Before I Get the Head Milled (Overheating)

[maxbraketorque]

What radiator did you install? Spectra Premium has fixed hot running for some people.

If your t-stat is new, it should work fine, but it couldn't hurt to toss in another t-stat. They only cost $5.

The heater core circuit aids in continually exposing the t-stat to a significant volume of flowing engine coolant. This allows the t-stat to more rapidly sense the coolant temperature while the t-stat is still closed. If your heater core becomes clogged, your stat will not open until your engine gets hot enough to make the water in the vicinity of the t-stat higher than 195F. Other parts of the coolant in the motor may be much warmer by the time that happens.

 

[Anak]

To be clear, it boiled over when I had the burping funnel attached and had shut it off after burping it for 45 mins. During this burping event, it ran at 225. I have not replaced the rad cap and taken it for a spin since, because if it ran hot at idle with the hood open I anticipate it'll run hot once I get on the street.

Water boils at 212 at atmospheric pressure (sea level to be precise, IIRC). One of the functions of your radiator cap is to increase the pressure so that water will not boil until it reaches a higher temperature.

The fact that your motor runs at 225 idling in your driveway is not good, but the boiling over with the system open is to be expected at 225.

 

[Cruzberg61]

What radiator did you install? Spectra Premium has fixed hot running for some people.

If your t-stat is new, it should work fine, but it couldn't hurt to toss in another t-stat. They only cost $5.

The heater core circuit aids in continually exposing the t-stat to a significant volume of flowing engine coolant. This allows the t-stat to more rapidly sense the coolant temperature while the t-stat is still closed. If your heater core becomes clogged, your stat will not open until your engine gets hot enough to make the water in the vicinity of the t-stat higher than 195F. Other parts of the coolant in the motor may be much warmer by the time that happens.

Yep, new radiator is a Spectra. You might be on to something with the heater core. If I bypass the heater core and the overheating goes away, I suppose that would be one way to diagnose, right? Are there any other ways you know of? I should have mentioned that when it overheated I pulled over and cranked up the heater, but the air coming out did not feel very hot. After I flushed the system the heater works better, but still doesn't feel as hot as it used to.

 

[Cruzberg61]

Water boils at 212 at atmospheric pressure (sea level to be precise, IIRC). One of the functions of your radiator cap is to increase the pressure so that water will not boil until it reaches a higher temperature.

The fact that your motor runs at 225 idling in your driveway is not good, but the boiling over with the system open is to be expected at 225.

That makes sense. I also figured once I shut off the motor the coolant isn't being circulated or cooled either, so makes sense that the temp would keep climbing a bit until things cool down.

 

[Evan03]

Ive found it often takes buying a handfull of thermostats to get one that functions properly. Good thing theyre cheap.

Sent from my SM-G781U using Tapatalk

 

[Cruzberg61]

Ive found it often takes buying a handfull of thermostats to get one that functions properly. Good thing theyre cheap.

Sent from my SM-G781U using Tapatalk

Is there anyway to test? I've heard of dropping them in boiling water but I wouldn't want to overheat it and get it stuck open permanently.

 

[75SV1]

I'd also question what brand of T-Stat you installed. I'd lean towards Stant, and the Super Stant line. I do have a MotorRad in my 2000 XJ. I did have issues with some Hi-Flow ones. One I know was a Mr. Gasket. The other ????. One came apart. The Mr. Gasket came apart. The other stuck open. Not good in wintertime. I do have a box of Carrol's, all brass and some others.

 

[Cruzberg61]

Bit of an update: I went for some low hanging fruit by disconnecting the battery for a night, unscrewed the t-sensor a bit to get it further away from the housing, and went to replace the muffler, since I thought that's where the rattling was coming from. Come to find out, the rattling was actually coming from the cat. A big chunk of honeycomb had come loose and had rotated 90 degrees and was kind of shoved into the cat's outlet (where the exhaust would go into the muffler). While I wait for the new cat to arrive, does anyone have any idea if this could have been the cause of the overheating?

 

[RCP Phx]

Re-read post #11!

 

[Anak]

Yes.

 

[Cruzberg61]

Just to close the book on this, I did end up getting the head milled and replacing the head gasket. While I was in there I noticed that the T-stat was damaged (I guess I must have squished it when I redid the water pump?) and was opening very little. The machine shop said the head was def warped and that "it'd seen some heat." Anyway, with a new T-stat and the head back on with a heavy duty gasket, she's been running at or below 210 every since! Thanks for all the help!

 

[maxbraketorque]

Just to close the book on this, I did end up getting the head milled and replacing the head gasket. While I was in there I noticed that the T-stat was damaged (I guess I must have squished it when I redid the water pump?) and was opening very little. The machine shop said the head was def warped and that "it'd seen some heat." Anyway, with a new T-stat and the head back on with a heavy duty gasket, she's been running at or below 210 every since! Thanks for all the help!

Great.