Jump to content

RPMs up...temp down??

Recommended Posts

First time it has run hot in MONTHS.


Today, I let it sit for about 5 minutes running....get back in and temp gauge reads 210. Shut it down for a little while and I notice that the tank (88 MJ) looks like it wants to burst and coolant is seaping out.


Start it back up, temp is normal, stop at a light and temp goes back to 210. Start to go and temp drops. Next light same thing, but at the light I upped the RPMs and temp dropped to normal.


It does have a new radiator with-in 8 months. When I got home I alsp replaced the bottle and cap..... I bought a new one a few months ago and did not replace yet b/c I had no issue since new radiator.


Cannot remember if there is a fan shroud.....


Thought it was weird that temp was normal at higher RPMs?????

Link to comment
Share on other sites

higher rpms will pull more air across the radiator.


210* is the normal operating temp for the 4.0L


Coolant should NOT be leaking out of a closed system. I would address that first. :thumbsup:


210, really! cool then..... mine has always been at 180.


I put new tank/bottle on and new cap, how much coolant should I ad? half full ? full?


Thanks fo all the help!!

Link to comment
Share on other sites

water pump??


MJ started running hot today..... was stopped at a light, temp was creeping up, but when I upped the RPMs, the temp dropped to normal.......


Thanks in advance

Fan clutch. Classic symptoms.


I put new tank/bottle on and new cap, how much coolant should I ad? half full ? full?

Half full when cold. It's a surge tank. The coolant expands when it gets hot. You NEED that air space for the expansion. If you fill it full when cold, you'll blow up the new tank.

Link to comment
Share on other sites

Might also have been a coincidence with the thermostat opening, allowing cooler coolant from the radiator into the engine. I can see the thermostat open and close just by watching the temp gauge go up and down. It will steadily climb to almost 210, then steadily drop to almost a full line below 210 before going back up.


I run a 195 degree thermostat, which I believe is the correct temperature for this engine.

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

  • Create New...