Hey everyone, this will be my first tech post from my new C3. Bought the car and had it shipped from California. I haven't had a chance to drive it yet, but today I went to the garage to start it up. Started the car and came back after 15 minutes and found a big puddle forming under the car. Turned the car off and felt the liquid and it felt like coolant but was brown. Found the leak, and it looks like it is coming from the heater core hoses because it was leaking by the passenger side tire by the fire wall.

Here is what freaks me out:

1. Why is my coolant brown? Head gasket issue?

2. When I was feeling for the leak, the heater hoses are crunchy when you squeeze them. After a few squeezes it feels like a regular hose. I've never felt this before. What is going on?

Should I do a leak down test? Any quick checks I can do first?

Car is a 1981 4sp.

 

 

Agree with Bats... Start by draining & flushing the entire system, including unhooking heater core hoses at the motor, attempting to blow through one (the brown junk will come out the other, so careful), replace those hoses (inexpensive and readily available). Pull the plugs on the block if possible, and drain it, along with the radiator. Flush the entire system with water and potentially a flushing agent, and start fresh with new coolant and distilled water. If you aren't confident doing this, take it somewhere where they are capable of a complete system flush. Replace the thermostat and radiator hoses, unless those appear to be new, but based on what you see now, I doubt it.

After all of this - if there is that much rust in the system - don't be surprised if leaks appear, or you may realize cooling is an issue (there may be plugged components, like the radiator and deposits in the block), or water pump failure not too far down the road just due to cleaning everything up and flushing.

The junk that is in there now will rot the cooling system from the inside if you leave it alone, so you need to address it anyhow. There's also the good chance that you flush it all out, replace coolant and freshen the hoses, and everything works out just fine. Good luck with your project and don't be discouraged - every one of us with these old C3's has tacked multiple projects like this, or worse. Post up a pic or two so we can enjoy a look!

 

You can easily bypass the heater core to get back on the road while you fix the heater separately. Many people do that mod to cut down on summer heat. Do a search, the quick way loops the heater hose back on itself at the front of the engine with a 5/8 to 3/4" adaptor.

Drain, flush, refill with 50% green concentrate, 50% distilled water. If the PO put in orange antifreeze, a bit of rust will make it look awful.

4 speed C3s from the 80s are favorite. Good choice!

 

Been flushing it like crazy....it was definitely rust , but I think the rust must be pretty bad. I've bypassed the heater core and will install a new one when I have time.

One thing I did find was that the motor must not be original. All of the vacuum lines don't match the engine picture. After some digging around, it looks like the sticker was for a 4sp, and my engine is out of an automatic. Kind of disappointed....but a pretty damn good excuse to do an LS1 swap.

One thing is I'm a little relieved that the sticker is for a 4sp car, but is there any other way to verify that it is an original 4sp car?

 

At least you are back on the road!

The emissions sticker says 4 speed, but your engine is for an automatic? Are you 100% certain the engine is NOM (not original motor)? Does the VIN on the engine not match your car's vin? A 1981 4-speed engine would be stamped ZDA or ZDC:
http://corvettec3.ca/engines.htm

The sticker on the gas tank (if it's still there) would confirm the original options of the car. Otherwise, it may be possible to tell from the opening for the shifter, but you'd have to search for how to do that.

Otherwise, is the transmission stamped with a partial VIN? I don't know, and wouldn't assume that it is, but that would also be worth checking.

Another difference, in 1980 (and possibly in 1981), the differential yokes, u-joints, and half-shafts are different, with Dana/Spicer 1350 U-joints used on the half-shafts of a manual car. You may want to Google that one, too.

 

I didn't know about the stamp on the engine, I'll take a look in the morning! Thanks for the help

 

The size of the bolts that hold the straps on for the U-joints are lager for a manual transmission car versus that of an automatic car,. BUT in 1982 I have seen NUMEROUS Corvettes with an automatic ( because that is all that they came with) that had a manual differential side yokes in them.

Your engine block suffix will either be a ZDA or ZDC. The ZDC is a California emission engine. If it has hat...then that is the engine that was used with a 4 speed.

Did you remove the block drains when you did your flushing out of the cooling system??? IF NOT...your engine still had crap in it due to the lowest point in the engine block has not allowed this crap to be drained out. Simply draining the radiator is not getting all of this crap out.

DUB

 

you squeeze the lower hose and it felt crunchy after squeezing it a little now it feels like I'm normal hose you just there's a spring inside that hose to stop suction from collapsing it. It rusted out and you just crushed it and now it's sucking all those pieces of spring into the cooling system. Replace the lower hose.

 

 

Good news, it looks like it is a ZDC car, and the stamp matches the VIN! I guess the issue is that the EGR solenoid is impossible to replace with the right part, and someone grabbed one off of an automatic and rerouted the vacuum lines. Anyone know where to get the right EGR Solenoid?


As far as the coolant....it is finally running clear, but unfortunately, I think the water pump is weeping now because the belt was slinging water. Had to clean everything like crazy because I had CLR in there and I didn't want to leave acid anywhere. How much work is a water pump replacement?

 

Water pumps are not that bad of a job to do. Make sure you pay VERY CAREFUL attention to the casting so you do not snap the aluminum bracket on the right side of it for the snog pump.

Did you drain the block by removing the block drains when you flushed the cooling system???

DUB

 

That is good news. A 1981 4-speed car is very rare. And a California one at that.

Unfortunately, that means you have your work cut out for you to replace that EGR solenoid. I take it that you need to get the car back together to pass the California emissions test? I wish I could help. Does the state need a 1981 manual C3 EGR valve to pass, or just an EGR valve, period? I can't imagine there are more than a few hundred of those still on this planet, and most of those are probably installed in other cars in California.

Two sites I've found to help cross-reference not-too-obscure parts are the AC Delco site, and RockAuto:
https://parts-catalog.acdelco.com/ca...log_search.php
https://www.rockauto.com/en/catalog/...egr+valve,4968

I didn't see an EGR solenoid, but RockAuto does have the correct EGR valve, if that helps. Can you use a temperature controlled vacuum switch instead?

Best of luck to you!

 

I didn't, but I haven't filled it back up with 50/50 yet so I am more than willing to do that. What general area are the plugs in? I'll take a look int the morning and see what else I can get out!

 

Thanks for all of your help, I'm new to C3's so its great to have some input. Fortunately, I don't need the egr to pass, I just was hoping to button it back up like it was originally done. I'm guessing I'll have to figure something out using what I have.

 

The block drains are located in the center of the engine block on each side. JUST above where the oil pan attaches to the block. They may be hidden by the spark plug wire shields if they are still installed. They will take 9/16" SIX POINT socket to get out and may be a bit tight to get out. DO NOT USE a 12 point socket.

Do not be surprised that when you remove them nothing comes out and you will need to take an ice pick or sharp tool to poke through the crap that collected at the bottom of the block.

I use my air impact and barely squeeze the trigger so I can shock the plug to aid it in freeing itself. Then I will slowly increase on how much I squeeze the trigger and watch the socket to see if it starts to remove the plug. If it does not come free.. I switch to my long breaker bar and use it so I can get a feel of it and YES...it can take a bit of effort to get it to come free due to probably no one has ever removed them

In some RARE cases I heat up the block around the plug with my torch to warm it up and then try it.

So far...I have never had not one of these plugs not be able to come out. And even though many people never want to touch them or remove them What I have seen that comes out of the block would amaze you. where it takes numerous filling and draining's. Putting the plugs back in hand tight...filling the block back up and draining it over and over to get all of the crap out.

DUB