Hello,

I had a 351 Windsor built for my 73 Bronco. I installed a BC Broncos serpentine system and bi-directional water pump. It is a ummer vehicle, so I have bypassed the heater. It also has an oversized aluminum radiator (designed to keep 850 horse big blocks ice cold) mated to a Mark 8 electric fan (some 5k cfm). Without a thermostat, it runs around 220. Edelbrock MPI fuel system recommends a 195 thermostat, after install, she cleared 250 and burnt my burrito. Thermostat opened whe heated on stove in pot of water. I can see flow in the radiator fill neck, and the system is not using the overflow. Any idea why it's so hot?
Thank you,
David

 

Is this a fresh install or a motor that has been running fine and suddenly now it's overheating? On a fresh rebuild you need to make sure all the air is out of the motor, it helps to have the front of the vehicle uphill a bit, and run it with the rad cap off untill the level stops dropping.
If the motor is running excessive lean it will also run hot, what A/F ratio is it currently producing?

 

The engine was just built, I had it running ok with a smaller radiator, but was warmer than it should have been. I have more idle time than miles on this engine. I re-fabricated the front end (the front clip is 2" tubing with no fenders or hood, used for rock crawling) to fit the larger radiator and had it running much cooler. I had the exhaust hooked up to the headers, and drove it home. Installed the thermostat and can't get it to calm down now, even without the thermostat. I am wondering, after reading some old threads on here, if I have the transmission module hooked up to the wrong vacuum. I worked on that about the same time, but the tranny doesn't seem to shift right (fluid is at proper level). What type of vacuum should bo hooked up to a C4 to make it shift properly? Edelbrock only gives me four ports on the MPI intake manifold, they told me run one to the tranny, and then from the tranny to the other manifold port. I dunno jack about vacuum, timing, or engines for that matter, it's a wonder I got the thing to run at all. As far as running lean, the on-board computer for the MPI gives me a green light for rich and a red light for lean. I get a green light every now and then, no red. I had to kick up the fuel on the computer just to get it to idle without surging. Maybe the vacuum and a little more fuel?
Thanks for your help,
David

 

Speaking of timing, what have to got it set at?

FYI.. it doesn't matter what vacuum port you connect to what, it all comes from the same place.

 

Base timing is at 10 btdc. The onboard computer says something about 32 degrees, which is what others have told me what it should be. I read somewhere in here, on another thread, about the wrong vacuum. I know that if I hooked up the wrong vacuum to the tranny, it ran like crap. The way I have it hooked up is the only way it would still run decent. Damn, I was hoping for something simple. Does bypassing the heater cause problems? I had a short hose just completing the circuit, then I tried a longer hose pretending it was going to a heater core and right back (again, wishfull thinking). I have the coldest plugs the parts store had. Could it be wrong intake gasket? Wrong head gasket? It didn't do this till a thermostat was installed and exhaust was connected to the headers. I'm getting scared of destroying a 10k engine. Thanks for your input and time,
David

 

Bypassing the the heater should not cause this problem. I did that for a while on my 74 bronco that I raced in the mud. I didn't loop it as you did, but put a large bolt into the 5/8 heater hose, so that the bolt fit real good, and then put on a hose clamp. How old is your temp gauge? How old is it? I would suggest checking again for an air bubble in the system. You can buy a funnel for that for probly $20-$25 or so. They attatch to the radiator like a cap, then the funnel attatch's to it. It makes the anti-freeze the high point in the system. Also might want to check into some "water wetter" that can help drop you coolant temps also. Just my .02

 

Sounds like you have trapped air in the motor or a head gasket problem, there's no way it should run more than 150 degrees or so with the thermostat removed. Are you getting any bubbles in the rad at idle?

 

So, is the funnel the only way to force the air pocket out? I'm not quite sure I know what you mean by bubbles. If I open the cap, I can see the fluid moving, but not really any bubbles. I will start using an additive, but I thhink my issues are more serious than that right now. After I get the main issue resolved, I will definitley check into that. Worst case scenario, head gasket problem, is the only way to find out by tearing the heads off? Thanks again,
David

 

i put a hundred dollars on the air in the motor problem put a new head gasket on and look into getting new plugs.

 

I guess I don't understand the air in the motor. How'd it get there? Did it destroy the head gasket and how? This engine probably has less than 30 hours run time, most of that at idle.

 

Well.. when the motor is first built it has nothing but air in the water passages, and it's common to get pockets of air trapped inside when the motor when it is filled with coolant. Usually these get circulated out pretty quickly, but not always, and if the motor was assembled with the wrong intake or head gaskets and a water passage is blocked then it'll never get out. You didn't mention but what year is this motor? Is it a newer block with older heads on it or vise versa? Anything else different or special about it?

 

First, Thank you so much for your help. I pulled the engine from a lifted 79 f-100 4x4 shortbed. We found later the truck was originally a V6, 2 wheel drive, step side. I have no idea where the engine originated. I am certain the heads matched the engine. It must have been a later model engine, it was equiped with the thermactor system (air ports in the back of the heads) and a fomoco aluminum intake and 2 bbl. Any idea what year this may be?

The machine shop threaded plugs into the air ports at the back of the heads. I had a very reputable shop do the work, they have been around forever. I just assumed they would have matched the gaskets to the heads and block (of course, assuming has never got me very far before). I have also questioned the intake gaskets, which I think were supplied from the shop as part of the rebuild kit.

What I had done to the engine-
Magnafluxed the block and heads to ensure they were buildable. Bored 30 over, flat top pistons, B&B, P&P heads, 1.6 full rollers, double timing chain, high volume oil pump, Milodon 7 qt. pan, Edelbrock MPI fuel system, complete MSD ignition, JBA shorty headers.

I don't know if this is right or not, the coolant seems to have a foggy consistency. There does not seem to be any coolant in the oil pan.

Thanks again, David

 

Ok.. this goes back to my question about bubbles in the coolant. If there is a gasket problem... either a faulty gasket or an improper install, you may get combustion gases into the coolant. If it's a fairly large leak this can produce bubbles, but a small leak may show as foggy or oily coolant. This coolant contamination may also just be the result of the assembly process, but in any case this is a new motor and it has a real problem, so I'd suggest you go see the builder and see if he will stand behind his work and find and fix the problem.

 

Thanks for all your time and knowledge. I'll talk to the shop this week. Have a great day, David