92 Turbo Supra taking a long time to warm up, possible cooling issue.

[carvener]

Before you say anything, I've already checked the oil for signs of clouding. There are none. The coolant level does not change. As for the problem...
Recently, I've noticed that it takes a long time for my car to warm up. The gauge sticks below C for at least 5 minutes before slowly creeping up. I am worried about this. Also, Occasionally, after extended periods of driving the car begins to slightly overheat, or the temp gauge creeps above the middle and approaches the H zone. This only happens when the RPM's drop or at idle, then will slowly revert to stress free temps once I'm traveling quickly again. When it does this, coolant is pushed into the overflow bottle, to the point it fills up. It used to be that my car would warm up within a mile of driving, now it's taking 3-4 miles of driving and has me worried. I have a feeling it might be the water pump going out, but I want to be sure before I go forking out the money for parts. No codes are showing up, and it hasn't been overheated, and the head gasket checks out on the pressure test.

It's also worth mentioning, that my heat suffers the same delay as my temp does, and also seems to blow at only 50% of the heat it normally should.

 

[Devin LeBlanc]

Did you try burping the cooling system? Any air in it?

 

[RazoE]

thermostat?

 

[super.secret.supra.club]

i just got over that same problem yesterday. if i was to post it, i would type the same thing you did. i found out my fan clutch was going out. rebuilt the fan clutch and now works fine again

GL

 

[carvener]

the t stat opens once it has reach a predetermined temp. only then will your needle go up since the sensor is on the cold side of the t stat.

as for your heating, i just got over that same problem yesterday. if i was to post it, i would type the same thing you did. i found out my fan clutch was going out. rebuilt the fan clutch and now works fine again

GL

I'll check out the fan clutch tomorrow and make sure there isn't any excess air hiding in the system. I will post an update.

 

[JonnyZ(Socal)]

I would check the t stat and the radiator cap!

 

[jetjock]

This only happens when the RPM's drop or at idle, then will slowly revert to stress free temps once I'm traveling quickly again.

As mentioned this indicates a fan clutch problem. Overtemp when slow is typically air flow related while overtemp at speed is typically coolant flow related.

 

[mkIIIman089]

the t stat opens once it has reach a predetermined temp. only then will your needle go up since the sensor is on the cold side of the t stat.

This is incorrect, the sensor is on the hot side of the thermostat and rises slowly with engine temp before the thermostat opens.

Agree with jj, sounds like a fan clutch issue. I was very happy with how much better mine was performing after I replaced the 22 year old original. Also could be a cooler/condenser that's jammed with foliage/bugs/road cruft.

Can't hurt to check the thermostat as well, encase it has become somehow stuck in a partially open position. If nothing else to rule out one more thing.

 

[stevenr816]

If your T Stat is stuck open it will take forever to heat up, and if your driving for along period of time without stop it may get hot cause it doesnt have time to cool down with it not closing. Takes 2 screws to take off, and probably the easiest besides thee radiator cap.

 

[Nick M]

It is the heater control unit that locks out coolant until there is some heat in the coolant.

 

[jetjock]

As Colin pointed out the stock gage sensor is on the engine side of the thermostat, as is the EFI sensor. And frankly, your other issues aside, 5 minutes for the needle to come off the peg doesn't seem overly long. Iirc mine would take at least that long even after I jumped on the highway from full cold.

 

[carvener]

Well, Since i just replaced the thermostat, i doubt it would be a situation where it was stuck open. However, I will go ahead with the replacement of the fan clutch, and the radiator cap since a lot of people are pointing toward that. Is there any way to remedy the heating issue without replacing the entire module?

 

[mkiiichip]

A bad fan clutch will not make the car warm up slowly.

 

[3p141592654]

Some people have reported new thermostats to be defective. I think jdub claims you need to test the new ones before installing. For me, I've never had a problem with a new one.

 

[super.secret.supra.club]

if your gonna buy a new fan clutch make sure its aisin brand or you get it from toyota. the ones autozone and kragen sells are junk. if you cannot afford to purchase a new one i suggest replacing the silicone inside your current clutch.

---------- Post added at 12:00 PM ---------- Previous post was at 11:59 AM ----------

corrected

 

[SideWinderGX]

Hate to bump a thread from the dead, but OP didn't post what ended up being the problem.

Carvener, care to follow up?

edit: shitballs, he hasn't logged in since January.