Any suggestion would help a lot. Rebuilt m20 help

[Kevin_e30]

Hello members I have problem with my rebuilt m20, it has less then 20 miles. And the engine is overheating. The engine got a complete overhaul, the car has new water pump, fan clutch, heater core, coolant sensor, thermostat was from oreillys but am getting a oem instead.

Also members would the transmission overheat the car, it's a rebuilt transmission.

OVERHEATING OVERHEATING OVERHEATING OVERHEATING GO AWAY LOL

[mpowerful]

Cooling system could have a bubble in the block. Did you try rebleeding it?

[Kevin_e30]

I am gonna rebleed it, when I get the oem thermostat.

[jlevie]

If it is overheating, bleed it again now. Or don't drive the car until you get the new thermostat. Bleed by:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

[Kevin_e30]

I will let you what happens

If it is overheating, bleed it again now. Or don't drive the car until you get the new thermostat. Bleed by:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

[Kevin_e30]

It's not overheating anymore drove it. But I do have more question. The engine has less then 30 miles and it's idling rough. What should I do.

If it is overheating, bleed it again now. Or don't drive the car until you get the new thermostat. Bleed by:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

[SkiFree]

It depends on what went into your "rebuild". Rebuild constitutes new pistons/rockers/cam among other things.

What have you done as part of your break in procedure so far? check for vacuum leaks?

[jlevie]

After work on an engine, the first suspect when faced with a rough idle would be intake leaks. A smoke test will find any leaks.

[Kevin_e30]

Lol I haven't drive It much. But what can I do speed up to break in the engine. Can I lift the rear end of the ground and have it gear and give it gas ?

[Kevin_e30]

New on the engine

New piston rings
New main bearing
New rod bearings
New oil pump
New gaskets from bottom too top.
New timing belt n tensioner
Head rebuilt
New water pump
New fan clutch
Crank was cut

[jlevie]

Lol I haven't drive It much. But what can I do speed up to break in the engine. Can I lift the rear end of the ground and have it gear and give it gas ?

The best break in of the engine is to get it up to normal operating temperature and then run it at 2500rpm for 30 minutes. Best to do this with the car on jack stands so that you can check for leaks and to monitor head temperature and oil pressure during the run.

[Kevin_e30]

And it also has rebuilt transmission. I will try this method have you done it before or someone you know ?

[jlevie]

That is how we break in race engines. And I'm told this is also how motor cycle are broken in.

[Kevin_e30]

That is how we break in race engines. And I'm told this is also how motor cycle are broken in.

Thanks a lot will try this method.

[redlightpete]

Have you checked the valve clearances since you installed the motor? That could be the cause of your bad idle.