89' XJ blew hose, now runs ice cold

I did a search before writing this up, if there is a good link on this just let me know.

Yesterday my vacuum actuated valve for the heater core broke, the one with the three way splitter 6 inches from the plastic fill bottle. Truck got hot fast, pulled into my friends house 5 inutes away, steaming but not in the red zone on the gauge. Vatozone did not have the three way valve with the swedged fittings as I expected so I jigged up a hose to bypass the heater core. Now the hose from the head goes straight to the plastic bottle. I also plugged the upper heater core hose. I filled it with water, maybe less the 1/2 gallon and stopped as it filled up the bottle. I "did not burp the system" since I was only 7 miles from home. Drove home at 35 mph and the engine never got over 150 degrees. Outside temp today is 65 degrees. The bottle level was normal when I got home, truck was running fine.

First, I thought if you do not "burp" the closed loop system it would run hot.

I also have a thermostat that fails open, PO put it in.

Any ideas why it would never get above 150 degrees.

BTW, the truck runs great, gets good mileage and normally runs at a consistant 200 degrees. The only thing different is the change in the hose config above.

I do intend to rig up the three way again so I have heat, I am thinking that maybe something else happen causing the vacuum fitting hose to break.

Or maybe it's as simple as, burp and be done. Any ideas?

I run the fail safe thermostat as well. When my heater valve broke last month, I bypassed it to get home. The thermostat had stuck open after the truck overheated(it was brand new I might add). So I suggest you check it out.

Good input, I'll pull the thermostat and take a look at it.

I have seen numerous write ups concerning crazy thermostat results with various manufacturers.

Is there a good thermostat manufacturer that you or anyone else recommend?

OEM from the dealer or Stant SuperStat Premium. Whichever you chose, get ONLY 195degree.

I go through alot of the failsafe thermostats. They seem to fail often. But...better than failing shut. They are warrentied however. The one that failed during this incident, popped right back into place when pushed with my finger. I replaced it anyway. I guess if it was a big deal replacing them, I'd use something else.

bdahlg said:

OEM from the dealer or Stant SuperStat Premium. Whichever you chose, get ONLY 195degree.

Click to expand...

x2.

I'll put a new thermostat in this weekend and let y'all know the results. I'll build the heater 3 way hose assembly later, I need to figure out what parts I need to get especially the valve to get water to my heater core. I assume the dealer 3 way with the valve is expensive, if they still make it. I know all of the hoses are goofy sizes. More to come, thanks for the help.

So I put a new 195 thermostat in, burped the system and topped it off with 50/50. It now idles about 210. It runs a little cooler maybe 200 ish when I am on the road. Today it was 65 degrees. I assume I need to burp it again or the new thermo calibration is a little off. It did idle near 195 with the old thermostat in 80 degree weather. I'll get to the heater hose config at a later time.