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First off I have a rebuilt 351C. It has hardly any miles on it since the built and everything is torqued to spec with ALL new gaskets and seals.
Here is what is happening: When the engine is at operating temperature you hear loud knocking sounds coming from the lower part of the engine, almost seems like it’s coming from the oil pan. Turn the engine off and the knocking will continue until the engine is cool. When you put your hand on the hose coming from the rad to the water pump, you feel it big time IN THERE. Like you can clearly tell it has something to do with that area.
Here is what is not happening: The engine does not overheat. It actually runs at perfect temperature despite this problem. I have a mechanical temp gauge installed to verify correct temp. There is no coolant in the oil or coming out the exhaust, so I assume that it’s not leaking anywhere inside the engine. Also there are no leaks.
Here is what I’ve done. I’ve ran the car for hours trying to let the air come out on it’s own. I’ve completely disconnected the heater core to isolate any trapped air to the engine to try and help burp it out (I don’t plan to reinstall it anytime soon because I don’t use the car in the cold anyways).
What do you guys think? Is it just air in the coolant system or is there a bigger problem here? I’m thinking about picking this up: http://www.ebay.com/bhp/spill-free-funnel
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Replies
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Wow this is a strange one. It sounds like your boiling/steaming in the block.
You can try the burping procedure. The spill free funnel is a good investment.
If you look into the radiator with the vehicle running do you see flow? What vehicle
are we working on?http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
You’re right it sounds a lot like boiling water trying to escape. I’m actually 99% confident that’s what it is but I was too tired to describe it that way in the morning.
There is indeed flow when I look inside the radiator. The weird thing is, and I want to just post it again is that there is no overheating at all. The temp gauge and sending unit is all new.
Forgot to add that I’m working on a 71 Mustang
[quote=”styrofoamnoise” post=134134]You’re right it sounds a lot like boiling water trying to escape. I’m actually 99% confident that’s what it is but I was too tired to describe it that way in the morning.
There is indeed flow when I look inside the radiator. The weird thing is, and I want to just post it again is that there is no overheating at all. The temp gauge and sending unit is all new.
Forgot to add that I’m working on a 71 Mustang[/quote]
Do you have coolant in the motor or just water? Did you bypass the heater core with a
loop of heater hose or cap it?I have premixed coolant. It’s what I used before the rebuild without any problems.
The heater core is bypassed with a loop.
[quote=”styrofoamnoise” post=134141]I have premixed coolant. It’s what I used before the rebuild without any problems.
The heater core is bypassed with a loop.[/quote]
What I was going to suggest was disconecting the upper rad hose and hold your
hand over the rad opening to plug it and stick a garden hose in the radiator and run the
car with the hose on to see if the boiling noise goes away. if it does its either air or flow.
But I don’t want you to waste coolant. Try the burping procedure first. water pump new or
the old one? T-sat installed? 2v or 4v clevland?2V, new T-sat, water pump is old. I wouldn’t have reinstalled it if it looked worn or damaged however that’s not to say something didn’t go wrong since. Is there anything that could really go wrong with those old water pumps? My 351W had the original factory one on it and it was fine that’s why I ended up reusing it.
[quote=”styrofoamnoise” post=134169]2V, new T-sat, water pump is old. I wouldn’t have reinstalled it if it looked worn or damaged however that’s not to say something didn’t go wrong since. Is there anything that could really go wrong with those old water pumps? My 351W had the original factory one on it and it was fine that’s why I ended up reusing it.[/quote]
The only thing that goes wrong with them is the impeller rots out or they leak.
I need a little clarification do you have the Cleveland or windsor motor? Your
opening post said 351 C and the last post said W? I just want to be on the same
page.My bad so I mentioned the Windsor because I had an original from the factory and the water pump on it still worked like a charm. Anyways, the motor I’m currently working on is a Cleveland.
Would there be any way to check if the impeller is rotted out? It was in good condition when I rebuilt it but stranger things have happened. I do have flow, but maybe it needs to be replaced? I don’t want to buy a new one and take the entire front end apart just to find out it’s good and then have to replace the seals.
Something else to consider is that the sensor for the temp is not in the place where the problem is. To be clear, if a head gasket is not placed correctly it can block coolant passages and cause a problem. Coolant will flow through the rest of the engine fine except on that cylinder head. I guess what I’m saying is that you might have a localized overheating issue OR trapped air as you suspect. The thing that sets off alarm bells here is that you just rebuilt it. If something didn’t go together correctly, that could be the cause of the problems you’re having. Anytime you have issues after a rebuild, it’s often something you did or didn’t do that causes the issue.
Good luck and please keep us posted on your progress.
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