: '94 Deville n* h2O pipes behind engine rusted out

Andrew M. Franklin
05-12-05, 07:36 AM
I started leaking coolant onto exhaust manifold and discovered two 3/4" steel pipes are rusted out. These are just in front of the firewall and just above the exhaust manifold. Appear to bring coolant from water pump to intake manifold and beyond. Has anyone replaced these pipes before? Doesn't look easy to get at these. Please don't tell me I have to drop the cradle! Anything else I should keep my eyes open for while doing this job? Thanks. Sincerely, Andy.

05-12-05, 12:18 PM

I looked in my '96 manual - it shows the pipes but not how to replace... I know the pipes you're speaking about.

They will come out, but it is tough to get to the brackets. You'll probably want to move the coil packs - I have the N* so if you have that motor you'll want to do the same.

One of the pipes connects under the ERG. A bitch to get to in my case b/c after the fuel rail recall the damn design team locked the EGR under the fuel rail stud - so I'd have to pull it just to get to the point where it connects.

If these pipes are rusted I bet your heater core is in bad shape, as well. I've lucked out in that case so far.

Now, can you tell me why these pipes are not made of stainless steel? God, for 45K you'd expect better design characteristics. I also understand you're comment about dropping the cradle - seems that's the answer to everything involving this platform...

Good luck!!!

p.s. my hoses to these pipes were really on there - you have to twist 'em hard to get a release.

05-12-05, 12:29 PM
Contrary to popular opinion, stainless steel and aluminum in a wet environment can be a very bad situation. If both alloys are not carefully chosen the aluminum can sacrifice to the stainless and fall to pieces. I have seen aircraft aluminum skins turn to lace when covered by sheet stainless.

05-12-05, 01:20 PM

You're right! How about brass clips to fasten the ss pipe. I don't believe the issue is between the coolant and alum/ss, unless that is the "wet" point in discussion.

My pipes were pretty bad upon doing my last coolant change - in fact I was shocked to see how much rust had accumulated in these pipes. I wonder how much longer my heater core will hang in there...

Good catch!!!

05-14-05, 05:22 PM
uhh... maybe the problem was with the coolant and not the pipes. If the coolant is maintained to a reasonable level to keep the corrosion inhibitors up to strength the pipes nor the heater core will rot out... corrosion inside the cooling system means one thing and one thing only...lack of cooling system maintenance somewhere along the line. The materials in there will simply not corrode/rust if the coolant is up to snuff.