I just finished my VA install and have some engine temp issues. Before the install, I had a ball valve I installed in the heater hose from the intake to help reduce cabin temp. When I would close it, eliminating flow, my engine temp was higher. Normally it ran around 180 with the valve open and around 215 with it closed.

With the VA installed, my temp is around 210 when the VA system is off. If I turn on the heat, the team stays about the same or may decrease 5 degrees. When I turn on the a/c, the temp immediately starts to climb to at least 250. As soon as I turn on the heat, it immediately starts to come by down.

Why is this happening? We ran the a/c to charge the system with the engine running and the temp never climbed above 200. I’m so confused.

thanks
Keith

 

Just in a short, it sounds like you need more air flow through the radiator

 

It sounds like you need more flow via that heater flowpath. You can buy a diverter valve that will isolate your heater but still allow recirc flow. Or buy manual valves and make your own. It is easy enough to do and you'll find out quickly if the problem is related to that.
Here you go. For 30 bucks you can find out if it is something along those lines.

 

Time for a new radiator perhaps (and an electric fan assembly that comes on with the AC)?

When is it overheating? At idle in your driveway, or while cruising down the road at 45mph?

What is your timing set to?

 

Sounds unusual to me as well. If routing coolant through the heater core is making a difference in engine temps it certainly doesn't sound like your air-con is to blame.
Is your condenser totally blocking air flow??? If so, How?
Is your radiator just not up to the task?
Air pockets in your cooling system?
Loss of pressure in your cooling system?
(loose clamps).
Ign. Timing specs way out?
Insufficient fan/fans?

 

You state that even before the Air-con. If you closed off coolant to the heater core your temps would rise.
This just shouldn't happen!
You definitely need to find the issue and fix it. But it's not the Air-con. Perhaps the Air-con really brought the problem up. And up. But it's not the cause.
How big is your rad?
How new is your rad?
How well is it sealed to make certain ALL air goes through the rad?
do you run a front spoiler? How about a spoiler extension?
Fan or fans??? What are you running?
And THE biggest thing with running hot! Your ignition timing specs!
And details of your engine so others can advise if your specs look close to what will work.
Believe it or not, a bone stock low compression L48 Will require different timing specs than an engine at 10-1 compression and a fair whack of cam!

 

The heater core is not going to cool down a 210 degree engine to 180 degrees.......the fact that is goes to 180 when the old heater valve was open tells me your thermostat is or is partially blocked.......and you basically are bypassing most of the coolant through the heater core........

Jebby

 

Thanks, everyone, for the responses and questions. I'll elaborate with details I omitted.

The car is a '72 coupe with the original motor that is now a 383. It has aluminum heads, a little bit of a larger cam and less than 5K miles. So a mild 383. Thermostat and Water Pump are new. Almost everything under the hood is new, except the radiator. The body is stock, including all spoilers etc.

The thermostat was replace with a 160 when the engine was build. I believe my timing is off, which will create some heat issues. The radiator was removed, flushed and painted when the engine was out. I didn't see any issues with it, at least to my untrained eye.

Important note: After I installed the VA, and before I had charged the system, Ieft the binary switch unplugged and had the heater control valve improperly grounded. So when I turned on the heater, the switch was not working and no water was flowing though the heater core. Once I discovered my ground issue, I drove the car for the first time to my buddies house to charge the system and the heater was now working. During my drive, I notice the temp was almost at 250, so I immediately turned on the heater to try and correct it. This worked, so I assumed I might have had an air bubble or something. So the problem was happening before the system was charged but I did not notice it happening during my first test drive when my heater valve was not grounded and operating properly.

Before Vintage Air install
The car was an AC car that still had all the components installed. I installed a manual ball valve in the heater hose from the intake to help cabin heat. The car would run around 180 degrees with the valve open and around 210 closed. I drove the car for about 2K miles with no overheating issues.

After Vintage Air install
The hood is currently off the car. The VA condenser is smaller than the stock condenser, so I wouldn't think air flow to the radiator decreased any. I drove the car on the interstate at 75mph for 40 miles (one way) to get to a buddies house who could charge the ac system. We let the car sit and idle for 15 mins to check the system and the temp never climbed above 190. Driving it home (40 miles on the interstate at 75 mph) and the temp held consistent at 210 until I turned on the AC. Within 5 seconds of turning on the AC, the temp starts to climb. Within 10-15 seconds the temp is at 250. As soon as I turn on the heater, the temp drops back to 210.

Hopefully all of this detail helps. I really appreciate everyone's help.

 

The hood is off the car? That will severely limit the flow of air through your radiator. Lead with that info next time.

210 to 250 in 10-15 seconds from switching the AC on? I'd first suspect that the AC wiring is changing the reading of your temp sensor. Pick up an IR temp gun and confirm what you are seeing. The other possibility is that @Jebbysan is exactly correct, and you thermostat is stuck closed, and all or much cooling is happening in your heater core.

I'd also swap out that thermostat for a 180 high-flow thermostat with a tiny bypass hole drilled in it, but please confirm your temp readings, and post some photos, first.

 

@Bikespace Thanks. Learn something new everyday. I would have led with the hood being off if I would have known.

But again, air flow seems to be fine keeping the engine cool until I turn on the a/c. Engine is running a little warmer (210 instead of 180) with the hood off. So I can see where that air flow change is warming it up.

Also, I just thought about the intake not being stock. It's a edelbrock performer intake, if that matters. Not sure if it requires flow from the intake to water pump or not.

Keith

 

Intake will have nothing to do with it.......replace your thermostat.

Jebby

 

Jeb,

Before replacing, is there a way to test? Since I replaced it less than 3K miles ago, I would be surprised if it was bad. Could I just remove it to see if it overheats? Just checking, as I seem to constantly be through money at the car to solve a problem and just want to make sure before doing it again, even if it's not much money.

Thank you,
Keith

 

Just remove it for this test. You'll know promptly. Won't hurt nuffin'

 

And while it's out, see if it opens in boiling water (don't touch it to the bottom of the pan).

Another use of an IR temp gun! Pick one of those up, too. And perhaps a camera...

 

Bikespace and Jebby are correct, your issue is elsewhere, was there prior to VA install and it makes perfect sense in your situation.
The valve in the heater hose in the VA system only closes when AC is on, per the folks at VA.
If your t stat or rad is malfunctioning, your heater core is supplementing cooling and keeping it reasonable. As soon as you switch on A/C, heater valve closes and you are no longer getting that cooling boost from the heater core, and temp jumps up.
I put VA in my ‘71 350 that originally had factory air (inop), and saw absolutely zero change in the coolant temp behavior.

 

OK, all of this makes perfect sense. One other thing I think I'll check is the lower radiator hose, to make sure it's not collapsing.

Thank you all for your help. It may be a week or so before I can get back behind it, but I will respond with the results and hopefully the cause/solution to help the next person dealing with this issue.

Keith

 

Yes.....just remove it........
You see...I have seen this before.......what happens is the thermostat only opens part way or gets stuck in a partially open state......and when it will not flow enough, your heater plumbing becomes the bypass for the whole system......out through the top of the manifold and in on the side of the pump.......it is the only thing that can explain the behavior, unless something else up there is blocked......

Jebby

 

Ok, I’ll start there and pray nothing else up there is blocked.

thanks
Keith

 

Be sure to check your vacuum lines as they can rot easily and cause the advance to not kick in which would make the engine run warmer.
I had the problem pop up on my C3 and it was the vacuum hose had leaks in it.

We replaced all the hoses just to be sure my vacuum system on my 1968 still works as it should. On a 1968 C3 the vacuum tubing system uses a lot of pre-cut parts.

 

***UPDATE***

I pulled the thermostat but had issues getting the housing to seal without it in. Ultimately I decided to just go ahead and install a new thermostat, since I was back at the parts store for another gasket. I replaced the 195 with a 180 (I know that may start a debate, but I thought keeping the temp down a little isn't going to hurt) and went for a drive. The hood is still off and I only drove on a backroad where I could only keep a constant speed of around 60 mph for about 5 miles, as opposed the the previous conditions where I was on the interstate at 70 mph for 25 miles.

The temp stays on 180 degrees until I move the temp controls to "cool" and close the valve. At that point, the temp is climbing, but only to 220 degrees now. It is also climbing much slower. Where it was climbing in about 10 seconds, now it takes over a minute.

I also adjusted my timing, as I am having some Dieseling issues. I believe this was part of the reason I was running around 210 with a 195 thermostat.

So not ideal, but better. At this point I have to suspect my radiator is not flowing as well as it should. Before going any further with it, I want to get the hood installed to see if/how that impacts it. Maybe it will provide better airflow and drop the temp down closer to 200 degrees, where I would be more comfortable. I have a couple small adjustments to make before putting the hood on, so it may be a couple weeks before I can provide another update.

Another thought and detail: I only running water in the radiator at the moment; not antifreeze. I had an issue with the radiator neck that I had to have braised, which was causing it to leak previously. Now it is air tight and I need to put antifreeze in. I'm not sure if that will help drop the temp any or not.

Thanks again, everyone, for your help,
Keith