Oil and coolant questions for '79 X19

EJP

EJP

Daily Driver
I am fairly new to this car so bear with me.
Is there supposed to be crush washer or seal between the oil drain bolt and the oil pan?
What is the tightening torque for this oil drain plug bolt?
Is 20W-50 weight oil too heavy for these engines?
Looking to replace my stuck heater valve. What is the best way to drain the coolant system? The owners manual that I have says to loosen the two drain plugs on the lines that are about 12" back from the radiator and the pet cock on the engine. Doesn't look like the pet cock on my car has ever been loosened and I am worried I may get it loose, but will it ever get tight again and leak proof?
Do you need to loosen the pet cock and drain the block when replacing the heater control valve?
If I don't, how much antifreeze will run into the car when I remove the heater valve.
Thanks in advance for the advice.
Ed
 
There should be a copper washer for the plug. I just torque it by hand to what feels tight. I’ve been running Castrol GTX 20W-50 for 30 years. I drain the coolant at the engine block.

EJP said:
I am fairly new to this car so bear with me.
Is there supposed to be crush washer or seal between the oil drain bolt and the oil pan?
What is the tightening torque for this oil drain plug bolt?
Is 20W-50 weight oil too heavy for these engines?
Looking to replace my stuck heater valve. What is the best way to drain the coolant system? The owners manual that I have says to loosen the two drain plugs on the lines that are about 12" back from the radiator and the pet cock on the engine. Doesn't look like the pet cock on my car has ever been loosened and I am worried I may get it loose, but will it ever get tight again and leak proof?
Do you need to loosen the pet cock and drain the block when replacing the heater control valve?
If I don't, how much antifreeze will run into the car when I remove the heater valve.
Thanks in advance for the advice.
Ed
Click to expand...
 
Personally - I've switched to Driven HR1 oil 15W50 (it's conventional), with high ZDDP but still OK for cars equipped with catalytic converters. All of the new API certified off the shelf oils have very low ZDDP - it'll work, but not great for flat tappet camshafts in the long run.

I drain my cooling system from several places, block, the pipes have drains as well, and the rad. You can remove the lower rad hose at the pipe connection as well.
 
The oil drain plug (on the oil pan) may be one of a couple styles, depending if it is the original one or if it has been changed (as many seem to be). One style has straight cut threads (like a regular bolt) and a step or landing where a sealing washer fits. The other style has tapered threads (like a pipe fitting) and no step because it does not use a sealing washer. So that will depend on which type you have.

I'd drain as much coolant from as many places as you can. You really do not not want it pouring into the interior of the car when you disconnect the heater hoses from the valve...it could be a LOT of coolant depending on how well the system has been drained.
Those little drain bolts on the lower metal pipes (the ones you described as near the radiator) will likely be frozen and attempts to remove them may create a real problem. It may be easier to just remove the large coolant hoses from the end of the pipes.
As for the petcock on the block, I had the same thought as you - I was hesitant to try and open it for fear of similar damage as I described for the little drain bolts. But to my surprise those petcocks seem to work well without any drama. I believe they are brass(?) and don't get stuck or have problems resealing. I'd try it gently to see how it feels and go from there.
Otherwise draining the coolant out of the block should happen if you remove the hoses at the bottom and remove the cap from the overflow tank, but you might need to also remove the thermostat cover to break that seal. There are other ways to do it as well, so do whatever gets the coolant out before opening the heater valve lines.

There are good write ups on replacing the heater valve. I'm not sure if your '79 has A/C or not, but A/C cars use a different valve. So be sure you can get a replacement valve that matches yours first. Otherwise there are also write ups on how to use aftermarket valves in place of the stock one if needed.
 
+1 to what Dr. Jeff has said, the drain cap screws on the undercar pipes ahead of where they come out of the tunnel are Da Bomb if you are confident in their integrity. They take care of draining the rad and the pipes themselves. But as Dr, Jeff said, if you have never loosened them and they look like they haven't been loosened in ages, maybe a case of letting sleeping dogs lie. But there is no need to drain the rad or the pipe for your heater valve work.

To do the heater valve:

0. Remove cap from expansion tank

1. Use the drain cock on the lower back side of the block to drain the expansion tank and the block. You will need to drain off about 5-6 quarts so use a big pan. I squish a thin plastic funnel with a screw-on drain tube between the block and a the driveshaft to keep from making a big mess.

The original petcock is brass, not known for seizing up so it should not be a big deal. If too tight for fingers to loosen, a small pair of pliers will help.

2. At about 5-6 quarts, you have lowered the coolant level in the engine area enough to do the job.

3. Under the car, Locate the small metal pipe coming out of the rear of the central tunnel. This is the heater return line. Place another pan under it and remove the hose from the pipe. You will get some coolant from the hose but most from the pipe. In the next step you will likely get an additional rush of coolant out of the return line under the car, so place your pan accordingly. Here you'll probably drain off about 3-4 quarts, tops.

4. From above, on the right rear corner of the head, locate the 90 degree metal elbow, which is the heater circuit feed. Place some rags under it, and remove the hose from the elbow and quickly elevate the open hose end. You will get a little coolant spillage but not much.

5. For good measure, blow into the hose end to encourage trapped coolant in the heater feed line, heater core, and heater return line to drain out into the previously placed pan. If you really wanted to throroughly blow it out I'd use a shop vac set up to exhaust air from the pickup hose. Others might suggest shop air, but I think that might be asking too much of an old heater core :)

6. Now you can do the heater valve job and pretty much not spill a drop!

FYI the coolant drain and fill spec for the X is 12-2/3 quarts, aka a little over 3 gallons. A bone-dry system will take a hair under 4 gallons of coolant.

The most important part of this job is to properly "burp" the system after replacing the valve and filling it back up. It's not uncommon to need 3 or more burping sessions to really get it where it needs to be for trouble-free operation.

If you are buying a new valve from our vendors BE SURE to order the associated gaskets/seals on the same order, to prevent waiting for an additional parts delivery at additional expense. Order the seals that join the return pipe to the heater core and the seals that join the valve to the core and the elbow, you'll be glad you did.
 
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Many thanks for the replies and advice. I was thinking, why do you need to drain the entire cooling system? Why not just drain out those things that physically sit higher than the heater valve like the expansion tank and the engine block? All the other lines with coolant in them sit lower in the car below the height of the valve so just leave them alone. How would that coolant rise up and leak out? I realize there will be some coolant loss when the heater valve is removed. Don't know how much if I do what I am thinking. Could be a big mess inside of the car?
Does this sound like it makes sense or am I just wishing for the easiest way out? Thanks.
Ed
 
I've changed heater valves without draining the system, you just need a shallow catch pan and lots of rags - the core will drain.

Ideally you should flush/fill the coolant - any idea of how old it is? I change mine every 5 years.
 
EJP said:
Many thanks for the replies and advice. I was thinking, why do you need to drain the entire cooling system? Why not just drain out those things that physically sit higher than the heater valve like the expansion tank and the engine block? All the other lines with coolant in them sit lower in the car below the height of the valve so just leave them alone. How would that coolant rise up and leak out? I realize there will be some coolant loss when the heater valve is removed. Don't know how much if I do what I am thinking. Could be a big mess inside of the car?
Does this sound like it makes sense or am I just wishing for the easiest way out? Thanks.
Ed
Click to expand...

Yep, that's the intent of the procedure I posted.

Remember, the heater circuit by default is open to the engine coolant jacket, so you have to drain off coolant to lower the level to slightly below the water pipe on the rear of the engine (which is the heater circuit return). That means the expansion tank, the small hoses into the stat housing, the cyl head, and about 1/3 of the block. Adds up to 5-6 quarts. Then the contents of the heater circuit outside of the block, probably another 4 quarts.

Now that I think some more about this, you could probably skip the drain cock step and go right to pulling the hose off the return hard line under the car, then after sufficient time to drain, do the last step of removing the feed hose from the elbow on the cyl head. If the HCV is stuck open that's better than being stuck closed, if stuck open you will get a better drain of the core and heater hoses. You'd need enough drain pan capacity to catch at least 2 gallons (if not a bit more) gushing out at a pretty good clip.

IMO an extra 10 minutes to get a better drain is vastly preferred to 1-2 hours of washing/rinsing/shop vaccing recovering from a coolant soaked carpet.
 
One can successfully clamp the two hoses inside the engine compartment to stop flow after depressurizing the tank by removing the cap.

They make specific pliers for this but a pair of Vice Grips wrapped with tape will prevent damage to the hoses.

Yes you will need to collect the coolant as it escapes the hoses and the heater core. Putting a stopper in the hoses will reduce further escape of coolant. Additionally you won’t have to do a full bleed of the cooling system.
 
All good advice. You can do it without draining the hole system. However if it hasn't been done recently, it is well worth doing the full drain. Then before you make the repair, flush the system as much as you can. You may find you have rust coloured coolant. If you can disconnect the 2 thermostat housing hoses and give that a good flush. Then do the same with the heater hoses (if there is no longer the heater valve add a short bit of hose so it drains out of the car). Only after its all clean put the new valve in. That way you won't risk clogging up your new valve. Then a nice dose of new antifreeze (50/50 mix).

You may already know all this, but if not I hope it helps give you a working heater and a cooler running engine as a bonus.
 
A full replacement of coolant is a very good idea after 2-5 years depending on the type of coolant you are running in your X.

This year is my year. Coolant, hoses, clamps, heater valve, thermostat and radiator fan temp switch. All are OE from the factory o_O...Busy busy busy
 
Personally I would completely drain the entire cooling system before doing a valve replacement. But that's just me. I fully agree it can be done without that. However in my experiences if there is any possibility of something happening, allowing coolant to leak inside the car or in my face, it will. And that is a mess I don't like to clean up.

Furthermore, as has been said, it is a great time to flush the system. I really like the idea of doing the flush first so the new valve does not get contaminated. Plus that way if any does leak inside the car (or on me) it will only be water and not antifreeze.

Like I said, that's just me. Everyone will have their preferences how they approach any job. ;)
 
Since I have all of this apart, I thought I would drop the heater core and check for leaks and cleaning. Found some antifreeze sitting near the back of it.
If I can get the black fan housing out. It removes to the left side of the car? Can someone tell me where to remove the electrical connections to the fan or will the fan box come out with it still connected. I see 3 wires going into the box. One or two seem to go the fan switch. Are they removed at the switch? Where is the ground connected?
I cant imagine doing this whole heater valve and core thing with the console/dash center stack and carpet still in the car!!! Mine have been removed. What a PITA job.
Thanks for the help.
 
I think someone made a pretty good thread describing the whole process awhile back (guess its been awhile ago).
 
Got it all drained and apart. Surprised I didn't get a lot of coolant when I pulled the hoses from the heater valve, but it's time to reassemble.
I want to thank all of you that helped guide me through this. Your help was much appreciated.
And sorry I beat this thread to death with all of the questions. I tend to get a little nervous working on a new car that I don't yet know much about. Will try to improve.
Ed
 
Nothing to be sorry about, we all have been through the unfamiliar, not breaking what you may not understand is a good path to not spending money unnecessarily.

Looking forward to your next project.
 
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