I also posted this on the 351m forum


I just fired up rebuilt 1979 351m. Looks great,sounds good. Here is my problem. When I increase the RPM's the lower Rad hose collapses. I think I might have a bigger problem than that. I was reading and I am afraid that I put the pass side headgasket on backwards. The temp guage stays in the middle,but the eng seems hot. I also hear strange sounds coming from the passanger side of the eng,Sounds like boiling cracking sounds. The overflow tank fills at low idle and empty's when I increase rpm! Can anyone help! My gallery tells you what I did. Thanks Art

 

The lower radiator hose needs a spring in there to prevent colapsing.

 

If you think you put the gasket on backwards you will want to fix it. Yeah, it'll be a pain but it's better than having it go out miles from nowhere, and the having to fix it anyway.

 

If you DID put the head gasquet on wrong, it will cook the head, burn the valves, and will break at the worst possible time. The coolant flow is metered by holes in the head gasket. Take a look, and you will see that the holes in the water passages are different sizes, from front to rear. This allows even flow, given the distance from the water pump that the coolant has to travel. If you put the gasket on wrong, it will not keep the head evenly cooled and may cause cracking.
If you want to check, get one of those thermometers you aim at the target, and compare temps from side to side and cylinder to cylinder. It wil tell you real quick if you have uneven cooling/heating. Crackling sounds are not normal, and scare the beans out of me... If it can boil liquid, under pressure, coated with coolant, causing a crackling sound, it is REALLY HOT.
My 2 pennies.

tom

 

Thanks! I got a Rayteck temp gun I will try tonight. Something is not right with the flow. The flow is quite simple through the eng. I am willing to bet I have the head gasket on wrong. I have a new Felpro headgasket and a new header Gasket. I think for piece of mind I will pull the head anyway! Thanks Art

 

Ok Here is what I found. Compared Temp of both heads from inital start to 10 min run. Both heads same temp on start. After 10 min of runing a 50 to 75 degree difference between heads. Pass side higher! Well I guess I know what I will be doing this weekend. Thanks Art:-(

 

Might wanna check that head for warpage while it's off. High overheating, even for a short while, can warp them. Just use a known good straight edge and lay it across the length of the head surface from a front corner to the opposite back corner. Don't push down too hard cause even a straight edge can flex. Measure for any gap at the middle with a feeler gauge. I believe the allowable gap is about .002 but you can look it up. If it exceeds the measurement, you might want to have it resurfaced just enough to make it flat. I like the Fel-Pro Torque Once head gaskets. They actually seem to work!

 

I might ahve posted this to late to help, but here it goes. Your system sounds like it needs to be burped. With the engine cold remove the radiator cap and let it warm up to operational tempetature. When its warm turn the blower fan on high and set the temp control to the high side also. Have someone rev the engine and watch the water flow in the radiator. You will probably see bubbles coming threw the system. That is the air that was trapped in the heater core. keep reving the engine between idel and 3000 rpms until you no longer see the bubbles (you'll probably notice a large drop in the amount of water in the radiator too). Refill the system and cap it off and you should be good to go.

BTW if were leaking water into one side of the engine there are a few things you should have noticed. First, steam coming out of the exhaust. Second is water in the oil or, third, an oil flim in the radiator. Fourth the side is sucking water would actually run cooler then the other side. Fifth by pulling the plugs you would see them look completely different then the other bank. Sixth it is not uncommon at all to see just a 50* temperature differental between one bank and the other. If you dont have a perfectly ballanced carb or FI one side will always be a litte leaner and thus a little warmer then the other.

It sounds like to me you just have air trapped in the cooling system.

 

Thanks for the reply. I found the problem. It was a backwards head gasket. I took it down this weekend and there it was! The main passage way was blocked from the block. I had the front on the back. Put new head gasket on and all is fine. Thanks Again Art