350 hot!

[dempsy1]

Got this new longblock motor runs hot VERY quickly---failed on a block test--no water in oil or exhaust any ideas?

 

[nowajeepman]

Could be the thermostat.Is this a reman or rebuilt engine?

 

[SteelHeadz]

Head gasket or a hairline crack on the cylinder head.

 

[xjmarc]

Have you checked the timing. I know sounds dumb but just a thought.

 

[glenn beck]

engine hot...is the radiator hot or cool?

possible air lock try turning cab heater to hot air to allow air to move with out having to go past thermostate. if the motor is on a engine stand ensure the heater pipes are joined and not plugged

with a cool engine if you remove the cap and start do you see water movement. do you see smoke bubbles.

 

[HiHood]

Check for pinhole leaks in system. Check head gasket (even if it's new) and head for cracks. Usually a very small leak maybe between cylinders will do this and you won't see smoke or wtr in oil. Also make sure your thermostate is not bass ackwards, I know it sounds stupid but it's a common oversight.

 

[jps4jeep]

I agree with the air lock.
Cause could be a couple things..
-was the block hot dipped prior to machining and assembally? if not you could have a scale build up in a water jacket.
- do you have the right water pump?

Also..
- what are you running for a cooling fan?

 

[Ggg]

dempay1 specifically what do you mean by failed on a block test? Just trying to make sure I am on the right page before throwing out ideas.

 

[dempsy1]

Had a friend that is a little better w/ engines take a look at it for me Im not 100% sure but I thought it was checking the pressure in the engine, we are going to call the place I bought the engine from next week and try to get a replacement.

 

[Ggg]

Ok then if the block is not holding pressure then that eliminates all the ancillary stuff like water pump, radiator, etc. You either have a flawed block or a bad head gasket. Either way depending on miles and time since the rebuild I would contact the engine rebuilder.

 

[JumpinJackFlash]

All of these posted ideas are great and must be checked first...............

NOT saying this is what it is........but....one more thing to check.....I HAVE seen it where the piston to cylinder wall clearances on a remanufacturd engine where slightly to tight.

All it takes is a few thousands and the increased friction resulting when the motor is run causes a TON of heat. If you've exhausted all these other suggestions pull the plugs and turn the motor over with the appropriate tool on the crank pulley bolt. It should turn over fairly easily without causing a hernia.

Good Luck,

JJF