overheating issues - 79 k10

[tommartin]

Ok guys I need some help here.

I just put a 350 in my truck and its running hot. I tried to use all original parts, so it does not have any performance parts on it.

After running for about 5 or 10 minutes the temp light comes on, and it will over heat if I’m driving it, so I don’t think it’s just them the temp sensor.

Here is what it has:

New thermostat
New water pump
New upper and lower radiator hoses
New heater hoses
New radiator
New radiator cap

The fan is running and seems to be moving air rather well
I do have my shroud on
Exhaust seems to be flowing fine, no blockage, after they Y pipe it has a muffler bolted up.

Oil seems clear of any coolant
It’s been block tested

One thing I did notice that my exhaust manifold on the passenger side that has the EFE valve on it got hot enough to glow, I did check to make sure the EFE valve is open also.

Outside of what I mentioned what else would be good to check?

Maybe I just need some electric fans?

Thanks for any help.

Here are some pictures:

[INSIDIOUS '86]

If your running hard enough to make BOTH manifolds glow then that's not an issue. But just one side means there is an issue

Check to make sure that side has valves lashed right, check fuel mixture , what's your timing set at? An exhaust manifold glowing tells you that it's the engine not running right not the cooling system necessarily
Posted via Mobile Device

[tommartin]

thanks, that information helps out, i was thinking it was the cooling system. Do you think its too rich or too lean on the side that has the glowing manifold? Or is it just where i need to kind of adjust and see what happens?

[INSIDIOUS '86]

A lean mix burns hotter and so does to much advance on the timing but if it was a timing issue it would be both sides not one.

Make sure the exhaust valves aren't stuck open.
Posted via Mobile Device

[tommartin]

thanks again for the info, i'll have to check it out this evening. Hopefully its just running too lean.

by the way, what should vacuum read if i put a gauge on it?

[gchemist]

Vaccuum above 16 Hg is good. What is the out side air temp? If it's hot like here, 100+ degrees, engine will run hotter at slow speeds cause air is not helping cool enough.
Since you live in a warm climate, you can change the thermostat to a lower temp. I ran 180 in the summer and 190-195 in winter. I did this until I install a ZZ4 with aluminum heads. Aluminum heads like heat. I have to keep temps as close to 195 as possible for optimum performance and efficiency.
You didn't mention changing the fan clutch. Consider a higher flow water pump like Stewart water pumps.

Definately check your air mixture settings. Use a vacuum gauge to tune the carb.

[russgt]

Do you have any more info on the 350 that you just put in?

[Fixwhataintbroke]

What brand, actually more like what part store did you acquire the thermostat at?

[tommartin]

Originally Posted by russgt

Do you have any more info on the 350 that you just put in?

compression test was good
block test was good
under the vavle covers was nice and clean

other then that, no. I bought it for $160 from a guy with a c10. He said he bought the c10 with the motor and it was running but swapped it after for a built motor.

[tommartin]

Originally Posted by Fixwhataintbroke

What brand, actually more like what part store did you acquire the thermostat at?

Autozone thermostat.

I plulled it out, just to see if it would get hot without it, and it still got hot...

[Fixwhataintbroke]

Coolant mixture percentage (50/50, 70/30 etc)???... rent a radiator and cap pressure test kit and see if they both hold pressure, i'd inspect the intake manifold for blockage, same with the heads.

[Sodell]

Simple thing to check, but make sure the lower radiator hose has the spring in it....

[INSIDIOUS '86]

Most importantly vacuum should be steady unless you have a rumpety cam. If you can do a leak down test on the hot side of the engine.

What's the color of the plugs?
Posted via Mobile Device

[78trk]

There is a fluid that automotive shops or radiator shops use to test for combustion gases in the radiator. It is blue and will turn yellow if there is a problem. This simple test will let you know if you have a head problem.

[tommartin]

Originally Posted by 78trk

There is a fluid that automotive shops or radiator shops use to test for combustion gases in the radiator. It is blue and will turn yellow if there is a problem. This simple test will let you know if you have a head problem.

So I tested it and it looks to be good. No color change in the liquid. I got a new radiator cap, and it still getting hot.

[tommartin]

Originally Posted by INSIDIOUS '86

A lean mix burns hotter and so does to much advance on the timing but if it was a timing issue it would be both sides not one.

Make sure the exhaust valves aren't stuck open.
Posted via Mobile Device

It still running hot, and I did notice it was both sides of the exhaust manifolds that were glowing.

the timing is set to 8 degrees

im going to get a new carb, mine is shot, hopefully this will help out.

[78trk]

If the carb is plugged up it will make the exhaust glow. If the engine is not running right your have to fix that 1st. The fan clutch may look like it is working but it can slip enough that the engine will slowly overheat. I use a flex fan with no clutch because of the problems fan clutches have.

[Dead Parrot]

Is the Y pipe OEM? My 75 OEM Y was double wall. The inner wall collapsed on one side while I was in college and my dad owned the truck. This forced one side of the exhaust to go through the manifold crossover. Lots of backpressure plus overheating the carb. The heat warped carb then ran very rich.

Currently have ceramic coated headers, 3 row radiator, 195 thermostat and no overheat problems. Have towed a boat + 800lbs of crap in bed, running the AC, in 100+ temps. Using stock fan with fan clutch.

[tommartin]

At one point i was thinking my muffler was too restrictive... but it seemed like the exhaust was flowing ok.

I do have the stock Y pipe also.

I suppose the best way to check it is to pull it off and have a look?

[Blackpony]

are you sure there is not an air bubble in the engine? does the water pump seem to be moving coolant through the radiator core pretty good?

[tucsonjwt]

x2 on air bubble theory. I think you run the engine with the cap off to allow air to escape. Some run a garden hose through it with engine running.

[nheller76]

I was thinking the same thing. It my be vapor locking on u.
Posted via Mobile Device

[Dobok]

Maybe its a spun bearing !!!!

[tommartin]

the truck sounds good when it is running, and seems to idel fine.

I did run a hose in the radiator, but as soon as i closed it back up, it started to get warm again...

[wilkin250r]

Ignition timing can be a funny thing. Too much advance can cause heat buildup, but it's usually a slow buildup and doesn't result in glowing exhaust pipes. Retarded timing, if severe, can cause glowing exhaust pipes because the spark is so late that the fuel is still burning as it exits the combustion chamber into the exhaust. Retarded timing can also cause overheating (I know, odd that both advanced and retarded timing can cause overheating) because as the burning exhaust exits the combustion chamber, it passes a lot of heat into the cylinder heat.

A lean fuel/air mixture will cause overheating and glowing exhaust pipes.

And keep in mind, you might actually have SEVERAL issues. You might have a lean mixture AND a water flow problem, and they both manifest as an overheating issue.

My advice would be to deal with the glowing exhaust first, and check all possibilities there. That's still a problem even if your cooling system was working perfectly fine.