Northstar gurus - help please!

Hello all,

A co-worker just replaced the starter on his '94 Cadillac Seville STS (the old one broke the nose cone?!) and since putting it back together the car runs rough and blows a ton of white smoke out the tailpipe. I lent him a hand today and we pulled the intake back apart (starter is in the V of the block under the intake) and I think I've found where the coolant is getting into the motor. I also double checked all this work, didn't find any coolant or vacuum lines mixed up that I could tell.

Below is cyl #8 intake port. To the left of the port is a shallow passage way, and this is where coolant is coming from. Here's a better shot, the big thing on the right is the water pump manifold.

Now I can't figure out why there would be coolant there. The rear bank has the same thing going on. I can make the coolant move by squeezing a rad hose. That valley used to be packed with gunk before he cleaned it all out when he put new intake gaskets on. It seems coolant is going in that passage way then getting sucked into the intake via the little slot on each port. Here's what the gasket looks like: As you can see the gasket seals around both areas, and there is no gasket between the intake port and that other small passage that is now filling with coolant. Oh yes, it looks like he's got that gasket on the wrong side (you're looking at the bottom of the little spacer thing where the gasket says TOP) but even flipped around it wouldn't change our problem I don't think.

Can anybody help me figure out what's going on here? I basically want confirmation if there is supposed to be coolant there or not (I don't think there is) and if not, what could fail that would allow coolant into that passageway on both banks?

Hotlinked image for reference:

Yeah I considered headgasket but what I've found above is a definite way for coolant to go directly into the combustion chamber. If it had hydrolocked I don't think it would be running now? No plugs where pulled at any time. And between the starter breaking and installing a new starter was maybe 2 days? I'm not sure if the coolant would have leaked down past the rings in that time.

There should be no way for coolant to get in unless one of the coolant lines is leaking and the gasket on the intake manifold is letting it in. I would perform a leak down test next, or at the very least if you don't want to go through the process or don't have the tools go buy a block dye test kit from NAPA $50 and use it on the coolant reservoir, it'll tell you quick if you've got a headgasket problem. If it's really blowing white smoke almost guaranteed it's the HG. I know, I popped both mine. It would run like crap until it warmed up, no smoke, and then it would run fine when everything heated up and sealed. Finally popped them and the car looked like Spyhunter smoke screen, stumbled like crap. Intake manifold leak will cause stumble, but I just don't believe that's be the source of the white smoke.

The only other thing I can think of is if while doing the starter he moved or damaged the fuel pressure regulator. If it's gone it can cause crap running and smoke exhaust but a quick way to tell is to smell the exhaust, if it's sweet, it's coolant, if it's gas, well...

i believe Quai Chang Caine would say, "to find the right answer, you must first ask the right question."

What is the function of the passage that was all gunked up, that has the little slots leading to the intake ports? It looks like it used to be all carboned up, and you said it used to be all full of gunk, so I'm going to guess that it's part of the EGR system. So how is coolant getting into the EGR system? I'd check for correct plumbing to the EGR valve.

I mean, think about it for a minute. Those slots to the intake ports are not there because of unusual wear or poor durability. They were machined there by the factory, which means they were designed in as a way to get something into the intake ports. Gotta be EGR.

AngryCorvair got it, those were EGR passages. Coolant was coming from the water pump housing/manifold and into the EGR passages from the gaskets between the manifold and the two heads. Rear bank. Top most round hole is EGR, others are coolant: Same thing on the front bank: Coolant manifold/engine mount/EGR solenoid/water pump assembly

Have not put it back together yet but we're confident those were the problem. P.S. these suck to change, don't buy a caddy

Run_Away wrote: P.S. these suck to change, don't buy a caddy

With a N*, you ain't seen nothing yet.

Here's the advice I can give you, it involves ligher fluid, and a few matches, maybe even a cheap lighter, and a steep cliff/bluff.

Soak the back seat in ligher fluid and ignite, then place car in gear, or push, down or over a steep cliff or bluff. Shoot off fireworks in celebration at this moment, for now your worries are over.

Then take the insurance money and buy an American luxury car that's much easier to work on. Say, a Lincoln.

Sorry, can't help you.

MrJoshua wrote:

Run_Away wrote: P.S. these suck to change, don't buy a caddy

With a N*, you ain't seen nothing yet.

HAHA, yeah, there's a reason I sold my N* powered Eldo. I miss that car, but then I think about all the times I worked in that engine bay, and the feeling passes...

BoostedBrandon wrote: Then take the insurance money and buy an American luxury car that's much easier to work on. Say, a Lincoln.

Yeah, no, they're not much better and have their own host of problems...

I also would be curious as to why the starter broke the nose cone. One more reason for the lighter fluid and matches.

Run_Away wrote: AngryCorvair got it, those were EGR passages. Coolant was coming from the water pump housing/manifold and into the EGR passages from the gaskets between the manifold and the two heads. ... Have not put it back together yet but we're confident those were the problem. P.S. these suck to change, don't buy a caddy

and i ain't never even worked on no northstar neither. what do i win? ;-)

You get three attaboys.