grandpa + northstar = headgasket in a bottle

So I get to my grandparents for an early thanksgiving vacation and find out about their car stable. In addition to buying a new Lincon MKZ their 2003 caddy deville has two bottles of head gasket seal in it to keep it from using water. I drove it yesterday and upon firing it up, its obviously not running on all cylinders. Maybe down 1 or 2. Holds a steady idle. Driving is ok, not down lots of power, but I didn't floor it to keep cylinder pressure down. Seemed to be steady at 197-205deg depending on how much the AC was blasting. He says it gets to 210-213 on the highway and stays there. "Doesn't use anymore water/coolant" or so he claims, and its been a month or two since it happened.

I know these northstars are not big fans of this kind of abuse and crack cylinder heads a lot and are expensive to rebuild, or more so than my cheap Nissans.

Say I were to replace the engine next month when I'm back for christmas. He doesn't want to spend much to fix it, but hes also giving me a large interest free load to buy a fixer up house. A quick search for northstars around here (sanford,fl) seem to be around $600-800.

Thoughts GRM? The car is other wise in great shape and "it rides better than the lincon" which means the current one, or the 2002 town car the MKZ replaced....

Given the frequency and commonality of Northstar headgasket issues, what makes you think the bargain, JY sourced Northstar is going to be better than the Northstar that you have?

If it were me, and I were going to engine swap it, I would sell it almost immediately after getting it completed.

At the very least, I'd replace the gaskets and cylinder head studs on the JY engine before installing it.

A new radiator and coolant hoses wouldn't be a bad idea to ensure that as much of the gunk in the cooling system was eliminated.

http://www.northstarperformance.com/sgstuds.php

Wait, so it runs and drives right now and isn't using water?

Sounds fixed to me.

Tom Suddard wrote: Wait, so it runs and drives right now and isn't using water? Sounds fixed to me.

This.

Drive it until it dies. Then call the junk yard. Around here Devilles are dirt cheap.

Didn't Cadillac do some kind of tuning trickery in the later Northstars to make the engine with no coolant with out melting down? I remember it involved deactivating cylinders to draw cool air in.

If the car is down on power, not running on all cylinders, and not leaking anything, you might check to see exactly how much coolant is actually in the system.

The Northstar head gasket issue is actually a cylinder block alloy issue. Seems the al-you-minium alloy Caddy chose was actually too soft for the required head bolt torque, thus causing the threads in the block to eventually stretch and ultimately strip. And no, a standard Heli-coil repair will not hold. This is way to do it: http://www.timesert.com/html/gm.html I discovered this when a friend's 2.4 Camry had the same thing happen; same cause, same fix (slightly different repair kit).

I would absolutely not swap a northstar that wasn't using coolant and may have a misfire or two.

Solve the misfire or two, and drive it until it stops.

Yeah it's not going to be pretty swapping a junkyard engine in there. Those Northstars are total pieces of crap.

I would be looking at the ignition system. When did it last get plugs. I know many a mechanic that basically skipped the rear cylinders on those as they were a real PITA.

WildScotsRacing wrote: The Northstar head gasket issue is actually a cylinder block alloy issue. Seems the al-you-minium alloy Caddy chose was actually too soft for the required head bolt torque, thus causing the threads in the block to eventually stretch and ultimately strip. And no, a standard Heli-coil repair will not hold. This is way to do it: http://www.timesert.com/html/gm.html I discovered this when a friend's 2.4 Camry had the same thing happen; same cause, same fix (slightly different repair kit).

Read this ^ carefully.

Are you going to drop the bedplate and reseal it to stop the inevitable oil ooze for a year or two?

I'd crush the thing, but then I've tried to repair those buckets of crap in the past.

In reply to Streetwiseguy:

You got that right. The Northstar was really the victim of poor execution of a brilliant idea. Aw hell, if it were me, I'd find a wrecked Z28 or Vette and swap that LS drivetrain and ECM into the Caddy

Stefan (Not Bruce) wrote: At the very least, I'd replace the gaskets and cylinder head studs on the JY engine before installing it. A new radiator and coolant hoses wouldn't be a bad idea to ensure that as much of the gunk in the cooling system was eliminated. http://www.northstarperformance.com/sgstuds.php

$550 on top of gaskets and am $500-800 engine? hahahaha nope. I wanted to be nice but thats a bit much.

If the leak has stopped, don't mess with it. Fix the misfire. Add a bottle of water wetter (in the name of science) and some "Cadillac Tablets" or one or the other just for science.

Going back to science though... couldn't the car be running hot and misfiring due to a lean condition?

They could all be related though if there was something physically wrong with the head in the plug threads.

He have full coverage on it? Crash it for him...or just let grandpa do it. Won't take much of a hit to total it. Pay the deductible. Cheaper than even the most basic engine swap, and without the manual labor. Direct him to a more reliable purchase. I kid....sort of.

Ls4 swap?

The misfire was the worst on first start up, after driving it about 20 miles and parking it in the garage the idle misfire was almost gone. Its probably a semi fouled plug. I'll probably look at when I'm here next month for christmas....but its working now so why possibly screw that up?

No non northstar swaps. Why would I custom swap my grandpas car? everything including ac would have to work perfectly, that'd be a nightmare.

oldopelguy wrote: Ls4 swap?

If he really really wanted to keep the caddy this makes the most sense. Is the trans the same on the Northstar and LS4?

$550 on top of gaskets and am $500-800 engine? hahahaha nope. I wanted to be nice but thats a bit much.

I respect you for wanting to do something nice, but this is your best bet. Repairing problem vehicles for relative to be nice is a rusty razorblade lined rabbit hole. I've been down it before. Buy him some nice scotch, or cigars or something. Don't lay a wrench on that thing, you'll end up looking less than great when it inevitably blows up despite your best efforts.

ultraclyde wrote:

$550 on top of gaskets and am $500-800 engine? hahahaha nope. I wanted to be nice but thats a bit much.

I respect you for wanting to do something nice, but this is your best bet. Repairing problem vehicles for relative to be nice is a rusty razorblade lined rabbit hole. I've been down it before. Buy him some nice scotch, or cigars or something. Don't lay a wrench on that thing, you'll end up looking less than great when it inevitably blows up despite your best efforts.

Yup. Best intentions get sideways when family is involved. You'll always be the guy that screwed it up, or failed to fix it, or whatever- even if it was beyond help before you got hold of it. You can help by telling him you consulted a panel of your buddies and got back "screw it, car is done." as a reply.

Rustspecs13 wrote: The misfire was the worst on first start up, after driving it about 20 miles and parking it in the garage the idle misfire was almost gone. Its probably a semi fouled plug.

Plastic intake manifold?

Knurled wrote: Yup. Best intentions get sideways when family is involved. You'll always be the guy that screwed it up, or failed to fix it, or whatever- even if it was beyond help before you got hold of it. You can help by telling him you consulted a panel of your buddies and got back "screw it, car is done." as a reply.

He came to that conclusion before I did really. It'll die a not very peaceful death and be donated to charity for them to auction off.

No plastic intake manifold but I didn't look closely. Its a 2004 Deville.