I did the search but couldn't find all the answers so here is the problem:


The engine overheats to the point of boiling over and dumping out the recovery/overflow tank.


I've got a 79 351M that has been stroked, with the help of Tmeyer and I installed a March serpentine system.


I have performed the following checks: Thermostat, 180 degree,(hat style),
New stock radiator flushed, Pulled the top hose off radiator and connected an extension hose then started the engine to see if the water pump was working properly.


What direction does the stock water pump turn?

 

The stock water pump turns clockwise as viewed from the front of the engine. A serpentine pulley arrangement often turns the pump counterclockwise. The pump will pump some water turning backwards but not as much as required.

What did the March kit say about water pump?

I checked March's website. The pump should have been included in the kit and turns clockwise. Is the belt tight enough?

I had overheating with my '77 400. The truck would puke green blood everywhere after 5 miles so of driving.

On yours, were the head gaskets installed so the word "front" is towards the front of the engine? One word would be facing up, the other bank would have it facing the block, but both words at the front of the engine.

Is the thermostat hat blocking the bypass (hole under the thermostat) when the engine is at operating temperature? I drove a short length of tubing into the hole to bridge the gap. I don't know if this helped.

My main problem turned out to be a huge pile of crap in the water jacket in the rear of the passenger side. After cleaning that out and reassembling, no more overheating.

Good Luck!!

R.

R.

 

I checked with Edelbrock and their water pump for the 351M is correct and turns clockwise. I just ran another test with the TS in and just water. Got up to 190 and boiled out over the overflow. I've got a blockage or the TS is the problem. NOTE: The top hose is hot and the bottom hose is cold.

 

Yes on the Head Gaskets. I think I found the problem. I removed the Thermostat and ran the temp. up to 145, shut it down and hand felt both hoses and they are the same temp. Now, How to fix this problem?

 

Do you have the right thermostat? I'm not sure what "hat style" means, but a thermostat for these engines has a bell-shaped (hat-shaped?) piece on the bottom. Is that what you have?

 

Yes, looks like a "top hat"

 

Perhaps you have a bad 'stat. Put it in a can of water and start heating it while watching the temp.

 

That was the first test I performed. The Stat opened at 180 degrees.

 

So, the 'stat opens at 180 and it overheats with it in. But it doesn't overheat when it is out? Is this idling or driving? If driving, what speed?

I've seen a bad head gasket cause an engine to blow coolant out when driving above about 45 MPH, but it would idle all day without doing so. And, I have a friend on the forum, Bruno2, that has an engine with a cracked block that kills head gaskets.

So, did you have your block Magnafluxed? Has it been badly overheated?

 

So remove the thermostat and put the engine through its paces. Go run some steep grades or else do the high speed in top gear to increase cylinder pressure and see that it isn't for sure a bad head gasket. If it does all these things right, get a different thermostat and it should be OK.

I put my 400 back together after having it apart for overheating, see earlier reply. Thermostat stuck closed right away and I had to replace it. Don't ask me why.

R.

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OK guys here is where I am now. Still overheating with the TS in so this is what I have done:

1.) Removed the radiator and flushed both ways and got rusty water, I think it is coming from the block.

2.) Removed the water pump to check for problems - non found.

3.) Checked the water passage openings in the block - clear

4.) Removed the heater hoses and upper radiator hose, housing and thermostat

4.) Ran a garden hose into the block water passage openings (see attached picture)

5.) When the hose was inserted into the lower right passage I had water come out of the upper thermostat housing and the heater outlet on the block ONLY.

6.) When the hose was inserted in the lower left passage water did not come out of any passage other then the lower left passage.

This would tell me that the left water passage is blocked. Is this correct?

After contacting a Professional engine builder he suggested: I remove the thermostat, remove the radiator cap, start the engine, watch to make sure I had enough water and not air trapped in the system.





NOTE: The Professional engine builder is the person that rebuilt the engine.

 

FOUND the problem. The "professional" engine builder put the gasket on incorrectly blocking the water opening on the front of the block into the head No water was circulating thru the right head. The left head is on correctly.

 

Wow! All of that because a pro built the engine wrong. Glad you found it.

 

This is why I don't let other people build my stuff... lol


Glad you found that before catastrophe ensued!!

 

Well you found a common problem but you got it backwards.

The hole on the front of the engine is blocked, otherwise coolant short-circuits on that bank. And water flow around the back cylinder is nonexistent.

EACH GASKET is clearly marked "front" and that word goes towards the radiator. Problem is, on one head it faces up and on one it faces down, IIRC. Many builders who don't know, think that the word "front" should be visible. That's wrong.

R.