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!

[bolivardigriz]

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.

[starxlr]

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.

[CHguy]

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!

[Tom-wqmz]

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

[chrislemaster]

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.

[tjoyce]

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... 

[gregoryduffin]

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.

[starxlr]

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!

[thatonegmguy]

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.

[PistolPete]

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

[clintonrand]

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

[CHguy]

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.

[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?

[UberTrooper]

you should start a channel dedicated to automotive repair.

[troyspace]

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

[jameswhite]

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

[tjoyce]

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.  

[pablopicaro]

April 2021 - still rolling in that ol Caddy?

[clintonrand]

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

[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?