HELP Cooling Problem

[hebertracing]

ok i am really stumped right now. ive just put my 3rd motor in my xj.

my 2nd motor only lasted 2 days due to a cooling issue.

heres the problem. the coolant is full and i just replaced my thermostat, water pump, both upper and lower coolant hoses, and all hose clamps on heater core lines. the guy i purchased my xj from showed me a receipt for a new radiator, and it appears it is new also.

the coolant keeps getting pushed back into my coolant reserve tank. both upper and lower coolant lines feel like theres a throbbing, as well as you can feel it in the radiator cap. the upper coolant line has little to no coolant flowing through it. the radiator also is stone cold. the system is not leaking anyhwere and i do not know where to start now. any suggestions

thanks ahead, and sorry if theres something already posted on here. is preetty big lol

 

[solomon7]

Year???
2 styles of cooling were used.

Also have you replaced the cap? 16lbs right?

 

[ktwalker01]

does the coolant go right into the overflow tank right when you start it? if so sounds like a blown head gasket.

 

[ParadiseXJ]

Where are you sourcing the motors? Are they new/rebuilt? Are you rebuilding them? Are they junkyard engnes? Same year? Same year as the radiator? Same year as the cooling system? Tell us what you are working with.

The extra info really does make a difference. Somthing is way FdUp

 

[birchlakeXJ]

Yes, supply details on your XJ and donor engine. Did the engine run fine before you installed it? The more information you give us, the better the replies will be.

I'd double check the application part number for the water pump to be sure you have correct rotation.

 

[hebertracing]

used motor put it in a 96 cherokee, appears to be a 97 wrangler motor.

yes i replaced my cap. it is a 16lb as well.

also i installed a chevy 350 thermostat today and i did not see much results. i was hoping this would correct any air behind the thermostat being this one had a bleeder in it, and my stant crap one didnt. i will be purchasing a new one from chrylser tomorrow to ensure that is not causing any issues.

not sure how the motor ran before, for it was already out from the donor. i know it has 110k on it, and potentially was neglected due to the shape the old plugs were in, as well as i just did an oil change, 4 miles ago and the oils blacker than black.

i have gone through every single clamp and fitting to ensure they are sealed with 0% chance of air leaking through it.

do wranglers from 97 have much different cooling than a 96 cherokee?

and finally, the truck runs great sitting in the parking lot. gets up and down from temp fine. it ONLY does this while driving it. it seems like as soon as the thermostat opens fully the coolant goes directly into the resevior tank.

thank you so much for your help guys.

 

[hebertracing]

also may i add, it appears my cooling issue on my 2nd motor was due to a defective rad hose and a bad cap. the 1st motor had NO cooling issues, and the 2nd was perfect until the hose and cap went bad.

 

[ChiXJeff]

Wait a minute, a *WRANGLER* motor? Check the water pump, IIRC, for a 96 XJ motor, you need a reverse rotation water pump impeller, it's driven backwards compared to a Wrangler.

 

[hebertracing]

yes thermostat and waterpump are same except pulley designs are different. same flow tho.

 

[ParadiseXJ]

So, you have a Chevy thermostat (temp?) and a XJ water pump with a Wrangler pulley on an XJ 4.0?

How different are the pulley designs? If the pulley is ribbed, it's a forward flow, if the the pulley is smooth it's a reverse flow because of the belt routing. I don't mean to question your methods, but you are doing something wrong there. It can't be just coincidental that you've been thru 3 motors, unless of course you're buying already broken motors.

 

[hebertracing]

no i installed the xj pump on this motor. it is NOT a wrangler pump. and yes paradiseXJ the 2nd motor i purchased was already bad, with 249k on it. i just made it really bad and snapped a connecting rod. the chevy thermostat is only to ensure its not airbound behind the thermostat due to lack of a bleeder on the aftermarket ones.

 

[hebertracing]

found the problem. its a bad headgasket, not leaking into the cylinders which is why it passed compression tests, as well as its not leaking into the oil. simply blowing directly out of the head and block. put a little stop leak in for a temporary fix.

thank you so much