Heater house connection on 1971 LT1

[Daniel B.]

I'm rebuilding the cooling system on my 71 LT1. The heater hose nipple on the manifold has excess corrosion and needs to be replaced. However the nipple seized itself to the manifold. At this point a breaker bar will not brake it loose. Before I try my impact wrench i want to make sure I am not risking damage to the manifold.

Has anyone had any experience with this issue?

Thank
Dan

[Joe L.]

Re: Heater house connection on 1971 LT1

I'm rebuilding the cooling system on my 71 LT1. The heater hose nipple on the manifold has excess corrosion and needs to be replaced. However the nipple seized itself to the manifold. At this point a breaker bar will not brake it loose. Before I try my impact wrench i want to make sure I am not risking damage to the manifold.

Has anyone had any experience with this issue?

Thank
Dan

Dan------


This is a very common problem with heater hose (or by pass) nipples. It's an even worse problem for situations involving an aluminum manifold. That's because the nipple is steel and the manifold is aluminum and in a liquid environment. This sets up the PERFECT conditions for galvanic corrosion. This will virtually "weld" the nipple to the manifold.

You could try various penetrants including melted candle wax. You could also try mild heat (nothing more than a propane torch). It's worth a try but I don't think you'll be successful. Believe me, I've "been down this road". Is it possible to damage the manifold in the process? Most definitely.

Here's what I would suggest: re-assess the continued usability of the existing nipple. As long as the nipple is still structurally sound, clean it thoroughly with a drill-mounted wire wheel. Very little of the nipple is visible with the hose installed.

[Edward D.]

Re: Heater house connection on 1971 LT1

Dan,
Agree with Joe on this, leave it if possible. Otherwise if you must remove, use heat on the manifold around the fitting, then take a long breaker bar on fitting and strike it sharply with he heel of your hand. Do not use an air or electric impact driver, you risk cracking the manifold or stripping the thread.

[Paul D.]

Re: Heater house connection on 1971 LT1

Joe's advice is spot on as usual. That situation can go from bad to worse in a second. Unless it has rusted away all of the raised edge or ring, I would clean it up good and use some gasket sealer or silicone inside the hose before you slide it on. Give it time to cure before adding coolant.

[Daniel B.]

Re: Heater house connection on 1971 LT1

Thanks guys. Good thing I checked with you. I suspected it would crack, or worse, the manifold. I am lucky enough to have an older mechanic at the local Chevy dealership who was certified on the C2 and C3's. He constantly reminds that these cars were only expected to survive around 3 years so the problems we have 50+ years later weren't considered.