Engine Overheating with Vortec Heads

[REDDIEDAD]

I just rebuilt a generation one 350 and used a set of 1996 Vortec heads. I am having problems with it over heating. I have good flow of coolant in the radiator and I have tried cooler thremostats. There is no compression in the radiator. I used the head gaskets for the gen one engine. Should I have used different? I am grasping at straws and any advice would be appreciated. The engine is running up to 230 w/a temp gun. I am using a 4 core radiator with shroud and the correct temp sensor. The temp gauge in the car is showing above 220.

[clinebarger]

Is this idling? cruising? towing? high speeds? all the time? Gen 1 gaskets are fine. Were is the sender located?

[cdowns]

i'd take a known good thermomoter and take the temperature of the coolant
you can get good cheap termometers in the grocery store

[Captainfab]

Have you set your timing correctly? That can affect the engine temp.

[vasquezmrysvll]

your vortec specific intake should have a coolant passage with a pipe plug in the front of the intake.you may need to connect that coolant passage to the port on your water pump, directly above the water pumps suction spout. water pump may be cavitating?

[Hottrucks]

intake leak??? stock intakes dont work...also if the heads where machined ( or block) the angle where they meet may be off enough to cause it...

[REDDIEDAD]

Thanks for all the help. I found that the intake gaskets were leaking. I used the ones out of the overhaul kit. I replaced them with Fel Pro #1206 they are a little thicker and made of a different material. The engine runs about 170 now.

[Hottrucks]

yea we all learn that lesson

gaskets are no place to be cheap

[Captainfab]

I'm surprised that those even work with Vortec heads. Those are listed for 1995 and earlier heads. You must have had to modify them for use with the Vortec heads, unless yours have both the Vortec bolt pattern and the '85 and earlier bolt pattern.

A couple of the common intake gaskets for the Vortec heads are the Fle Pro 1255's and the MS98000T set

Originally Posted by REDDIEDAD

Thanks for all the help. I found that the intake gaskets were leaking. I used the ones out of the overhaul kit. I replaced them with Fel Pro #1206 they are a little thicker and made of a different material. The engine runs about 170 now.

[Gregski]

Originally Posted by Captainfab

I'm surprised that those even work with Vortec heads. Those are listed for 1995 and earlier heads. You must have had to modify them for use with the Vortec heads, unless yours have both the Vortec bolt pattern and the '85 and earlier bolt pattern.

A couple of the common intake gaskets for the Vortec heads are the Fle Pro 1255's and the MS98000T set

glad I found this thread, it's six years later almost to the day, apologies for resurecting it but I am so in the same boat, however I am running what I think are the proper intake manifold gaskets the Felpro 1255s and my '74 truck with '99 Suburban Vortec heads is running hot

you can dive right into my thread where I talk about the problem here Restoring Rusty I would really appreciate your help

[LeesTruk]

Hey Gregski. Funny talking to you in this section, but....
This is a long shot. Do you still have any of the cracked Vortex's around and possibly an old "take-off" head gasket? If yes, lay that gasket on a head and see if it covers any coolant passages. Just a thought....
Also, I think you said you painted your radiator, right? What kind of paint did you use? That could possibly be insulating the cooling fins instead of allowing them to radiate the heat properly. Again, just a thought...

[LeesTruk]

Another thing you might want to consider is going to a five or seven blade fan, to pull more air through the radiator

[Gregski]

Originally Posted by LeesTruk

Do you still have any of the cracked Vortex's around and possibly an old "take-off" head gasket? If yes, lay that gasket on a head and see if it covers any coolant passages. Just a thought....

No, I wish, like an idiot I returned them for a measly $5.00 dollar core refund, I had the same thought, as when building the engine we paused and hesitated when putting on the head gaskets, you know did the which side goes up which side goes down type a thing, and I am almost certain that yes indeed they covered up some coolant passages or at least took 1/2 inch openings and reduced them to 1/8th of an inch, but it was a part number 10105117 off of the Chevrolet Performance specification sheet so I thought heck it has to be right, they have to be the right gaskets for the application

now my money is on a gasket problem

[Gregski]

Originally Posted by LeesTruk

...I think you said you painted your radiator, right? What kind of paint did you use? That could possibly be insulating the cooling fins instead of allowing them to radiate the heat properly...

I deliberately did not paint the fins. I only painted the sides. I took the paint off the brass sides down to bare metal and applied too light coats only, no primer, I kept it light just for that reason, to freshen it up but to let it run cool.

[Gregski]

these are the cylinder head gaskets I am using part number 10105117, man I even remember asking questions about these reduced water passages on my other thread

[Gregski]

here's a Vortec head as I pulled it off of the donor 1999 Suburban, sure as snot it has the restrictive gasket still on it

[storm9c1]

Those "restrictions" are normal and likely not contributing to your overheating issue. The coolant needs to be slowed down as it circulates to keep the flow even amongst all 8, and give it some chance to absorb heat as it surrounds the cylinders. If the passages are too big, too much water volume will favor the first hole it finds and not circulate evenly. Under no circumstances should you enlarge them!

I have run Vortec heads on several applications, including on my C30 which is a 383 and it does heavy hauling. I do not over heat and I didn't do ANY of the weird stuff everyone is talking about on your other thread.

All I have is a working heater core that constantly flows, I run a 180 degree thermostat with a 1/8" hole (I do this on ALL thermostats on all of my engines to bleed air bubbles), a 4-core stock (replacement) radiator from a local parts store, and a 7-blade mechanical fan + severe duty clutch + shroud. I run 12-14 degrees of base timing (can't remember where it finally settled down exactly). I run a Holley Street Avenger 670 on a Weiand intake. My C30 never overheats.

Your other thread is huge, so we need to know more about your engine setup and WHEN you overheat. Does it happen on residential streets, the highway, stop and go, or just at idle? This will help narrow down the potential culprits. For example, I'm wondering if your carb is lean.

[kray59]

i never had a overheating problem created by wrong gasket ( just luck i guess ) but i will remember this thread for sure . thanks , lots of good info . learn new thing on this site often

[bjhbowtie]

Did you ever get this problem figured out?
I had this issue & fought it for about 6 years. After 2 sets of heads, 3 different sets of head gaskets & intake gaskets, 2 water pumps, 2 different radiators, stock fan, electric fans, flex fan, 3 pulley changes, multiple thermostat changes & adding plumbing from a water neck under the thermostat to the rear of the intake, I gave up and put my 454 in my truck with no overheating problems now & using the same radiator & flex fan setup.
What helped the most for mine was the largest pulley I could find in my parts stock on the water pump & two 1/2" water lines bypassing the thermostat from a jegs water neck/bock under thermostat, running to the rear of the intake. While this did not totally fix the issue, I was able to use my truck to pull & haul. I still had to be careful on hot days.