I said coolant flow through the engine. The lower hose does not connect to the engine. It connects to the t-stat housing 'in' flow, which is part of the coolant crossover manifold on the Northstar. Coolant flow is constantly flowing through a Northstar. It flows from the res tank - through the block - then heads - then heater core, in a continuous loop, in that order. All the t-stat does in a Nstar in allow coolant to flow through the radiator, that's it. When the t-stat closes, coolant still flows at 100% through the system.

[@tjoyce81]

The system is not like a normal gm engine system (of the era). If there is exhaust gases in the coolant, waiting for the t-stat to open is a waste of time.

[@F8LXEPSHN]

Tom Joyce Right now I don't have a t-stat in my 1997 Eldo (just haven't put it in yet) and my car still gets a bit hot then the fans kick on. With the T-stat the car never gets hot and the needle never goes past the middle mark??? Doesn't that bottom hose connect right to the water pump? Shit. Now I'm gonna have to go out there and look. Don't remember.

[@udrgrndpyro5107]

How much coolant did you take out to test it with the block tester ?

[@mikeshinobi4688]

You don't have to take out any because you don't fill the reservoir to the top in these cars

[@thatonegmguy5521]

Either the wrong coolant or coolant that went acidic is the culprit for leaking head gaskets on these Northstar engines as well as other GM engines. My mom still drives her 1999 Deville with almost 200k and its never given us any problems. Great cars they are and very heavy duty and solid.

[@AutoAuctionRebuilds]

+That One GM Guy Very cool.

[@lonewolf56308]

I heard about replacing the antifreeze every 2 years and it's worked well for mine.

[@starxlr7863]

Coolant flushes should be done religiously on any GM vehicle running Dexcool antifreeze. On my Dexcool running Cadillac's, I flush out the system every 2-3 years and add in fresh coolant. You will not have a problem if you maintain your car properly.

[@capacitiveguitarresistance]

I have a 90k mile 97 Deville De'Elagence. I hope it is good but today while sitting in a parking lot of grocery store for 30 min and driving 2 miles home with AC pumping stop and go and noticed temp was at 238. Is this okay?

[@CH67guy1]

Yesterday I tested my newly acquired 1994 Eldorado with just 24,000 original and documented miles. Test fluid stayed perfectly blue! I ran the test from cold engine, and all the way through 204 degrees displayed on the digital dash.

[@noneomarxistactor2863]

Not familiar with the Vin. #s you mention . How do I determine which I have ? 1997 Seville SLS !

[@Vic9mm]

You have a Northstar vulnerable to head gasket failure. My 97 Seville SLS suffered from it around 100,000 mark. Had to get the head bolts redone cost my grandparents thousands (was there car at the time). It has 170,000 miles on it now and running great.

[@clarkgriswold4057]

How long did it last you?

[@darrenharris2978]

Looking at 08 dts car 131000 miles what do I need to look for on checking car out sir ? Buying from car lot

[@mrkeez013]

How much did you buy it for?

[@ronlouis930]

Never leave your tools,nuts bolts oil cap in the engine bay they can fall in and good luck fishing them out.

[@galegregory97comcast]

I HAVE A 1999 JUST THE LEFT SIDE AND JUST RIGHT SIDE OF MY RADIATOR GETS HOT FAN IS NOT ON CENTER IS ICE COLD NEW WATER PUMP IN IT. ITS OVER HEATS WHEN I DRIVE IT, JUST SETING AND RUNING IT WILL NOT GET HOT LOL?? WHAT YOU THINK

[@AutoAuctionRebuilds]

99.9% blown head gasket. Losing compression into the cooling system.

[@starxlr7863]

That would be blockage somewhere in the radiator or thermostat. That is not a blown head gasket. Also on these engines being DOHC it would be a leaking head gasket and NOT blown. That is on OHV engines.

[@floydmac2712]

Clean purge line...I just checked every line on my 99 cadi to make sure water flowing..if temp stay good I'm going to get green antifreeze

[@peterlehmkuhl1985]

Where can I buy that tool to test the heads?

[@AutoAuctionRebuilds]

AutoZone

[@troyspace8384]

From.my experience 97% of Cadillac's that were owned by either old folks or people who properly matained the vehicle and did regular maintenance and didnt drive it like a high school kid in a mustang had less problems compared to the people who buy the older models like 94-05 today and abuse the crap out of it just because it has a v8 not knowing how to maintain the car especially the 97-99 models were notorious for blowing gaskets but certain cars require a little more attention then others like these northstars, not a car for a young man with led foot

[@user-rf4sg2qc2t]

Im 19 and own my first vehicle a Seville 96' Sts and for that to be in Norway is very special, these cars has high value here. I watch it like a baby, and maintenance is top priority for me. I'd say the car is safe here

[@BigRobMC]

@@user-rf4sg2qc2t hahaha I’m 19 aswell and just purchased a 97 deville currently researching up on how to maintain it the best I can

[@dondesnoo1771]

Mom had a 79nova 6 the anti frz coming out the tailpipe put some bars leak. Stopped lasted 2yrs trans went .not driven far she was 90 yrs rip.

[@johnguerard1355]

Remember this relevant to now blast from the past?, I do 😉

[@tomray166]

Looking into getting fail safe thermostat. Any info appreciated

[@AKNAM-cv4qu]

That's a great thermostat especially for that type of vehicle which is prone to overheating issues

[@JohnGomezUGA]

Was also given this tip. Fairly cheap and easy swap it looks like. Good to do every 5 years or so I'm sure

[@quintanshelton7491]

I have an 01 fully loaded sts & to take it easy on the short head bolts and from overheating I dont drive over 65mph most trips. Just as my or maintenance

[@trizkial7592]

Man these engines were meant to live in the higher rpms... look it up they were built as performance motors. Your engine will carbon up doing that. Just change the coolant every couple years and you will be fine bro. Drive the piss out of it and use it for what it was designed for. Trust me it will run better just use good synthetic oil

[@chriscrystalhood6260]

Yeah they need the snot drove out of them once in a while like Trizkial was saying or the rings will get carbon build up and get stuck in the ring grooves causing smoke out the exhaust, the rings are supposed to spin/float around in its groove. That is one of the ways to sometimes fix smoke from the exhaust, a couple of WOT runs on the interstate will free up the stuck piston rings that are usually stuck from carbon deposits from being babied too much.

[@blackericdenice]

I just uploaded a video and my 2001 Deville turned the fluid green. This mean I have a small leaking HG.

[@slimrhodes9697]

What is the normal temp

[@azimmey]

Are the 2006 Northstar in a DTS a problem too?

[@AutoAuctionRebuilds]

They sure are.

[@azimmey]

How long have they been building this engine and still a problem. really.

[@AutoAuctionRebuilds]

It started for most Cadillacs in 1994. I believe some were in the early 90s allante.

[@azimmey]

Thanks, I saw Dexcool approved on a prestone bottle but afraid to buy.

[@starxlr7863]

2006 Dts are great cars and not a problem if its properly maintained. The Northstar is easily Cadillac's Best powertrain ever put into a Cadillac and is why GM produced it for 20 years, more than any other Cadillac built engine and used in several other luxury GM cars. The Northstar was already out in 1991 but was saved for its debut in the final year Allante for the 1993 model year.

[@tho4life611]

would anyone happen to know if the v6 engines have the same problem? like in an 05-07 sts?

[@johntaheri2047]

yes v6 is ok lam not sure but I think made by Toyota.

[@starxlr7863]

The 3.6L V6 is just like the Northstar 32 valve V8 with 2 less cylinders. They are both DOHC and built very strong. Coolant flushes should be performed religiously on any Dexcool running GM vehicle!

[@bayarea1974]

What year is that car??

[@melmcgaha1216]

1995

[@Fernandez.1987]

I notice you were running the car with out the reservoir cap on and no fluid came out , I ran mine with the reservoir cap till it got to mid temp and it started splashing water out , there is no water in oil or oil cap no white smoke when I rev , and I did replace thermostat , temp sensor and fan relay which fans don't work yet .. question is , that's normal for water to spill out f

[@ivanshapli1827]

if the coolant is overfilled once the car warms up it will spill out but otherwise it shouldnt.

[@Fernandez.1987]

It was full and I kept trying to fill it and it would keep splashing out idk of that's normal .

[@ivanshapli1827]

@@Fernandez.1987 does it spill out once you put the cap on?

[@Fernandez.1987]

No once the cap is on it won't spill out ... Only reason why I had the cap off was cause I was trying to get the air bubbles out cause I out a thermostat in and temp sensor .

[@ivanshapli1827]

@@Fernandez.1987 if it doesnt spill out with the cap on and doesnt overheat its probably fine.

[@belliose]

Wow! You proved absolutely NOTHING! Way to go!

[@mikeshinobi4688]

He proved the HG aren't blown, duh

[@belliose]

@@mikeshinobi4688 No, he didn't. He didn't show the product works in the presence of methane.

[@galegregory97comcast]

will any thing else go in it but a northstar ???? Any Recommendations. it will only go out agian.

[@starxlr7863]

What exactly is your question?? If you properly maintain your Northstar Cadillac, you have nothing to worry about. These are some very stout, well built engines and are extremely reliable!

[@francolopez2328]

I have a 95 Seville that over heats what should I do

[@da324]

Find out what's causing it to over heat would be a good start.

[@AKNAM-cv4qu]

Check your Water pump, thermostat, radiator, radiator overflow Reservoir upper and lower radiator hoses, heater core, make sure you're not using any dex cool use the cool conventional greens make sure your radiator fans are properly working make sure your sensors are functioning properly, when does your car start to overheat does it overheat after you go a few miles while driving or does your temperature gauge starts to rise while you're still idling? Do u still have this issue?

[@edgarmatta1588]

I have a 97 EDLORADO. I find myself having to add coolant every morning before work and evening after work. I replaced the thermostat, radiator. I don’t see a leak anywhere , yet if I don’t do these everyday, it over heats. What should I do ??

[@thomasfletcher4109]

Possibly the water pump

[@kennethskipper8512]

Why put deathcool coolant back in,jesus,thats one of the big things that corrode the head bolts and make them pull out,ugh.

[@AutoAuctionRebuilds]

+Kenneth Skipper Because it's what GM calls for. I follow the manufacturers recommendations, as they built it.

[@kennethskipper8512]

Your a dumbass or uneducated then.

[@johnross5578]

LOL ITS MADE FOR DEXCOOL NOTHIN ELSE

[@kennethskipper8512]

John ross Dexcool is not a coolant designed by GM,its a Texaco product and its shit,get some long life green up in your engines or pay the price.G.M has made lots of bad moves over the years,hence why they went bankrupt,but no company is perfect.

[@johnross5578]

where do u see me say anything about gm i said its made for it the green stuff messes is up

[@tomray166]

Can you get to the head bolts easy to check and or tighten them ??

[@chrisj197438]

tom ray That would be a horrible idea

[@mikeshinobi4688]

No, and tightening them wouldn't help anyway. They pull out the threads with them when the start coming out

[@AKNAM-cv4qu]

Fug no lol it's a hard-ass job the engine is in sideways but their is a head bolt conversion kit with longer bolts that you can use I've heard great things about it makes the engine way more reliable and fixes that little head bolt issue

[@suwanneekid2616]

I buy them,run 'em to death and scrap them.I have a 2005 looks almost showroom paid 2500 2 years ago and when that North Star starts messing up it gets crunched.

[@Samuelfish2k]

Dude, stop apologizing for stuff nobody cares about.

[@sunflowerstatehistoricalin9803]

Stay away from cadillacs

[@AutoAuctionRebuilds]

amen

[@starxlr7863]

Yeah stay away from them and anyone else who don't appreciate a well built car and engine like these!

[@rubydoobie9717]

😂😂😂😂

[@AKNAM-cv4qu]

Yea if you cant afford it or dont like doing proper upkeep and maintenance stay away

[@nfarnell1]

Nobody is going to give you any decent money for a northstar car, why would you even play with one?

[@super20dan]

good luck gm is junk

[@AutoAuctionRebuilds]

So is every other American made car. WGAF?

[@starxlr7863]

Proper maintenance is everything whether its GM or not!

[@zoticus1]

pointless, it is a northstar motor, they are junk, plain and simple.

[@AutoAuctionRebuilds]

zoticus1 They sure are!

[@starxlr7863]

zoticus1 Respectfully disagree.....they are not junk motors. They only turn to junk when they are not maintained. I have seen a lot of good cadillacs with this engine here with out any problemsand ones with very high mileage. I have one and never a problem.

[@zoticus1]

AMCNorthstar 93 anything will do ok if you know its weakness, it just so happens, the weakness of the engine is catastrophic failure. Remember the yamaha engines for the gen 3 taurus sho? Had to weld the cams to the sprockets!

[@starxlr7863]

zoticus1 It is well worth putting money into these cars! Rebuild the engine and keep driving them. These cars are very well built, excellent build quality, excellent safety and great interiors. You really get a lot of car and luxury for a small investment. These engines do last forever IF maintained properly. They fail when its owner FAILS to maintain it. I have two of them different years and they have been the best running and most reliable engines we ever had. No problems at all. The Northstar is one of Cadillac's Best Engines. There's a reason why they made them for almost 20 years. They are even popular in some custom speed boats, dune buggy's and some custom cars with the Cadillac Northstar powering them!!!!

[@thatonegmguy5521]

+zoticus1 Pointless for you to say such a stupid comment, plain and simple! Junk motors....HAH. If you ever worked or even rebuilt one of these engines, they are one of the best made and very well built V8 engine by Cadillac.