Exhaust manifolds are RED HOT and 2k idle!

I just finished putting my engine together after changing the head gaskets.

I started it up and it runs good no check engine lights, but it had a vac leak and would barely stay running. So I fixed the vac leak at the tubes and top, it runs now but only about 10" of vac. I still have a vac leak somewhere because I can hear it whistling.

The first problem is the car wants to idle at 2000 rpm. I just pulled off the TPS and inspected it, reinstalled it, and it makes no difference. I even unplug it and the car idles higher. Maybe this sensor is bad? What would cause a car to idle at 2000 rpm? The throttle cable is adjusted fine.

Second problem the car gets hot after only a few minutes of running. I looked and the exhaust manifolds are glowing red hot both sides of the engine, and the resonator was damn near glowing. The cats are off this car but it still has the factory resonator and mufflers. There is air blowing out of the tail pipes so I know its not plugged. Also it's not blowing any smoke of any kind thank god. I want to get it to run cooler before it pops the head gaskets again. I have a 160 degree t-stat in it but I'm going to take it out since I think it might be sticking. I also am going to replace the radiator cap even though this one is brand new 16 lbs pressure release.

Also when I rev it up its smooth until it goes into boost. The plugs and wires are new and I just traced them back to make sure they aren't crossed at the coil.

That motor is running lean because of a big vac leak. Once you get the vac leaks fixed and if it still idles that high check the AIC on the throttle body. Hard to give anymore info till you get all vac leaks stopped.

Ok the IAC is fine, I cleaned it while I had the motor apart. I think the vac leak is coming from behind the blower, I'll have to take it back apart and check.

Now this pisses me off. I pulled out the T-Stat and am running w/o it right now, within 2 minutes of running the temp gauge goes past red and the manifolds are glowing, we shut the car off.

I might also bypass the heater core when I pull the blower off incase its clogged. Any suggestions as to why the car runs so damn hot? I'll pull the plugs later or tomorrow when it cools down to double check and make sure I'm not dealing with leaking head gaskets but I torqued them down spec according to the FORD shop manual.

check for coolant flow , maybe the radiator needs rodded?

it might be your timing is off

It sounds like the whole source of your problems is not due to the cooling system, but rather due to a large vacuum leak. That would account for the engine idling high, running hot, and extremely high exhaust temps. The vacuum leak is allowing a lot of unmetered air into the engine, which is causing it to run extremely lean (and extremely hot) with a high idle. Fix the vacuum leak, and I'll bet your problems disappear.

-Rod

I'm with Rod on this one. Better find those leaks fast and dont run that engine till the manifolds are glowing or you are gonna need another set of headgaskets and possably a set of heads as well.

Ok, I checked all the IC connections, and vac lines and nothing is leaking. It might be leaking where the return adaptor connects to the intake manifold. Also when we put the intake manifold on we used permatex blue gasket maker instead of the cork end pieces. I don't know for sure if it would leak there or not but its possible. I just really don't want to tear this engine down again.

I didn't know a vac leak would make it run that hot.

Sure it can! Lean mixtures=more heat. Extremely lean mixtures=MELTDOWN. Have you shot propane around ALL joints in the intake system. Are you sure that NO vac hoses are disconnected? If your manifolds are that hot imagine what the poor exhaust valves are going through.
Its gonna be a big leak or a group of smaller ones at once to make your engine idle up that high and get that hot so quick.
Be carefull or your gonna scrap that engine.
How did you check for leaks?

I just did a visual inspection of all the vacuum hoses to make sure they weren't cracked. I also don't hear the hissing coming from any of the hose connections but I can hear it along the back side of the engine which is why I'm thinking its something to do with the rear of the intake manifold or the supercharger where the plenums connect. But I remember tightening everything down and using all the gaskets that came in the set.

Also I numbered all my vac hoses and they all went back to the right numbered connection.

Well if youre 100% sure none of the intake system(meaning every joint between the intake valves all the way through the system back to the throttlebody) is leaking, then yes the manifold ends could be a possability.
Shoot some propane back there and see if it affect the idle speed.

I'm 95% sure the intake system is sealed up. I'll try getting a miniature propane tank tomorrow and try it before the engine gets hot. I swear within about 4 minutes the manifolds are glowing.

I might just take the supercharger off the car again tomorrow and check to see if its all sealed up good. I hope its just this and that the block or heater core isn't plugged. My next try was going to be bypassing the heater core. But that wouldn't take care of my high idle. I know its a leak somewhere cuz I can hear it whistling quite loud.

Dont make extra work for yourself right now by removing anything. Just get the propane and test every joint in the system, you'll find it.
Since it heats up so quick only do as many joints as you test in about 60 seconds.Shut down the engine and let things cool down,then start it back up and test some more. DO NOT get the manifolds glowing again. DO NOT spray propane with the manifolds glowing either.
Once you find the leak then you will know what to take off to fix it.
Dont complicate things by removing and reinstalling parts until you check for the leak.

MIKE 38sc said:

Dont make extra work for yourself right now by removing anything. Just get the propane and test every joint in the system, you'll find it.

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Exactly. Like I said earlier, I really think that the vacuum leak is the source of your problems. It can definitely cause all of those symptoms.

As far as your cooling system is concerned, a 160 degree thermostat is probably a bit too cool. The radiator may have trouble cooling the coolant if the thermostat is constantly open.

But that's not your main problem, so don't mess with that yet! Fix the vacuum leak, then if the car is still running warmer than you like, start messing with the cooling system. The first thing I would recommend is installing an aftermarket gauge. The factory gauge really doesn't tell you anything at all (no actual temperature reading, since there aren't any numbers on the gauge). My splitport tbird overheated with the factory gauge at "N" of "NORMAL", which was evidently a little warmer than normal operating temps.

-Rod

I'm just hoping my head gaskets didn't get damaged by letting it get that hot. It's not smoking so I'll take that as a good sign. I hope these fel-pro gaskets are as good as they claim. I'd be pissed if I melted the fire rings in the gasket.

I am gonna pull the wiper cowl off so I can get down by the back of the blower w/ the propane. I'll let you guys know what I find.

What will it do when I find the leak? Rev up, or idle down?

Thats gonna depend on how bad the leak is, sounds like you got a bad one. Once you apply the propane to a joint if the idle goes up or down you have found 1 leak, but check everything you could have more than 1.

are you using stock heads and a stock manifold or hav eyou had porting work done at all...Maybe something was milled off...If it appears all your connections are sealed probperly it is possable teh lower intake isnt seating properly to intake ports...Definately soudsliek an intake leak..The silicone on the ends wouldnt be teh problem..What cam do you have??....Some regrids do give you around 10inches at idle

Damon, the cam is stock. I had the heads milled and ported and polished on the exhaust side only. The manifolds have been painted with 1200 degree Aluminum Silver paint but they are stock. The cats have been removed but the factory exhaust is still under there till I get it running right and to the exhaust shop.

The mods are: 190 lph fuel pump, 70mm MAF, K&N filter, a/s removed, vac caps on the SC crosstalk hose connections (not leaking there), and a trans-go shift kit, plus the ported heads.

I did bypass the throttle body coolant lines that early SC's have. From the metal coolant lines that run to and from the heater core there were two smaller connections that go into the throttle body. I took a piece of hose and connected them from one side of the engine to the other. So the throttle body now has no coolant flowing through it to heat it up. I don't know if it will help any or not, but now I can change the TB without having to figure this out later. I know some of the LT-1 guys talk about the throttle body bypass so I did it on my car.

Scott how much was removed when you got your heads milled?

Mike, the heads were only milled .005" since they weren't warped at all. The car had high mileage and the gaskets blew one night at the beginning of winter. The motor was real clean coming apart, no bolts broke, pistons looked good except for a little carbon build up which I removed.