Fhead Radiator Puking . . .

Gents-

Need some help/ideas on Percival. He's been puking out the radiator - at first I thought I had a bad radiator cap, but replacement didn't help. He'll heat up normally, and about when the thermostat seems to open, he's puking AF out the overflow. Then the temp gauge will climb to H.

Engine is new, no (obvious) signs of a headgasket leakage - no froth in oil, or oily anifreeze.

The radiator is also ~2 yrs old, but could it be plugged?

Thanks in advance-

Eck

 

sounds like you have a bad water pump to me. if you run it without water circulating, the water in the block will boil, so when the thermostat opens, excess pressure goes strait out the top. could be a blown head gasket, but i dont think so. check you plugs for any dampness.
to check pump, fill it full of water..turn it on and rev it up WITHOUT the cap and watch the liquid. if it moves down then back up, your pump is working. i doubt its the radiator, but it might be..had a radiator clog on an old ford p/u. but it was a 71 model and original radiator. if the radiator is new, i would deffinately focus on water pump and/or thermostat. pull the stat out and boil it. stick a thermometer in the water and when it reaches setpoint (160, 185, 200..whatever its rated for) it should be wide open. if its working, then pump. look at the bottom of the pump. if its the kind with the pee hole, see if there is any liquid coming out or if its damp.
just doesnt sound like water is circulating.
it only costs around $40 to rod out a radiator. might be worth it just for piece of mind if you dont see movement and you absolutely trust the waterpump.
git 'er done...=)

 

If you have an infrared thermometer, you can see what the difference between the upper and lower hoses are. IIRC, if it's more than 20° or so, then it could be the pump.

Also, I've heard of some instances where the hose would collapse and block off the system, then return to normal. Talk about confounding! See how "crush proof" your hoses are by giving them a good squeeze.

There was a good write up by Doc Vern in JP about a year ago about how to diagnose cooling issues. He took it step by step, and I could see that article saving someone a bunch of time and money. You may want to look through your back issues.....

 

never thought of the lower hose collapsing. thats good to know info.

 

"should" be a spring in it to prevent this from happening.

 

Thanks for all of the input. Between hunting yesterday, and my better half's "To Do" list, I didn't get a chance to fool with it this weekend. To answer a few questions (and generate more, I'm sure) Percival has had this problem now w/ 2 different engines!

My old motor ran pretty well, but puked oil from blowby. A friend (and damn good Jeep mechanic) put together a new engine for me that had been bored, etc. Different parts all around, so we didn't swap in the same bad water pump, or thermostat.

When the radiator gets "pressurized" it will pretty much empty it. The temp needle then runs WAY up.

When we first put the new motor in, we assumed at first a bad temp sender (we did swap that in from the old engine) or the temp gauge was bad until I checked the radiator, and found it was running way low - so the temp gauge wasn't lying.

I've put about 500 mi on the new engine and not retorqued the head bolts yet, but I don't think that is the problem - since I don't have any forth in the oil, or oily radiator. I do get a whiff of antifreeze once in awhile when I first fire him up, but given all that has been shooting out of the overflow pipe . . . not sure.

I did notice the other week when I had been barreling down the highway that the radiator was cool to the touch after stopping. The heater was putting out plenty of heat, so there was liquid somewhere, and the heater core was the defactor "radiator"

Not sure I answered any questions . . . but now you know as much as I do-

Thanks-

Eck

 

if everything is new and the only common thing Is the radiator, then that must be atleast one of the things wrong. lemme ponder this, and go do maintenance (i am at work).
more to follow.

 

There is some extensive discussion about this archived on the 3B site.

http://www.film.queensu.ca/cj3b/Tech/CoolingTips.html

I had a similar problem several years ago. Adding the bypass hose and drilling a 1/8" hole in the thermostat worked for me.

 

All-

Thanks for the info. The discussion on the 3B site was particularly edifying. I ended up solving (I think) the problem by drilling 2 small holes in the thermostat. I did notice when I pulled the thermostat that it appeared to be "stuck" closed. I had to work to break it loose the 1st time, and then exercise it a bit.

After drilling the thermostat, I fired the old guy up and drove him around the neighborhood to get him warmed up, and the temp gauge only went to about a needle width above the middle line, and stayed there. No more spewing from the overflow as well.