5.7 Overheating

[Darcher99]

Ok. Coming back to the knowledge pool. Put a new long block in. Got it to start and running. Now, it overheats at idle. I believe that there may be a small exhaust leak...would that cause it to run hot? I am fairly new to this. I just need to know if I should be looking for a new thermostat, or just tighten up the exhaust.

 

[Bondo]

Ayuh,..... Is the drive on it,..??

You are supplin' water to it, Right,..?? How,..??

 

[Darcher99]

Ayuh,..... Is the drive on it,..??

You are supplin' water to it, Right,..?? How,..??

Yep. Outdrive is on and Im putting water to it via earmuffs.

 

[flashback]

You have a new motor but no mention of peripheral parts. How old are the exhaust?

 

[Darcher99]

You have a new motor but no mention of peripheral parts. How old are the exhaust?

I’m going to assume original. The motor that had these manifold on it had no overheating issues however.

 

[Bondo]

Yep. Outdrive is on and Im putting water to it via earmuffs.

Ayuh,..... Pull the in-comin' hose off the t-stat housin', 'n run it for a few seconds,....
You should have a massive water flow outa the hose,....

If not, work yer way back to the drives impeller,....

If so, is there water in the block,..??
Is there flow outa the hoses to the manifolds/ risers,..??

 

[Darcher99]

Water in the block? What do you mean? It's newly rebuilt engine. I hope there's no water in the block. Ha Ha.

 

[flashback]

Assuming has bitten me more than once. How old are they?

 

[Bondo]

Water in the block? What do you mean? It's newly rebuilt engine. I hope there's no water in the block. Ha Ha.

Ayuh,..... Pull a drain plug, 'n check if there's water in the block,.....

 

[flashback]

My hope is that you find water in the block. HAHA
It just has to be in the proper place!

 

[QBhoy]

What outdrive is she attached to ? Presumably it has suitable cooling set up ?

 

[flashback]

Where is your small exhaust leak?

 

[Darcher99]

Ayuh,..... Pull the in-comin' hose off the t-stat housin', 'n run it for a few seconds,....
You should have a massive water flow outa the hose,....

If not, work yer way back to the drives impeller,....

If so, is there water in the block,..??
Is there flow outa the hoses to the manifolds/ risers,..??

Just pulled the intake hose to the thermostat hosing and there is no water. Smh. Which is confusing, because everything was working before I put it back on the boat after the engine swap.

 

[Darcher99]

What outdrive is she attached to ? Presumably it has suitable cooling set up ?

It's an alpha 1.

 

[flashback]

Just pulled the intake hose to the thermostat hosing and there is no water. Smh. Which is confusing, because everything was working before I put it back on the boat after the engine swap.

Flush the intake and replace the impeller before you cook your new engine.

 

[tank1949]

at idle and muffs on with water ON from spigot, disconnect hoses, one at a time, from exhaust manifolds. You should get sprayed with water. If not, examine water pump in lower unit and the tube that goes to upper unit. But, if you have plenty of water, your thermostat may be defective. Remove stat and see if temperature goes down. If so, replace stat. You may want to purchase an inexpensive inferred temperature tester from Harbor Freight

 

[Darcher99]

at idle and muffs on with water ON from spigot, disconnect hoses, one at a time, from exhaust manifolds. You should get sprayed with water. If not, examine water pump in lower unit and the tube that goes to upper unit. But, if you have plenty of water, your thermostat may be defective. Remove stat and see if temperature goes down. If so, replace stat. You may want to purchase an inexpensive inferred temperature tester from Harbor Freight

ok, I took the inlet hose to the thermostat hosing and it didn't spray me. I don't think Im getting water to the thermostat.

 

[Darcher99]

The other thing that is really confusing me too is....I am getting water out of the exhaust on the outdrive. How is this happening.

 

[QBhoy]

Is there a power steering cooler

The other thing that is really confusing me too is....I am getting water out of the exhaust on the outdrive. How is this happening.

is it coming out the prop and or the transom shield ? Have you got the intake hose on right side of thermostat

 

[Bondo]

ok, I took the inlet hose to the thermostat hosing and it didn't spray me. I don't think Im getting water to the thermostat.

Ayuh,..... Pull the drive, 'n rebuild the raw water pump,......

Back-flush the system, by hookin' yer garden hose, to the hose ya pulled off the t-stat housin',....
While the drive is off,....

I am getting water out of the exhaust on the outdrive. How is this happening.

The entire inside of the drive housin' is Wet,.....
Could be the pipe from the pump is misaligned,.....

Pull the drive, 'n split it to find yer issue,....