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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #1 ·
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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2010 DTS
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I don't know if the crossover manifold has to be removed or not, but pray that it doesn't. It's very labor intensive.

I thought these things didn't have freeze plugs. :hmm:
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #3 ·
Would the crossover manifold be the aluminum housing that the water pump is installed into? Because that's exactly what's in the way. It looks like it continues over to the other head, or at least somewhat past the throttle body.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #5 ·
Oh god. Any possibility it's accessible through the hole the pump sits in (if I removed the pump)? I just found a picture of the crossover. Looks like it covers the whole backside of the engine, around the throttle body opening and everything. Should I start crying?
 

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Yes you should. It's a bitch of a job.

I don't know if it is accessible through the water pump opening. If it is, thank the Northstar Gods.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #7 ·
Ranger, what's involved in removing and reinstalling the crossover? I can see I'll have to remove throttle linkage, some bracketry, a few hoses and wires etc. I definitely don't trust any of my local mechanics to touch it, and I have a feeling the dealer would have some ridiculous price for the job, think it's worth it? I'm not an amateur mechanic, but I'm not ASE certified either. Is it a hard job, or just time consuming? Thanks.
 

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Yes, the dealer price is high. Mine was done under warranty and they had the car for a day. I don't recall the price, but it was high. Well over $1000 I think.

I'm not sure what exactly is involved with it as I have never had to do one. Johnny Kannapo did it not long ago. I'll ask him to chime in with some advice.
 

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1996 Eldorado
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You are not the first one to have this occur. There are threads addressing this in the recent past. (last 3-4 months) I suggested using a rubber expansion plug & I think they were able to pull it off but I will have to find the thread to verify. If the coolant is removed it might gain you enough access to cinch up the bolt to expand & seal the plug. That part would look like this,



You don't want to get into removing the X-over manifold if it can be avoided, It a genuine PITA but not the end of the world. I'll see if I can find that old thread for you.

To replace the original type plug you would have to remove the X-over manifold.
 

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2000 Seville STS
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As an owner who has done the coolant crossover removal with the engine in the car, a word of advice: Get a ratcheting box end wrench in the size that the crossover bolts are (I think 13mm). It WILL save you at least an hour's time in removal and an hour in reinstall. at least 4 of the 8 bolts on the crossover are too tight quarters to get a socket on.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #12 ·
Thanks everyone.Johnny, I actually read that thread late last night, too bad there wasn't a follow up. I've used those plugs before, not for anything like this though. Im not sure if one of that diameter would be short enough to squeeze between the head and crossover, then add the height of the bolt, I'm not optimistic. Plus, how long do you think the rubber would last in extreme temperatures? 15 degrees on a winter day, then sitting in 230 degree coolant in a matter of minutes, then back again. Sounds rough for $2.00 rubber plug, I don't want to have to replace it every year or two. Plus I'm tired of working on the cooling system, in the past year I've replaced the water pump, thermostat, surge tank and radiator (all ac delco), I don't want to see or smell coolant for the next 10 years.

The other thing is, I don't like to half ass anything, even on an old beater, let alone my own car that I rely on every day. My Seville only has 72,000 miles on it and is in great shape, id rather do it right.

Ok I went outside to look, there's no way I'm fitting my hand down in between there, the gap is too narrow and the hole is too far down. I'd love to just take it to the dealer and have them deal with it, but I just bought and installed struts, strut mounts and spring isolators on all 4 corners, so I'm a bit low on funds.

If I end up doing this myself (most likely) does anyone have any tips or guidance? I already have plenty of tools and have learned many "magic words" over the years. Thanks again.
 

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Maybe I should clarify post #8. When I said Johnny did it not long ago I was talking about the crossover manifold. I forgot about the freeze plug.

P.S.
Check the Tech Tips section. You may find a tutorial in there.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #16 ·
Thanks johnny. I've been looking for crossover threads all day, I've seen that one and a few others. The picture in that thread makes it look like there's plenty of clearance to get an expanding plug and a wrench into. In person, it is VERY tight, even with pump removed, it's the crossover itself that's in the way. Besides that I've decided not to go that route, I just wouldn't trust it to last. I think I'm going to bite the bullet, order new gaskets, and do it myself. It's a shame, since there is ZERO trace of any dried dexcool around any of the gaskets. All this work just to spend 2 minutes slapping in a 1" plug. So to you, and anyone else that has done this, Is there anything I should know before starting? Any part of the process that's extremely difficult? I assume the hardest part is keeping the seals in place during reinstallation, am I right? Any info will be GREATLY appreciated.
 

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1996 Eldorado
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I feel for you. You can see the freeze plug is right on top of the lower port.

DO GET new gaskets & 9" or more of silicone hose. Those are the biggies & don't kink the fuel line as I did.

I diconnected the grounds at the front of the block for more harness movement. Others have removed the ground below the coolant sensor It may be better to unfasten both harness grounds.

Which ever you do you will soon find out the harness being in the way is the main problem of this entire job.
 

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The green silicone hoses on the crossover. They are more heat resistant and you do not want to have to replace them again in the future due to their inaccessibility.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Discussion Starter · #20 ·
Ohhh, as in silicone heater hose. Sorry, when I read silicone hose I immediately pictured something along the lines of fish tank tubing, confused myself. I've seen the bright green hoses on other Cadillacs, I wasn't aware they were silicone. None of the hoses going to my crossover are green, however the car spent the first 9 years of it's life in Clearwater Florida, maybe they were replaced at some point because of the heat. I was planning on replacing all the hoses while I was in there, I'll make sure to use the right hose. Thanks for the heads up on the harness. I've read that the gaskets go on dry, is it not a good idea to use gasket adhesive? Or by dry do they mean don't use sealant?
 
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