Need Help with coolant lines on back of LT1

[Mr Nice Guy]

I was working on the hard coolant lines in the back of my LT1. The one that runs up to the throttle body(already did TB bypass) and between the heads. I took the bolt out on the passenger side (It has one of those round fittings where the lines come out and a Hollow bolt with holes goes through). When I put the bolt back in, I put RTV on the threads, tightened everything up and refilled the water and it poured out of there like crazy. Are there supposed to be a couple copper crush washers on either side of the round fitting (between the block and also between the bolt) that I may have lost or are you supposed to RTV it or maybe something else I haven't figured out yet? If you have to RTV it how do you get the stuff back there? I am totally lost and getting really frustrated. This is my only car and I have to get to work tomorrow. Any help would be greatly apreciated. Thanks in advance.

[fastTa]

The steam pipe uses what they call a steam pipe seal between the steam pipe and the back of the head.

Here is a pic of what they look like with the part number. Give credit to Shoebox(Rob):

[Mr Nice Guy]

Thanks Fast TA and shoebox. I didn't know that was called a steam pipe. I wonder why it's called that? I know water comes through it. Anyways I only need one of those steam pipe seals and it goes between the fitting and the head, right? Also just curious is the steam pipe hard to replace if it goes bad? I know there are two bolts and it comes off but it runs under some other line that loops on the back of the engine so I don't know how you'd get it out from there. Does it serve a purpose other than running water to the throttle body? I was thinking if didn't and it gave me trouble I could just plug the holes in the head. It's impossible to see back there so everything I know is from feel. Is there a diagram somewhere of the back of the engine? It'd be nice to see what really going on there. Sorry for so many questions. Thanks so much for your help.

[fastTa]

Because the LT1's have a reverse cooling system and because the cylinder heads are subject to the greatest heat of the entire motor, this steam "crossover" pipe allows pockets of steam to escape.

You do not want to ever plug those holes in the back of the cylinder heads or you will greatly increase the potential for detonation and/or timing to be pulled because of reported spark knock; not to mention an adverse affect on the coolant system as a whole.

Here's a pretty good shot of the rear of the LT1:

[thenuge876]

Thanks Fast TA and shoebox. I didn't know that was called a steam pipe. I wonder why it's called that?

Its there to keep steam pockets from building up in the back of the heads, it has a bleeder i believe somewhere on the line to remove air from the system to keep the cooling flow even.

[Mr Nice Guy]

Thanks guys that pic really helps. I'll call the stealership tomorrow. Hope they have it. Guess I'll ride the motorcycle to work tomorrow.......Later

[Rob B (shoebox)]

Thanks Fast TA and shoebox. I didn't know that was called a steam pipe. I wonder why it's called that? I know water comes through it. Anyways I only need one of those steam pipe seals and it goes between the fitting and the head, right? Also just curious is the steam pipe hard to replace if it goes bad? I know there are two bolts and it comes off but it runs under some other line that loops on the back of the engine so I don't know how you'd get it out from there. Does it serve a purpose other than running water to the throttle body? I was thinking if didn't and it gave me trouble I could just plug the holes in the head. It's impossible to see back there so everything I know is from feel. Is there a diagram somewhere of the back of the engine? It'd be nice to see what really going on there. Sorry for so many questions. Thanks so much for your help.

There should be a seal on each side of the pipe assy, so you need a total of 4 of them.

[Injuneer]

The bleeders for air removal are not on the steam line. They are on the t'stat housing and the heater hose. The steam line returns to the passenger side end tank on the radiator, where there is supposedly a small vapor/liquid separator built in. Only the 93/94 engines have it going directly to the radiator. The 95-97 setups pass it through the throttle body first. I just read a post on another forum that indicated the Corvette LT1 has some sort of liquid/vapor separator tank in the line.

I have a temperature sensor in the steam line, and it doesn't seem to indicate any significant difference from the temp sensor in the water pump housing, alhough it might read a bit higher. But given the general tendancy of the #7 cylinder to run hotter than the others, the tube would seem to be fairly critical in eliminating any air pocket or vapor buildup in the "back" of the heads.

[Mr Nice Guy]

Aaarghhhhh!!! I got the new seals but the old ones seem to be still stuck on the fitting and on the back of the head. How do I get them off? I can reach back there but it's so tight it's hard to get a tool or anything to pry them off with. I have to get this fixed tonight or I am seriously screwed for getting to work tomorrow. Thanks again all help is greatly apreciated

[fastTa]

Aaarghhhhh!!! I got the new seals but the old ones seem to be still stuck on the fitting and on the back of the head. How do I get them off? I can reach back there but it's so tight it's hard to get a tool or anything to pry them off with. I have to get this fixed tonight or I am seriously screwed for getting to work tomorrow. Thanks again all help is greatly apreciated

You just need to pry them off with a flathead screw-driver or something similar. It is not uncommon for them to feel "stuck".

A small mirror is always helpful when working on hard to see locations.

[Mr Nice Guy]

Thanks again. I got them off, put the new ones on, tightened it down and it still leaks like crazy when I fill the radiator. I think the steam pipe itself has a leak by the fitting so I guess I'll need to get a new one. Anyone know if this is a common part that dealerships carry? Is it expensive? Anyone know the part number? Also any hints for getting it out? It looks like I just take out the two bolts at either fitting. It also looks like I need to take that flexible line that it runs under off too. Do I just unbolt that at the top and bend it out of the way? Thank God that my brother is lending me his daily driver tomorrow or I'd be really up a creek. Thanks again guys you are life savers.

[97 Zee]

Part # Should be 12556260. Make sure the dealer double checks.

[fastTa]

Thanks again. I got them off, put the new ones on, tightened it down and it still leaks like crazy when I fill the radiator. I think the steam pipe itself has a leak by the fitting so I guess I'll need to get a new one. Anyone know if this is a common part that dealerships carry? Is it expensive? Anyone know the part number? Also any hints for getting it out? It looks like I just take out the two bolts at either fitting. It also looks like I need to take that flexible line that it runs under off too. Do I just unbolt that at the top and bend it out of the way? Thank God that my brother is lending me his daily driver tomorrow or I'd be really up a creek. Thanks again guys you are life savers.

I've got a perectly good used one. Let me know if you want it.

You just need to unbolt the EGR feed pipe from the back of the intake manifold and bend it out of the way. It is made to be flexible and it will not hurt it.

There is also a small tab attached to the steam pipe line about 6-8" behind the TB that needs to be unbolted.

And then of course just remove the rubber hose that attaches to the TB.

[Mr Nice Guy]

Hey Fast how much do you want for it? I'd like to get this done tomorrow but if the dealer has to order it or wants an exhorbitant amount for it I'd rather wait a few days and get it from you. I could paypal you the money and if you shipped it priority mail it usually takes only 2 days so I'd have it for the weekend. Also wondering if I can reuse the seals from the driver side, I bought new ones for the passenger side and they're like $7 a piece so if I can reuse them I'd like to. Thanks again.

[fastTa]

Hey Fast how much do you want for it? I'd like to get this done tomorrow but if the dealer has to order it or wants an exhorbitant amount for it I'd rather wait a few days and get it from you. I could paypal you the money and if you shipped it priority mail it usually takes only 2 days so I'd have it for the weekend. Also wondering if I can reuse the seals from the driver side, I bought new ones for the passenger side and they're like $7 a piece so if I can reuse them I'd like to. Thanks again.

Sending you a PM.