Jump to content

No heat STILL! Gauge not going above 155


Recommended Posts

  • Replies 91
  • Created
  • Last Reply

Top Posters In This Topic

I'm not 100% sure, but does the 88 MJ have the same vacuum actuated heater core valve as my 90?

 

Mine was not giving any heat last winter, and I discovered that the valve that opens for the hot coolant to flow in to the heater core was not operating properly. I ended up manually opening it and leaving it there. It gets a bit warmer in the cab in the summer, but I'll never have to worry about not getting heat when I need it.

Link to comment
Share on other sites

  • 4 weeks later...

Your heater core is plugged up with scale... Yet another good reason to dump the pressurized plastic bottle system. :ack:

 

You need to flush out your heater core. I was amazed at the amount of crud that came out.

 

When I converted to open cooling, I removed all that mess and ran 5/8 hoses direct from the water outlet to the heater core (Just like its setup in my 08 KK) and capped the vac line. Just two 5/8 rubber hoses now, and ALOT less sources of potential problems.

 

IMO better to have coolant circulating through the heater core rather than sitting there half the year every year.

 

Use distilled water for refill of course.

 

Hope that helps

Link to comment
Share on other sites

what you need to do is start it and run it YES I KNOW IT leaks but it has to get warm THEN titen it up not to much it will break. and its not the heator core its your little heater sensor on the right side inside the cab under the dash. it has little springs and when it gets to hot it reduces the amount of heat thus you have no heat when its full blast its low right . the little sensor is behind the heator fan but to take it out its inside the cab :yes:

Link to comment
Share on other sites

and its not the heator core its your little heater sensor on the right side inside the cab under the dash. it has little springs and when it gets to hot it reduces the amount of heat thus you have no heat when its full blast its low right . the little sensor is behind the heator fan but to take it out its inside the cab :yes:

:huh???:

 

There are no sensors for the heating system inside the cab. The only thing I can think of from the way you are describing it is the resistor pack that controls the speed of the fan. There are no sensors there, and the resistors ONLY affect fan speed, they have nothing at all to do with how much heat the heater core can transfer.

 

If the thermostat housing leaks after sitting for twelve hours, either you didn't get all the old sealant and gasket material off one of the surfaces, or the flange of the thermostat slipped out of the recess and got between the housing and the head. If that happened and you try to tighten it, you'll crack the head. Better would be to remove it, clean both surfaces, and reinstall. If you can save the gasket, reuse it if you don't have a new one. Otherwise, just use RTV.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share


×
×
  • Create New...