I just finished installing my rebuilt 302. Everything has been replaced. I'm trying to break the cam in by running at 2000rpm for 20 minutes but it starts to overheat too quickly. I just installed a new 2 row radiator, thermostat, hoses, water pump. Its got me stumped? I know I installed the head gaskets right, they were stamped with "front" on the top side. Any ideas?

 

It's not unheard of for a brand new thermostat to stick. Try putting it in a pan of water on the stove with a cooking thermometer and see if it opens and at the proper temp. Try putting an old known good t-stat in the engine.

Did you get the correct water pump and not one that's made to rotate the reverse direction of what you're supposed to have? No other blockages that could impede the coolant flow?

 

I did a little research after I posted this. I know the pump is working, with the cap off and the truck running I am getting good flow from the throttle body return line. Also with the cap off and the engine running, it will start to over flow the radiator after about 1 minute, not because its hot yet, its like its backing up some where and the pump keeps pushing it out of the radiator and then I have to put the cap back on.

When I installed my 2 row radiator my fan shroud will not fit now. I had a single row before and it was always overheating when the A/C was on. But even with the shroud off, it shouldn't overheat within 2 minutes running at 2000 rpm's should it? I let it get as far as the A "NORMAL" and I shut her down again, the hoses were rock hard and gurgling like crazy. I really don't want to risk damaging this motor, I have over $2500 into the rebuild.

Is this going to screw up my cam, breaking it in by only running it at 2000 rpm at 2 minute intervals?

If it is the thermostat, what a PITA to have to take it back out. Its not like FORD put it in an easily accessible location to begin with.

Are there any difinative signs that you have installed your head gaskets upside down?

 

Your Cam should be fine as long as you maintain the 2000 rpm during the break-in period. The 2000 rpm is required to maintain proper lubrication during the initial break-in of the cam, since the cam is lubricated indirectly by the oil flying off the rotating assembly.

One note about head gasket installation that I noticed when rebuilding my 302, was that the head gaskets are identical and like you stated earlier they are marked to indicate the front. On one side of the engine the gasket is facing up with the word "front" showing and on the other side you end up having to flip the gasket upside down in order to maintain the "front" orientation. The top and bottom of these head gaskets look different and I could see how someone might end up installing them both with the top side facing up and end up with the wrong gasket orientation on one side.

 

cracked head or bad head gasket.

 

Cracked head would mean anti-freeze in the oil or steam coming out the exhaust right? Correct me if I am wrong.

 

Ok, went into the shop this morning and decided to cut down the fan shroud so it will fit. Worked out great!
Did some more research.... After sitting all night, started it up (with fan shroud in place) ran it at 2000 rpms, it took 4 minutes for it to reach the M in "NORMAL" on the gage, shut her down and checked the hoses.
Top hose hard as a rock, but COLD! Radiator is cold, Bottome hose rock hard and warm but not hot. No gurgling noises.
Thermostat????

 

Update: Took the thermostat out, bought a new one and dropped both of them in a pan of water. Just as the water was starting to come to a boil, both stats started opening??? So now i'm really confused, so I hook the housing and hoses back up without the stat. Started it up and it was running fine for about a minute, then I heard this clanking noise in the front of the motor. I checked it out, it sounds like something is clanking around in the water pump housing???

So now I'm thinking there was something clogging the water passage inside the pump and now its broke loose and rattling around inside my waterpump. So I'm back in the shop to do yet another tear down in the front of this beast.
What in the world could be rattling around in there? Sounds like a bolt!

 

sounds just like a cracked head or bad head gasket....That sound you are hearing is the water pump cavitating with exhuast.....

You can also rig up an air connection to the spark plug hole and send 100 pounds of air in it. Then turn it over with the radiator cap off, when that cylinder comes up on compression stroke with a bad gasket or a crack in the combustion chamber it will empty the radiator so be careful you can get wet…..do every cylinder…

 

The sound I heard was rythmic and increased with the rpm's. At first I thought I threw a bearing or something, so I disconnected the serpetine belt and started it back up to rule out the water pump and the all the accessories. Sound was gone and ran smoothly, shut her down and hooked the belt back up and the noise was right there again. So I started accelerating up and down trying to figure out exactly what it was, but then it just disappeared and it was quiet again. The temp gauge never got past the "O" in NORMAL so I decided to shut her down and see what the hell was clanking around in the pump housing. I got the pump off and split the pump apart from the cover plate to find nothing. Thinking maybe it got knocked into the block cavity.


Don't have a way to fill the cylinder with 100psi of air. Is there any other test that can be done before I break down and decide to pull these freaking heads back off. What a pain that will be.
Oil is good, no water
Exhaust is clear and has no odors
No smell of exhaust in the coolant.

I think I'm gonna just put this new thermostat in and see what happens, if it overheats again I guess I'm back to square one on this rebuild.

 

If you have a cooling system pressure tester put it on and see if it looses pressure, it will most likely drop fast, if so keep it under constant pressure for a few minutes then pull the plugs and spin it over.........look for water in one or two of the spark plug holes but you have to get enough in the cylinder for it to work so keep the cooling system under constant pressure for as long as you can.

If it holds pressure (25lbs) that does not mean it's not a bad head gasket or a crack in the head it just means 25 pound is not enough pressure for it to leak into the cylinder. But when it fires it's got plenty of pressure to blow hot thin gasses into the cooling system, hot gasses are a lot thinner then coolant.

They also make a tester that snifs the air at the radiator cap, I got one used it once and never used it again. the air pressure test is a sure tool to check for this type of problem.

Good luck

 

Thanks for the tip! I will give it a shot in the morning and let you know what I find.

Thanks for your help

 

As stated before, are you sure that your head gaskets are installed correctly with the FRONT stamp pointed to the front of the engine??

 

Well, this is not my first 302 I have rebuilt, but it is my first efi rebuild. I know to put the head gaskets marked front towards the front of the engine and I remember paying close attention to that fact. But I wouldn't bet the farm on it, hell were all human and have brain farts (especially when your in your fortys)

Thats why I was asking if there is any way to test the engine to see if the gaskets were backwards or not. I was looking at the old engine that I pulled out of this beast and noting the water flow as it works it way thru the engine. It appears that the water flows from the intake down into the front of the head but the head gaskets block the water from going down into the block which forces it to flow across the head and then dumps down into the block at the back of the head and then back to the water pump. Even if you did put the head gasket on backwards it will still flow through the intake except it would dump into the head at the front and then dump right into the block. But the head would still fill with water, it just wouldn't be able to flow across the head affectively, so the rear of the head would be hotter than the front which could cause the heads to warp if the motor was running hot. But it shouldn't really cause an overheating situation should it?

 

if the system is building pressure (hard hoses) with in the first few minutes of running it's not over heating. it's being pressurized by combustion......

putting the gaskets on backwards will still seal the chambers and wont cause hard hoses or coolant pushing out the radiator.

you can look at the block where the head gasket is and there is a tab on the gasket that sticks out, the tabs should be up front on both sides.......







I had the same problem you are having and it drove me nuts...I did the 100 psi test and found one hole that just about emptied the radiator. I took the heads off and found a crack in the chamber.