hagstir

First things first, the car is an '84 N/A being built for hpde's and down the road eventually spec racing

So the other night I decided to change my lower rad hose, and while warming up the car something at the rear of the engine literally sprung a leak. A very thin stream of coolant shot out from the center rear of the engine towards the passenger side, actually made it as far as my workbench(making sure to hit the battery and exhaust manifold as well). I thought I had found the culprit, but now am realizing what I saw was a hard A/C line with a beat up outer hose which I don't believe is responsible for this leak.

This happened right as the thermostat and fans were kicking in so I know it's related to the system being fully pressurized, but just now as I went to take pics for this thread I noticed the little stubby hose from the rear neck to the HC Valve seems to have a cut and still some moisture on top so I guess that is it. Problem is, I already ordered the block of plate and cap for the water pump. This is a track build so I'm fine with deleting unnecessary stuff, although I don't plan on removing the dash until winter as I'd like to keep using the car for a couple of months and that is going to be a big project I'm sure. I had planned to delete A/C and do bearings over the winter so pulling the heater core could easily go on that list.

Should I try to just replace that stubby hose or should I go ahead and bypass the heater core circuit?

If I don't remove the dash to get at the heater core itself, what should i do with the hoses from the firewall?

Is there a fuse/relay I should pull to disable the heater?

Do I need to remove the Intake Manifold to get at that water neck?

What do I do with the vacuum thing screwed into the water neck?

Thank you guys so much in advance, this site has helped me so much. Pics below. Distance of spraying coolant was an arch ending on my bench. I am guessing this is the offending hose. The valve was totally dry on the outside. Mistaken A/C hose. I can see the copper pipe beneath the rubber. What do I do with this?

Tiger03447

There are two hoses behind the engine. One goes to a water fitting at the top rear of the head. The other goes to the heater control valve. Disconnect both of them from the engine, and run a 5/8" section of heater hose to both the of the engine fittings, bypassing the heater, and deleting the heater control valve. The heater will be non-functional after this, but no more leaks. Replacing those two hoses under the passenger side dash is a real deal..should be some threads on this..be ready for a whole day to change them if you go that way. Good luck!

hagstir

Thanks Tiger03447!

I guess I may just do that for the time being, I do have a couple of threads saved for the heater core removal, but still am a bit confused about using the block off plate.

What is that vacuum fitting on the nozzle for? Is it alright to bypass?

Sorry for my ignorance I'm away from the car at the moment and still need to trace the lines.

So has anybody installed a block off plate without removing the intake manifold?

hagstir

Sorry for the double bump but wanted to add this. After doing a little research I see that the vacuum fitting is a thermo valve involved with the charcoal canister... so whew, not worried in the least about that anymore.

So after the grand prix tomorrow the plan is to close off the heater core circuit, and probably go ahead and remove the intake manifold just to get to work cleaning up vacuum lines, etc. until the package from LR comes in.

FRporscheman

The coolant flow at the back of the head is worse than at the front, and many people believe it's one of the causes of blown head gaskets. Having coolant flow out from the nipple leading to the heater does help the flow back there. You can block it off, but it might not be a bad idea to leave it looped, allowing constant flow.

If you do want to block it off, it would probably be faster to just take off the intake. But you might be able to do it with the intake on if you're determined!

hagstir

Thank you FRPorscheman! I hadn't heard about the water flow issues at the rear, good to know. I'll be researching that later tonight. It's so muggy here currently that to minimize sweat time I think I will pick up some heater hose and just close that loop and revisit that area later in the year.

hagstir

Just a quick update:

I hooked up 5/8" heater hose from the outlet to the pipe by the exhaust manifold... Very tight fit! But doable. However because the only failure in my system was the topmost hose from the hcv to the head I decided to replace that and keep the heater hooked up for now. Very fiddly and tight with the intake manifold still on, but after some foreign language practice I got everything back on. Taking a break then going back out to bleed and check for leaks.

Thanks for the help guys!

mel_t_vin

Wise choice...you will be counting your blessings come Nov/Dec.