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Please help. Northstar freeze plug.

97488 Views 389 Replies 26 Participants Last post by  Ranger
Hello guys. I have a 2001 Seville STS, a freeze plug (core plug, welch plug) fell out. The plug is (was) located on the rear of the left cylinder head, left front corner of the engine bay, behind the water pump housing. I can't upload pics because I'm posting this from my phone but even if i could it would be hard to see the hole, it is barely visible, it's somewhat blocked by the water pump belt as well as the housing (have to look very closely at a strange angle). I have already bought the new plug, but how do I access the hole to install? Does the entire housing have to be removed? If so, how involved is this going to be? I've already removed the air filter box/ducting, water pump belt shield and disconnected the hoses from the housing.

Any help would be greatly appreciated. Thank you.
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I know the lower bolts need to all be in place when the X-over is positioned into place.

It seems to me there may not be room to fit a plastic tie. Sounds like a good plan if they fit in the bolt holes with the bolts. The in board bolts are really hard to deal with(restricted) & may be difficult to snip remove the tie.
AHHHHHHHHHHHHH!!!........... Ok I feel better now.

As you may have guessed I started work on my coolant crossover today. I got my parts from Rippy earlier today and started taking parts off and bagging/labeling nuts and bolts. 2 hours later and it's out, 20-30 minutes of that was spent on the 4 lower crossover bolts. It took a combination of a ratchet and socket, 2 different length erections, a universal joint and a low profile racheting wrench, it didn't help that I have huge hands and fingers.

On my journey I discovered a broken vacuum line and pcv hose fitting (maybe I broke them, I thought I was being gentle). Also the trans vent hose was cracked at the nipple on the transmission and very loose. I'll be ordering more parts before I can finish the job it seems. There was one blessing in disguise, 3 of the 4 crossover gaskets were cracked or cracking, so I would have been doing this job soon anyway even if the freeze plug didn't fall out.

I can tell it's going to be REALLY fun getting it back in with the gaskets and lower bolts in place. A few questions so far. I removed the fuel rail (with the injectors still on them). Do I need to lube the o rings before I reinstall them? And what should I use to clean the throttle body and EGR valve? carb or TB cleaner? Any specific procedure for the EGR valve? Thanks.
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Lubing "o" rings is always a good idea, engine or transmission oil.
i think there's a tech tip on cleaning the egr valve

carbcleaner (same as tb cleaner) is probably what is recommended in there

IIRC the procedure is similar to cleaning the IAC (or is it ISC) actuator
Rippy, (or anyone) black, plastic, cylindrical part with a 2 pin connector and one small hose. Attached to the crossover between the plenum and TB, held on with one bolt. Delphi 1997279. EVAP purge valve? If I could upload a pic I would.
possibly ... i'll check in the morning... send me a pm to remind me if i forget... it's late...
It's a very common GM part used on all GM brands its about $20 to replace.
Went out earlier and bought a couple of cans of carb/TB cleaner. My TB wasn't that dirty really, looks brand new now. Cleaned the IAC and EGR valve next, again, were pretty clean to start with. The EGR passage in the crossover from the valve to TB, however, was pretty grimy. Filled it with the cleaner, let it sit a while, scrubbed what I could reach with a toothbrush, poured it out, rinse and repeat. I think it came out pretty good.

Need a few little things before I start putting it all back together, I'm sure I'll have more questions when that time comes. Thank you, everybody, for all your help so far.
just to confirm, yes that's the evap purge valve ... list price is about $37
My living room floor is covered in removed parts and labled bags of nuts, bolts and screws. Seemed like a good idea at the time since nobody uses the room...... Until my dog chased a ball that was rolling towards the couch and trampled my engine cover. "CRACK!!!" :annoyed: I'l deal with it another time.
I'm going to the parts store to pick up a few things. Coolant, a length of hose for the trans vent and sealant for the crossover bolts. Questions: I know I've asked what to use for sealant before, johnny recomended ordinary pipe sealant. Is there an automotive equivalent? Something from permatex maybe? Also, how many gallons of coolant will I need to refill?

Update: permatex makes two thread sealants. Regular and high temp. High temp is recommended for extreme temperature changes. Should I grab that? And another thing came up. I'd like to remove the fuel rail and move the fuel lines out of the way when I reinstall the crossover. Do I use a regular quick disconnect tool? If so, what size?
3/8th's works for both lines. NAPA had a set of 5 release tools 5/16ths to 7/8ths for $6.

I'm sure the other chain stores have similar offering if not the same.
Thanks for the disconnect tool size Johnny. Any suggestion on the sealant? It's not that I don't trust your rectorseal recommendation, I just have a pet peeve about fixing cars with stuff from the hardware store :)
They should have a small tube of thread sealant.

This one is 0.20 oz. Thats 5 X more than you need.

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Yup. That's exactly the tube I was holding. I'll run back out and pick up that and the disconnect tool. Thanks again.
You can find Permatex at most hardware stores & Walmart.
Got the last of my parts from Chris a few days ago, been waiting for good weather, might finish today.

QUESTION: Do I need to recess the freeze plug into the head at all, or leave it flush?
It looks like there is a champher you want to clear on this N* head.

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Hmmm, mine didn't look like it was chamfered. I guess I'll call the service department, maybe they'll have a definitive answer. Thanks for the pic though.
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